WorldWideScience

Sample records for arid zones

  1. Potential of arid zone vegetation as a source of substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bassham, J.A.

    1977-11-01

    Three aspects of the potential of vegetation in arid zones as a source of substrates are discussed. The first includes the limitations on efficiency of conversion of solar energy to the stored chemical energy of biomass in green plants, and the subsequent biochemical pathways of carbon dioxide fixation and biosynthesis. Second is the potential of plants endogenous to arid zones. Finally, the use of covered agriculture or controlled environmental agriculture (CEA) is considered both in its present form and in terms of possible extenion to the large scale production of stable crops. (JGB)

  2. Review of several problems on the study of eco-hydrological processes in arid zones

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ecosystem degradation is a common and cardinal environmental problem in arid zones. The change in the eco-hydrological processes is the basic cause responsible for such a problem. The study on the eco-hydrological processes in arid zones has become a forefront and focus of the eco-environmental research. Recent studies on eco-hydrological processes in arid zones show that the primary vegetation pattern and its eco-hydrological effect are of the most stable state of the ecosystem in arid zones. Special water absorption ways of plants in arid zones and the hydraulic lift and reverse hydraulic lift functions of some plants are the key mechanisms to maintain the stability of the ecosystem in arid zones. In the case of water shortage, ensuring ecological water requirement and maintaining proper ecological ground- water table are the prerequisite to keep healthful operation of the ecosystem in arid zones. The paper reviews some advances in the study of eco-hydrological processes in arid zones. It puts forward the concepts of critical ecological water requirement, optimal ecological water requirement and saturated ecological water requirement, and discusses their determination methods. It also emphasizes that the studies on natural vegetation pattern and eco-hydrological effect, on plants with hydraulic lift function, on water sources for plant absorption, on ecological water requirement and ecological groundwater table for different plant species should be strengthened to determine the species composition and pattern suitable for the restoration and reestablishment of vegetation in different arid zones in China.

  3. Dairy Heifer Rearing in Hot Arid Zone: An Economic Assessment

    Directory of Open Access Journals (Sweden)

    M. A. Razzaque

    2010-01-01

    Full Text Available Problem statement: Economic losses due to high mortality in young calves born in hot arid zone including Kuwait and a high cost of rearing are the main constraints to this region. Therefore, dairy producers have to depend on importation of pregnant heifers for herd replacement. Research data on cost of heifer rearing from their weaning to first lactation were lacking. The objectives of the present investigation were to compare the costs/benefits of raising heifers born in Kuwait without and with intervention measures and project the future financial benefits. Approach: Present study methods involved using cost-benefit model where without and with intervention scenarios were compared using a total of 58 herd parameters. These variables included in the spreadsheets in the model could be varied during each year of projection period. Production turnoff of 3 herds each of 245 cows in three scenarios namely baseline, improved and future were evaluated. Input costs of imported heifers (baseline, locally raised heifers with interventions (improved and projected 10 year (future and the income generated from these scenarios were analyzed. Results: Total income generated from baseline, improved and the future projection were KD 268,715/-, 281,246/-and 342,251/-respectively (1 KD Kuwaiti Dinar = US $3.45; total operating costs of these scenarios were KD 249,372/-, 242,276/-and 205,929/-respectively. Financial analyses showed that benefits were double when interventions were applied KD 19,343/-Vs KD 38,970/-in baseline and improved operation respectively. Conclusion: Fifty percent of the total heifers needed for herd replacement could be sourced locally showing an increased net income as an outcome of intervention measures. Locally born adapted heifers could be used for dairying in this hot arid zone with a phase-wise increase in their herd size reducing dependence on imported dairy cattle.

  4. Torpor and basking in a small arid zone marsupial

    Science.gov (United States)

    Warnecke, Lisa; Turner, James M.; Geiser, Fritz

    2008-01-01

    The high energetic cost associated with endothermic rewarming from torpor is widely seen as a major disadvantage of torpor. We tested the hypothesis that small arid zone marsupials, which have limited access to energy in the form of food but ample access to solar radiation, employ basking to facilitate arousal from torpor and reduce the costs of rewarming. We investigated torpor patterns and basking behaviour in free-ranging fat-tailed dunnarts Sminthopsis crassicaudata (10 g) in autumn and winter using small, internal temperature-sensitive transmitters. Torpid animals emerged from their resting sites in cracking soil at ˜1000 h with body temperatures as low as 14.6°C and positioned themselves in the sun throughout the rewarming process. On average, torpor duration in autumn was shorter, and basking was less pronounced in autumn than in winter. These are the first observations of basking during rewarming in S. crassicaudata and only the second direct evidence of basking in a torpid mammal for the reduction of energetic costs during arousal from torpor and normothermia. Our findings suggest that although overlooked in the past, basking may be widely distributed amongst heterothermic mammals. Therefore, the energetic benefits from torpor use in wild animals may currently be underestimated.

  5. Rainwater harvesting in arid and semi-arid zones (repr. 1997)

    NARCIS (Netherlands)

    Boers, Th.M.

    1994-01-01

    In arid and semi-arid regions, the scarcity of water can be alleviated by rainwater harvesting, which is defined as a method of inducing, collecting, storing, and conserving local surface runoff for agriculture. Rainwater harvesting can be applied with different systems, and this dissertation deals

  6. Characteristics and laws of MODS coupling relation in arid zone under global change

    Institute of Scientific and Technical Information of China (English)

    WANG Ranghui; ZHANG Huizhi; HUANG Qing

    2006-01-01

    Global change has influenced the distribution pattern and spatio-temporal changes of resources in arid zone, and has restrained the land use and land cover change, which is shown by water-heat state, landscape structure, climate effect, and human activities. The above-mentioned characteristics have a close coupling relation with the mountain-oasisdesert system (MODS). The climate in Central Asia arid zone is warm and wet, which is different from that in northern China which takes a tendency of aridity, and the mechanism has restricted the characteristics and laws of MODS. Systematic interface characteristics and process, especially the formation,transformation and consumption laws of water resource reflect directly MODS's response to global change in arid zone. Spatio-temporal pattern, dynamic change, scale change and coupling mode of MODS reflect the ecology mechanism between the systems and within the systems.

  7. Ecological condition of central Australian arid-zone rivers.

    Science.gov (United States)

    Choy, S C; Thomson, C B; Marshall, J C

    2002-01-01

    Australian arid-zone rivers are known to be ecologically variable and go through "boom and bust" cycles based on highly variable and unpredictable flow regimes. They are facing increasing pressure from land and water resources development and, whilst they are considered to be still in relatively good condition, no studies have yet been carried out to verify this. Such baseline studies are crucial if we are to assess any ecological changes in response to development and management interventions. The ecological condition of four of these endorheic rivers (Georgina, Diamantina, Cooper-Thomson and Bulloo) flowing into the Lake Eyre and Bulloo Basins in central Australia was assessed using several criteria (level of human influence, habitat condition, water chemistry and aquatic macroinvertebrate composition). Using criteria based on the level of human influence, most of the sites were assessed to be relatively unimpacted (reference) condition. The most discernible and widespread impact was riparian and bank damage by stock access. However, the level of this impact was considered to be only moderate. Most aquatic macroinvertebrates found in the area are considered to be opportunistic and tolerant of a wide range of environmental conditions, but with their life histories known to be linked to flow conditions. Their trophic guild was dominated by collectors and predators. The AusRivAS modelled observed to expected values of macroinvertebrate composition indicated that there were differences in ecological condition between sites (e.g. different waterholes) and between times (e.g. seasons and years). Overall, 75% of sites were assessed to be good condition with the remainder being mildly impaired. Water chemistry of the sites was characterised by high spatial and temporal variability with low conductivity and alkaline pH, relatively high turbidity, total nitrogen and total phosphorus, and wide-ranging dissolved oxygen. Given the high variability in water quality and

  8. Rainwater harvesting in arid and semi-arid zones (repr. 1997)

    OpenAIRE

    Boers, Th.M.

    1994-01-01

    In arid and semi-arid regions, the scarcity of water can be alleviated by rainwater harvesting, which is defined as a method of inducing, collecting, storing, and conserving local surface runoff for agriculture. Rainwater harvesting can be applied with different systems, and this dissertation deals with the system of micro-catchments. A microcatchment consists of a runoff area and a basin area in which a tree is planted. The purpose of this study was to develop a design procedure for micro-ca...

  9. Sensitivity of Vadose Zone Water Fluxes to Climate Shifts in Arid Settings

    Energy Technology Data Exchange (ETDEWEB)

    Pfletschinger, H. [Federal Waterways Engineering and Research Inst. (BAW), Karlsruhe (Germany); Technical Univ. of Darmstadt (Germany). Inst. of Applied Geosciences; Prömmel, K. [Freie Univ., Berlin (Germany); Schüth, C. [Technical Univ. of Darmstadt (Germany). Inst. of Applied Geosciences; Herbst, M. [Agrosphere (IBG-3), Julich (Germany); Engelhardt, I. [Technical Univ. of Darmstadt (Germany). Inst. of Applied Geosciences; Agrosphere (IBG-3), Julich (Germany)

    2014-01-01

    Vadose zone water fluxes in arid settings are investigated regarding their sensitivity to hydraulic soil parameters and meteorological data. The study is based on the inverse modeling of highly defined soil column experiments and subsequent scenario modeling comparing different climate projections for a defined arid region. In arid regions, groundwater resources are prone to depletion due to excessive water use and little recharge potential. Especially in sand dune areas, groundwater recharge is highly dependent on vadose zone properties and corresponding water fluxes. Nevertheless, vadose zone water fluxes under arid conditions are hard to determine owing to, among other reasons, deep vadose zones with generally low fluxes and only sporadic high infiltration events. In this study, we present an inverse model of infiltration experiments accounting for variable saturated nonisothermal water fluxes to estimate effective hydraulic and thermal parameters of dune sands. A subsequent scenario modeling links the results of the inverse model with projections of a global climate model until 2100. The scenario modeling clearly showed the high dependency of groundwater recharge on precipitation amounts and intensities, whereas temperature increases are only of minor importance for deep infiltration. However, simulated precipitation rates are still affected by high uncertainties in the response to the hydrological input data of the climate model. Thus, higher certainty in the prediction of precipitation pattern is a major future goal for climate modeling to constrain future groundwater management strategies in arid regions.

  10. Arid-zone groundwater recharge and palaeorecharge: insights from the radioisotope chlorine-36

    International Nuclear Information System (INIS)

    AGSO's collaborative 'Western water' study of groundwater resources in Aboriginal lands in the southwest Northern Territory arid zone, has applied the radioisotope 36CI and 14C to investigate the sustainability of community water supplies drawn from shallow aquifers in the Papunya-Kintore-Yuendumu area. The 36CI results have important implications for groundwater management throughout the arid zone, because substantial recharge occurs only during favourable, wet, interglacial climatic regimes. this has important implications for groundwater management in this area and elsewhere in central Australia, where most of the community water supplies depend on 'old' stored groundwater

  11. A Reservoir of Natural Perchlorate in Unsaturated Zones of Arid and Semi-Arid Regions, Southwestern USA

    Science.gov (United States)

    Rao, B. A.; Stonestrom, D. A.; Anderson, T. A.; Orris, G. J.; Rajagapolan, S.; Sandvig, R. M.; Scanlon, B. R.; Walvoord, M. A.; Jackson, W.

    2006-12-01

    Natural perchlorate (ClO4-) is generally present in unsaturated zones of steppe-to-desert regions of the arid and semi-arid southwestern United States. The perchlorate is associated with atmospherically deposited chloride that has accumulated throughout the Holocene. To assess this natural reservoir, we analyzed unsaturated-zone profiles from ten sites across Nevada, New Mexico, Texas, and Utah for perchlorate and other anions. The sampled sites represent a wide range of precipitation (0.1 0.5 m yr-1), dominant vegetation, soil type, underlying geology, and include five distinct ecological regions: Chihuahuan, Mojave, and southern Great Basin deserts; Arizona-New Mexico semi-desert; and Texas High Plains dry steppe. Concentrations of perchlorate correlated closely with chloride and bromide. The perchlorate reservoir (up to 1 kg ha-1) is sufficiently large to impact groundwater when natural recharge during pluvial periods or induced recharge after conversion to agriculture flushes accumulated salts from the unsaturated zone. This little explored source can explain perchlorate in milk and other agricultural products far from anthropogenic contamination, and should be considered when evaluating overall exposure risk.

  12. Water sources accessed by arid zone riparian trees in highly saline environments, Australia.

    Science.gov (United States)

    Costelloe, Justin F; Payne, Emily; Woodrow, Ian E; Irvine, Elizabeth C; Western, Andrew W; Leaney, Fred W

    2008-05-01

    The flow regimes of arid zone rivers are often highly variable, and shallow groundwater in the alluvial aquifers can be very saline, thus constraining the availability and quality of the major water sources available to riparian trees-soil water, shallow groundwater and stream water. We have identified water sources and strategies used by riparian trees in more highly saline and arid conditions than previously studied for riparian trees of arid zone rivers. Our research focused on the riparian species Eucalyptus coolabah, one of the major riparian trees of ephemeral arid zone rivers in Australia. The water sources available to this riparian tree were examined using delta(18)O isotope data from xylem, soil water, groundwater and surface water. Additionally, soil chloride and matric potential data were used to infer zones of water availability for root uptake. Despite the saline conditions, the trees used a mixture of soil water and groundwater sources, but they did not use surface water directly. The study identified three strategies used to cope with typically high groundwater and soil water salinities. Firstly, the trees preferentially grow in zones of most frequent flushing by infiltrating streamflow, such as the bank-tops of channels. Secondly, the trees limit water use by having low transpiration rates. Thirdly, the trees are able to extract water at very low osmotic potentials, with water uptake continuing at chloride concentrations of at least 20,000-30,000 mg L(-1). PMID:18270743

  13. The ecohydrology of the soil-vegetation system restoration in arid zones: a review

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Arid zones, which cover approximately 40 percent of the earth’s land surface, support complicated and widely varied ecological systems. As such, arid zones are an important composition of the global terrestrial ecosystem, and water is the key and abiotic lim-ited factor in ecosystem-driven processes in these areas. Ecohydrology is a new cross discipline that provides, in an objective and comprehensive manner, novel ideas and approaches to the evaluation of the interaction and feedback mechanisms involved in the soil-vegetation systems in arid zones. In addition, ecohydrology provides a theoretical basis of ecological restoration that is cen-tered on vegetation construction. In this paper, long-term monitoring and local observations in the transitional belt between a de-sertified steppe and a steppified desert at the Shapotou Desert Research and Experiment Station, Tengger Desert, in northern China, were evaluated. The primary achievements and related research progress regarding ecohydrology in arid zones were analyzed and summarized, as a keystone, and the response of soil ecohydrological processes to the changes in the species composition, structure, and function of sandland vegetation was discussed. Meanwhile, the long-term ecological effects and mechanism of regulation of vegetation on soil habitat and on water-cycling were considered. As a vital participant in the ecohydrological processes of soil-vegetation systems, the studies on biological soil crusts was also summarized, and related theoretical models of restoration based on the water balance was reviewed.

  14. Hydrogeologic characterization of an arid zone Radioactive Waste Management Site

    International Nuclear Information System (INIS)

    An in-depth subsurface site characterization and monitoring program for the soil water migration pathway has been planned, implemented, and completed to satisfy data requirements for a waiver from groundwater monitoring, for an exemption from liner leachate collections systems, and for different regulatory driven performance assessments. A traditional scientific approach has been taken to focus characterization and monitoring efforts. This involved developing a conceptual model of the hydrogeologic system and defining and testing hypotheses about this model. Specific hypotheses tested included: that the system was hydrologically heterogenous and anisotropic, and that recharge was very low or negligible. Mineralogical, physical, and hydrologic data collected to test hypotheses has shown the hydrologic system to be remarkably homogenous and isotropic rather than heterogenous and anisotropic. Both hydrodynamic and environmental tracer approaches for estimating recharge have led to the conclusion that recharge from the Area 5 RWMS is not occurring in the upper region of the vadose zone, and that recharge at depth is extremely small or negligible. This demonstration of ''no migration of hazardous constituents to the water table satisfies a key requirement for both the groundwater monitoring waiver and the exemption from liner leachate collection systems. Data obtained from testing hypotheses concerning the soil water migration pathway have been used to refine the conceptual model of the hydrogeologic system of the site. These data suggest that the soil gas and atmospheric air pathways may be more important for transporting contaminants to the accessible environment than the soil water pathway. New hypotheses have been developed about these pathways, and characterization and monitoring activities designed to collect data to test these hypotheses

  15. A geochemical and isotopic approach to recharge evaluation in semi-arid zones. Past and present

    International Nuclear Information System (INIS)

    The magnitude of any recharge to aquifers in semi-arid and arid zones is the principal uncertainty in estimating a water balance. Recent studies in Cyprus and Libyan Arab Jamahiriya are currently being used to demonstrate the application of geochemical and isotopic techniques, to the determination of both current and palaeo-recharge. In Cyprus, solute profiles of the unsaturated zone have been interpreted to provide estimates of the direct recharge component using a steady-state, mass-balance approach; results from the chloride profiles compare well with recharge estimates using tritium. In addition, it is found that some solute peaks, notably for specific electrical conductance, give a reasonably accurate record of the rainfall history during the period 1950-1975. The solute profile method is relatively unsophisticated and could be more widely applied to recharge estimation in other semi-arid areas of the world. In Libya, a clear distinction can be made using the combined isotopic, hydrological and geochemical results between regional groundwaters recharged to the upper, unconfined aquifer of the Sirte Basin before 13,000 years BP and younger waters recharged locally during the period 5000-7800 years BP. A well-defined fresh-water channel, superimposed upon the regional water quality pattern, can be traced within the aquifer for some 130 km and represents direct evidence of recharge during the Holocene. Some shallow groundwaters of similar composition to the fresh-water channel are also considered to represent recent, if intermittent, recharge which took place during historical times. It is concluded that geochemical and isotopic studies of both the unsaturated zone and of shallow groundwaters in semi-arid regions, can be used to determine not only the present-day direct recharge component, but also a recharge chronology of immediate historic times, which may be important in the estimation of long-term water resources. (author)

  16. Ecotonal Control on Vadose-Zone Fluxes in Arid Regions Over Very Long Time Scales

    Science.gov (United States)

    Phillips, F. M.; Walvoord, M. A.; Sandvig, R.

    2003-12-01

    Recent studies indicate that vegetation plays an important role in regulating recharge in semiarid and arid basins over very long time scales. Several lines of evidence from desert floor environments in the southwestern United States suggest that vegetation has established essentially permanent upward hydraulic gradients, effectively precluding diffuse recharge since the transition from woodland to xeric scrub in the early Holocene. However, less xeric vegetation (such as the pygmy piñon and juniper forest) may support significant diffuse recharge. We show comparative water potential and porewater chemistry profiles collected from various vegetation communities in the Chihuahuan Desert of west Texas. The modeled soil water (vapor and liquid) flux regimes illustrate a conversion from substantial downward fluxes under the mixed woodland to upward fluxes under grassland and xeric scrub. Model results also indicated a trend in increasing drying front propagation depth from the grassland to recently-encroached xeric scrub to well-established xeric scrub. Drying fronts are the result of upward soil water fluxes initiated up to 16 thousand years ago in the xeric scrub community. In contrast, the nearby woodland community supports active, and likely episodic, recharge on the order of 5 to 15 mm yr-1. The mechanism by which some vegetation takes up essentially all seasonally available moisture within the root zone, preventing downward soil water fluxes for periods of thousands of years, but adjacent vegetation communities regularly permit downward fluxes, remains to be determined. Nevertheless, these results suggest that understanding the relation between vegetation community and vadose-zone hydrological processes may be the most profitable avenue toward quantifying diffuse groundwater recharge. We hypothesize that vegetation type may be a reasonable proxy for estimating recharge in semiarid and arid basins. Ongoing research is intended to test the hypothesis of ecotonal

  17. A method of characterizing land-cover swap changes in the arid zone of China

    Institute of Scientific and Technical Information of China (English)

    Yecheng YUAN; Baolin LI; Xizhang GAO; Haijiang LIU; Lili XU; Chenghu ZHOU

    2016-01-01

    Net area change analysis can dramatically underestimate total change of land cover,even sometimes seriously misinterpret ecological processes of the ecosystem,especially in arid or semiarid zones.In this paper,a suite of indices are presented to characterize land-cover swaps that may seriously damage the ecosystem in arid or semiarid zones,based on swap-change areas extracted from remotely sensed images.First,swap percentage of total area and swap intensity of total changes were used to determine the status of land-cover swap change in an area.Then,dominated swap category and individual swapchange intensity for a land-cover category were used to determine flagged land-cover swap-change categories.Finally,swap-change mode and Pielou's index were used to determine the land-cover swap-change processes of dominant categories.A case study is conducted using this approach,based on two land-cover maps in the 1980s and 2000 in Naiman Qi,Tongliao City,Inner Mongolia,China.This study shows that the approach can clearly quantify the severity and flagged classes of land-cover swap-change and reveal their relationship with ecological processes of the ecosystem.These results indicate that the approach can give deep insights into swap change,which can be very valuable to land-cover policy making and management.

  18. Systematic revision of the marbled velvet geckos (Oedura marmorata species complex, Diplodactylidae) from the Australian arid and semi-arid zones.

    Science.gov (United States)

    Oliver, Paul M; Doughty, Paul

    2016-03-08

    Lizards restricted to rocky habitats often comprise numerous deeply divergent lineages, reflecting the disjunct nature of their preferred habitat and the capacity of rocky habitats to function as evolutionary refugia. Here we review the systematics and diversity of the predominantly saxicoline Australian marbled velvet geckos (genus Oedura) in the Australian arid and semi-arid zones using newly-gathered morphological data and previously published genetic data. Earlier work showed that four largely allopatric and genetically divergent lineages are present: Western (Pilbara and Gascoyne regions), Gulf (west and south of the Gulf of Carpentaria), Central (central ranges) and Eastern (Cooper and Darling Basins). None of these four populations are conspecific with true O. marmorata, a seperate species complex that is restricted to the Top End region of the Northern Territory. Top End forms share a short, bulbous tail whereas the other four lineages treated here possess a long, tapering tail. Morphological differences among the arid and semi-arid lineages include smaller body size, tapering lamellae and a shorter tail for the Gulf population, and a partially divided rostral scale in the Western population compared to the Central and Eastern populations. Accordingly, we resurrect O. cincta de Vis from synonymy for the Central and Eastern lineages, and regard this species as being comprised of two evolutionary significant units. We also describe the Gulf and Western lineages as new species: Oedura bella sp. nov. and O. fimbria sp. nov., respectively. We note that a predominantly arboreal lineage (the Eastern lineage of O. cincta) is more widely distributed than the other lineages and is phylogenetically nested within a saxicoline clade, but tends to have a deeper head and shorter limbs, consistent with morphological variation observed in other lizard radiations including both saxicoline and arboreal taxa.

  19. Arthropods in Natural Communities in Mescal Agave (Agave durangensis Gentry in an Arid Zone

    Directory of Open Access Journals (Sweden)

    Maria P. Gonzalez-Castillo

    2011-01-01

    Full Text Available Problem statement: The arthropods have a very important role in the arid zones due to their interactions with many organism and because they constituted an important element in the structure of the plant community. Nevertheless their importance there are few knowledge about the community of arthropods associated to vegetation in arid zones in the North of Mexico. The present study had the objective of determining the abundance, richness and diversity of arthropods in three localities where there are natural populations of mescal agave in the State of Durango, Mexico. Approach: In order to know the structure community of the arthropods associated to the mescal agave, we perform a sampling schedule during March 2008 to November 2010 by direct collection, using transects in three different localities with the presence of mescal agave. The relative abundance, species richness, Shannon’s diversity index, Pielou’s Index of evenness, Jaccard’s similitude and Simpson’s dominance indexes were determined. Results: A total of 4665 individual arthropods associated to mescal agave corresponding to 39 species were found. El Mezquital had the highest abundance and relative abundance (44.1% with 29 species. The mean species abundance was not significantly different between localities using Turkey’s test. The highest density per unit of area was found in El Mezquital (La Brena had the highest species diversity (1.89, evenness (0.61 and dominance (0.78. At the taxon level, Hymenoptera had the highest number of species represented (14, followed by Coleoptera (9 and hemiptera (5, with the remaining taxons with four, two and one species each. Conclusion: The greatest similitude was observed between La Brena and El Mezquital (46% which shared seven taxons, while the least similitude was observed between El Venado and La Brena (29%. Dominance/diversity curves are presented for each locality. The species Caulotops sp., Acutaspis agavis, Chilorus sp

  20. Different responses of MODIS-derived NDVI to root-zone soil moisture in semi-arid and humid regions

    Science.gov (United States)

    Wang, Xianwei; Xie, Hongjie; Guan, Huade; Zhou, Xiaobing

    2007-06-01

    SummarySurface representation of the root-zone soil moisture is investigated so that feasibility of using optical remote sensing techniques to indirectly map root-zone soil moisture is assessed. Specifically, covariation of root-zone soil moisture with the normalized difference of vegetation index (NDVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) is studied at three sites (New Mexico, Arizona, and Texas) selected from the Soil Climate Analysis Network (SCAN). The three sites represent two types of vegetation (shrub and grass) and two types of climate conditions: semi-arid (New Mexico and Arizona) and humid (Texas). Collocated deseasonalized time series of soil moistures at five depths (5 cm, 10 cm, 20 cm, 50 cm, and 100 cm) and NDVI (8-day composite in 250 m resolution) during the period of February 2000 through April 2004 were used for correlation analysis. Similar analysis was also conducted for the raw time series for comparison purposes. The linear regression of both the deseasonalized time series and the raw time series was used to estimate root-zone soil moisture. Results show that (1) the deseasonalized time series results in consistent and significant correlation (0.46-0.55) between NDVI and root-zone soil moisture at the three sites; (2) vegetation (NDVI) at the humid site needs longer time (10 days) to respond to soil moisture change than that at the semi-arid sites (5 days or less); (3) the time-series of root-zone soil moisture estimated by a linear regression model based on deseasonalized time series accounts for 42-71% of the observed soil moisture variations for the three sites; and (4) in the semi-arid region, root-zone soil moisture of shrub-vegetated area can be better estimated using NDVI than that of grass-vegetated area.

  1. Microbial colonisation of chasmoendolithic habitats in the hyper-arid zone of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    J. DiRuggiero

    2013-04-01

    Full Text Available Efforts in searching for microbial life in the driest part of Atacama Desert, Chile, revealed a small number of lithic habitats that can be considered as environmental refuges for life. In this study, we describe for the first time chasmoendolithic colonisation of fissures and cracks of rhyolite-gypsum and calcite rocks collected in the hyper-arid zone of the desert. The use of high-throughput sequencing revealed that the Atacama rock communities comprised a few dominant phylotypes and a number of less abundant taxa representing the majority of the total community diversity. The chasmoendolithic communities were dominated by Chroococcidiopsis species cyanobacteria and supported a number of heterotrophic bacterial lineages. Micro-climate data and geomorphic analysis of the mineral substrates suggested higher water availability in the calcite rocks in the form of enhanced water retention in the complex network of cracks and fissures of these rocks as well as increased occurrence of liquid water in the form of dewfall. These characteristics were associated with a diverse community of phototrophic and heterotrophic bacteria in the calcite chasmoendolithic ecosystem. This study is another example of the diversity of adaptive strategies at the limit for life and illustrates that rock colonisation is controlled by a complex set of factors.

  2. Microbial colonization of chasmoendolithic habitats in the hyper-arid zone of the Atacama Desert

    Directory of Open Access Journals (Sweden)

    J. DiRuggiero

    2012-11-01

    Full Text Available Efforts in searching for microbial life in the driest part of Atacama Desert, Chile, revealed a small number of lithic habitats that can be considered as environmental refuges for life. In this study, we describe for the first time chasmoendolithic colonization of fissures and cracks of rhyolite-gypsum and calcite rocks collected in the hyper-arid zone of the desert. The use of high-throughput sequencing revealed that the Atacama rock communities comprised a few dominant phylotypes and a number of less abundant taxa representing the majority of the total community diversity. The chasmoendolithic communities were dominated by Chroococcidiopsis species cyanobacteria and supported a number of novel heterotrophic bacteria. Micro-climate data and geomorphic analysis of the mineral substrates suggested higher water availability in the calcite rocks in the form of enhanced water retention in the complex network of cracks and fissures of these rocks as well as increased occurrence of liquid water in the form of dewfall. These characteristics were associated with a diverse community of phototrophic and heterotrophic bacteria in the calcite chasmoendolithic ecosystem. This study is another example of the diversity of adaptive strategies at the limit for life and illustrates that rock colonization is controlled by a complex set of factors.

  3. [Microecological characterization of parasitic nematoda present in goats of arid zones of Venezuela].

    Science.gov (United States)

    Morales, G; Pino, L A; Aldana, E; Perdomo, L; Molina, E

    1986-01-01

    Goats from the Venezuelan northern arid zones were found infested by the following nematodes: Haemonchus contortus, Trichostrongylus axei, T. colubriformis, Cooperia curticei, Oesophagostomum columbianum, Skrjabinema ovis y Trichuris globulosa. The Shannon-Weaver index of diversity values oscillated between 0.045 and 1.73 bits (means = 1.16 +/- 0.24 bits). The maximum value of montly diversity ranged from 1 to 2.80 bits (means = 2.49 +/- 0.28 bits) and the equitability ranged from 0.045 to 0.67 (means = 0.44 +/- 0.09). Parasitic associations were found among 1) T. axei, T. colubriformis and H. contortus, 2) T. colubriformis, H. contortus and O. columbianum and 3) T. colubriformis, S. ovis and T. globulosa. The above results suggest that in months when the diversity index is close to the maximum value and the equitability index is near unity, wide spectrum antihelmintic treatment should be used for poly-parasitized animals. PMID:3587000

  4. Underground Corrosion of Activated Metals in an Arid Vadose Zone Environment

    Energy Technology Data Exchange (ETDEWEB)

    Adler Flitton, Mariana Kay; Mizia, Ronald Eugene; Bishop, Carolyn Wagoner

    2002-04-01

    The subsurface radioactive disposal site located at the Idaho National Engineering and Environmental Laboratory contains neutron-activated metals from nonfuel nuclear-reactor- core components. A long-term corrosion test is being conducted to obtain site-specific corrosion rates to support efforts to more accurately estimate the transfer of activated elements in an arid vadose zone environment. The tests use nonradioactive metal coupons representing the prominent neutron-activated material buried at the disposal location, namely, Type 304L stainless steel, Type 315L stainless steel, nickel-chromium alloy (UNS NO7718), beryllium, aluminum 6061-T6, and a zirconium alloy, (UNS R60804). In addition, carbon steel (the material presently used in the cask disposal liners and other disposal containers) and a duplex stainless steel (UNS S32550) (the proposed material for the high- integrity disposal containers) are also included in the test program. This paper briefly describes the test program and presents the early corrosion rate results after 1 year and 3 years of underground exposure.

  5. Underground Corrosion of Activated Metals in an Arid Vadose Zone Environment

    Energy Technology Data Exchange (ETDEWEB)

    Adler Flitton, M.K; Mizia, R.E.; Bishop, C.W.

    2001-10-24

    The subsurface radioactive disposal site located at the Idaho National Engineering and Environmental Laboratory contains neutron-activated metals from nonfuel nuclear-reactor- core components. A long-term corrosion test is being conducted to obtain site-specific corrosion rates to support efforts to more accurately estimate the transfer of activated elements in an arid vadose zone environment. The tests use nonradioactive metal coupons representing the prominent neutron-activated material buried at the disposal location, namely, Type 304L stainless steel, Type 315L stainless steel, nickel-chromium alloy (UNS NO7718), beryllium, aluminum 6061-T6, and a zirconium alloy, (UNS R60804). In addition, carbon steel (the material presently used in the cask disposal liners and other disposal containers) and a duplex stainless steel (UNS S32550) (the proposed material for the high- integrity disposal containers) are also included in the test program. This paper briefly describes the test program and presents the early corrosion rate results after 1 year and 3 years of underground exposure.

  6. Energy use pattern in production agriculture of a typical village in arid zone India: Pt. 2

    Energy Technology Data Exchange (ETDEWEB)

    Singh, H.; Mishra, D.; Nahar, N.M.; Ranjan, Mohnot [Central Arid Zone Research Inst., Div. of Agricultural Engineering and Energy, Rajasthan (India)

    2003-05-01

    The Indian hot arid zone, occupying an area of 31.71 Mha, spreads over Western Rajasthan, North Gujrat, South West Haryana and Punjab, some parts of Andhra Pradesh and Karnataka State, but the major part of it (61.8%) lies in the western part of Rajasthan, covering 12 districts commonly known as 'Thar Desert' and characterized by harsh climatic conditions with active dunal activities. To add to the misery, there is continuous occurrence of severe drought in the region since the last 2-3 years (1997-98 and 1999-2000). Data on the energy input for cultivating different selective crops for 1999-2000 (drought year) were collected, analysed and presented for the village 'Siwas' district, Pali (Zone-IV, rainfall >400 mm/yr). Owing to the drought, farmers of the village have grown kharif crops (being rainfed) by providing life saving irrigation. The maximum energy is required for raising the cotton crop, followed by wheat, mustard, maize and cluster bean. There is more non-renewable form of energy input (73.2%) than renewable form (26.8%) in all the crops. Further, more non-renewable energy is required for cultivating rabi crops compared to kharif. Among the kharif crops, the energy ratio varied from 3.4 to 7.0, suggesting that cotton, having an energy ratio 7.0, is most profitable compared to other crops. However, among the rabi crops, mustard is found most profitable. The crop yield can be correlated with energy input in the form of a second degree polynomial. During a drought period, by providing life saving irrigation, the yields of kharif crops were in agreement with the average yield obtained during a normal rainfall year. (Author)

  7. Urban market gardening and rodent-borne pathogenic leptospira in arid zones : a case study in Niamey, Niger

    OpenAIRE

    Gauthier Dobigny; Madougou Garba; Caroline Tatard; Anne Loiseau; Max Galan; Ibrahima Kadaouré; Jean-Pierre Rossi; Mathieu Picardeau; Eric Bertherat

    2015-01-01

    Leptospirosis essentially affects human following contact with rodent urine-contaminated water. As such, it was mainly found associated with rice culture, recreational activities and flooding. This is also the reason why it has mainly been investigated in temperate as well as warm and humid regions, while arid zones have been only very occasionally monitored for this disease. In particular, data for West African countries are extremely scarce. Here, we took advantage of an extensive survey of...

  8. The affect and importance of the Lichens in the Arid zone conservation and protection of water resource

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-liang; ZHANG Yuan-ming; Adil Abdulla; Anwar Tumur; Abdulla Abbas

    2004-01-01

    Desertification has already become the global social problem. On the Arid zone it has closer relation with the frail ecotope. The system of the arid zone mountain belongs to crisscross between the farming ,forestry and husbandry . The frailty of the ecosystem manifests on the internal frailty, depends on the plant ,intensity of the contradictory between the landscape transitional and natural reservation area,physical weathering strong,the development of the soil surface is slowly but the erode of the rain ,soil erosion very grave. Lichens not only rein force the intensity and depth of the weathering of rocks and formation ,accelerate of the mineral weathering making and accumulating the organic compound, at the same time lichens have strongly water protection abilities and inestimable role in the prevent soil erosion. In this paper we were according to on-the-spot investigation and analysis of the laboratory from 1985 to now on the middle and west of the Mt . Tianshan and Mt. Altay kanas where mainly probe into the significance of the protection water and conservation water resources of the Arid zone. This research works will be provide scientific basis and reference of the government for put into effect ,improving environment of the mountain region ,major construction oasis ecotope and make great efforts for protection desert ecotope.

  9. Non conventional livestock feeds of arid zone of India: Potential need to tap effectively and efficiently

    International Nuclear Information System (INIS)

    bulk processing and detoxification facility. Since most of those plants are having ethno veterinary importance, so there is dire need to explore hidden medicinal attributes in those resources, which can supplement nutritional value of feeds. Combining traditional biomass with recent technology can bring forth a potential option for their effective incorporation and efficient utilization. This new focus on their nutritional values and medicinal and industrial use will prompt and attract future conservation and propagation of these resources. This in turn can solve nutrient crisis for livestock in arid zones of India along with improving socio-economic status of the poor and marginal farmers

  10. State of radionuclides in seawater. Comparison of natural stable and artificial radioactive isotope s of mercury and zinc in natural waters of the arid zone of the USSR

    International Nuclear Information System (INIS)

    This paper studies the state of stable and artificial radioactive isotopes of merury and zinc in natural waters of the arid zone of the USSR by radioactivity and radiochemical methods. Convergent results have been obtained for the dissolved forms of mercury and zinc in natural waters of the arid zone in a comparison of the results of radioactivation analysis and laboratory simulation using the radionuclides mercury-203 and zinc-65

  11. Modelling streamflow in a large anastomosing river of the arid zone, Diamantina River, Australia

    Science.gov (United States)

    Costelloe, J. F.; Grayson, R. B.; McMahon, T. A.

    2006-05-01

    Anastomosing rivers form a subset of the anabranching family of river types and provide considerable challenges to modelling of their streamflow because of complex flow patterns across greatly varying floodplain widths. Estimates of distributed flow data are required for catchment management purposes and ecological studies of these rivers but are hindered by a paucity of measured discharge data. A grid-based, semi-distributed, conceptual model structure is applied to a 330 km reach of the arid zone Diamantina River of central Australia. Model complexity is constrained by data availability with only a single gauging station located at the downstream end of the reach to provide discharge data for model calibration. The model uses a simple conceptual bucket structure and accounts for exceptionally high transmission losses as well as flow patterns and wave speeds that vary with discharge within the reach. The intricate flow patterns across the floodplains widths of up to 50 km are simulated using a grid-based structure that required the following features: (i) cell connections that are explicitly defined using a code that allows for multi-directional flow from a cell; and (ii) each cell having a binary flow pattern, with the second connection pattern being triggered when the surface storage of the cell exceeds a calibrated level for a given land-type. Satellite images were used to define the flow paths, and hence cell connection patterns, utilised by various sized floods. The model was able to provide acceptable simulation of large floods but with decreasing model performance in the simulation of small to medium sized floods. Simulation suggested that incorrectly defined flow paths for the smaller floods were a major factor in this decreased performance. The capability of the model would be improved by further detailed mapping, using satellite imagery, of spatial patterns of inundation as discharge varies.

  12. Transitions in Land Use Architecture under Multiple Human Driving Forces in a Semi-Arid Zone

    Directory of Open Access Journals (Sweden)

    Issa Ouedraogo

    2015-07-01

    Full Text Available The present study aimed to detect the main shifts in land-use architecture and assess the factors behind the changes in typical tropical semi-arid land in Burkina Faso. Three sets of time-series LANDSAT data over a 23-year period were used to detect land use changes and their underpinning drivers in multifunctional but vulnerable ecologies. Group discussions in selected villages were organized for mapping output interpretation and collection of essential drivers of change as perceived by local populations. Results revealed profound changes and transitions during the study period. During the last decade, shrub and wood savannahs exhibited high net changes (39% and −37% respectively with a weak net positive change for cropland (only 2%, while cropland and shrub savannah exhibited high swap (8% and 16%. This suggests that the area of cropland remained almost unchanged but was subject to relocation, wood savannah decreased drastically, and shrub savannah increased exponentially. Cropland exhibited a null net persistence while shrub and wood savannahs exhibited positive and negative net persistence (1.91 and −10.24, respectively, indicating that there is movement toward agricultural intensification and wood savannah tended to disappear to the benefit of shrub savannah. Local people are aware of the changes that have occurred and support the idea that illegal wood cutting and farming are inappropriate farming practices associated with immigration; absence of alternative cash generation sources, overgrazing and increasing demand for wood energy are driving the changes in their ecosystems. Policies that integrate restoration and conservation of natural ecosystems and promote sustainable agroforestry practices in the study zone are highly recommended.

  13. Seed weight and germination behavior of the submerged plant Potamogeton pectinatus in the arid zone of northwest China

    OpenAIRE

    Li, Zhongqiang; Lu, Wei; YANG, Lei; Kong, Xianghong; Deng, Xuwei

    2015-01-01

    Variation in seed weight is common within and among plant species, but few studies have attempted to document the pattern of seed weight and germination attributes for aquatic macrophytes at a large scale. This study examined within-species variation in seed weight and germination attributes and the effects of environmental factors on seed traits of the submerged plant Potamogeton pectinatus in the arid zone of northwest China. Our results showed that the average seed weight was 0.24 g per 10...

  14. Design parameters of a non-air-conditioned cinema hall for thermal comfort under arid-zone climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, G.N. (Indian Inst. of Tech., New Delhi (India). Centre for Energy Studies); Lugani, N. (Indian Inst. of Tech., New Delhi (India). Centre for Energy Studies); Singh, A.K. (Indian Inst. of Tech., New Delhi (India). Centre for Energy Studies)

    1993-01-01

    In this communication, a design of a cinema hall suitable for climatic conditions in an arid zone has been presented. The various cooling techniques, namely evaporative cooling, wind tower, ventilation/infiltration and natural cooling, have been incorporated in the design to achieve thermal comfort during the period of operation. The design parameters have been optimized on the basis of numerical computations after establishing an energy balance for each component of a cinema hall. It is observed that cooling treatment, i.e., a wind tower with a cooling pool on the roof provides reasonable thermal comfort inside the enclosure. (orig.)

  15. Influence of biological soil crusts at different successional stages in the implantation of biogeochemical cycles in arid and semiarid zones

    Science.gov (United States)

    Gil-Sotres, F.; Miralles, I.; Canton-Castilla, Y.; Domingo, F.; Leiros, M. C.; Trasar-Cepeda, C.

    2012-04-01

    Influence of biological soil crusts at different successional stages in the implantation of biogeochemical cycles in arid and semiarid zones I. Miralles1, F. Gil-Sotres2, Y. Cantón-Castilla3, F. Domingo1, M.C. Leirós2, C. Trasar-Cepeda4 1 Experimental Estation of Arid Zones (CSIC), E-04230 La Cañada de San Urbano, Almería, Spain. 2 Departamento Edafología y Química Agrícola, Grupo de Evaluación de la Calidad del Suelo, Unidad Asociada CSIC, Facultad de Farmacia, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain. 3 University of Almería, Departamento de Edafología y Química Agrícola, E-04230-La Cañada de San Urbano, Almería, Spain. 4 Departamento Bioquímica del Suelo, IIAG-CSIC, Apartado 122, E-15708 Santiago de Compostela, Spain. Crusts (BSCs) are formed by a close association between soil particles and cyanobacteria, algae, lichens, bryophytes and microfungi in varying proportions. Their habitat is within or immediately on top of the uppermost millimetres of the soil and are the predominant surface cover in arid and semiarid zones. Among the diverse functions developed by BSCs in the ecosystem (hydrology, erosion, soil properties, etc.), one of the most important is its role in nutrient cycling. Within arid and semiarid environments, BSCs have been termed 'mantles of fertility' being considered hotspots of biogeochemical inputs, fixing C, N and P above- and below-ground. However, there are differences in N and C fixation rates between BSCs types. Early successional BSCs, dominated by cyanobacterial species, fix lower quantities of C and N than mature BSCs dominated by lichens. Although the positive effects of BSCs on biogeochemical soil cycles are widely accepted, no previous studies have evaluated the activities of the enzymes involved in C, N and P cycles of BSCs and how they are affected by the successional stage of the BSC. In this work, performed in the Tabernas desert (SE Spain), we studied the hydrolase enzymes

  16. Rodent middens, a new method for Quaternary research in arid zones of South America

    Science.gov (United States)

    Betancourt, J.L.; Saavedra, B.

    2002-01-01

    In arid and semi-arid regions of South America, historical evidence for climate and vegetation change is scarce despite its importance for determining reference conditions and rates of natural variability in areas susceptible to modern desertification. Normal lines of evidence, such as pollen stratigraphies from lakes, are either rare or unobtainable in deserts; studies of late Quaternary vegetation history are few and generally inconclusive. This gap in knowledge may be corrected with discovery and development of fossil rodent middens in rocky environments throughout arid South America. These middens, mostly the work of Lagidium, Phyllotis, Abrocoma and Octodontomys, are rich in readily identifiable plant macrofossils, cuticles and pollen, as well as vertebrate and insect remains. In the North American deserts, more than 2,500 woodrat (Neotoma) middens analyzed since 1960 have yielded a detailed history of environmental change during the past 40,000 years. Preliminary work in the pre-puna, Monte and Patagonian Deserts of western Argentina, the Atacama Desert of northern Chile/southern Peru, the Mediterranean matorral of central Chile, and the Puna of the Andean altiplano suggest a similar potential for rodent middens in South America. Here we borrow from the North American experience to synthesize methodologies and approaches, summarize preliminary work, and explore the potential of rodent midden research in South America.

  17. CO2 production rate maxima in the deeper unsaturated zone of a semi-arid floodplain at Rifle, Colorado

    Science.gov (United States)

    Tokunaga, T. K.; Kim, Y.; Wan, J.; Dong, W.; Conrad, M. E.; Bill, M.; Hobson, C.; Williams, K. H.; Long, P. E.

    2015-12-01

    Fluxes of CO2 from soils are important to understand in order to predict subsurface feedbacks to the atmosphere and responses to climate change. Such fluxes are commonly monitored at the soil surface and generally assumed to largely originate within shallow depths. Relatively little is understood on the depth distribution of CO2 production below the rhizosphere. We monitored CO2 fluxes at the soil surface, and measured vertical profiles of vadose CO2 concentrations, matric potentials, and temperatures at the Rifle Site, a saline semi-arid floodplain along the Colorado River in order to determine the significance of deeper vadose zone respiration. Vadose zone CO2 profiles exhibit temperature-dependent seasonal variations, and are consistent with CO2 fluxes measured at the soil surface. The measured vadose zone CO2 concentration profiles combined with gas diffusion coefficients estimated from soil properties indicated that local maxima in rates of CO2 production persist in the deeper vadose zone, about 1 m below the rhizosphere, and above the water table (~3.5 m below the soil surface). We hypothesized that water and oxygen activities, nutrient levels, and temperatures remain favorable for microbial respiration throughout the year in the subrhizosphere, unlike overlying drier soils and the underlying poorly aerated aquifer. Using soils and sediments from the field site, the hypothesized existence of deeper subsurface maxima in CO2 production rate is currently being tested in the laboratory through sediment incubation experiments and in 2.0 m tall vadose zone columns. Initial results from the laboratory support the hypothesized persistence of a subrhizosphere "hot zone" for microbial respiration, partly sustained through seasonal pulses of dissolved and labile organic carbon originating from the rhizosphere. These findings suggest that similar sustained deeper local maxima in respiration rates may occur in many other regions where near-surface conditions are

  18. Analysis and environmental diagnosis of rural habitat in arid zones of the Province of San Juan, Argentina

    Directory of Open Access Journals (Sweden)

    María Guillermina Re

    2015-03-01

    Full Text Available This paper presents the environmental analysis on rural communities on arid zones of the province of San Juan. The objective of this research is to perform a diagnosis and to develop proposals for future improvements on this region. The analysis was carried out at two different scales: one on the natural environment (macro scale, and another one, on the humanized environment (micro scale, represented by the productive farms, considered as the core of the rural domestic and productive habitat. This research allowed a characterization of the environment and an understanding of the rules that structure the rural habitat in San Juan, and also to perform an evaluation and diagnosis of this type of rural habitat.

  19. Unveiling the status of alien animals in the arid zone of Asia

    Science.gov (United States)

    Zhang, Lyubing

    2016-01-01

    Biological invasion is one of the most threatening factors for biodiversity conservation. Lacking information on alien species in certain regions of the world hampers a balanced understanding of invasion processes and efficient data exchange among stakeholders. Current knowledge gaps are in need of urgent concern. We therefore conducted a review on alien animals in Xinjiang, an unknown region of invasion ecology. Xinjiang lies in the heartland of the Asian continent, covering an area of 1,664,900 km2. In the past 64 years, 128 alien animal species were recorded in this region, 39% of which became invasive and led to loss of native biodiversity. Most of these species were introduced through diversification of local agriculture and aquaculture. This process was aggravated by improving transportation and flourishing trade. Multiple linear regression models and correlation analysis were run for explaining influence of environmental and anthropogenic factors on status of alien animals: economically developed areas with abundant water resource, oases in particular, were prone to be hotspots of alien animal species in this arid and semi-arid region. This study also revealed that taxonomically biased and lagged research were critical problems that impeded studies on biological invasions in Xinjiang, and proposed feasible solutions. PMID:26793423

  20. Pharmacognostical studies of important arid zone plants Estudos farmacognósticos de plantas importantes de zonas áridas

    Directory of Open Access Journals (Sweden)

    Satish C. Jain

    2010-11-01

    Full Text Available Arid zone of Rajasthan, India, has its own importance, great diversity and specific characteristic with respect to endemic and large number of plants of economic importance and medicinal use. Out of these, three arid zone plants Gisekia pharnaceoides L., Gisekiaceae, Sericostoma pauciflorum Stocks ex Wight, Boraginaceae, and Trianthema decandra L., Aizoaceae, which are traditionally used for different ailments (hepatitis, asthma, jaundice, skin-infections etc. have been selected for the study. In the present paper, detailed pharmacognostical evaluation of these plant species using microscopy, standard physicochemical determinations and authentic phytochemical parameters has been carried out. Later, these morphological characteristics could be used for rapid identification of the drugs, particularly in case of powdered materials, and may possibly help to differentiate the drug from its other species.A zona árida de Rajasthan, Índia, é importante pela grande diversidade e especificidade de plantas endêmicas de importância econômica e medicinal. Destas, três plantas de zonas áridas, Gisekia pharnaceoides L., Gisekiaceae, Sericostoma pauciflorum Stocks ex Wight, Boraginaceae, e Trianthema decandra L., Aizoaceae, que são tradicionalmente utilizados para diversas doenças (hepatite, asma, icterícia, infecções da pele etc., foram selecionados para o estudo. Neste trabalho trabalho, a avaliação farmacognóstica detalhada destas espécies, através de estudo morfoanatômico, determinações físico-químicas e parâmetros fitoquímicos, foram realizados. As características morfológicas podem ser utilizados para rápida identificação das drogas, particularmente no caso de materiais em pó, e possivelmente ajudar a diferenciar a droga de outras espécies.

  1. Research-Based Learning for Undergraduate Students in Soil and Water Sciences: A Case Study of Hydropedology in an Arid-Zone Environment

    Science.gov (United States)

    Al-Maktoumi, Ali; Al-Ismaily, Said; Kacimov, Anvar

    2016-01-01

    This article reports the efficacy of a research-based learning (RBL) exercise on hydropedology of arid zones, with guided and open research projects (OPR) carried out by teams of undergraduate students in Oman. A range of activities and assessments was used to support student learning during the three-month course. Assessment included monitoring…

  2. Urban Market Gardening and Rodent-Borne Pathogenic Leptospira in Arid Zones: A Case Study in Niamey, Niger.

    Directory of Open Access Journals (Sweden)

    Gauthier Dobigny

    Full Text Available Leptospirosis essentially affects human following contact with rodent urine-contaminated water. As such, it was mainly found associated with rice culture, recreational activities and flooding. This is also the reason why it has mainly been investigated in temperate as well as warm and humid regions, while arid zones have been only very occasionally monitored for this disease. In particular, data for West African countries are extremely scarce. Here, we took advantage of an extensive survey of urban rodents in Niamey, Niger, in order to look for rodent-borne pathogenic Leptospira species presence and distribution across the city. To do so, we used high throughput bacterial 16S-based metabarcoding, lipL32 gene-targeting RT-PCR, rrs gene sequencing and VNTR typing as well as GIS-based multivariate spatial analysis. Our results show that leptospires seem absent from the core city where usual Leptospira reservoir rodent species (namely R. rattus and M. natalensis are yet abundant. On the contrary, L. kirschneri was detected in Arvicanthis niloticus and Cricetomys gambianus, two rodent species that are restricted to irrigated cultures within the city. Moreover, the VNTR profiles showed that rodent-borne leptospires in Niamey belong to previously undescribed serovars. Altogether, our study points towards the importance of market gardening in maintain and circulation of leptospirosis within Sahelian cities. In Africa, irrigated urban agriculture constitutes a pivotal source of food supply, especially in the context of the ongoing extensive urbanization of the continent. With this in mind, we speculate that leptospirosis may represent a zoonotic disease of concern also in arid regions that would deserve to be more rigorously surveyed, especially in urban agricultural settings.

  3. Richness and diversity of Leguminosae in an altitudinal gradient in the tropical semi-arid zone of Brazil

    Institute of Scientific and Technical Information of China (English)

    Jacira R.LIMA; Vidal F.MANSANO; Francisca S.ARA(U)JO

    2012-01-01

    Many studies are based on the premise that,on a local scale,diversity is the result of ecological processes,whereas on a regional scale factors such as the topography,geology,hydrology,and historical and evolutionary events would influence this control.The Baturité Mountain Range (Ceará state),located in the Brazilian semi-arid zone,is considered an area of extreme importance for conservation with its vegetation varying with the altitude and slope (windward vs.leeward).On the windward (wet) slope,rainforest dominates,whereas the leeward (dry) slope is dominated by seasonal forests and thorny woodland.The aim of this study was to contribute to the knowledge of the patterns of richness and diversity of the family Leguminosae on a local scale (Baturité Mountain Range) as well as a regional scale (northeastern Brazil).The two slopes present quite distinct floras.The dry slope presents higher richness and diversity indices for Leguminosae than the wet slope.The highest diversity of Leguminosae in the dry areas did not corroborate the ideas of other studies carried out in neotropical forests (total flora) that the higher species richness was predicted for wet areas.The present study indicates that the historical and evolutionary processes influence the diversity patterns on a local scale (Baturité Mountain Range),as well as on a regional scale (Brazilian semi-arid).Our results reinforce the uniqueness of each portion of this area and its importance for conservation.

  4. Urban Market Gardening and Rodent-Borne Pathogenic Leptospira in Arid Zones: A Case Study in Niamey, Niger.

    Science.gov (United States)

    Dobigny, Gauthier; Garba, Madougou; Tatard, Caroline; Loiseau, Anne; Galan, Max; Kadaouré, Ibrahima; Rossi, Jean-Pierre; Picardeau, Mathieu; Bertherat, Eric

    2015-01-01

    Leptospirosis essentially affects human following contact with rodent urine-contaminated water. As such, it was mainly found associated with rice culture, recreational activities and flooding. This is also the reason why it has mainly been investigated in temperate as well as warm and humid regions, while arid zones have been only very occasionally monitored for this disease. In particular, data for West African countries are extremely scarce. Here, we took advantage of an extensive survey of urban rodents in Niamey, Niger, in order to look for rodent-borne pathogenic Leptospira species presence and distribution across the city. To do so, we used high throughput bacterial 16S-based metabarcoding, lipL32 gene-targeting RT-PCR, rrs gene sequencing and VNTR typing as well as GIS-based multivariate spatial analysis. Our results show that leptospires seem absent from the core city where usual Leptospira reservoir rodent species (namely R. rattus and M. natalensis) are yet abundant. On the contrary, L. kirschneri was detected in Arvicanthis niloticus and Cricetomys gambianus, two rodent species that are restricted to irrigated cultures within the city. Moreover, the VNTR profiles showed that rodent-borne leptospires in Niamey belong to previously undescribed serovars. Altogether, our study points towards the importance of market gardening in maintain and circulation of leptospirosis within Sahelian cities. In Africa, irrigated urban agriculture constitutes a pivotal source of food supply, especially in the context of the ongoing extensive urbanization of the continent. With this in mind, we speculate that leptospirosis may represent a zoonotic disease of concern also in arid regions that would deserve to be more rigorously surveyed, especially in urban agricultural settings. PMID:26437456

  5. Fishery Resources in Arid Zone Mangroves in Gulf of Kachchh, Gujarat, Northwest Coast of India

    Institute of Scientific and Technical Information of China (English)

    A. Saravanakumar; M. Rajkumar; J. Sesh Serebiah; G. A. Thivakaran

    2009-01-01

    The finfish and shellfish resources were assessed quantitatively and qualitatively in regard to their abundance in creek waters at three sites within a period of two years, from January 1999 to December 2000, in the western mangrove areas of Kachchh.The catch rate varied from 0.69 to 6.99 kg h-1. It was low during monsoon (July to October), which could be due to the freshwater-flow-induced salinity reduction in all the sites. Among 38 species recorded, 5 were shellfish and 33 were finfish. The spawning period of fishes was found to be during summer and early monsoon period (May to August). Surface water temperatures varied from 17 ℃ to 37 ℃. Salinity values varied from 34 to 44 and the pH ranged between 7 and 8.9. Variation in dissolved oxygen content was from 3.42 to 5.85 mLL-1. The high fishery densities in these semi arid mangrove creek areas were recorded during monsoon and early winter season.

  6. On evaluating characteristics of the solute transport in the arid vadose zone.

    Science.gov (United States)

    Yu, Zhongbo; Dong, Weiquan; Young, Michael H; Li, Yiping; Yang, Tao

    2014-01-01

    The transport of bromide (Br) under matric heads of 0, -2, -5, and -10 cm using undisturbed soil columns was investigated for understanding the solute transport in arid soils. Undisturbed soil cores were collected at ground surface, directly below where tension infiltrometer measurements were made in the Amargosa Desert, Nevada, United States. Laboratory experiments were conducted by introducing water containing Br tracer into a soil column maintained at steady-state conditions. The observed data of breakthrough curves (BTC) were well fitted to an one-region model, except for the cores at saturation, and a core at the matric head of -5 cm, from which the observed data were better fitted to a two-region model. Fitted pore water velocities with the one-region model ranged from 1.2 to 56.6 cm/h, and fitted dispersion coefficients (D) ranged from 2.2 to 100 cm² /h. Results for the core analyzed with the two-region model indicated that D ranged from 27.6 to 70.9 cm² /h at saturation, and 25.7 cm² /h at the matric head of -5 cm; fraction of mobile water (β) ranged from 0.18 to 0.65, and mass transfer coefficient (ω) ranged from 0.006 to 0.03. In summary, the water fluxes and Br dispersion coefficients at investigated matric heads were very high due to the coarseness of the soils and possibly due to preferential flow pathways. These high water fluxes and Br dispersion coefficients would lead to a higher risk of deeper leaching accumulating nitrate nitrogen to the groundwater, and have significant effects on the desert ecosystem. PMID:23406385

  7. Human response and adaptation to drought in the arid zone: lessons from southern Africa

    Directory of Open Access Journals (Sweden)

    W. R.J. Dean

    2009-12-01

    Full Text Available Human adaptation and response to drought is primarily through evasion or endurance. A review of historical agricultural practices in southern Africa demonstrates evidence of drought evasion response strategies in well-established transhumance routes, where herders move livestock on a seasonal basis in order to exploit resources subject to different climatic regimes. European settlers to the arid regions of South Africa quickly recognised the necessity of these evasion options to survive drought, and adopted the transhumance practices of indigenous farmers. Areas of geographically diverse resource bases became hotly contested by settlers and indigenous farmers. The success of evasion systems are shown to hinge on good social and institutional support structures. When movement is not an option, drought endurance is pursued by attempting to limit the damage to the natural resource base. This is through a number of means such as forage conservation, varying livestock types and numbers, water and soil conservation and taking up alternative livelihood options. State responses to drought over the last century reflect the general South African pattern of racially divided and unjust policies relating to resource access. Historically the state provided considerable support to white commercial farmers. This support was frequently contradictory in its aims and generally was inadequate to enable farmers to cope with drought. Since the advent of democracy in 1994, the state has intervened less, with some support extended to previously disadvantaged and poor communal farmers. Climate change predictions suggest an increase in drought, suggesting that the adoption of mitigating strategies should be a matter of urgency. To do this South Africa needs to build social and institutional capacity, strive for better economic and environmental sustainability, embed drought-coping mechanisms into land restitution policy to ensure the success of this programme, and

  8. Multimodel analysis of anisotropic diffusive tracer-gas transport in a deep arid unsaturated zone

    Science.gov (United States)

    Green, Christopher T.; Walvoord, Michelle Ann; Andraski, Brian J.; Striegl, Rob; Stonestrom, David A.

    2015-01-01

    Gas transport in the unsaturated zone affects contaminant flux and remediation, interpretation of groundwater travel times from atmospheric tracers, and mass budgets of environmentally important gases. Although unsaturated zone transport of gases is commonly treated as dominated by diffusion, the characteristics of transport in deep layered sediments remain uncertain. In this study, we use a multimodel approach to analyze results of a gas-tracer (SF6) test to clarify characteristics of gas transport in deep unsaturated alluvium. Thirty-five separate models with distinct diffusivity structures were calibrated to the tracer-test data and were compared on the basis of Akaike Information Criteria estimates of posterior model probability. Models included analytical and numerical solutions. Analytical models provided estimates of bulk-scale apparent diffusivities at the scale of tens of meters. Numerical models provided information on local-scale diffusivities and feasible lithological features producing the observed tracer breakthrough curves. The combined approaches indicate significant anisotropy of bulk-scale diffusivity, likely associated with high-diffusivity layers. Both approaches indicated that diffusivities in some intervals were greater than expected from standard models relating porosity to diffusivity. High apparent diffusivities and anisotropic diffusivity structures were consistent with previous observations at the study site of rapid lateral transport and limited vertical spreading of gas-phase contaminants. Additional processes such as advective oscillations may be involved. These results indicate that gases in deep, layered unsaturated zone sediments can spread laterally more quickly, and produce higher peak concentrations, than predicted by homogeneous, isotropic diffusion models.

  9. Significance of water fluxes in a deep arid-region vadose zone to waste disposal strategies

    Energy Technology Data Exchange (ETDEWEB)

    Johnejack, K.R.; Blout, D.O.; Sully, M.J.; Emer, D.F.; Hammermeister, D.P. [Reynolds Electrical and Engineering Co., Inc., Las Vegas, NV (United States); Dever, L.G.; O`Neill, L.J. [DOE Nevada Operations Office, Las Vegas, NV (United States). Waste Management Div.; Tyler, S.W. [Desert Research Institute, Reno, NV (United States). Water Resources Center; Chapman, J. [Desert Research Institute, Las Vegas, NV (United States). Water Resources Center

    1994-03-01

    Recently collected subsurface site characterization data have led to the development of a conceptual model of water movement beneath the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site (NTS) that differs significantly from the conceptual model of water movement inherent in Resource Conservation and Recovery Act (RCRA) regulations. At the Area 5 RWMS, water fluxes in approximately the upper 75 m (250 ft) of the vadose zone point in the upward direction (rather than downward) which effectively isolates this region from the deep (approximately 250 m (820 ft)) uppermost aquifer. Standard RCRA approaches for detection and containment (groundwater monitoring and double liners/leachate collection/leak detection systems) are not able to fulfill their intended function in this rather unique hydrogeologic environment. In order to better fulfill the waste detection and containment intentions of RCRA for mixed waste disposal at the Area 5 RWMS, the Department of Energy, Nevada Operations Office (DOE/NV) is preparing a single petition for both a waiver from groundwater monitoring and an exemption from double liners with leachate collection/leak detection. DOE/NV proposes in this petition that the containment function of liners and leachate collection is better accomplished by the natural hydrogeologic processes operating in the upper vadose zone; and the detection function of groundwater monitoring and the leak detection system in liners is better fulfilled by an alternative vadose zone monitoring system. In addition, an alternative point of compliance is proposed that will aid in early detection, as well as limit the extent of potential contamination before detection. Finally, special cell design features and operation practices will be implemented to limit leachate formation, especially while the cell is open to the atmosphere during waste emplacement.

  10. Semi-arid zone caves: Evaporation and hydrological controls on δ18O drip water composition and implications for speleothem paleoclimate reconstructions

    Science.gov (United States)

    Markowska, Monika; Baker, Andy; Andersen, Martin S.; Jex, Catherine N.; Cuthbert, Mark O.; Rau, Gabriel C.; Graham, Peter W.; Rutlidge, Helen; Mariethoz, Gregoire; Marjo, Christopher E.; Treble, Pauline C.; Edwards, Nerilee

    2016-01-01

    Oxygen isotope ratios in speleothems may be affected by external processes that are independent of climate, such as karst hydrology and kinetic fractionation. Consequently, there has been a shift towards characterising and understanding these processes through cave monitoring studies, particularly focussing on temperate zones where precipitation exceeds evapotranspiration. Here, we investigate oxygen isotope systematics at Wellington Caves in semi-arid, SE Australia, where evapotranspiration exceeds precipitation. We use a novel D2O isotopic tracer in a series of artificial irrigations, supplemented by pre-irrigation data comprised four years of drip monitoring and three years of stable isotope analysis of both drip waters and rainfall. This study reveals that: (1) evaporative processes in the unsaturated zone dominate the isotopic composition of drip waters; (2) significant soil zone 'wetting up' is required to overcome soil moisture deficits in order to achieve infiltration, which is highly dependent on antecedent hydro-climatic conditions; (3) lateral flow, preferential flow and sorption in the soil zone are important in redistributing subsurface zone water; (4) isotopic breakthrough curves suggest clear evidence of piston-flow at some drip sites where an older front of water discharged prior to artificial irrigation water; and (5) water residence times in a shallow vadose zone (<2 m) are highly variable and can exceed six months. Oxygen isotope speleothem records from semi-arid regions are therefore more likely to contain archives of alternating paleo-aridity and paleo-recharge, rather than paleo-rainfall e.g. the amount effect or mean annual. Speleothem-forming drip waters will be dominated by evaporative enrichment, up to ˜3‰ in the context of this study, relative to precipitation-weighted mean annual rainfall. The oxygen isotope variability of such coeval records may further be influenced by flow path and storage in the unsaturated zone that is not only

  11. Impact of climate change on surface water resource and tendency in the future in the arid zone of northwestern China

    Institute of Scientific and Technical Information of China (English)

    施雅风; 张祥松

    1995-01-01

    The surface water resource in the arid zone of northwestern China is pregnant in the 6great mountain systems induding snow covers,glaciers,rivers and lakes.Though the climate fluctuates,becoming warmer and drier,and the water resource trends to wither during the 20th century,it is evident thatin the Holocene Megathermal there would be a more plentiful water resource.During the Little Ice Age,theglacier area and the amount of runoff and lake water were also higher than those at present.It is estimated thatthe temperature in mountains of western China would be 1℃ warmer by 2030 A.D.,when the precipitationand evaporation would be some higher,the snow cover would be lower in plains and higher in mountains,gla-ciers would retreat further,many small glacier would disappear,river runoff would increase with a highervariability,most of the lakes would be in a negative balance state and would wither further.

  12. Marine isolates of Trichoderma spp. as potential halotolerant agents of biological control for arid-zone agriculture.

    Science.gov (United States)

    Gal-Hemed, Inbal; Atanasova, Lea; Komon-Zelazowska, Monika; Druzhinina, Irina S; Viterbo, Ada; Yarden, Oded

    2011-08-01

    The scarcity of fresh water in the Mediterranean region necessitates the search for halotolerant agents of biological control of plant diseases that can be applied in arid-zone agriculture irrigated with saline water. Among 29 Trichoderma strains previously isolated from Mediterranean Psammocinia sp. sponges, the greatest number of isolates belong to the Trichoderma longibrachiatum-Hypocrea orientalis species pair (9), H. atroviridis/T. atroviride (9), and T. harzianum species complex (7), all of which are known for high mycoparasitic potential. In addition, one isolate of T. asperelloides and two putative new species, Trichoderma sp. O.Y. 14707 and O.Y. 2407, from Longibrachiatum and Strictipilosa clades, respectively, have been identified. In vitro salinity assays showed that the ability to tolerate increasing osmotic pressure (halotolerance) is a strain- or clade-specific property rather than a feature of a species. Only a few isolates were found to be sensitive to increased salinity, while others either were halotolerant or even demonstrated improved growth in increasingly saline conditions. In vitro antibiosis assays revealed strong antagonistic activity toward phytopathogens due to the production of both soluble and volatile metabolites. Two marine-derived Trichoderma isolates, identified as T. atroviride and T. asperelloides, respectively, effectively reduced Rhizoctonia solani damping-off disease on beans and also induced defense responses in cucumber seedlings against Pseudomonas syringae pv. lachrimans. This is the first inclusive evaluation of marine fungi as potential biocontrol agents.

  13. Long-term spatio-temporal precipitation variability in arid-zone Australia and implications for groundwater recharge

    Science.gov (United States)

    Acworth, R. Ian; Rau, Gabriel C.; Cuthbert, Mark O.; Jensen, Evan; Leggett, Keith

    2016-06-01

    Quantifying dryland groundwater recharge as a function of climate variability is becoming increasingly important in the face of a globally depleted resource, yet this remains a major challenge due to lack of adequate monitoring and the complexity of processes involved. A previously unpublished and unique dataset of high density and frequency rainfall measurements is presented, from the Fowlers Gap Arid Zone Research Station in western New South Wales (Australia). The dataset confirms extreme spatial and temporal variability in rainfall distribution which has been observed in other dryland areas and is generally explained by the dominance of individual storm cells. Contrary to previous observations, however, this dataset contains only a few localised storm cells despite the variability. The implications of spatiotemporal rainfall variability on the estimation of groundwater recharge is assessed and show that the most likely recharge mechanism is through indirect and localised, rather than direct, recharge. Examples of rainfall and stream gauge height illustrate runoff generation when a spatially averaged threshold of 15-25 mm (depending on the antecedent moisture conditions) is exceeded. Preliminary assessment of groundwater levels illustrates that the regional water table is much deeper than anticipated, especially considering the expected magnitude of indirect and localised recharge. A possible explanation is that pathways for indirect and localised recharge are inhibited by the large quantities of Aeolian dust observed at the site. Runoff readily occurs with water collecting in surface lakes which slowly dry and disappear. Assuming direct groundwater recharge under these conditions will significantly overestimate actual recharge.

  14. LONG-TERM COLLOID MOBILIZATION AND COLLOID-FACILITATED TRANSPORT OF RADIONUCLIDES IN A SEMI-ARID VADOSE ZONE

    Energy Technology Data Exchange (ETDEWEB)

    Markus Flury; James B. Harsh; Fred Zhang; Glendon W. Gee; Earl D. Mattson; Peter C. L

    2012-08-01

    The main purpose of this project was to improve the fundamental mechanistic understanding and quantification of long-term colloid mobilization and colloid-facilitated transport of radionuclides in the vadose zone, with special emphasis on the semi-arid Hanford site. While we focused some of the experiments on hydrogeological and geochemical conditions of the Hanford site, many of our results apply to colloid and colloid-facilitated transport in general. Specific objectives were (1) to determine the mechanisms of colloid mobilization and colloid-facilitated radionuclide transport in undisturbed Hanford sediments under unsaturated flow, (2) to quantify in situ colloid mobilization and colloid-facilitated radionuclidetransport from Hanford sediments under field conditions, and (3) to develop a field-scale conceptual and numerical model for colloid mobilization and transport at the Hanford vadose zone, and use that model to predict long-term colloid and colloid- facilitated radionuclide transport. To achieve these goals and objectives, we have used a combination of experimental, theoretical, and numerical methods at different spatial scales, ranging from microscopic investigationsof single particle attachment and detachment to larger-scale field experiments using outdoor lysimeters at the Hanford site. Microscopic and single particle investigations provided fundamental insight into mechanisms of colloid interactions with the air-water interface. We could show that a moving air water interface (such as a moving water front during infiltration and drainage) is very effective in removing and mobilizing particles from a stationary surface. We further demonstrated that it is particularly the advancing air-water interface which is mainly responsible for colloid mobilization. Forces acting on the colloids calculated from theory corroborated our experimental results, and confirm that the detachment forces (surface tension forces) during the advancing air-water interface

  15. Absent otoacoustic emissions predict otitis media in young Aboriginal children: A birth cohort study in Aboriginal and non-Aboriginal children in an arid zone of Western Australia

    OpenAIRE

    Stokes Annette; Finucane Janine; Elsbury Dimity; Jacoby Peter; Weeks Sharon; Lehmann Deborah; Monck Ruth; Coates Harvey

    2008-01-01

    Abstract Background Otitis media (OM) is the most common paediatric illness for which antibiotics are prescribed. In Australian Aboriginal children OM is frequently asymptomatic and starts at a younger age, is more common and more likely to result in hearing loss than in non-Aboriginal children. Absent transient evoked otoacoustic emissions (TEOAEs) may predict subsequent risk of OM. Methods 100 Aboriginal and 180 non-Aboriginal children in a semi-arid zone of Western Australia were followed ...

  16. Effects of temperature on embryonic and larval development and growth in the natterjack toad (Bufo calamita in a semi-arid zone

    Directory of Open Access Journals (Sweden)

    Sanuy, D.

    2008-06-01

    Full Text Available Temperature affects the duration of embryonic and larval periods in amphibians. Plasticity in time to metamorphosis is especially important in amphibian populations of Mediterranean semi-arid zones where temperatures are high and precipitation is low, increasing the rate of pond desiccation. In order to test the influence of water temperature on the larval development and growth of the natterjack toad (Bufo calamita, we collected two spawns in a semi¿arid zone at Balaguer (Lleida, NE Iberian peninsula. Approximately 50 (+/-10 eggs (stage 14-16 were raised in the lab at different temperature conditions: 10, 15, 20, 22.5 and 25ºC with 12:12 photoperiod. The results show a lengthening of development time with decreasing temperatures and a better survival performance of B. calamita to high temperatures. However, mean size at metamorphosis was not different across treatments, thus, suggesting that this population of B. calamita requires a minimum size to complete the metamorphosis. This study is the first approach to examine the effects that climatic factors have on the growth and development of B. calamita in semi-arid zones.

  17. ANTI- MICROBAL EFFICACY OF MEDICINALLY IMPORTANT PLANTS (C. PHLOMIDIS USED IN FOLKARIC MEDICINES IN ARID ZONE

    Directory of Open Access Journals (Sweden)

    Chahal Jasvinder Kaur

    2012-05-01

    Full Text Available The present investigation was undertaken to evaluate in vivo antimicrobial activity of different extracts (Methanol, Benzene and Aqueous of Clerodendrum phlomidis plants parts. In vivo antimicrobial efficacy of various extracts of Clerodendrum phlomidis was assessed by disc diffusion method against Gram positive - Bacillus subtilis (ATCC 6633, Staphylococcus aureus (ATCC 25923 Gram negative- Escherichia coli (ATCC 25922, Psedomaonas aeruginosa (ATCC 27853 and fungal strains Aspergillus niger (ATCC 16404, Aspergillus flavus (ATCC 9807, Candida albicans (ATCC 5027 and Candida glabrata (ATCC 66032. The methanol leaf extract exhibited highest zone of inhibition against the bacterial stain in S. aureus (15.6±0.6mm with low MIC values (0.078 mg/ml and in the case of fungal strains C. albicans (14.0±0.0mm with low MIC values (0.156 mg/ml.However, none of activity is shown by aqueous extract against pathogenic bacteria. Result of the present investigation indicates that Clerodendrum phlomidis possess compounds with antimicrobial properties and hence can be exploited for future natural plant based antimicrobial agents.

  18. Bacterial community structure and nitrogen transformation in hyporheic zones of arid-land streams

    Science.gov (United States)

    Zeglin, L. H.; Crenshaw, C. L.; Dahm, C. N.; Takacs-Vesbach, C.

    2007-12-01

    Hyporheic zones of desert streams can be areas of high biological activity and consequent nutrient transformation, particularly where land use change increases nutrient concentrations in a stream. Does hyporheic bacterial community composition vary, and does this biotic heterogeneity covary with water and nutrient supply? Bromide (Br-) and 15N-NO3- was injected for 24 hr in six streams (three "natural" reference streams, three streams in agricultural/urbanized catchments) in New Mexico and Arizona, USA. Four transects of 3 to 4 wells were placed along a longitudinal gradient within the study reach, and from these hyporheic water and gas samples were collected during and after each experiment. Gas samples were analyzed for O2, 15N2O, and 15N2. Hyporheic water samples were analyzed for major cations and anions, DOC, 15NO3- and 15NH4+. Bacterial diversity of hyporheic water was assessed using Denaturing Gradient Gel Electrophoresis (DGGE). There was high spatial and temporal variability in hyporheic bacterial community structure, connection with surface water and nutrient concentrations both within and among streams. For example, mean subsurface DGGE band richness per stream ranged from 9 to 21, and surface water comprised between 0 to 100 percent of hyporheic water in each well. There were strong differences in bacterial richness between streams (ANOVA, p nutrient concentration. 15NH4+ levels were higher in modified stream than reference stream subsurface waters, suggesting dissimilatory nitrate reduction to ammonium (DNRA) may be an important process in these hyporheic sediments. Our results to date suggest that though hyporheic microbial community structure is highly heterogeneous, this biological variability may be due to different factors than variability in stream nitrogen cycling function. Further work will identify dominant sequences within these bacterial communities and investigate within-stream heterogeneity.

  19. 干旱区对降水变化响应的研究进展%Progress in the Study on Response of Arid Zones to Precipitation Change

    Institute of Scientific and Technical Information of China (English)

    朱雅娟; 吴波; 卢琦

    2012-01-01

    水分是干旱区的主要限制因子之一,降水是干旱区最重要的水分来源.根据气候变化研究的预测,未来我国干旱区的降水格局会改变,包括降水量、降水频率和降水强度等.降水变化会影响干旱区的土壤变化,植被变化,土地荒漠化和水文变化等方面.我国极端干旱区和干旱区的降水有总体增加趋势,而部分半干旱区和亚湿润干旱区的降水则出现减少趋势.降水的增加能够促进生物土壤结皮的发育,改善土壤水分状况,促进植物生长,提高植被盖度,促使荒漠植被向草原植被方向发展,有利于土地荒漠化的逆转;另外,降水增加会增加河流的径流量和湖泊水量,促进洪水的发生,降水减少则具有相反的效应.这些研究有助于人们预测干旱区在未来降水格局改变之后可能发生的变化,对于天然植被保育以及荒漠化防治等实践工作等具有重要的理论指导意义.未来的研究需要加强实验,如增雨、升温、模拟氮沉降和CO2浓度增加等对干旱区的土壤、植被、荒漠化和水文等方面的影响,才能获得更有说服力的结果.%The pattern of precipitation, including precipitation amount, frequency and intensity, may change in the future according to the prediction of climate change. In arid zones, the soil dynamics, plant growth and vegetation change, desertification and hydrology might be affected by precipitation change. In general, the precipitation in extreme arid zone and arid zone showed an increase tendency whereas the precipitation in some area in semi-arid zone and sub-humid arid zone showed a decrease tendency. The increase of precipitation could enhance the growth of biological soil crust, improve soil water status, promote plant growth, increase vegetation coverage, facilitate the change from desert vegetation to grassland vegetation, and it is benefit to the reversion of land desertification. In addition, the increase of

  20. WEATHER CONDITIONS OF MAIZE VEGETATION IN CONNECTION WITH THE PLANTING DATES IN THE ARID ZONE OF CENTRAL CISCAUCASUSIA

    Directory of Open Access Journals (Sweden)

    Kravchenko R. V.

    2016-02-01

    Full Text Available There were reviewed the results of the study of the dependence of main phenological phases of development of corn hybrids of different maturity groups of the selection of Krasnodar Research Institute of Agriculture named after P.P. Lukyanenko in the arid zone of Central Ciscaucasia (Ross 199, Ross 299, Krasnodar 382 and Krasnodar 410 and the AllRussian Research Institute of Corn (Mashuk 170, Newton, RIC 345 and Eric, as well as early-middle Rossiyskaya 1 from the changes of average daily air temperature of planting dates and preplant seed treatment by the preparation "TMTD-plus", containing the growth promoter called Krezatsin in its composition. The studies were conducted in accordance with the thematic plan of scientific researches of the department of crop and forage production of Stavropol State Agrarian University. The technology of maize growing on the experimental plot corresponds to the standard technology for this area and culture. The sowing was performed in three stages. The first (early sowing period was at t = + 7 ... +8 ° C. The second (recommended – was at t = + 10 ... + 12 ° C. The third (later sowing period was at t = +15 ° C. There was identified a high inverse correlation between the average daily air temperature and the duration of the intraphase periods of maize propagation. Thus, at the shifting of maize sowing dates with the second half of May on the second half of April we have optimization of heat regime in the generative period and rising of the efficiency of use of thermal resources of the region. There was marked the acceleration of development of corn seedlings when the average daily air temperatures was up to 12 ° C at the samples with the application of the disinfectant TMTD-plus

  1. Breeding habitat selection of an endangered species in an arid zone: the case of Alytes dickhilleni Arntzen & García-París, 1995

    Directory of Open Access Journals (Sweden)

    Andrés Egea-Serrano

    2006-11-01

    Full Text Available The influence of environmental variables on the selection of a particular water body as breeding habitat by Alytes dickhilleni was studied in the southeastern and most arid zone of its distribution range. From November 2002 to October 2003, 50 water bodies were monitored in the south east of the Iberian Peninsula. Environmental data were submitted to a stepwise logistic regression analysis at macrohabitat, water body typology and microhabitat scales in order to establish the main factors influencing the use of a given water body as breeding habitat by this species. Statistical analysis showed that the reproduction of Alytes dickhilleni is associated with the macrohabitat variable topography, and the water body typology. This species breeds mainly in permanent water bodies located in mountainous topography in the study area. These results should be taken into account when populations of this species are subjected to management and/or recovery programmes in arid areas.

  2. Semi-arid zone caves: Evaporation and hydrological controls on δ18O drip water composition and implications for speleothem paleoclimate reconstructions

    Science.gov (United States)

    Markowska, Monika; Baker, Andy; Andersen, Martin S.; Jex, Catherine N.; Cuthbert, Mark O.; Rau, Gabriel C.; Graham, Peter W.; Rutlidge, Helen; Mariethoz, Gregoire; Marjo, Christopher E.; Treble, Pauline C.; Edwards, Nerilee

    2016-01-01

    Oxygen isotope ratios in speleothems may be affected by external processes that are independent of climate, such as karst hydrology and kinetic fractionation. Consequently, there has been a shift towards characterising and understanding these processes through cave monitoring studies, particularly focussing on temperate zones where precipitation exceeds evapotranspiration. Here, we investigate oxygen isotope systematics at Wellington Caves in semi-arid, SE Australia, where evapotranspiration exceeds precipitation. We use a novel D2O isotopic tracer in a series of artificial irrigations, supplemented by pre-irrigation data comprised four years of drip monitoring and three years of stable isotope analysis of both drip waters and rainfall. This study reveals that: (1) evaporative processes in the unsaturated zone dominate the isotopic composition of drip waters; (2) significant soil zone 'wetting up' is required to overcome soil moisture deficits in order to achieve infiltration, which is highly dependent on antecedent hydro-climatic conditions; (3) lateral flow, preferential flow and sorption in the soil zone are important in redistributing subsurface zone water; (4) isotopic breakthrough curves suggest clear evidence of piston-flow at some drip sites where an older front of water discharged prior to artificial irrigation water; and (5) water residence times in a shallow vadose zone (flow path and storage in the unsaturated zone that is not only drip specific but also influenced by internal cave climatic conditions, which may vary spatially in the cave.

  3. Biogeochemical anomaly above oil-containing structures in an arid zone. [Growth stimulation of plants by sodium naphthenate used for prospecting

    Energy Technology Data Exchange (ETDEWEB)

    Grishchenko, O.M.

    1983-01-01

    Visual biological anomalies above the oil-containing structures are characterized by bright green coloring of the vegetation cover, gigantism of the plants, extended vegetation period of the plants, deformity of the plants, etc. Biological anomalies are associated with geological features and are observed only above the zone of fault disorders of the earth's crust, above deep faults. A conclusion is drawn about the presence above the oil-bearing structures in the arid zone of a biogeochemical anomaly whose origin is explained by the biological activity of oil and its derivatives. The petroleum growth matter is the sodium salt of naphthene acid, a growth stimulator of plants and animals. The oils of the USSR contain 0.8-4.8% naphthene acids, which effuse through the faults into the root area levels of the soil. As a result of stimulation of growth and development by the petroleum growth matter, the vegetation period of the plants is prolonged. Under the influence of natural petroleum growth substances, the height and productivity of the anomalous plants increases 2-3-fold. Formation and manifestation of signs of biogeochemical anomalies above the oil-bearing structures in the arid zone predetermine the following conditions: presence of fault disorders of the earth's crust; salinity of the root area of the soil layer necessary for neutralization of the naphthene acids with subsequent formation of the biologically active naphthenates; aridity of the desert landscape; plain relief excluding color diversity in vegetation cover because of nonuniform wetting, etc. The established biogeochemical anomaly can be used in prospecting and exploration of oil, gas and bitumen, and also in determining the fault disorders of the earth's crust.

  4. Ground water input to a rare flood event in an arid zone ephemeral river identified with isotopes and chemistry

    International Nuclear Information System (INIS)

    Various isotope studies in temperate climates have shown that the shallow groundwater component feeding perennial rivers during rainfall events can be more important than surface runoff. We report, here on possibly unique isotopic and chemical evidence of groundwater contributions to a rare Hood event of the ephemeral Auob River during the exceptional rains of 1999/2000 in the arid/semi-arid Kalahari of southeastern Namibia. The recognition of this process was enabled by a detailed knowledge of the isotope hydrology of groundwater in the area and provided insights into aspects of the palaeo-hydrology of the Auob River catchment. (author)

  5. Extracting wetlands information of arid zone based on index method%干旱区湿地信息的指数提取方法

    Institute of Scientific and Technical Information of China (English)

    张芳; 塔西甫拉提·特依拜; 熊黑钢; 丁建丽; 田源

    2011-01-01

    以和田绿洲湿地为研究靶区,针对干旱区特有的地貌、气候特点,利用热红外波段在解译水体、湿地信息方面具有独特的优势,提出了基于热红外特征的干旱区湿地指数AZWI( Arid Zone Wetlands Index),详细叙述了AZWI的计算方法及过程,在总结传统主流方法的基础上,分别采用非监督分类、监督分类、决策树法和AZWI方法对研究区的湿地信息进行提取,并对提取结果进行比较.试验表明:AZWI方法对水层较浅的河床和植被较密的沼泽提取精度较高,生产者精度可达88.5%,产生误差的原因主要有两个,一方面是水体与沼泽之间的阈值划分具有一定的主观性;另一方面沼泽边缘与草地的过渡带容易造成混分.若将坑、塘等水域部分和沼泽统一作为湿地资源考虑,则AZWI对于本研究区湿地资源提取精度可达96.5%.AZWI方法简便易于操作,可以作为干旱区湿地时空分布与动态变化监测的有效技术手段.%The arid zone wetlands are closely related to ecological processes of desert mechanism, but they have obvious environment vulnerability. The arid zone wetlands are an important index factor of environment changes in arid zones. The wandering, constringency and disappearing of arid zone wetlands produce a faithful representation of the quality and capability of oasis which is the only living space for people in arid zones. Taking advantage of remote sensing and spatial data and aiming at particular characteristics of landform and climate in Hotan oasis in Xinjiang, this paper presented an AZWI (Arid Zone Wetlands Index) based on thermal and infrared characteristics by using their powerful capability of identifying water and wetlands in arid areas. The idea and method of constructing AZWI are described in detail. Based on summarizing the traditional methodologies to remotely sense wetlands besides AZWI, several general methods were also applied, including: unsupervised

  6. Tailoring conservation agriculture technologies to West Africa semi-arid zones: Building on traditional local practices for soil restoration

    NARCIS (Netherlands)

    Lahmar, R.; Bationo, B.A.; Lamso, N.D.; Guéro, Y.; Tittonell, P.A.

    2012-01-01

    Low inherent fertility of tropical soils and degradation, nutrient deficiency and water stress are the key factors that hamper rainfed agriculture in semi-arid West Africa. Conservation Agriculture (CA) is currently promoted in the region as a technology to reduce soil degradation, mitigate the effe

  7. Composition and intraspecific chemical variability of the essential oil from Artemisia herba-alba growing wild in a Tunisian arid zone.

    Science.gov (United States)

    Mighri, Hédi; Akrout, Ahmed; El-jeni, Hajer; Zaidi, Slah; Tomi, Félix; Casanova, Joseph; Neffati, Mohamed

    2010-11-01

    The intraspecific chemical variability of essential oils (50 samples) isolated from the aerial parts of Artemisia herba-alba Asso growing wild in the arid zone of Southeastern Tunisia was investigated. Analysis by GC (RI) and GC/MS allowed the identification of 54 essential oil components. The main compounds were β-thujone and α-thujone, followed by 1,8-cineole, camphor, chrysanthenone, trans-sabinyl acetate, trans-pinocarveol, and borneol. Chemometric analysis (k-means clustering and PCA) led to the partitioning into three groups. The composition of two thirds of the samples was dominated by α-thujone or β-thujone. Therefore, it could be expected that wild plants of A. herba-alba randomly harvested in the area of Kirchaou and transplanted by local farmers for the cultivation in arid zones of Southern Tunisia produce an essential oil belonging to the α-thujone/β-thujone chemotype and containing also 1,8-cineole, camphor, and trans-sabinyl acetate at appreciable amounts. PMID:21072770

  8. When to stay, when to go: trade-offs for southern African arid-zone birds in times of drought

    OpenAIRE

    Dean, W. R. J.; Anderson, M. D.; Barnard, P.

    2009-01-01

    Arid environments remind one of the punctuated equilibriumtheory of evolution: they experience long periods of stasis and low productivity, interrupted with episodic rainfall which spurs reproduction and movement. Birds, as highly dispersive organisms, are among the most dramatic indicators of these fluctuations. Here we review birds’ two main strategies, residency and nomadism, and the trade-offs faced by individuals in uncertain times. In general, wet years stimulate higher densities of nes...

  9. Water quality assessment of highly polluted rivers in a semi-arid Mediterranean zone Oued Fez and Sebou River (Morocco)

    OpenAIRE

    Perrin, Jean-Louis; Rais, N; Chahinian, Nanée; Moulin, P.; Ijjaali, M.

    2014-01-01

    Oued Fez (one of the Sebou River tributaries - Morocco) allowed us to study and quantify the effect of the lack of wastewater treatment on surface water quality in semi-arid hydrological context. The analysis is based on field data collected from June 2009 to December 2011. Concentration and load patterns of nitrogen, phosphorus and chromium (used in the processing of leather) are compared in stable hydrological conditions during low flow and high flow periods in an eight-location sampling ne...

  10. Integrating variations in the soil chloride profile and evaporativity for in-situ estimation of evaporation in arid zones: an application in south-eastern Morocco

    Science.gov (United States)

    Bouhlassa, Saïdati; Ammary, Bouchaib; Paré, Samuel; Safsaf, Naima

    2016-06-01

    In arid regions, knowledge of the evaporation rate from the water table is essential for appropriate management of scarce resources and to prevent land degradation. Soil chloride profiles in the unsaturated zone of a bare soil in an arid area of south-eastern Morocco were used to assess the evaporation flux, using chloride inventories in conjunction with evaporative demand. Moisture fluxes were calculated from measured chloride concentrations on the basis of a steady-state flow model. The chloride profiles displayed large variations in concentrations and had (1) low chloride concentrations near the soil surface, (2) maximum chloride concentrations at depths of 11-14 cm beneath the soil surface, respectively in July and February, and (3) gradually decreasing chloride concentrations while depth increased below these peaks. Evaporative demands were found to be inversely proportional to the depth of evaporation fronts and proportional to evaporation fluxes. In addition, the evaporation along the profiles seems to be controlled by the soil composition and texture. The investigation of chloride profiles in February and July enabled the determination of a value for annual evaporation (˜30 mm), which is in good agreement with the value estimated by the Allison-Barnes type model (˜32 mm).

  11. Ground water input to a rare flood event in an arid zone ephemeral river identified with isotopes and chemistry

    International Nuclear Information System (INIS)

    Various isotope studies in temperate climates have shown that the shallow groundwater component feeding perennial rivers during rainfall events can be more important than surface runoff, We report here on possibly unique isotopic and chemical evidence of groundwater contributions to a rare flood event of the ephemeral Auob River during the exceptional rains of 1999/2000 in the arid/semiarid Kalahari of south-eastern Namibia. The recognition of this process was enabled by a detailed knowledge of the isotope hydrology of groundwater in the area and provided insights into aspects of the palaeo-hydrology of the Auob River catchment. (author)

  12. Soil moisture transport in arid site vadose zones. [Evaluation of Hanford as national site for radioactive waste storage

    Energy Technology Data Exchange (ETDEWEB)

    Brownell, L.E.; Backer, J.G.; Isaacson, R.E.; Brown, D.J.

    1975-07-01

    Data are presented from measurements of soil moisture at the Hanford Reservation. Possible mechanisms for moisture transport in arid and semi-arid climates were studied. Measurements for the lysimeter experiment and the thermocouple psychrometer experiment were continued with a new series of measurements using closely spaced sensors installed to a depth of 1.52 meters. During the 1973-1974 water year the percolation envelope of higher moisture content penetrated to a depth of four meters in the closed-bottom lysimeter and then was eliminated by upward transport of water in late summer. Precipitation during the 1973-1974 water year percolated to a depth of about six meters in the open-bottom lysimeter and remains as a residual perched envelope. The increase over normal percolation was due in part to a residual envelope of higher moisture content from the previous water year. Results obtained indicate the advantages of Hanford as a site for a national repository for radioactive waste. (CH)

  13. When to stay, when to go: trade-offs for southern African arid-zone birds in times of drought

    Directory of Open Access Journals (Sweden)

    W.R.J. Dean

    2009-12-01

    Full Text Available Arid environments remind one of the punctuated equilibriumtheory of evolution: they experience long periods of stasis and low productivity, interrupted with episodic rainfall which spurs reproduction and movement. Birds, as highly dispersive organisms, are among the most dramatic indicators of these fluctuations. Here we review birds’ two main strategies, residency and nomadism, and the trade-offs faced by individuals in uncertain times. In general, wet years stimulate higher densities of nests (i.e. smaller territories, larger clutch sizes, unseasonal breeding, and at some times of year, higher breeding success. Rainfall above a certain threshold triggers breeding in resident species and an influx of nomadic species which breed and then move on. The environmental cues which trigger nomadism are sometimes poorly understood, but include distant thunderstorms for aquatic species, and perhaps for insectivores. Environmental cues that draw nomadic granivores to areas that have had recent rain are not known.

  14. Appraisal of nuclear waste isolation in the vadose zone in arid and semiarid regions (with emphasis on the Nevada Test Site)

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, H.A.; Wang, J.S.Y.; Korbin, G.

    1983-05-01

    An appraisal was made of the concept of isolating high-level radioactive waste in the vadose zone of alluvial-filled valleys and tuffaceous rocks of the Basin and Range geomorphic province. Principal attributes of these terranes are: (1) low population density, (2) low moisture influx, (3) a deep water table, (4) the presence of sorptive rocks, and (5) relative ease of construction. Concerns about heat effects of waste on unsaturated rocks of relatively low thermal conductivity are considered. Calculations show that a standard 2000-acre repository with a thermal loading of 40 kW/acre in partially saturated alluvium or tuff would experience an average temperature rise of less than 100{sup 0}C above the initial temperature. The actual maximum temperature would depend strongly on the emplacement geometry. Concerns about seismicity, volcanism, and future climatic change are also mitigated. The conclusion reached in this appraisal is that unsaturated zones in alluvium and tuff of arid regions should be investigated as comprehensively as other geologic settings considered to be potential repository sites.

  15. Appraisal of nuclear waste isolation in the vadose zone in arid and semiarid regions (with emphasis on the Nevada Test Site)

    International Nuclear Information System (INIS)

    An appraisal was made of the concept of isolating high-level radioactive waste in the vadose zone of alluvial-filled valleys and tuffaceous rocks of the Basin and Range geomorphic province. Principal attributes of these terranes are: (1) low population density, (2) low moisture influx, (3) a deep water table, (4) the presence of sorptive rocks, and (5) relative ease of construction. Concerns about heat effects of waste on unsaturated rocks of relatively low thermal conductivity are considered. Calculations show that a standard 2000-acre repository with a thermal loading of 40 kW/acre in partially saturated alluvium or tuff would experience an average temperature rise of less than 1000C above the initial temperature. The actual maximum temperature would depend strongly on the emplacement geometry. Concerns about seismicity, volcanism, and future climatic change are also mitigated. The conclusion reached in this appraisal is that unsaturated zones in alluvium and tuff of arid regions should be investigated as comprehensively as other geologic settings considered to be potential repository sites

  16. Habitat Fragmentation in Arid Zones: A Case Study of Linaria nigricans Under Land Use Changes (SE Spain)

    Science.gov (United States)

    Peñas, Julio; Benito, Blas; Lorite, Juan; Ballesteros, Miguel; Cañadas, Eva María; Martinez-Ortega, Montserrat

    2011-07-01

    Habitat fragmentation due to human activities is one of the most important causes of biodiversity loss. In Mediterranean areas the species have co-evolved with traditional farming, which has recently been replaced for more severe and aggressive practices. We use a methodological approach that enables the evaluation of the impact that agriculture and land use changes have for the conservation of sensitive species. As model species, we selected Linaria nigricans, a critically endangered plant from arid and semiarid ecosystems in south-eastern Spain. A chronosequence of the evolution of the suitable habitat for the species over more than 50 years has been reconstructed and several geometrical fragmentation indices have been calculated. A new index called fragmentation cadence (FC) is proposed to quantify the historical evolution of habitat fragmentation regardless of the habitat size. The application of this index has provided objective forecasting of the changes of each remnant population of L. nigricans. The results indicate that greenhouses and construction activities (mainly for tourist purposes) exert a strong impact on the populations of this endangered species. The habitat depletion showed peaks that constitute the destruction of 85% of the initial area in only 20 years for some populations of L. nigricans. According to the forecast established by the model, a rapid extinction could take place and some populations may disappear as early as the year 2030. Fragmentation-cadence analysis can help identify population units of primary concern for its conservation, by means of the adoption of improved management and regulatory measures.

  17. Evolution of chemical and isotopic composition of inorganic carbon in a complex semi-arid zone environment: Consequences for groundwater dating using radiocarbon

    Science.gov (United States)

    Meredith, K. T.; Han, L. F.; Hollins, S. E.; Cendón, D. I.; Jacobsen, G. E.; Baker, A.

    2016-09-01

    Estimating groundwater age is important for any groundwater resource assessment and radiocarbon (14C) dating of dissolved inorganic carbon (DIC) can provide this information. In semi-arid zone (i.e. water-limited environments), there are a multitude of reasons why 14C dating of groundwater and traditional correction models may not be directly transferable. Some include; (1) the complex hydrological responses of these systems that lead to a mixture of different ages in the aquifer(s), (2) the varied sources, origins and ages of organic matter in the unsaturated zone and (3) high evaporation rates. These all influence the evolution of DIC and are not easily accounted for in traditional correction models. In this study, we determined carbon isotope data for; DIC in water, carbonate minerals in the sediments, sediment organic matter, soil gas CO2 from the unsaturated zone, and vegetation samples. The samples were collected after an extended drought, and again after a flood event, to capture the evolution of DIC after varying hydrological regimes. A graphical method (Han et al., 2012) was applied for interpretation of the carbon geochemical and isotopic data. Simple forward mass-balance modelling was carried out on key geochemical processes involving carbon and agreed well with observed data. High values of DIC and δ13CDIC, and low 14CDIC could not be explained by a simple carbonate mineral-CO2 gas dissolution process. Instead it is suggested that during extended drought, water-sediment interaction leads to ion exchange processes within the top ∼10-20 m of the aquifer which promotes greater calcite dissolution in saline groundwater. This process was found to contribute more than half of the DIC, which is from a mostly 'dead' carbon source. DIC is also influenced by carbon exchange between DIC in water and carbonate minerals found in the top 2 m of the unsaturated zone. This process occurs because of repeated dissolution/precipitation of carbonate that is dependent on

  18. Effect of Wetting-Drying Cycles on Redistribution of Lead in Some Semi-Arid Zone Soils Spiked with a Lead Salt

    Institute of Scientific and Technical Information of China (English)

    H.KHODAVERDILOO; M.RAHMANIAN; S.REZAPOUR; S.GHORBANI DASHTAKI; H.HADI; F.X.HAN

    2012-01-01

    Mobility and bioavailability of lead (Pb) could be affected considerably by soil physicochemical properties; however,less is known about the effect of Pb levels and aging time.This study was conducted to evaluate the effects of Pb levels and wetting-drying (WD) cycles on distribution and bioavailability of Pb in three semi-arid zone soils treated with different levels of Pb(NO3)2.Wetting-drying cycles simulated the actual field irrigation in the semi-arid soils.A soil with a long history of Pb contamination was also taken as a reference soil.The soils were spiked with various levels of Pb and incubated under WD cycles for 160 d.Sequential extractions and batch sorption experiments were performed to assess the fractionation of Pb in the spiked soils.Redistribution index (Uts) and reduced partitioning parameter (IR) were applied to semi-quantify the distribution of Pb in the spiked soils.A small amount of Pb sorbed was desorbed by the soils,indicating a strong and irreversible binding of Pb in the studied soils.Contribution of carbonate-bound (Car) and residual (Res) Pb fractions to the total Pb of the soils was more than 97%.The Car,soluble plus exchangeable (SE),and organic matter-bound (OMB) fractions of Pb were transferred to the Res fraction under the WD cycles.The IR and Uts values were influenced by Pb loading levels and WD; therefore,the Pb lability and/or redistribution pattern could semi-quantitatively be assessed via these parameters.At the end of the experiment,the IR and Uts values for the Pb salt-spiked soils did not show the quasiequilibrium state.The lability of Pb in the soils decreased with increasing incubation time and showed a strong dependence on Pb levels and soil chemical composition.WD cycles significantly affected the overall lability of Pb in soils through influencing the redistribution of Pb among solid-phase components.

  19. The use of unsaturated zone solutes and deuterium profiles in the study of groundwater recharge in the semi-arid zone of Nigeria

    International Nuclear Information System (INIS)

    Two unsaturated zone profiles (MF and MG) in NE Nigeria have been sampled for inert tracers (Cl, Br, NO3 and δ2H to investigate recharge rates and processes. The upper MF and MG profiles have sandy lithology, lower moisture content (2H around -30 per mille. All these indicate that present day recharge is taking place. The lower section of the MF profile shows a distinct contrast with high moisture content (up to 27%), very high chloride (average 2892 mg/L) and relatively enriched deuterium (-12 per mille), indicating the effect of evaporative enrichment. This lower section corresponds to low permeability lacustrine deposits probably representing the former bed of Lake Chad where little or no infiltration has been occurring since the mid-Holocene when the lake extended over this area. The sand-covered areas of the Sahel of the NE Nigeria provide an important phreatic aquifer. An estimation of the amount of recharge using the unsaturated zone chloride mass balance gives significant rates of 14 mm/a and 22 mm/a for the upper MF and MG profiles respectively. These rates mainly span the period of the recent Sahel drought and even higher recharge rates may occur during wetter periods. These rates fall within the 14 mm/a to 53 mm/a range estimated for the Manga Grasslands area in the NE Nigeria obtained in an earlier study. From the water resource point of view, the region has potential for perennially-recharged groundwater resources that can sustain the present abstraction level which is mainly via dug wells. (author)

  20. Influence of climate variability on water partitioning and effective energy and mass transfer in a semi-arid critical zone

    Science.gov (United States)

    Zapata-Rios, Xavier; Brooks, Paul D.; Troch, Peter A.; McIntosh, Jennifer; Rasmussen, Craig

    2016-03-01

    The critical zone (CZ) is the heterogeneous, near-surface layer of the planet that regulates life-sustaining resources. Previous research has demonstrated that a quantification of the influxes of effective energy and mass transfer (EEMT) to the CZ can predict its structure and function. In this study, we quantify how climate variability in the last 3 decades (1984-2012) has affected water availability and the temporal trends in EEMT. This study takes place in the 1200 km2 upper Jemez River basin in northern New Mexico. The analysis of climate, water availability, and EEMT was based on records from two high-elevation SNOTEL stations, PRISM data, catchment-scale discharge, and satellite-derived net primary productivity (MODIS). Results from this study indicated a decreasing trend in water availability, a reduction in forest productivity (4 g C m-2 per 10 mm of reduction in precipitation), and decreasing EEMT (1.2-1.3 MJ m2 decade-1). Although we do not know the timescales of CZ change, these results suggest an upward migration of CZ/ecosystem structure on the order of 100 m decade-1, and that decadal-scale differences in EEMT are similar to the differences between convergent/hydrologically subsidized and planar/divergent landscapes, which have been shown to be very different in vegetation and CZ structure.

  1. [Inventory of reptiles in 2 semi-arid zones from Northeastern of the Peninsula de Araya, Sucre State, Venezuela].

    Science.gov (United States)

    Pablo Cornejo, E; Antulio Prieto, A

    2001-01-01

    The fauna of reptiles in two localities from Northeastern Peninsula de Araya (Guayacán and El Morahal), Sucre State, Venezuela, was evaluated. Both zones are characterized by a vegetation of thorny tropical mount type, and semiarid climate of scarce precipitations (less than 700 mm). Field trips were made between june 1997 and june 1998. The samples were collected both during day and night, with the aid of conventional accessories. The information was complemented with visual registrations and bibliography revision. A total of 21 species were captured and/or observed, distributed in 10 families belonging to 2 of the 3 orders present in Venezuela. The most important families from the point of view of the diversity of species, were the Gekkonidae (2.00 bits/species) for the lizards and the Colubridae (2.33 bits/species) among the snakes. It was also reported one species of tortoises and three of cinegetic interest, being Cnemidophorus lemniscatus, Ameiva bifrontata y Tropidurus hispidus the only species of constant presence during the study. PMID:11915444

  2. Absent otoacoustic emissions predict otitis media in young Aboriginal children: A birth cohort study in Aboriginal and non-Aboriginal children in an arid zone of Western Australia

    Directory of Open Access Journals (Sweden)

    Stokes Annette

    2008-08-01

    Full Text Available Abstract Background Otitis media (OM is the most common paediatric illness for which antibiotics are prescribed. In Australian Aboriginal children OM is frequently asymptomatic and starts at a younger age, is more common and more likely to result in hearing loss than in non-Aboriginal children. Absent transient evoked otoacoustic emissions (TEOAEs may predict subsequent risk of OM. Methods 100 Aboriginal and 180 non-Aboriginal children in a semi-arid zone of Western Australia were followed regularly from birth to age 2 years. Tympanometry was conducted at routine field follow-up from age 3 months. Routine clinical examination by an ENT specialist was to be done 3 times and hearing assessment by an audiologist twice. TEOAEs were measured at ages Results At routine ENT specialist clinics, OM was detected in 55% of 184 examinations in Aboriginal children and 26% of 392 examinations in non-Aboriginal children; peak prevalence was 72% at age 5–9 months in Aboriginal children and 40% at 10–14 months in non-Aboriginal children. Moderate-severe hearing loss was present in 32% of 47 Aboriginal children and 7% of 120 non-Aboriginal children aged 12 months or more. TEOAE responses were present in 90% (46/51 of Aboriginal children and 99% (120/121 of non-Aboriginal children aged Overall prevalence of type B tympanograms at field follow-up was 50% (n = 78 in Aboriginal children and 20% (n = 95 in non-Aboriginal children. Conclusion The burden of middle ear disease is high in all children, but particularly in Aboriginal children, one-third of whom suffer from moderate-severe hearing loss. In view of the frequently silent nature of OM, every opportunity must be taken to screen for OM. Measurement of TEOAEs at age 1–2 months to identify children at risk of developing OM should be evaluated in a routine health service setting.

  3. FEATURES OF THE DEVELOPMENT OF CORN HYBRIDS DEPENDING ON THE TERMS OF PLANTING AND TMTD-PLUS DISINFECTANT IN THE ARID ZONE CENTRAL CISCAUCASIA

    Directory of Open Access Journals (Sweden)

    Kravchenko R. V.

    2015-11-01

    Full Text Available There was given the review of the results of the study in the arid zone of Central Ciscaucasia, the influence of planting terms and presowing seed treatment by the drug called "TMTD-plus", containing the growth stimulator Krezatsin in its composition, on the development of corn hybrids of different maturity groups of the selection of Krasnodar Research Institute of Agriculture named after P.P. Lukyanenko (Ross 199, Ross 299, Krasnodar 382 and Krasnodar 410 and the All-Russian Research Institute of Corn (Mashuk 170, Newton, RIC 345 and Eric, as well as middlematurity population Rossiyskaya 1. The studies were conducted in accordance with the thematic plan of scientific researches of the chair of crop and forage production of the Stavropol State Agrarian University. The soil surface was presented as southern black earth. The technology of growing of maize on the experimental plot corresponds to the standard one for the present area and cultivar. The predecessor is winter wheat. Sowing was performed in three terms. The first (early sowing term was carried out at t = + 7 ... +8 ° C. The second (recommended - when t = + 10 ... + 12 ° C. The third (later sowing time was carried out at t = +15 ° C. The plant density: early-maturing hybrids – 70 thousand pieces/ha, is mid-maturing ones – 60 thousand pieces/ha, middle-ripe – 50 thousand piece/ha, middle-later ones – 45 thousand pieces/ha. The scheme is single-row, with spacing of 70 cm. The application of the studied drug TMTD-plus helped to reduce the growing season of maize plants for one - two days. Thus, changing the sowing terms of maize hybrids and populations, we can largely control the development of plants changing the length of the growing season to two weeks and form a harvesting conveyor, thereby reducing the intensity of field work

  4. Timing and causes of gully erosion in the riparian zone of the semi-arid tropical Victoria River, Australia: Management implications

    Science.gov (United States)

    McCloskey, G. L.; Wasson, R. J.; Boggs, G. S.; Douglas, M.

    2016-08-01

    Gully erosion in the seasonally wet tropics of Australia is a major source of sediment in rivers. Stabilization of gullies to reduce impacts on aquatic ecosystems and water storages is a focus for management. However, the cause of the gully erosion is poorly understood and so a critical context for soil conservation is missing. It is uncertain if they are the result of post-European cattle grazing or are they much older and related to non-human factors. The causes of riparian gully erosion along a reach of the Victoria River in the semi-arid tropics of Australia were investigated using several methods. Gully complexes were described and characterised by two major components: a Flood Drainage Channel (FDC) and upslope of this an Outer Erosion Feature (OEF) characterised by badlands set within an amphitheatre. The OEF is likely to be a major source of sediment that appears to be of recent origin. A review of historical records, combined with Optically Stimulated Luminescence (OSL) dating, showed that the FDCs were well established prior to the introduction of domestic stock. It also showed that the badlands began to develop about 90 years ago; that is, about 40 years after the arrival of domestic stock. In addition, an analysis of aerial photos coupled with an on-ground survey and analysis of fallout radionuclides revealed that erosion processes are still active within the gully complexes. While the FDCs are natural drainage channels, cattle grazing probably triggered the badland formation, with the expansion aided by increased rainfall in the past 40 years. Therefore, the OEFs are of human origin and protection from grazing of the riparian zone should slow badland erosion and reduce sediment input to the river.

  5. Isotherms and kinetic study of dihydrogen and hydrogen phosphate ions (H{2}PO{4}- and HPO{4}2-) adsorption onto crushed plant matter of the semi-arid zones of Morocco: Asphodelus microcarpus, Asparagus albus and Senecio anthophorbium

    Science.gov (United States)

    Chiban, M.; Benhima, H.; Saadi, B.; Nounah, A.; Sinan, F.

    2005-03-01

    In the present work H{2}PO4- and HPO42- ions adsorption onto organic matter (OM) obtained from ground dried three plants growing in arid zones of Morocco has been studied. The adsorption process is affected by various parameters such as contact time, particle size and initial concentration of phosphate solution (Ci ≤ 30 mg/l). The uptake of both ions is increased by increasing the concentration of them selves. The retention of phosphate ions by Asphodelus microcarpus, Asparagus albus are well defined by several isotherms such as the Langmuir, Temkin and Freundlich.

  6. Sandy soil plantation in semi-arid zones by polyacrylamide gel conditioner prepared by ionizing radiation. Part of a coordinated programme on radiation modified polymers for biomedical and biochemical applications

    International Nuclear Information System (INIS)

    Polyacrylamide gel prepared by ionizing radiation was found to be capable of furnishing adequate conditions for sandy-soil plantation in semi-arid zones. The gel can be tailored for any soil texture under various climatic conditions. The sand-gel combination maintains three cycles of complete destruction and reformation without significant changes in erosion index. Water holding capacity and retention at different suctions in treated sand are increased. This increases water use efficiency. Fertilizers use efficiency is also increased to almost three times that of fertile clayey soil

  7. Ecological opportunity and the evolution of habitat preferences in an arid-zone bird: implications for speciation in a climate-modified landscape

    OpenAIRE

    Norman, Janette A.; Les Christidis

    2016-01-01

    Bioclimatic models are widely used to investigate the impacts of climate change on species distributions. Range shifts are expected to occur as species track their current climate niche yet the potential for exploitation of new ecological opportunities that may arise as ecosystems and communities remodel is rarely considered. Here we show that grasswrens of the Amytornis textilis-modestus complex responded to new ecological opportunities in Australia’s arid biome through shifts in habitat pre...

  8. Diarrhea in Pre-Weaned Calves: Relative Risk Rates for Morbidity and Mortality in 13 Commercial Farms of Hot Arid Zone

    OpenAIRE

    M. A. Razzaque; Al-Mutawa, T; S.A. MOHAMMED

    2010-01-01

    Problem statement: In many hot arid countries, pregnant Holstein Friesian heifers are imported for herd replacement. The calves obtained from exotic cows are exposed to adverse climate in feedlot system resulting in very high morbidity and mortality rates. Diarrhea, dehydration and deaths are causing a major loss to the producers. This study examines the Risk Rates (RR) for morbidity and mortality in pre-weaned calves. Approach: Thirteen commercial dairy farms of small, me...

  9. Quelques problèmes du gisement et de l'exploitation des eaux souterraines en zone aride, Koweit (Arabie Nord-Est)

    OpenAIRE

    Abusada, Saïd Mohammed

    1980-01-01

    L'Etat du Koweit, étant un pays aride dans lequel beaucoup de travaux intéressants sur les eaux souterraines ont été effectues et dont la plus grande partie des ressources en eaux souterraines est saumâtre, représente un exemple attrayant à considérer par les planificateurs des ressources en eaux et par les étudiants en hydrogéologie, soit pour en profiter dans les pays de conditions similaires, soit pour analyser les questions qu'il pose. Dans ce cadre, le but de cette étude est d'examiner l...

  10. Monitoring Tree Population Dynamics in Arid Zone Through Multiple Temporal Scales: Integration of Spatial Analysis, Change Detection and Field Long Term Monitoring

    Science.gov (United States)

    Isaacson, S.; Rachmilevitch, S.; Ephrath, J. E.; Maman, S.; Blumberg, D. G.

    2016-06-01

    High mortality rates and lack of recruitment in the acacia populations throughout the Negev Desert and the Arava rift valley of Israel have been reported in previous studies. However, it is difficult to determine whether these reports can be evidence to a significant decline trend of the trees populations. This is because of the slow dynamic processes of acaia tree populations and the lack of long term continuous monitoring data. We suggest a new data analysis technique that expands the time scope of the field long term monitoring of trees in arid environments. This will enables us to improve our understanding of the spatial and temporal changes of these populations. We implemented two different approaches in order to expand the time scope of the acacia population field survey: (1) individual based tree change detection using Corona satellite images and (2) spatial analysis of trees population, converting spatial data into temporal data. The next step was to integrate the results of the two analysis techniques (change detection and spatial analysis) with field monitoring. This technique can be implemented to other tree populations in arid environments to help assess the vegetation conditions and dynamics of those ecosystems.

  11. Ecological opportunity and the evolution of habitat preferences in an arid-zone bird: implications for speciation in a climate-modified landscape.

    Science.gov (United States)

    Norman, Janette A; Christidis, Les

    2016-01-01

    Bioclimatic models are widely used to investigate the impacts of climate change on species distributions. Range shifts are expected to occur as species track their current climate niche yet the potential for exploitation of new ecological opportunities that may arise as ecosystems and communities remodel is rarely considered. Here we show that grasswrens of the Amytornis textilis-modestus complex responded to new ecological opportunities in Australia's arid biome through shifts in habitat preference following the development of chenopod shrublands during the late Plio-Pleistocene. We find evidence of spatially explicit responses to climatically driven landscape changes including changes in niche width and patterns of population growth. Conservation of structural and functional aspects of the ancestral niche appear to have facilitated recent habitat shifts, while demographic responses to late Pleistocene climate change provide evidence for the greater resilience of populations inhabiting the recently evolved chenopod shrubland communities. Similar responses could occur under future climate change in species exposed to novel ecological conditions, or those already occupying spatially heterogeneous landscapes. Mechanistic models that consider structural and functional aspects of the niche along with regional hydro-dynamics may be better predictors of future climate responses in Australia's arid biome than bioclimatic models alone. PMID:26787111

  12. MONITORING TREE POPULATION DYNAMICS IN ARID ZONE THROUGH MULTIPLE TEMPORAL SCALES: INTEGRATION OF SPATIAL ANALYSIS, CHANGE DETECTION AND FIELD LONG TERM MONITORING

    Directory of Open Access Journals (Sweden)

    S. Isaacson

    2016-06-01

    Full Text Available High mortality rates and lack of recruitment in the acacia populations throughout the Negev Desert and the Arava rift valley of Israel have been reported in previous studies. However, it is difficult to determine whether these reports can be evidence to a significant decline trend of the trees populations. This is because of the slow dynamic processes of acaia tree populations and the lack of long term continuous monitoring data. We suggest a new data analysis technique that expands the time scope of the field long term monitoring of trees in arid environments. This will enables us to improve our understanding of the spatial and temporal changes of these populations. We implemented two different approaches in order to expand the time scope of the acacia population field survey: (1 individual based tree change detection using Corona satellite images and (2 spatial analysis of trees population, converting spatial data into temporal data. The next step was to integrate the results of the two analysis techniques (change detection and spatial analysis with field monitoring. This technique can be implemented to other tree populations in arid environments to help assess the vegetation conditions and dynamics of those ecosystems.

  13. Effet du biotope sur la diversité floristique et le polymorphisme phénotypique des groupements à Tamarix africana Poir. dans les zones arides de la région de Khenchela (Est Algerien

    Directory of Open Access Journals (Sweden)

    Khabtane Abdelhamid

    2012-12-01

    Full Text Available RESUME Le genre Tamarix (Tamaricaceae regroupe plus de 80 espèces, parmi eux le Tamarix africana Poir. qui représente une très grande ubiquité en Algérie, soit du point de vue climatique (humidité et sécheresse, édaphique (sols salés et calcaires; où il représente l’espèce  à caractère typique des plantes thermo xérophytes. Pour contribuer à la connaissance de cette espèce et de son comportement nous avons essayé de suivre le comportement  phytosociologique ainsi que sa variabilité morphologique (l’hauteur, le recouvrement basale, nombre des ramifications à la base.. dans trois biotopes, extrêmement différents du point de vue climatique et édaphique,  dans les zones steppiques arides de la région de Khenchela (Est Algérien et qui sont  choisis  selon un transect Nord - Sud. Les résultats révèlent que les groupements à Tamarix africana Poir. représentent une richesse floristique importante, qui se diffère d’un site à l’autre, avec un polymorphisme phénotypique adaptée aux conditions spécifiques à chacun des trois sites et qui lui permet d’être l’espèce à forme arbustive  la plus adaptée pour la réhabilitation des écosystèmes dégradés dans les zones de transitions Désert-NordMots clés Tamarix africana P. - ubiquité- thermo xérophytes-  régions arides- halophytes- polymorphisme phénotypique

  14. Disentangling the impacts of climate and human colonization on the flora and fauna of the Australian arid zone over the past 100 ka using stable isotopes in avian eggshell

    Science.gov (United States)

    Miller, Gifford H.; Fogel, Marilyn L.; Magee, John W.; Gagan, Michael K.

    2016-11-01

    Throughout the Quaternary, the flora and fauna of Australia evolved and adapted to the high-amplitude, low- and high-frequency climate changes that characterized the ice-age cycles. However, during the last glacial cycle, between ∼120 and 15 ka, unprecedented irreversible changes in flora and fauna occurred, and in that same interval modern humans established their first firm presence in the landscape. Disentangling the impacts of the first-order trend toward a colder, drier planet through the Late Quaternary from the impacts of human colonization has been challenging, from both the chronological and paleoenvironmental perspectives. We utilize the stable isotopes of carbon and oxygen preserved in near-continuous time series of Dromaius (emu) eggshell from five regions across Australia to provide independent reconstructions of ecosystem status and climate over the past 100 ka. Carbon isotopes are determined by the diet consumed by the female bird, whereas oxygen isotopes record the status of local moisture balance in the months prior to breeding. Together, δ13C and δ18O provide ecosystem status and climate from the same dated sample, reducing correlation uncertainties between proxies. Combined with recent improvements in the chronologies of Late Quaternary shorelines fringing inland lake basins and deflation during arid times, these data collectively reaffirm that Australia generally became increasingly, albeit irregularly, drier from the last interglaciation through to the last glacial maximum. Dromaius eggshell δ18O documents peak aridity between 30 and 15 ka, but shows no evidence of exceptional climate change between 60 and 40 ka. In contrast, Dromaius δ13Cdiet documents an irreversible loss of the majority of palatable summer-rainfall-related C4 grasses across the Australian arid zone between 50 and 45 ka, about the same time that the giant megafaunal bird, Genyornis, became extinct, and coincident with human dispersal across the continent. Our data

  15. Spatial assessment of soil organic carbon and physicochemical properties in a horticultural orchard at arid zone of India using geostatistical approaches.

    Science.gov (United States)

    Singh, Akath; Santra, Priyabrata; Kumar, Mahesh; Panwar, Navraten; Meghwal, P R

    2016-09-01

    Soil organic carbon (SOC) is a major indicator of long-term sustenance of agricultural production system. Apart from sustaining productivity, SOC plays a crucial role in context of climate change. Keeping in mind these potentials, spatial variation of SOC contents of a fruit orchard comprising several arid fruit plantations located at arid region of India is assessed in this study through geostatistical approaches. For this purpose, surface and subsurface soil samples from 175 locations from a fruit orchard spreading over 14.33 ha area were collected along with geographical coordinates. SOC content and soil physicochemical properties of collected soil samples were determined followed by geostatistical analysis for mapping purposes. Average SOC stock density of the orchard was 14.48 Mg ha(-1) for 0- to 30-cm soil layer ranging from 9.01 Mg ha(-1) in Carissa carandas to 19.52 Mg ha(-1) in Prosopis cineraria block. Range of spatial variation of SOC content was found about 100 m, while two other soil physicochemical properties, e.g., pH and electrical conductivity (EC) also showed similar spatial trend. This indicated that minimum sampling distance for future SOC mapping programme may be kept lower than 100 m for better accuracy. Ordinary kriging technique satisfactorily predicted SOC contents (in percent) at unsampled locations with root-mean-squared residual (RMSR) of 0.35-0.37. Co-kriging approach was found slightly superior (RMSR = 0.26-0.28) than ordinary kriging for spatial prediction of SOC contents because of significant correlations of SOC contents with pH and EC. Uncertainty of SOC estimation was also presented in terms of 90 % confidence interval. Spatial estimates of SOC stock through ordinary kriging or co-kriging approach were also found with low uncertainty of estimation than non-spatial estimates, e.g., arithmetic averaging approach. Among different fruit block plantations of the orchard, the block with Prosopis cineraria ('khejri') has

  16. Effect of meteorologic conditions on total suspended particulate (TSP) levels and elemental concentration of aerosols in a semi-arid zone (Beer-Sheva, Israel)

    International Nuclear Information System (INIS)

    The total suspended particulate (TSP) levels in Beer-Sheva, situated in a semi-arid area with winds bringing in dust from the surrounding deserts, was measured 41 times between June 1977 and May 1978. The TSP levels are correlated with climatic conditions. High TSP levels (890 +- 250 μg m-3) were found during Sharav conditions and sandstorms (hot, dry weather, typical to this region). Low TSP levels (59 +- 28 μg m-3) were found in the winter following rain. Usual TSP levels were found to be 140 +- 20 μg m-3 occurring during normal weather conditions. The elemental composition of the Beer-Sheva aerosols were determined using instrumental neutron activation analysis (INNA) and X-ray Fluorescence (XRF). The concentrations of the following elements Fe, Na, Br, K, Sm, Au, Sb, Ga, La, Yb, Lu, Se, Hg, Cr, Sc, Rb, Co, Ta and Zn were determined by INNA and Ca, Si, S, Ti, Cl, Pb, Fe, V, Ni and Mn by XRF. Their relative abundances were found to depend on the prevailing TSP level. (Auth.)

  17. 宁夏中部干旱带天然草地气候生产潜力研究%Potential Climatic Productivity of Natural Grassland in the Middle Arid Zone of Ningxia

    Institute of Scientific and Technical Information of China (English)

    马甜; 王俊波; 张治华; 徐秀梅

    2013-01-01

    The annual potential productivity of grassland in the middle arid zone of Ningxia during 1975 to 2006 was estimated according to the ten-day period temperature and precipitation of these years (1975 - 2010) recorded by 10 meteorological observatories using Miami model and Thornthwaite Memorial model. The objects were to analyze the change regulation of the potential climatic productivity and provide a theoretical basis for improving grassland and increasing vegetation. Results showed that the climate in the middle arid zone of Ningxia had a change tendency toward "warm dry". The inter-annual variation range of the grassland potential climatic productivity was 2668. 56~7499. 53 kg · hm-2 · a-1 and the potentiality was large. The grassland potential climatic productivity increased or decreased 58. 68 kg · hm-2 · a-1 with the maximum temperature increasing or decreasing 1℃. The grassland potential climatic productivity increased or decreased 18. 64 kg · hm-2 · a-1 with the annual precipitation increasing or decreasing 1 mm. The annual precipitation and potential climatic productivity in the middle arid zone of Ningxia had an extremely significant linear correlation and the correlation coefficient was 0. 984 ~0. 997, whereas the average annual temperature and potential climatic productivity did not have a significant correlation. Therefore, the natural tolerance, namely potential climatic productivity of the natural grassland of the area, should be considered when planting.%依据宁夏中部干旱带同心县、盐池县等10个代表性气象台站36年(1975-2010年)逐旬气温、降水资料,基于Miami模型和Thornthwaite Memorial模型对宁夏中部干旱带1975-2006年间草地生产潜力作估算,并分析其变化规律,旨在为改良草地、植被恢复提供理论依据.结果表明:宁夏中部干旱带气候具有向“暖干化”变化的趋势,草地气候生产潜力年际变化范围为2668.56~7499.53kg·hm-2·a-1,气候生产潜力较

  18. Diarrhea in Pre-Weaned Calves: Relative Risk Rates for Morbidity and Mortality in 13 Commercial Farms of Hot Arid Zone

    Directory of Open Access Journals (Sweden)

    M. A. Razzaque

    2010-01-01

    Full Text Available Problem statement: In many hot arid countries, pregnant Holstein Friesian heifers are imported for herd replacement. The calves obtained from exotic cows are exposed to adverse climate in feedlot system resulting in very high morbidity and mortality rates. Diarrhea, dehydration and deaths are causing a major loss to the producers. This study examines the Risk Rates (RR for morbidity and mortality in pre-weaned calves. Approach: Thirteen commercial dairy farms of small, medium and large sizes were surveyed using 1,280 newborn calves. A survey was conducted for calves from their birth to weaning at 90 day. Parameters of the study were birth weights, colostrum feeding, growth rate, incidences of diseases, clinical symptoms, post-mortem findings and results of laboratory investigations of samples obtained from sick and dead calves. Calf housing and feeding management of 13 farms were investigated. Results: RR for morbidity and mortality ranged from 0.3-1.00 and being highest during the first week. Most common disease was diarrhea representing 90.6% of the total calves affected. Common pathogens causing diarrhea were E. coli, Salmonella sp. Klebsiella, Pasturella and rotavirus. Relationship between calf management and morbidity RR for diarrhea was significant (r2 = 627, p = 0.01 and the growth rate was positively correlated (r2 = 0.761, p = 0.1. Diarrhea caused a significant negative impact on gross margins of the calf enterprises. Conclusion: Colostrum feeding and housing management were the key factors for causing a high RR for morbidity and mortality. Gross margin loss was significantly influenced by morbidity and mortality RR of calves.

  19. Intercomparison of Aerosol Optical Thickness Derived from MODIS and in Situ Ground Datasets over Jaipur, a Semi-arid Zone in India.

    Science.gov (United States)

    Payra, Swagata; Soni, Manish; Kumar, Anikender; Prakash, Divya; Verma, Sunita

    2015-08-01

    The first detailed seasonal validation has been carried out for the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua satellites Level 2.0 Collection Version 5.1 AOT (τMODIS) with Aerosol Robotic Network (AERONET) Level 2.0 AOT (τAERONET) for the years 2009-2012 over semi-arid region Jaipur, northwestern India. The correlation between τMODIS versus τAERONET at 550 nm is determined with different spatial and temporal size windows. The τMODIS overestimates τAERONET within a range of +0.06 ± 0.24 during the pre-monsoon (April-June) season, while it underestimates the τAERONET with -0.04 ± 0.12 and -0.05 ± 0.18 during dry (December-March) and post-monsoon (October-November) seasons, respectively. Correlation without (with) error envelope has been found for pre-monsoon at 0.71 (0.89), post-monsoon at 0.76 (0.94), and dry season at 0.78 (0.95). τMODIS is compared to τAERONET at three more ground AERONET stations in India, i.e., Kanpur, Gual Pahari, and Pune. Furthermore, the performance of MODIS Deep Blue and Aqua AOT550 nm (τDB550 nm and τAqua550 nm) with τAERONET is also evaluated for all considered sites over India along with a U.S. desert site at White Sand, Tularosa Basin, NM. The statistical results reveal that τAqua550 nm performs better over Kanpur and Pune, whereas τDB550 nm performs better over Jaipur, Gual Pahari, and White Sand High Energy Laser Systems Test Facility (HELSTF) (U.S. site). PMID:26158600

  20. 宁夏中部干旱带不同枣品种有机栽培试验研究%Organic Cultivation Research on Different Varieties of Chinese Jujube in the Central Arid Zone of Ningxia

    Institute of Scientific and Technical Information of China (English)

    陈雀民; 陈晓群; 王建学

    2013-01-01

    [目的]形成该地区特色枣树产业有机生产的关键技术,大幅度地提高果品品质和安全,提升市场竞争力,增加经济效益.[方法]利用当地近原始的环境,集成有机枣果品生产关键技术,并进行试验、研究与示范.[结果]在宁夏中部干旱带的核心区近原始的环境条件下,在生产环境评价的基础上,在不同枣有机栽培关键技术上,通过创新、集成肥料安全使用技术、病虫害有机防控技术,可以达到有机果品生产的目的.[结论]不同枣树有机栽培技术研究是在特定的环境、品种条件下,在关键技术上通过创新,使位于宁夏中部干旱带核心区的枣树特色产业,在大发展的起步期就以高的起点参与市场竞争,推广前景远大.%[Objective] The purpose of this project was to form a kind of organic cultivation system about Chinese jujube in the local area,and increase the fruit quality and safety,market competitiveness and economic benefits.[Method] The key production technology of organic Chinese jujube was integrated by using the local nearly original environment,and then carried out test,research and demonstration.[Result] Under the central arid zone of Ningxia' s nearly original environment,based on ecological environment evaluation,the production goal of organic Chinese jujube could be obtained by developing and integrating the fertilizer safe use technology and the organic prevention and control technology of plant diseases and insect pests according to key different organic cultivation technology of Chinese jujube.[Conclusion] Different organic cultivation technology of Chinese jujube makes the special Chinese jujube industry of the central arid zone of Ningxia have high starting point to join into the market competitiveness by developing in the key technology under the specific environment and varieties,so has a good promotion prospects.

  1. The International Workshop on Environmental Changes and Sustainable Development in Arid and Semi-arid Regions

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Yang; Arthur Conacher

    2007-01-01

    @@ Arid regions,dominated by deserts,are characterized by a severe shortage of moisture,and a lack of perennial and integrated systems of drainage.Distributed over a very large range of temperatures,from the very hot to the very cold zones,arid regions cover about one third of the world's land surface and occur in every continent,including Antarctica.

  2. Simulation analysis on the regulation of overflow ecological water consumption in arid areas——A case study in the Canmrik ecological area of the mainstream zone of the Tarim River

    Institute of Scientific and Technical Information of China (English)

    CHEN Xi; HUANG Yue; QIAN Jing; LIU HaiLong; FENG XianWei; LIU Ying; BAO AnMing; WANG WeiSheng

    2007-01-01

    After analyzing the regulation of overflow ecological water consumption in the Canmrik ecological area of mainstream zone of the Tarim River, in this paper a model of ecological bifurcation is developed, the dynamic overflow process of ecological bifurcation is simulated, and the quantitative relationships between the volume of ecological water consumption and the ecological conservation extent and overflow time are analyzed using GIS, advance of freshet and RS means. The results reveal that the effects of discharge and time of ecological bifurcation on the efficiency of ecological water consumption are significant, there is a geometrical exponential relationship between the efficiency of ecological bifurcation and the water supply with different discharges and different times under the same ecological water consumption, hypsography plays an important role in ecological water consumption, the regulation of ecological water consumption cannot be equated with the ordinary farming irrigation system, a serious water waste will result and the prospective ecological benefits will not be able to be achieved if an ordinary ecological bifurcation is implemented. The efficiency of ecological water consumption can be increased by 30% by selecting the bifurcation schemes in an optimized way, which is of the utmost importance for arid areas with shortage of water resources.

  3. Trace Metals in Groundwater & Vadose Zone Calcite: In Situ Containment & Stabilization of 90Strontium & Other Divalent Metals & Radionuclides at Arid West DOE Sites

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W.; Fujita, Yoshiko; Ferris, F. Grant; Cosgrove, Donna M.; Colwell, Rick S.

    2004-06-01

    Radionuclide and metal contaminants such as 90Sr are present beneath U.S. Department of Energy (DOE) lands in both the groundwater (e.g., 100-N area at Hanford, WA) and vadose zone (e.g., Idaho Nuclear Technology and Engineering Center (INTEC) at the Idaho National Engineering and Environmental Laboratory). In situ containment and stabilization of these contaminants is a cost-effective treatment strategy. However, implementing in situ containment and stabilization approaches requires definition of the mechanisms that control contaminant sequestration. We are investigating the in situ immobilization of radionuclides or contaminant metals (e.g., 90Sr) by their facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Our facilitated approach, shown schematically in Figure 1, relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity. Subsurface urea hydrolysis is catalyzed by the urease enzyme, which may be either introduced with the urea or produced in situ by ubiquitous subsurface urea hydrolyzing microorganisms. Because the precipitation process tends to be irreversible and many western aquifers are saturated with respect to calcite, the co-precipitated metals and radionuclides will be effectively removed from the aqueous phase over the long-term. Another advantage of the ureolysis approach is that the ammonium ions produced by the reaction can exchange with radionuclides sorbed to subsurface minerals, thereby enhancing the availability of the radionuclides for re-capture in a more stable solid phase (co-precipitation rather than adsorption).

  4. Trace Metals in Groundwater and the Vadose Zone Calcite: In Situ Containment and Stabilization of Strontium-90 and Other Divalent Metals and Radionuclides at Arid West DOE

    International Nuclear Information System (INIS)

    Radionuclide and metal contaminants such as strontium-90 are present beneath U.S. Department of Energy (DOE) lands in both the groundwater (e.g., 100-N area at Hanford, WA) and vadose zone (e.g., Idaho Nuclear Technology and Engineering Center at the Idaho National Engineering and Environmental Laboratory). In situ containment and stabilization of these contaminants is a cost-effective treatment strategy. However, implementing in situ containment and stabilization approaches requires definition of the mechanisms that control contaminant sequestration. We are investigating the in situ immobilization of radionuclides or contaminant metals (e.g., strontium-90) by their facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Our facilitated approach, shown schematically in Figure 1, relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity. Subsurface urea hydrolysis is catalyzed by the urease enzyme, which may be either introduced with the urea or produced in situ by ubiquitous subsurface urea hydrolyzing microorganisms. Because the precipitation process tends to be irreversible and many western aquifers are saturated with respect to calcite, the co-precipitated metals and radionuclides will be effectively removed from the aqueous phase over the long-term. Another advantage of the ureolysis approach is that the ammonium ions produced by the reaction can exchange with radionuclides sorbed to subsurface minerals, thereby enhancing the availability of the radionuclides for re-capture in a more stable solid phase (co-precipitation rather than adsorption)

  5. Isotope techniques in water resource investigations in arid and semi-arid regions

    International Nuclear Information System (INIS)

    The Co-ordinated Research Project (CRP) on the Use of Isotope Techniques in Water Resources Investigations in Arid and Semi-arid Regions was initiated with the aim od contributing to the assessment of groundwater resources in arid areas through the use of environmental isotope techniques, and thereby to help in better management of these valuable fresh groundwater resources. The main emphases identified were in three key areas: (i) the evaluation of water balance components such as recharge rate estimation and recharge and discharge cycles at different spatial scales, (ii) paleohydrology and hydroclimatic change and, (iii) anthropogenic impacts and the assessment of the vulnerability of arid zone ground waters to salinisation and pollution impacts. This publication presents individual projects carried out within the frameworks of the CRP. Each paper has been indexed separately

  6. The Kibbutz landscape in arid zones

    Energy Technology Data Exchange (ETDEWEB)

    Sebba, R.; Enis, R.; Hoffman, M.E.

    1984-11-01

    This paper reports the preliminary stage of a research project on the role of landscaping with reference to human needs. The central premise is a correlation between the character of the vegetation and the phase of its appearance in a settlement on one hand, and the level of need it is designed to cater for on the other. The project was conducted in four kibbutz-type settlements in Israel's Negev desert where gardens were planted at a very early phase, characterized by extreme scarcity of resources. Results were obtained with the means of: micro- and macroclimatological data, including measurements of temperature, relative humidity, solar radiation, and wind speed; a historical survey based on data from kibbutz archives, and questionnaires of individual members.

  7. Ecological aspects of nephrolithiasis in arid zone

    International Nuclear Information System (INIS)

    The ecological aspects of Mangystau region were studied, which is considered to be the waterless area of Kazakhstan according to its climatic and geographic conditions. Also the water quality from the water sources and its micro- and macro- chemical structure were tested for the 10 years period, its pollution was shown. The analysis of samples produced oil at the Mangyshlak Peninsula proved that concentration of microelements with toxic effect (they are vanadium and molybdenum) exceeds allowed norm considerably

  8. Waste biorefinery in arid/semi-arid regions.

    Science.gov (United States)

    Bastidas-Oyanedel, Juan-Rodrigo; Fang, Chuanji; Almardeai, Saleha; Javid, Usama; Yousuf, Ahasa; Schmidt, Jens Ejbye

    2016-09-01

    The utilization of waste biorefineries in arid/semi-arid regions is advisable due to the reduced sustainable resources in arid/semi-arid regions, e.g. fresh water and biomass. This review focuses on biomass residues available in arid/semi-arid regions, palm trees residues, seawater biomass based residues (coastal arid/semi-arid regions), and the organic fraction of municipal solid waste. The present review aims to describe and discuss the availability of these waste biomasses, their conversion to value chemicals by waste biorefinery processes. For the case of seawater biomass based residues it was reviewed and advise the use of seawater in the biorefinery processes, in order to decrease the use of fresh water. PMID:27072789

  9. VOCs in Arid soils: Technology summary

    International Nuclear Information System (INIS)

    The Volatile Organic Compounds In Arid Soils Integrated Demonstration (VOC-Arid ID) focuses on technologies to clean up volatile organic compounds and associated contaminants in soil and groundwater at arid sites. The initial host site is the 200 West Area at DOE's Hanford site in southeastern Washington state. The primary VOC contaminant is carbon tetrachloride, in association with heavy metals and radionuclides. An estimated 580--920 metric tons of carbon tetrachloride were disposed of between 1955 and 1973, resulting in extensive soil and groundwater contamination. The VOC-Arid ID schedule has been divided into three phases of implementation. The phased approach provides for: rapid transfer of technologies to the Environmental Restoration (EM-40) programs once demonstrated; logical progression in the complexity of demonstrations based on improved understanding of the VOC problem; and leveraging of the host site EM-40 activities to reduce the overall cost of the demonstrations. During FY92 and FY93, the primary technology demonstrations within the ID were leveraged with an ongoing expedited response action at the Hanford 200 West Area, which is directed at vapor extraction of VOCs from the vadose (unsaturated) zone. Demonstration efforts are underway in the areas of subsurface characterization including: drilling and access improvements, off-gas and borehole monitoring of vadose zone VOC concentrations to aid in soil vapor extraction performance evaluation, and treatment of VOC-contaminated off-gas. These current demonstration efforts constitute Phase 1 of the ID and, because of the ongoing vadose zone ERA, can result in immediate transfer of successful technologies to EM-40

  10. 宁夏中部干旱区定位培肥对耕地土壤微生物的影响%Effect of Positioning Fertilization on Soil Microorganism in Middle Arid Zone of Ningxia

    Institute of Scientific and Technical Information of China (English)

    牛红霞; 马琨

    2015-01-01

    为了探明适宜宁夏中部干旱区的培肥方式,通过长期田间定位培肥,利用BIOLOG技术与田间试验相结合,研究了不同培肥方式对土壤微生物群落结构及功能的影响。结果表明:化肥配施羊粪能有效提高土壤有机质、全氮、速效磷和速效钾的含量,化肥配施生物有机肥提高了碱解氮和全磷含量;化肥配施黄腐酸钾能有效降低土壤中真菌的含量,提高土壤中细菌和放线菌的含量;化肥配施黄腐酸钾为土壤提供了丰富的碳源,可以提高土壤微生物活性,促进土壤微生物功能多样性,提高了土壤对氨基酸、芳香类化合物的利用率。综合分析认为,化肥配施黄腐酸钾对于改善土壤微生物群落结构及功能多样性效果最佳,其次为化肥配施羊粪。%In order to find the suitable soil fertilization approach for the Middle Arid Zone of Ningxia, the effects of different soil fertilization approaches on the structure and function of the soil microbial community were studied through long-term field positioning fertilization and combining the BIOLOG technology with field experiment. The results showed that using fer-tilizer together with sheep manure could upgrade the content of soil organic matter, total nitrogen, available phosphorus and available potassium effectively; using fertilizer together with biological organic fertilizer had improved the nitrogen and phos-phorus content; using fertilizer together with fulvic acid potassium could reduce the content of fungi in the soil, increase the content of bacteria and actinomycetes in the soil effectively; using fertilizer together with fulvic acid potassium provided a rich source of carbon and could improve the soil microbial activity, promote the microbial diversity and had improved the soil’s utilization rate of amino acids and aromatic compound. By comprehensive analysis, it is concluded that the effect of using fertilizer together with

  11. Entomological studies for surveillance and prevention of dengue in arid and semi-arid districts of Rajasthan, India

    Directory of Open Access Journals (Sweden)

    Anil Purohit

    2008-05-01

    Full Text Available Background & objectives: Rajasthan is one of the dengue endemic states of India. Very few studies have been published on entomological aspects of dengue in this state. Owing to water scarcity, inhabitants in desert areas overstore domestic water which leads to the persistence of dengue vectors within the domestic premises. Area specific knowledge on breeding, key containers and seasonal rhythms of vector population is essential for preparing an effective prevention plan against dengue. Present paper reports results of entomological investigations on dengue vectors in arid and semi-arid districts of Rajasthan. Methods: Longitudinal studies were undertaken during 2004–06 in one arid and two semi-arid dengue endemic districts of Rajasthan. Adult and larval Aedes were collected from the randomly selected houses in representative towns and villages with associated details of container types and water storage practices of inhabitants. Results: In urban areas during all the seasons adult house index (AHI of Aedes aegypti was maximum in desert zone (25 and least in semi-arid area with saline river III (1. The difference of AHI during three seasons was statistically significant (c2 = 16.1, p <0.01 for urban; and c2 = 50.71, p < 0.001 for rural. Breeding of Ae. aegypti among urban settings was maximum in desert zone. During all the seasons cement tanks were the key breeding habitats for Ae. aegypti in desert as well as semi-arid areas. Interpretation & conclusion: Water storage habits during summer season emerged to be the risk factor of vector abundance in urban areas of arid and semi-arid settings. A carefully designed study of key containers targeting cement tanks as the primary habitats of mosquito control may lead to commendable results for dengue prevention.

  12. Desempenho agronômico de genótipos de pinhão manso no Semiárido pernambucano Agronomic performance of different genotypes of physic nut in the semi-arid zone of Pernambuco state

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Drumond

    2010-02-01

    Full Text Available Com o objetivo de avaliar o comportamento silvicultural e a produtividade de genótipos de pinhão manso sob condições irrigadas no Semiárido nordestino, um experimento foi implantado na Fazenda Gabriela, localizada no Município de Santa Maria da Boa Vista, Pernambuco (PE. Usou-se o delineamento de blocos ao acaso com 10 tratamentos e três repetições. Os tratamentos constaram de 10 genótipos obtidos da seleção de plantas mais produtivas de um plantio introdutório de pinhão manso em Petrolina-PE. O espaçamento utilizado foi de 3,0 x 2,0m. Cada planta, por ocasião do plantio, foi adubada com 150g de NPK - fórmula 06:24:12. As plantas foram irrigadas semanalmente por gotejamento. Os resultados obtidos aos três meses de idade foram submetidos à análise de variância, sendo as médias comparadas pelo teste de Duncan, considerando-se uma probabilidade de 5%, para identificar a diferença significativa entre os genótipos. Os valores obtidos para os diferentes genótipos aos três meses de idade, para sobrevivência (100%, altura das plantas (1,3m e número de inflorescências por planta (12, não apresentaram diferenças significativas, enquanto que o número de bifurcações, com variação de 3,6 a 5,3 bifurcações por planta, foi significativamente diferente. Por ter se sobressaído dentre os genótipos estudados na avaliação feita aos 12 meses quanto à altura de planta (2,7m, ao diâmetro do caule (6,3cm, ao número de frutos por planta (1.211 e à produção de sementes (3.542kg ha-1, o genótipo 2304 pode ser recomendado para pesquisas com melhoramento vegetal que visem ao aumento da produção de sementes da espécie J. curcas.This research aimed to evaluate the silvicultural behavior and the yield of different genotypes of physic nut under irrigated conditions in the Semi-arid zone of Pernambuco State. An experiment was carried out at Gabriela Farm, located in the municipality of Santa Maria da Boa Vista-PE, Brazil. The

  13. Resistance Status of the Malaria Vector Mosquitoes, Anopheles stephensi and Anopheles subpictus Towards Adulticides and Larvicides in Arid and Semi-Arid Areas of India

    OpenAIRE

    Tikar, S. N.; M J Mendki; Sharma, A K; D. Sukumaran; Veer, Vijay; Prakash, Shri; Parashar, B. D.

    2011-01-01

    Susceptibility studies of malaria vectors Anopheles stephensi Liston (Diptera: Culicidae) and An. subpictus Grassi collected during 2004–2007 from various locations of Arid and Semi-Arid Zone of India were conducted by adulticide bioassay of DDT, malathion, deltamethrin and larvicide bioassay of fenthion, temephos, chlorpyriphos and malathion using diagnostic doses. Both species from all locations exhibited variable resistance to DDT and malathion from majority of location. Adults of both the...

  14. Erosion processes acting in semi-arid climate zone of the Ebro Basin (Bardenas Reales, NE of Spain); Procesos de erosion actuantes en una zona de clima semiarido de la Depresion del Ebro (Bardenas Reales, NE de Espana)

    Energy Technology Data Exchange (ETDEWEB)

    Marin, C.; Desir, G.

    2009-07-01

    Bardenas Reales is an erosive depression located in the central-western part of the Ebro Depression. May different erosion processes act on this zone: gullying, piping, mud slides and armoured mud balls among others that contribute to export great quantity of material outside the basin. Depending on lithology and physico-chemical properties erosion acting processes differ. The knowledge of that processes help us to understand the great amount of soil loss that take place on the studied zone, bigger than those recommended. (Author) 8 refs.

  15. Factores abióticos que influencian la germinación de seis especies herbáceas de la zona árida de Chile Abiotic factors effects influencing the germination of six herbaceous species of Chilean arid zone

    Directory of Open Access Journals (Sweden)

    Paola A Jara

    2006-09-01

    determinadas por las características ambientales del lugar de procedencia y de la época de germinación naturalThe arid zone of northern Chile has a dry climate that prevents the massive emergency of plant species. The exception to this general trend arises when scarce and irregular rainfall events occur, modify the environmental humidity, and stimulate the germination of seeds. The main external factors that modify the internal nature of the seeds are the hydration time, light, temperature and scarification. In this work two questions were addressed: (a is the germination of seeds of arid zones regulated by independent external factors or by a combined array of stimuli? and (b do exist correspondence between laboratory and in situ germinative conditions?. Seeds of six native and endemic herbaceous species of the north of Chile (Cistanthe salsoloides, Leucocoryne purpurea, Pasithea coerulea, Placea amoena, Schizanthus litoralis y Trichopetalum plumosum were subjected to two germination experiments, with factorial combinations of hydration time, temperature, light, dehydration and scarification. Schizanthus litoralis, was subjected to an aditional scarification-dehydration experiment (experiment 3. Results showed a common response of all the species in study to certain external factors. Maximum germination percentages were reached when exceeding a threshold of 96 h of hydration and at temperatures of 10 to 25 ºC. Light response was species-dependent. Agreement was found between the germinative conditions determined in laboratory and natural conditions of germination. Therefore, the seeds of plant species of arid zones display similar germinative thresholds and the techniques of germination in laboratory must be determined by the environmental characteristics of the place of origin and the time of natural germination

  16. Paleomadrigueras de roedores, un nuevo método para el estudio del Cuaternario en zonas áridas de Sudamérica Rodent middens, a new method for Quaternary research in arid zones of South America

    Directory of Open Access Journals (Sweden)

    Julio L. Betancourt

    2002-09-01

    formadores. Basados en la experiencia Norteamericana entregamos además, un resumen de los métodos existentes para la detección y análisis de dichos depósitos, los sesgos asociados, así como el aporte potencial que su análisis podría representar en futuros estudios paleoecológicos en las zonas áridas y semiáridas de SudaméricaIn arid and semi-arid regions of South America, historical evidence for climate and vegetation change is scarce despite its importance for determining reference conditions and rates of natural variability in areas susceptible to modern desertification. Normal lines of evidence, such as pollen stratigraphies from lakes, are either rare or unobtainable in deserts; studies of late Quaternary vegetation history are few and generally inconclusive. This gap in knowledge may be corrected with discovery and development of fossil rodent middens in rocky environments throughout arid South America. These middens, mostly the work of Lagidium, Phyllotis, Abrocoma and Octodontomys, are rich in readily identifiable plant macrofossils, cuticles and pollen, as well as vertebrate and insect remains. In the North American deserts, more than 2,500 woodrat (Neotoma middens analyzed since 1960 have yielded a detailed history of environmental change during the past 40,000 years. Preliminary work in the pre-puna, Monte and Patagonian Deserts of western Argentina, the Atacama Desert of northern Chile/southern Peru, the Mediterranean matorral of central Chile, and the Puna of the Andean altiplano suggest a similar potential for rodent middens in South America. Here we borrow from the North American experience to synthesize methodologies and approaches, summarize preliminary work, and explore the potential of rodent midden research in South America

  17. Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region

    Science.gov (United States)

    Fadaei, Hadi; Suzuki, Rikie

    2012-11-01

    Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 μm and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

  18. Experimental Study on Rainfall Harvesting and Microcatchment Model for Ecosystem Rehabilitation in the Transitional Zone Between Arid and Semiarid Regions%干旱半干旱过渡带雨水集流试验与微型生态集雨模式

    Institute of Scientific and Technical Information of China (English)

    李小雁; 高前兆

    2004-01-01

    干旱半干旱过渡带是生态环境变化的敏感和脆弱地带,气候的波动性和人口压力是生态脆弱的根本原因,干旱和半干旱区交界线在丰枯年份的空间摆动幅度最大达110-130km.水资源短缺是制约该区经济发展和生态环境改善的主要因素之一,有限的降水资源是生活和农业生产的主要水源,也是可以通过人为措施开发利用的水源.集水技术操作简单,适应性强,费用低,开发潜力大,从事的生产领域广泛,采用这种技术可以建立新的农业生态系统并改善该区生态环境.分析了干旱半干旱区过渡带降水的时空变异性,确定了250 mm降水量线在丰枯年份的空间摆动幅度.通过野外径流观测试验,系统研究了雨水集流系统集流面的产流特征和集水效率、水质和集水的高效利用,并为脆弱区生态环境建设提出小流域微型生态雨水集流模式.%The transitional zone between arid and semiarid regions of northwest China is the most sensitive ecotone to the global climate change and also a severe land degradation area in China. Climate fluctuation and population pressure are the main reasons resulting in the vulnerability of the regional ecology.The 250 mm isohyet is used as the climatic boundary line between arid and semiarid region and it shifts at a maximum distance of 110-130 km during the extreme dry and wet year. Precipitation is the major water source for domestic use, agricultural production and environmental improvement in this transitional area, and it has a great effect on the functions of the ecosystem. Characterized by simple operation, high adaptation and low cost, rainwater-harvesting techniques have a great potential to be used in many aspects and would provide the possibilities of setting up new agricultural ecological system and whereby improve ecological environments in the semiarid regions. This study deals with precipitation fluctuations in the transitional zone between

  19. ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 87016 CO-PRECIPITATION OF TRACE METALS IN GROUNDWATER AND VADOSE ZONE CALCITE: IN SITU CONTAINMENT AND STABILIZATION OF STRONTIUM-90 AND OTHER DIVALENT METALS AND RADIONUCLIDES AT ARID WESTERN DOE SITES

    International Nuclear Information System (INIS)

    Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) weapons complex. In situ containment and stabilization of these contaminants in vadose zones or groundwater is a cost-effective treatment strategy. Our facilitated approach relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal coprecipitation) by increasing groundwater pH and alkalinity (Fujita et al., 2000; Warren et al., 2001). Subsurface urea hydrolysis is catalyzed by the urease enzyme, which may be either introduced with the urea or produced in situ by ubiquitous subsurface urea hydrolyzing microorganisms. Because the precipitation processes are irreversible and many western aquifers are saturated with respect to calcite, the co-precipitated metals and radionuclides will be effectively removed from groundwater. The rate at which trace metals are incorporated into calcite is a function of calcite precipitation kinetics, adsorption interactions between the calcite surface and the trace metal in solution (Zachara et al., 1991), solid solution properties of the trace metal in calcite (Tesoriero and Pankow, 1996), and also the surfaces upon which the calcite is precipitating. A fundamental understanding of the coupling of calcite precipitation and trace metal partitioning, and how this occurs in aquifers and vadose environments is lacking. This report summarizes work undertaken during the second year of this project

  20. Trace Metals in Groundwater and Vadose Zone Calcite: In Situ Containment and Stabilization of Strontium-90 and Other Divalent Metals and Radionuclides at Arid Western DOE Sites: Final Report for Award Number DE-FG07-02ER63486 to the University of Idaho (RW Smith) Environmental Management Science Program Project Number 87016

    International Nuclear Information System (INIS)

    Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) energy research and weapons complex. In situ containment and stabilization of these contaminants represents a cost-effective treatment strategy that minimizes workers exposure to hazardous substances, does not require removal or transport of contaminants, and generally does not generate a secondary waste stream. We have investigated an in situ bioremediation approach that immobilizes radionuclides or contaminant metals (e.g., strontium-90) by their microbially facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Calcite, a common mineral in many aquifers and vadose zones in the arid west, can incorporate divalent metals such as strontium, cadmium, lead, and cobalt into its crystal structure by the formation of a solid solution. Collaborative research undertaken by the Idaho National Laboratory (INL), University of Idaho, and University of Toronto as part of this Environmental Management Science Program project has focused on in situ microbially-catalyzed urea hydrolysis, which results in an increase in pH, carbonate alkalinity, ammonium, calcite precipitation, and co-precipitation of divalent cations. In calcite-saturated aquifers, microbially facilitated co-precipitation with calcium carbonate represents a potential long-term contaminant sequestration mechanism. Key results of the project include: **Demonstrating the linkage between urea hydrolysis and calcite precipitation in field and laboratory experiments **Observing strontium incorporation into calcite precipitate by urea hydrolyzers with higher distribution coefficient than in abiotic **Developing and applying molecular methods for characterizing microbial urease activity in groundwater including a quantitative PCR method for enumerating ureolytic bacteria **Applying the suite of developed molecular methods to assess the feasibility of the

  1. Trace Metals in Groundwater and Vadose Zone Calcite: In Situ Containment and Stabilization of Stronthium-90 and Other Divalent Metals and Radionuclides at Arid Western DOE Sites: Final Report for Award Number DE-FG07-02ER63486 to the University of Idaho (RW Smith) Environmental Management Science Program Project Number 87016

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W.; Fujita, Yoshiko

    2007-11-07

    Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) energy research and weapons complex. In situ containment and stabilization of these contaminants represents a cost-effective treatment strategy that minimizes workers’ exposure to hazardous substances, does not require removal or transport of contaminants, and generally does not generate a secondary waste stream. We have investigated an in situ bioremediation approach that immobilizes radionuclides or contaminant metals (e.g., strontium-90) by their microbially facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Calcite, a common mineral in many aquifers and vadose zones in the arid west, can incorporate divalent metals such as strontium, cadmium, lead, and cobalt into its crystal structure by the formation of a solid solution. Collaborative research undertaken by the Idaho National Laboratory (INL), University of Idaho, and University of Toronto as part of this Environmental Management Science Program project has focused on in situ microbially-catalyzed urea hydrolysis, which results in an increase in pH, carbonate alkalinity, ammonium, calcite precipitation, and co-precipitation of divalent cations. In calcite-saturated aquifers, microbially facilitated co-precipitation with calcium carbonate represents a potential long-term contaminant sequestration mechanism. Key results of the project include: **Demonstrating the linkage between urea hydrolysis and calcite precipitation in field and laboratory experiments **Observing strontium incorporation into calcite precipitate by urea hydrolyzers with higher distribution coefficient than in abiotic **Developing and applying molecular methods for characterizing microbial urease activity in groundwater including a quantitative PCR method for enumerating ureolytic bacteria **Applying the suite of developed molecular methods to assess the feasibility of the

  2. New crops for arid lands.

    Science.gov (United States)

    Hinman, C W

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential of arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required.

  3. Management of nutrients and water in rainfed arid and semi-arid areas. Proceedings of a consultants meeting

    International Nuclear Information System (INIS)

    Sustainable food security is needed for the arid and semi-arid regions of the tropical, subtropical and warm-temperate climatic zones. In these regions the supply of locally grown food is unreliable because much of it is produced in conditions of highly variable rainfall. Even in favourable seasons, these regions re becoming increasingly dependent on imported food. The IAEA's involvement in field studies on soil-water use dates back several years. A five year Co-ordinated Research Project on ''The Use of Nuclear and Related Techniques in Assessment of Irrigation Schedules of Field Crops to Increase Effective Use of Water in Irrigation Projects''. That project, completed in 1995, laid a solid foundation for future research. Because of a scarcity of water in many developing countries and increasing needs for sustainable food security in the face of increasing populations and lack of funds for irrigation schemes of significant dimension, research must focus on improved management of (i) the modest quantities of fertilizers that are available to farmers, (ii) the natural resources that are available to farmers for increasing soil organic matter content, and (iii) rain water. The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture held a Consultants Meeting on Management of Nutrients and Water in Rainfed Arid and Semi-Arid Areas for Increasing Crop Production, 26-29 May 1997

  4. a Proposed New Vegetation Index, the Total Ratio Vegetation Index (trvi), for Arid and Semi-Arid Regions

    Science.gov (United States)

    Fadaei, H.; Suzuki, R.; Sakai, T.; Torii, K.

    2012-07-01

    Vegetation indices that provide important key to predict amount vegetation in forest such as percentage vegetation cover, aboveground biomass, and leaf-area index. Arid and semi-arid areas are not exempt of this rule. Arid and semi-arid areas of northeast Iran cover about 3.4 million ha and are populated by two main tree species, the broadleaf Pistacia vera (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but also genetically essential as seed sources for pistachio production in orchards. We investigated the relationships between tree density and vegetation indices in the arid and semi-arid regions in the northeast of Iran by analysing Advanced Land Observing Satellite (ALOS) data PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, and has one band with a wavelength of 0.52-0.77 μm (JAXA EORC). AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, and has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm) (JAXA EORC). In this study, we estimated various vegetation indices using maximum filtering algorithm (5×5) and examined. This study carried out of juniper forests and natural pistachio stand using Advanced Land Observing Satellite (ALOS) and field inventories. Have been compared linear regression model of vegetation indices and proposed new vegetation index for arid and semi-arid regions. Also, we estimated the densities of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. We present a new vegetation index for arid and semi-arid regions with sparse forest cover, the Total Ratio Vegetation Index (TRVI), and we investigate the relationship of the new index to tree density by analysing data from the

  5. A PROPOSED NEW VEGETATION INDEX, THE TOTAL RATIO VEGETATION INDEX (TRVI, FOR ARID AND SEMI-ARID REGIONS

    Directory of Open Access Journals (Sweden)

    H. Fadaei

    2012-07-01

    Full Text Available Vegetation indices that provide important key to predict amount vegetation in forest such as percentage vegetation cover, aboveground biomass, and leaf-area index. Arid and semi-arid areas are not exempt of this rule. Arid and semi-arid areas of northeast Iran cover about 3.4 million ha and are populated by two main tree species, the broadleaf Pistacia vera (pistachio and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper. Natural stands of pistachio in Iran are not only environmentally important but also genetically essential as seed sources for pistachio production in orchards. We investigated the relationships between tree density and vegetation indices in the arid and semi-arid regions in the northeast of Iran by analysing Advanced Land Observing Satellite (ALOS data PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, and has one band with a wavelength of 0.52–0.77 μm (JAXA EORC. AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, and has four multispectral bands: blue (0.42–0.50 μm, green (0.52–0.60 μm, red (0.61–0.69 μm, and near infrared (0.76–0.89 μm (JAXA EORC. In this study, we estimated various vegetation indices using maximum filtering algorithm (5×5 and examined. This study carried out of juniper forests and natural pistachio stand using Advanced Land Observing Satellite (ALOS and field inventories. Have been compared linear regression model of vegetation indices and proposed new vegetation index for arid and semi-arid regions. Also, we estimated the densities of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. We present a new vegetation index for arid and semi-arid regions with sparse forest cover, the Total Ratio Vegetation Index (TRVI, and we investigate the relationship of the new index to tree density by

  6. Preliminary evaluation of selected in situ remediation technologies for Volatile Organic Compound contamination at Arid sites

    Energy Technology Data Exchange (ETDEWEB)

    Lenhard, R.J.; Gerber, M.A.; Amonette, J.E.

    1992-10-01

    To support the Volatile Organic Compounds-Arid Site (VOC-Arid) Integrated Demonstration (ID) in its technical, logistical, institutional, and economical testing of emerging environmental management and restoration technologies. Pacific Northwest Laboratory(a) is evaluating several in situ remediation technologies for possible inclusion in the demonstration. The evaluations are made with respect to the initial focus of the VOC-Arid ID: the carbon tetrachloride contamination at the Hanford Site, where it was disposed to the vadose zone along with other volatile and nonvolatile organic wastes. heavy metals, acids. and radionuclides. The purposes of this report are (1) to identify candidate in situ technologies for inclusion in the program, (2) to evaluate the candidate technologies based on their potential applicability to VOC contamination at arid sites and geologic conditions representative of the ID host site (i.e., Hanford Site), and (3) to prioritize those technologies for future US Department of Energy (DOE) support.

  7. Stability measures in arid ecosystems

    Science.gov (United States)

    Nosshi, M. I.; Brunsell, N. A.; Koerner, S.

    2015-12-01

    Stability, the capacity of ecosystems to persist in the face of change, has proven its relevance as a fundamental component of ecological theory. Here, we would like to explore meaningful and quantifiable metrics to define stability, with a focus on highly variable arid and semi-arid savanna ecosystems. Recognizing the importance of a characteristic timescale to any definition of stability, our metrics will be focused scales from annual to multi-annual, capturing different aspects of stability. Our three measures of stability, in increasing order of temporal scale, are: (1) Ecosystem resistance, quantified as the degree to which the system maintains its mean state in response to a perturbation (drought), based on inter-annual variability in Normalized Difference Vegetation Index (NDVI). (2) An optimization approach, relevant to arid systems with pulse dynamics, that models vegetation structure and function based on a trade off between the ability to respond to resource availability and avoid stress. (3) Community resilience, measured as species turnover rate (β diversity). Understanding the nature of stability in structurally-diverse arid ecosystems, which are highly variable, yields theoretical insight which has practical implications.

  8. Remedial action technology - arid

    International Nuclear Information System (INIS)

    A summary is presented of the low-level waste remedial action program at Los Alamos. The experimental design and progress is described for the experiments on second generation intrusion barriers, subsidence effects on SLB components, moisture cycling effects on chemical transport, and erosion control methodologies. The soil moisture data from the bio-intrusion and moisture cycling experiments both demonstrate the overwhelming importance of vegetation in minimizing infiltration of water through trench covers and backfill. Evaporation, as a water loss component in trench covers, is only effective in reducing soil moisture within 40 cm of the trench cover surface. Moisture infiltrating past the zone of evaporation in unvegetated or poorly vegetated trench covers is in storage and accumulates until drainage out of the soil profile occurs. Judicious selection of vegetation species for revegetating a low-level waste site may prevent infiltration of moisture into the trench and, when coupled with other design features (i.e. trench cover slope, tilling and seeding practice), may greatly reduce problems with erosion. Standard US Department of Agriculture erosion plots, when coupled with a state-of-the-art water balance and erosion model (CREAMS) promises to be highly useful in screening proposed remedial action cover designs for low-level waste sites. The erosion plot configuration allows for complete accounting of the water balance in a soil profile. This feature enables the user to optimize cover designs to minimize erosion and infiltration of water into the trench

  9. Annual plants in arid and semi-arid desert regions

    Institute of Scientific and Technical Information of China (English)

    Xuehua LI; Xiaolan LI; Deming JIANG; Zhimin LIU; Qinghe YU

    2008-01-01

    Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants' seed germination strategies,seedling adaptability mechanism to environments,seed dispersal,and soil seed banks.We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities.Because annual plants have important ecological functions in desert vegetation systems,this study on annual plants will be of great bene-fit to the conservation and restoration of desert ecosys-tems,the rational utilization of resources,and the sustainable development of desert regions.

  10. Canola integration into semi-arid wheat cropping systems of the inland Pacific Northwestern USA

    Science.gov (United States)

    The inland Pacific Northwestern USA (iPNW) wheat-producing region has a diversity of environments and soils, yet it lacks crop diversity and is one of the few semi-arid wheat-growing regions without significant integration of oilseeds. Four major agroecological zones, primarily characterised by wate...

  11. Nutritive valve of some ingrediants from arid zone

    Energy Technology Data Exchange (ETDEWEB)

    Tejada de Hernadex, I.

    1976-01-01

    Vantress chickens 1 week old were given a standard diet of maize and soya or had 25 or 50% jojoba seed meal (Simondsia chinensis) from which most of the wax had been extracted, with lysine or methionine or both or neither. All diets had 20% protein. All chickens given jojoba for 1 week lost weight. For 3 weeks 15 male Wistar rats 28 days old had 30 or 15% guayule leaves (Parthenium argentatum) to replace lucerne meal wholly or partly. All given guayule lost weight and lesions of kidney, lung, liver and spleen were found. For 4 weeks 30 Wistar rats initially 30 days old got 35% of dietary energy from bastard saffron oil or with 25, 50, 75 or 100% of it replaced by oil from seeds of Yucca filifera. There was no difference in growth or feed conversion among groups.

  12. The nature, distribution and formation of pans in arid zones

    Science.gov (United States)

    Goudie, A. S.; Wells, G. L.

    1995-03-01

    Pans, closed depressions, are a widespread feature of many of the world's drylands. By using literature survey, air photographs, topographic maps, orbital photographs and imagery, combined with field work it is possible to describe the major areas where these features occur. Their distribution is controlled to a great extent by the availability of susceptible surfaces. They also develop in certain particular environmental settings: palaeolacustrine basins, palaeodrainages, interdunes, and on coastal plains. Many of the pans have a distinctive morphology while on their lee sides they may have lunette dunes. Many processes combine to create and maintain pans, and these can be considered in a general model which has certain key elements. The first of these is that the area should not be one where fluvial processes are fully integrated. It should also not be one where aeolian accumulation is such as to infill any irregularities in the land's surface. If these two predisposing conditions are fulfilled then under dryland conditions, if susceptible surfaces are present, there are various circumstances that may lead to hollow development and enlargement. Although in some cases such processes as solution, suffosion and animal activities may play a role, we believe that the predominant reason why pans have the characteristics that they do (including their shapes, lunettes, alignments, etc.) is that they result from the operation of the twin processes of salt weathering and aeolian deflation.

  13. Styles and rates of long-term denudation in carbonate terrains under a Mediterranean to hyper-arid climatic gradient

    Science.gov (United States)

    Ryb, U.; Matmon, A.; Erel, Y.; Haviv, I.; Benedetti, L.; Hidy, A. J.

    2014-11-01

    Carbonate minerals, unlike silicates, have the potential to dissolve almost completely and with high efficiency. Thus, in carbonate terrains denudation rate and style (the governing process of denudation, mechanical or chemical) should be more sensitive to climatic forcing. Using 36Cl measurements in 39 carbonate bedrock and sediment samples, we calculate long-term denudation rates across a sharp climatic gradient from Mediterranean to hyper-arid conditions. Our samples were collected along the Arugot watershed, which drains the eastern flank of the Judea Range (central Israel) to the Dead Sea and is characterized by a pronounced rain shadow. Denudation rates of flat-lying bedrock outcrops sampled along interfluves differ by an order of magnitude from ∼20 mm ka-1 in the Mediterranean zone to 1-3 mm ka-1 in the hyper-arid zone. These rates are strongly correlated with precipitation, and thus reflect the importance of carbonate mineral dissolution in the overall denudation process. In contrast, denudation rates of steep bedrock surfaces depend on the hillslope gradient, but only in the hyper-arid climate zone, indicating that mechanical processes dominate the overall hillslope denudation within this zone. The dominance of slope-dependent mechanical erosion in the hyper-arid zone is also reflected by an increase in spatially-average denudation rates from 17-19 mm ka-1 in the Mediterranean-semi-arid zones to 21-25 mm ka-1 in the hyper-arid zone. These higher rates are attributed to clast contribution from steep slopes under arid climate. This suggests an increased importance of mechanical processes to the overall denudation in the hyper-arid zone. We demonstrate that the transition between chemically-dominated denudation to mechanically-dominated denudation occurs between 100 and 200 mm of mean annual precipitation. Long-term denudation rates across the Judea Range indicate that between Mediterranean and hyper-arid climates, chemical weathering rates are limited by

  14. CHARACTERISTICS OF ARIDITY CONDITIONS IN SOUTH DOBRUDJA

    OpenAIRE

    A. TISCOVSCHI; GABRIELA MANEA; O. COCOS; IULIANA VIJULIE; ROXANA CUCULICI

    2013-01-01

    Characteristics of Aridity Conditions in South Dobrudja. For most people, the arid and semi-arid lands are those where precipitation is low (less than 200 mm per year), and yet enough for supplying streams capable of temporarily carrying the debris resulted from weathering, but insufficient for encouraging the development of a vegetal cover meant to protect the soil blanket against eroding agents. The drought is a major and permanent climatic risk for the Dobrudja territory as a whole and for...

  15. Salinization mechanisms in semi-arid regions

    International Nuclear Information System (INIS)

    During a period of three years the basins of the Pereira de Miranda and Caxitore dams, located in the crystalline rock area of Ceara, Brazil, were studied in order to determine the mechanisms of salinization of their waters. Isotope methods (18O/16O) and hidrochemistry (determination of the of the maior ions) were applied to surface, underground and rain water in this study. An isotope model was designed and applied to the determination of evaporation and percolation of dams in semi-arid zones during the dry season. The results are compared to those from a conventional chemical model. As causes of salinization of the water in the dams, the contributions of the rain itself and the lixiviation of the soil are quantified. An interaction between the dams and the underground water is imperceptible. The salinization of the underground water is attributed to recharge of the aquifer with rain water from the surface runoff followed by evaporation of the water rising, due to capilarity, in a one-directional flow to the surface. (Author)

  16. Effect of Partial Root-zone Drying on Potato Water Utilization on Semi-arid Conditions in China%隔沟交替灌溉对我国半干旱地区马铃薯水分利用的影响

    Institute of Scientific and Technical Information of China (English)

    谢开云; 王晓雪; 张若芳; 巩秀峰; 张世彪; MARES Victor; GAVILAN Carla; POSADAS Adolfo; QUIROZ Roberto

    2012-01-01

    隔沟交替灌溉(Partialroot-zonedrying,PRD)被认为是一种节水灌溉的方法,它可以提高多种作物的水分利用率。本研究开展于我国甘肃与内蒙两个半干旱马铃薯种植区,比较常规灌溉与隔沟交替灌溉对马铃薯产量和水分利用率的影响。结果表明,由于两个试验点的气候条件与土壤条件不同,所以马铃薯产量存在显著的差异。但是在两试验点中,PRD。处理(隔沟交替灌溉,灌水量为经验灌水量的1/2)的产量与常规灌溉处理(c100,经验灌水量)的产量没有显著的差别,水分利用率却显著提高。研究显示,运用合理的灌溉方式,可以在保证产量不变的基础上节省用水量。另外,在易发生干旱的地区,选用适合的品种,同时采用覆膜技术对于增加马铃薯产量有着重要的作用。%Partial root-zone drying (PRD) irrigation method was considered as a water-saving irrigation method which could increase the water use efficiency for many crops. To compare the partial root-zone drying as an alternative to the conventional irrigation method used in semi-arid potato producing areas in China and its impact on tuber yield and water use efficiency, field trials were conducted in Gansu and in Inner Mongolia where water was the main constraint to potato production. Due to different soil types and rainfalls, the yield of potatoes in two locations varied remarkably. However, the yield of PRD using half amount of water as conventional irrigation was very close to the yields of the full conventional irrigation method in the two locations. The results showed that water could be dramatically reduced in Inner Mongolia and Gansu without affecting the tuber yields by proper irrigation management. Results also supported the fact that the use of plastic mulching and a variety selected for drought-prone environments could increase the potato yield.

  17. Study of the effect of the nature of aggregates on the mechanical behaviour of the concrete in hot and dry zones «Contribution of the curing» Etude de l’effet de la nature des granulats sur le comportement mécanique du béton en zones chaudes et arides «Contribution de la cure»

    Directory of Open Access Journals (Sweden)

    Bendjillali K.

    2012-09-01

    Full Text Available Laghouat est parmi les villes de l’Algérie riches en matériaux de différentes natures, tels que les roches calcaires massives et les matériaux alluvionnaires meubles siliceux et silico-calcaires. L’objectif premier de ce travail est d’établir une comparaison des performances mécaniques des bétons préparés avec de granulats de natures différentes. Nôtre second objectif est l’étude de l’influence de la cure sur la résistance à la compression et la résistance à la flexion des bétons étudiés. Les échantillons sont conservés sous un climat chaud et sec réel qui est le climat de Laghouat. Nous avons utilisé comme cure: le film plastique, la toile de jute mouillée et l’immersion dans l’eau. A travers ce travail expérimental, nous avons pu constater que les meilleures résistances à la compression sont obtenues dans les bétons à sable siliceux et celles à la flexion sont obtenues dans les bétons à granulats calcaires. La conservation du béton dans une ambiance aride sans protection augmente sa résistance mécanique à jeune âge, mais à long terme, cette dernière chute d’une façon significative. L’étude a mis en évidence la nécessité de l’emploi d’un super plastifiant et de l’application immédiate de la cure pour le bétonnage en climat chaud. Laghouat is among the cities of Algeria rich in materials of various natures, such as the massive limestone rocks and the natural river materials. The first objective of this work is to establish a comparison of the mechanical performances between concretes with aggregates of different natures. The second objective is to study the effect of curing on the compressive and the flexural strength of concretes. Samples are conserved under a real hot and dry climate which is the climate of Laghouat. We used as curing: plastic film, wet hessian and immersing in water. Through this work, we noticed that the best compressive strengths are obtained in concretes

  18. Aridity, desalination plants and tourism in the eastern Canary Islands

    Directory of Open Access Journals (Sweden)

    José-León García-Rodríguez

    2016-05-01

    Full Text Available The islands of Lanzarote and Fuerteventura are the easternmost of the Canary Islands, and are located on the southern edge of the temperate zone, in the subtropical anticyclone belt. With less than 150 mm of rainfall a year, they are classified as an arid zone. Their inhabitants have devised original agricultural systems to combat the aridity, although low yields have historically limited socio-economic development and population growth. These systems were used until the introduction of seawater desalination plants and the arrival of tourism in the last third of the twentieth century, which improved living standards for the local population but also led to a cultural transition. Nevertheless, these farming systems have left behind an important regional heritage, with an environmental and scenic value that has played an integral role in the latest phase of development. The systems have become a tourist attraction and have been central to the two islands being designated biosphere reserves by UNESCO. This article aims to analyse the main socioeconomic and land-use changes that have come about as a result of desalination technology.

  19. Plant species diversity of wetland ecosystem in an arid and semi-arid region in northwest China

    Institute of Scientific and Technical Information of China (English)

    LI Rui; LIU Yunfang; ZHANG Kebin

    2007-01-01

    In order to study the changes of plant species diversity along the biotope gradient and its influencing factors in a wetland-add grassland ecosystem in the add and semi-arid regions of northwest China,four transect lines were set along the biotope gradient in four directions:east,northeast,west and northwest,and altogether 123 sample plots were investigated on species composition,density,foliage cover,height and biomass (calculated in fresh weight).The whole study area was divided into the Wetland zone,the ecotone and the arid grassland zone in terms of habitat characteristics and vegetation types.In this paper,we analyzed and compared the species diversity in the ecotone of a wetland-dry grassland ecosystem in Yanchi County,Ningxia Hui Autonomous Region,with the help of biodiversity software BioDiversity Pro and statistical software Microcal Origin,as well as the combined measurement of species diversity indices.The results revealed distinct differences between those three vegetation zones along each transect line.The ecotone had the highest richness indices (R) and comprehensive diversity indices (Y),reflecting the edge effect.The greatest evenness indices (E) were found in the add grassland zones.This result agreed with the phenomenon of desertification reversion,vegetation restoration and dominant communities' formation.As for the four transect lines,the east and the northeast scored higher in each diversity index than the others due to less human disturbance,gentler topography uplift and more intercepted materials and energies.The highest Simpson index value was found in the northeast transect line,which was 39.9% higher than the lowest in the Northwest.

  20. Eco-epidemiologia de Haemonchus contortus bahienses, ecotipo presente en ovinos de zonas aridas de Venezuela Eco-epidemiologia de Haemonchus contortus bahiensis, ecotipo presente em ovinos de zonas áridas da Venezuela Ecoepidemiology of Haemonchus contortus bahiensis: ecotype present in sheep of Venezuelan arid zone

    Directory of Open Access Journals (Sweden)

    Gustavo Morales

    1987-09-01

    Full Text Available Haemonchus contortus bahiensis Grisi, 1974 parasita a los ovinos de zonas áridas de Venezuela. En las hembras de dicho ecotipo la distribución de frecuencias por nosotros observada fue de un 15,32% para el morfotipo con lengüeta supravulvar, de un 51,61% para el botonado y de un 33,07% para el liso. Correspondiéndole a dicho ecotipo un índice de diversidad de Shannon-Weaver de 1,44 bits. Las medidas corporales, el tamaño de los huevos y el symlophe son similares en los tres morfotipos. La disposición espacial tanto de los machos como de las hembras en el seno de la población de hospedadores es de tipo contagiosa siendo bien descrita por el parámetro K de la distibución binominal negativa. Se evidenció la existencia de una compleja interacción entre la abundancia, la agregación y la prevalencia de dicho ecotipo y se discute su importancia sobre el equilibrio hospedador-parásito.Nas fêmesas do dito ecotipo a distribuição de freqüência observada foi de 15,32% para o morfotipo com lingueta supra-vulvar, de 51,61% para o tipo com botão vulvare de 33,07% para o tipo liso. A esse ecotipo corresponde um índice de diversidade de Shannon-Weaver igual a 1,44 bits. As medidas corporais, o tamanho dos ovos e o número de estrias cuticulares longitudinais são semelhantes nos três morfotipos. A disposição espacial, tanto dos machos quanto das fêmeas na população de hospedeiros é do tipo contagiosa, sendo bem descrita pelo parâmetro K da distribuição binomial negativa. Se verificou a existência de uma complexa interação entre a abundância, a agregação e a prevalência do citado ecotipo, discutindo-se sua importância no equilíbrio hospedeiro-parasito.The frequency distribution of female Haemonchus contortus bahiensis Grisi, 1974 in sheep from Venezuelan arid zones is 15.32% for the type with vulvar flap, 51.6% for the vulvar-knob and 33.07% for smooth type. A Shannon-Weaver diversity index corresponding to 1.44 bits was

  1. Heterogeneous aquifer system modelisation under semi-arid climate

    Science.gov (United States)

    Drias, Tarek; Toubal, Ahmed Cherif

    2010-05-01

    The studied zone is a part of the Mellegne's (North-East of Algeria) under pound, this zone is characterised by its semi-arid climate. The water bearing system is formed by the plio-quaternairy alluviums resting on a marley substratuim of age Eocene. The geostatiscitcs approach of the hydrodynamics parameters (Hydrolic load, transmisivity) allowed the study of their spatial distrubution (casting) by the method of Krigeage by blocks and the identification of zones with water-bearing potentialities. In this respect, the zone of Ain Chabro which, is situated in the South of the plain shows the best values of the transmisivity...... The use of a bidimensinnel model in the differences ended in the permanent regime allowed us to establish the global balence sheet (overall assessment) of the tablecloth and to refine the transmisivity field. These would vary more exactley between 10-4 to 10-2 m²/s. The method associating the probability appraoch of Krigeage to that determining the model has facilited the wedging of the model and clarified the inflitration value. Keys words: hydrodynamics, geostatiscitcs, Modeling, Chabro, Tébessa.

  2. Mitigating Climate Change in the Arid Lands of Namibia

    Science.gov (United States)

    Schneider, Martin B.; Sorensen, Marten

    2014-05-01

    Mitigating Climate Change in the Arid Lands of Namibia Namibia is the most arid country south of the Sahara, with scarce rainfall and perennial rivers only at its borders, > 80% of the area relies solely on groundwater. This has had devastating economic effects limiting opportunities for sustainable rural livelihoods that keep the population majority living below the World Bank poverty line (IFAD, 2013). A primary example of climatic variability which affects agrarian productivity is increased bush encroachment of Namibia's arid grazing land. The result has been a severe biodiversity loss, increased desertification and diminished water-use efficiency and underground water tables. Given these factors, Namibia's arid lands provide a unique opportunity to assess and test innovative / appropriate adaptation and mitigation strategies. Working toward sustainable management, restoration, and maintenance of balanced, resilient arid ecosystems in Namibia will also be a means to support and expand economic sectors incl. opportunities for job creation and potentially provide a model for similar arid regions. Main vegetation zones are: desert (46%), savannah (37%), and dry woodlands and forests (17%), i.e. human capacities are already in place. However, overall climate variability appears significantly higher than current plans and policies take into account. To improve livelihoods, reduce poverty, and food insecurity for rural Namibians in marginal/hyper-arid lands through sustainable climate change adaptation these objectives will be implemented: 1. Identify, assess and evaluate indigenous management strategies currently used by rural communities. 2. Capture and assess cultural and gender dimensions of management strategies within stakeholder groups using participatory approaches. 3. Determine science-based alternatives for adaptive land management strategies and test their acceptability to local communities and within the current policy framework. 4. Integrate identified

  3. Impacts of climate change on nutrient cycling in semi-arid and arid ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Belnap, J. [National Biological Survey, Moab, UT (United States)

    1995-09-01

    Effective precipitation is a major factor in determining nutrient pathways in different ecosystems. Soil flora and fauna play a critical role in nutrient cycles of all ecosystems. Temperature, timing, and amounts of precipitation affect population composition, activity levels, biomass, and recovery rates from disturbance. Changes in these variables can result in very different inputs and outputs for different nutrients. As a result, areas with less effective precipitation have very different nutrient cycles than more mesic zones. Climate change, therefore, can profoundly affect the nutrient cycles of ecosystems. Nitrogen cycles may be especially sensitive to changes in temperature and to timing and amounts of precipitation. Rainfall contains varying amounts of nitrogen compounds. Changes in amounts of rainfall will change amounts of nitrogen available to these systems. Because rainfall is limited in semi-arid and regions, these systems tend to be more dependent on microbial populations for nitrogen input. Consequently, understanding the effects of climate change on these organisms is critical in understanding the overall effect on ecosystems.

  4. SCIENCES IN COLD AND ARID REGIONS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aims and Scope Sciences in Cold and Arid Regions, an international Engiish-language journal, is devoted to publishing the latest research achievements on the process and the pattern of Earth surface system in cold and arid regions. Researches in cold regions 1) emphasize particularly on the cold-region-characterized physical, chemical and biological processes and their interactions, and on the response of Cryosphere to Global change and Human activities as well as its effect to environment and the acclimatizable

  5. Downwind effects on an arid dunefield from an evolving urbanised area

    Science.gov (United States)

    Hernández-Calvento, L.; Jackson, D. W. T.; Medina, R.; Hernández-Cordero, A. I.; Cruz, N.; Requejo, S.

    2014-12-01

    The impacts of urbanised zones on aeolian dynamics are little understood, particularly within arid areas. This study examines the large-scale influence of a growing tourist resort in Gran Canaria Island, Spain, on the sedimentary dynamics of an arid dunefield. Direct downwind effects from the urban area on the dune field surface are modelled for pre-growth and post-growth phases of the urban development. The geomorphological changes observed in the area stretching from the shoreline to the inland transgressive dune field were documented through aerial photographic and LiDAR evidence. Impacts of the urban growth on airflow, as well as those induced by tourists in the upper beach zone (de-vegetation), are examined through analysis of topographic changes. These impacts on the system are shown to have been synergistic in driving the development of a composite dune ridge, formed by the coalescence of smaller dunes into a distinctive aeolian accumulation ridge.

  6. Soil tillage and water infiltration in semi-arid Morocco: the role fo surface and sub-surface soil conditions

    NARCIS (Netherlands)

    Dimanche, P.H.; Hoogmoed, W.B.

    2002-01-01

    Production of cereals in a dryland farming system forms an important part of agricultural production in Morocco. Yield levels on the Saïs Plateau between Meknès and Fez in the semi-arid zone, however, remain low possibly because of sub-optimum water use due to inefficient tillage systems. A study wa

  7. Reuse of domestic wastewater treated in macrophyte ponds to irrigate tomato and eggplant in semi-arid West-Africa: benefits and risks

    OpenAIRE

    Akponikpe, PBI; Wima, K.; Yacouba, H.; Mermoud, A

    2011-01-01

    The scarcity of freshwater resources is a critical problem in semi-arid zones and marginal quality water is increasingly being used in agriculture. This paper aimed at evaluating the physico-chemical and biological risks on irrigated soils and fruits of macrophyte treated wastewater (TWW), the nutrients supply, and the effect on tomato and eggplant production in semi-arid Burkina Faso. During three years of experiments, treated wastewater was used, with fresh water as control, in combination ...

  8. Surficial weathering of iron sulfide mine tailings under semi-arid climate

    OpenAIRE

    Hayes, Sarah M.; Root, Robert A.; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

    2014-01-01

    Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid r...

  9. An Evaluation of Unsaturated Flow Models in an Arid Climate

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, J.

    1999-12-01

    The objective of this study was to evaluate the effectiveness of two unsaturated flow models in arid regions. The area selected for the study was the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site in Nye County, Nevada. The two models selected for this evaluation were HYDRUS-1D [Simunek et al., 1998] and the SHAW model [Flerchinger and Saxton, 1989]. Approximately 5 years of soil-water and atmospheric data collected from an instrumented weighing lysimeter site near the RWMS were used for building the models with actual initial and boundary conditions representative of the site. Physical processes affecting the site and model performance were explored. Model performance was based on a detailed sensitivity analysis and ultimately on storage comparisons. During the process of developing descriptive model input, procedures for converting hydraulic parameters for each model were explored. In addition, the compilation of atmospheric data collected at the site became a useful tool for developing predictive functions for future studies. The final model results were used to evaluate the capacities of the HYDRUS and SHAW models for predicting soil-moisture movement and variable surface phenomena for bare soil conditions in the arid vadose zone. The development of calibrated models along with the atmospheric and soil data collected at the site provide useful information for predicting future site performance at the RWMS.

  10. Rainfall-runoff relationship of some catchments with karstic geomorphology under arid to semi-arid conditions

    Science.gov (United States)

    De Vera, Maximo R.

    1984-02-01

    The relationship between rainfall and runoff of fourteen catchments with a total area of 5983 km 2 in the northeastern zone of Libya was reviewed in an attempt to determine the effect of karstic geomorphology on the runoff coefficient. Available data since 1965 were collated and eight wadis with at least eleven flood events were used for linear regression analysis. The selected catchments are under arid to semi-arid conditions with mean annual rainfall of 50-500 mm and with surface geology consisting mostly of marly limestone which is favourable to karstification phenomena. The ratio of runoff to rainfall is extremely variable with a range of 0.0001-0.830, and therefore it is not a reliable criterion for runoff estimation, especially with the limited data subjected to statistical analysis. The regression analysis shows correlation coefficients from 0.219 to 0.89 with no apparent effect of size of catchment area. As indicated by the coefficient of determination, 4.8-80.3% of the variation in runoff has been accounted for by the regression. The extent and degree of karstification, if properly quantified, can be a significant factor for runoff prediction, in addition to rainfall intensity and duration, antecedent soil moisture, effective catchment area and other geomorphological features.

  11. Study on RS- and GIS-based ecological capital assessment in arid areas

    Institute of Scientific and Technical Information of China (English)

    ZHOU Kefa; CHEN Xi; ZHOU Huarong; ZHANG Qing; ZUO Qiting; ZHANG Haibo; YAN Jinfeng; CHEN Chuan

    2006-01-01

    Ecological capital assessment is currently one of the important research contents in the interdisciplinary field of ecology, resources economics, environmental economics and ecological economics. To scientifically assess ecological capital redounds to decision-makers to consider the ecological cost in economic development, and is also necessary for sustainable economic development in arid areas. Based on the theory of landscape ecology,in this paper the per unit area ecological capital values in arid areas are researched by using the Landsat TM data, CBERS satellite data, meteorological data, MODIS satellite data and other ecological data,and the RS- and GIS-based models of assessing ecological capital values in arid areas are developed.Moreover, based on the field-measured data, a case study on ecological capital assessment in the Manas River basin, Xinjiang in 2003 is carried out. The basin is divided into 4 ecological capital areas so as to quantitatively calculate the ecological capital values of the ecosystems, analyze the spatial distribution of ecological capital, and chart the maps of spatial distribution of ecological capital. The results show that the total ecological capital value of the ecosystems in the Manas River basin in 2003 was 1.49454×1011yuan RMB. In spatial distribution, the ecological capital decreases from the alpine zones to the plains and from the oases to the deserts, which accords with the distribution of vegetation zonality in this arid area.The assessed results can objectively reflect the ecological capital and its spatial distribution in the arid basin, and can also provide reference for roundly carrying out the assessment of ecological capital in arid areas.

  12. Mitigating Climate Change in the Arid Lands of Namibia

    Science.gov (United States)

    Schneider, Martin B.; Sorensen, Marten

    2014-05-01

    Mitigating Climate Change in the Arid Lands of Namibia Namibia is the most arid country south of the Sahara, with scarce rainfall and perennial rivers only at its borders, > 80% of the area relies solely on groundwater. This has had devastating economic effects limiting opportunities for sustainable rural livelihoods that keep the population majority living below the World Bank poverty line (IFAD, 2013). A primary example of climatic variability which affects agrarian productivity is increased bush encroachment of Namibia's arid grazing land. The result has been a severe biodiversity loss, increased desertification and diminished water-use efficiency and underground water tables. Given these factors, Namibia's arid lands provide a unique opportunity to assess and test innovative / appropriate adaptation and mitigation strategies. Working toward sustainable management, restoration, and maintenance of balanced, resilient arid ecosystems in Namibia will also be a means to support and expand economic sectors incl. opportunities for job creation and potentially provide a model for similar arid regions. Main vegetation zones are: desert (46%), savannah (37%), and dry woodlands and forests (17%), i.e. management strategies currently used by rural communities. 2. Capture and assess cultural and gender dimensions of management strategies within stakeholder groups using participatory approaches. 3. Determine science-based alternatives for adaptive land management strategies and test their acceptability to local communities and within the current policy framework. 4. Integrate identified indigenous knowledge with appropriate science and new emerging technologies to develop a training toolkit of effective strategies relevant to all stakeholders. 5. Utilize training sessions, education workshops, curriculum revisions, and appropriate information and communication technologies (ICTs) including social media outlets to disseminate the toolkit strategies. 6. Apply a modified logic

  13. Study of energy partitioning and its feedback on the micro climate over different surfaces in an arid zone%干旱区不同下垫面能量分配机理及对微气候反馈的研究∗

    Institute of Scientific and Technical Information of China (English)

    李宏宇; 符淙斌; 郭维栋; 马芳

    2015-01-01

    Model simulations show that land use and land cover changes(LUCC) may alter surface energy budget and influence surface microclimate, but up to now, it still lacks of sufficient observations for explaining the mechanism of climate change brought about by LUCC. Grasslands and shrub lands are typical land covers in the mid-latitude arid zone of the northern hemisphere. The data used in this paper was collected from four sites which are related to grassland, open shrubland, savanna and closed shrubland, and all located in New Mexico, USA. The four sites are near each other and have the same background in climate and weather. Thus, the difference in surface energy partitioning over the four surfaces is induced by different land processes, which was explained in our study. The paper also analyzed the feedbacks of different land surface parameters and energy partitioning for the surface microclimate. We find that the leaf area index(LAI) and surface roughness of the four sites increases from the desert grassland to the closed shrubland. The difference in vegetation structures and functions also affects aerodynamic resistance and surface resistance to heat transfer and the resistances exhibit larger over sparse surfaces. Generally, the sites with high vegetation cover have higher net radiation, sensible and latent heat fluxes, particularly in the growing season. In addition, the contributions of impacting factors to the turbulent fluxes are diagnosed by Penman-Monteith equation and a mathematical formula combining net radiation with Bowen ratio. Compared to the desert grassland, the variations in net radiation over other three surfaces indicate positive contributions to both sensible and latent heat fluxes and govern their changes. The variations in the aerodynamic resistance and the surface resistance lead to opposite contributions. Besides, both radiative surface temperature and surface air temperature over the sparse surfaces are significantly higher than that over the

  14. Farmers'Perception of Water Resource Shortage and Adaption in Continental River Basin of Arid Zone:A Case of the Middle-lower Reaches of the Shiyang River%干旱区内陆河流域农户对水资源紧缺的感知及适应——以石羊河中下游为例

    Institute of Scientific and Technical Information of China (English)

    赵雪雁; 薛冰

    2015-01-01

    内陆河流域水资源极为紧缺,理解农户对水资源紧缺的感知及适应策略选择倾向对于制定科学的水资源管理政策至关重要.以石羊河中下游为研究区,基于农户调查数据,分析了农户对水资源紧缺的感知及适应策略,并利用经济计量模型分析了农户的水资源紧缺性感知对其适应策略选择的影响.结果发现:① 农户感知到的水资源紧缺可能性、严重性、适应功效及适应成本均较高,但感知到的自我效能处于中等水平;② 水资源紧缺风险感知与适应功效感知、适应成本感知呈显著正相关,其与自我效能感知虽呈负相关,但并不显著;③ 农户的适应策略多样化指数达2.80,水资源紧缺严重性感知、适应功效感知、适应成本感知及自我效能感知与适应策略多样化指数呈显著正相关;④ 随着风险感知与适应功效感知的增强,农户首选收缩型策略的概率增大,但随着自我效能感知的增强,农户首选收缩型策略的概率降低.最后,提出了增强农户适应能力的对策建议及未来需进一步关注的问题.%In recent years, the farmer's perception of environment change and their adaption strategies has been the research focus of the adaptation domain. Water resource shortage is the most serious environmental prob-lem in the continental river basin of arid zone, it is badly in need of looking for the effective adaptation strate-gies in order to reduce the adverse impact of water resource shortage. Understanding the farmers'perception of water resource shortage and adaption strategy selection is very important to determine the proper adaptation strategy and make scientific water resource management policy. Selecting the middle-lower reaches of the Shi-yang River as the study case and through stratified random sampling survey, participatory rural appraisal and investigation of plots, 367 household are investigated and sampled. Based on the

  15. Influences on the stable oxygen and carbon isotopes in gerbillid rodent teeth in semi-arid and arid environments: Implications for past climate and environmental reconstruction

    Science.gov (United States)

    Jeffrey, Amy; Denys, Christiane; Stoetzel, Emmanuelle; Lee-Thorp, Julia A.

    2015-10-01

    mammal teeth strongly reflects moisture availability in semi-arid and arid environments and would provide an excellent record of palaeo-aridity in a terrestrial setting. The results illustrate that an understanding of an animal's physiology is essential for interpreting the animal's isotopic responses to external contexts, especially in arid zones.

  16. Identifying Groundwater Recharge in Arid Regions

    Science.gov (United States)

    Thomas, B. F.; Famiglietti, J. S.

    2015-12-01

    Recharge epodicity in arid regions provides a method to estimate annual groundwater recharge given a relationship expressed as the recharge to precipitation ratio. Traditionally, in-situ observations are required to identify aquifer recharge events, while more advanced approaches such as the water-table fluctuation method or the episodic master recession method are necessary to delineate the recharge event. Our study uses the Gravity Recovery and Climate Experiment (GRACE) observations to estimate monthly changes in groundwater storage which are attributed to the combination of groundwater abstraction and episodic recharge in the arid southwestern United States. Our results illustrate the ability of remote sensing technologies to identify episodic groundwater recharge in arid regions which can be used within sustainable groundwater management frameworks to effectively manage groundwater resources.

  17. Transfer of 137Cs in Zea mays and Phaseolus vulgaris in a semi-arid ecosystem

    International Nuclear Information System (INIS)

    With the objective to analyse the transference of 137 Cs from soil to plants, it is realized a study in maize and bean plants in the Radioactive Waste Storage Center (CADER). This site is located in a semi-arid region with a characteristic vegetation of a sub humid temperature zone. So those plants maize and beans were cultivated in four zones near CADER during a four years period. The obtained results for 1991 to 1994 for 137 Cs in soil samples for those zones showed an evident contamination in zone 1, due to a rupture of an industrial source. In 1994 the effect of decontamination was evident since the values of specific activity found in roots were around magnitude lesser than found in 1992. In spite of exhaustive studies have been reported about the transference factors for 137 Cs in different agricultural foods, relatively few of them have paid attention to the interactions between cereals and leguminous associated in semiarid ecosystems. (Author)

  18. Vadose Zone Hydrology and Eco-hydrology in China

    Science.gov (United States)

    Wang, Wenke

    2016-04-01

    Vadose zone hydrology has long been a concern regarding groundwater recharge, evaporation, pollution, and the ecological effects induced by groundwater and water & salt contents in the unsaturated zone. The greater difference between day and night temperatures in arid and semi-arid areas influences water movement and heat transport in the vadose zone, and further influences the water and heat fluxes between the water table and the atmosphere as well as ecological environment. Unfortunately, these studies are lack in a systematic viewpoint in China. One of the main reasons is that the movement of water, vapor and heat from the surface to the water table is very complex in the arid and semi-arid areas. Another reason is lack of long term field observations for water content, vapor, heat, and soil matrix potential in the vadose zone. Three field observation sites, designed by the author, were set up to measure the changes in climate, water content , temperature and soil matrix potential of the unsaturated zone and groundwater level under the different conditions of climate and soil types over the period of 1-5 years. They are located at the Zhunngger Basin of Xinjing Uygur Autonomous Region in northwestern China, the Guanzhong Basin of Shaanxi Province in central China, and the Ordos Basin of the Inner Monggol Autonomous Region in north China, respectively. These three field observation sites have different climate and soil types in the vadose zone and the water table depth are also varied. Based on the observation data of climate, groundwater level, water content, temperature and soil matrix potential in the vadose zone from the three sites in associated with the field survey and numerical simulation method, the water movement and heat transport in the vadose zone, and the evaporation of phreatic water for different groundwater depths and soil types have been well explored. The differences in water movement of unsaturated zone between the bare surface soil and

  19. Generalized provisional seed zones for native plants.

    Science.gov (United States)

    Bower, Andrew D; St Clair, J Bradley; Erickson, Vicky

    2014-07-01

    Deploying well-adapted and ecologically appropriate plant materials is a core component of successful restoration projects. We have developed generalized provisional seed zones that can be applied to any plant species in the United States to help guide seed movement. These seed zones are based on the intersection of high-resolution climatic data for winter minimum temperature and aridity (as measured by annual heat : moisture index), each classified into discrete bands. This results in the delineation of 64 provisional seed zones for the continental United States. These zones represent areas of relative climatic similarity, and movement of seed within these zones should help to minimize maladaptation. Superimposing Omernik's level III ecoregions over these seed zones distinguishes areas that are similar climatically yet different ecologically. A quantitative comparison of provisional seed zones with level III ecoregions and provisional seed zones within ecoregions for three species showed that provisional seed zone within ecoregion often explained the greatest proportion of variation in a suite of traits potentially related to plant fitness. These provisional seed zones can be considered a starting point for guidelines for seed transfer, and should be utilized in conjunction with appropriate species-specific information as well as local knowledge of microsite differences. PMID:25154085

  20. Groundwater Diffuse Recharge and its Response to Climate Changes in Semi-Arid Northwestern China

    Directory of Open Access Journals (Sweden)

    Lin Deng

    2015-01-01

    Full Text Available Understanding the processes and rates of groundwater recharge in arid and semi-arid areas is crucial for utilizing and managing groundwater resources sustainably. We obtained three chloride profiles of the unsaturated-zone in the desert/loess transition zone of northwestern China and reconstructed the groundwater recharge variations over the last 11, 21, and 37 years, respectively, using the generalized chloride mass balance (GCMB method. The average recharge rates were 43.7, 43.5, and 45.1 mm yr-1, respectively, which are similar to those evaluated by the chloride mass balance (CMB or GCMB methods in other semi-arid regions. The results indicate that the annual recharge rates were not in complete linear proportion to the corresponding annual precipitations, although both exhibited descending tendencies on the whole. Comparisons between the daily precipitation aggregate at different intensity and recharge rates reveal that the occurrence of relatively heavy daily precipitation per year may contribute to such nonlinearity between annual precipitation and recharge. The possible influences of vegetation cover alterations following precipitation change cannot be excluded as well. The approximately negative correlation between the average annual recharge and temperature suggests that changes in temperature have had significant influences on recharge.

  1. Arbuscular mycorrhizal fungi in Mimosa tenuiflora (Willd.) Poir from Brazilian semi-arid.

    Science.gov (United States)

    de Souza, Tancredo Augusto Feitosa; Rodriguez-Echeverría, Susana; de Andrade, Leonaldo Alves; Freitas, Helena

    2016-01-01

    Many plant species from Brazilian semi-arid present arbuscular mycorrhizal fungi (AMF) in their rhizosphere. These microorganisms play a key role in the establishment, growth, survival of plants and protection against drought, pathogenic fungi and nematodes. This study presents a quantitative analysis of the AMF species associated with Mimosa tenuiflora, an important native plant of the Caatinga flora. AMF diversity, spore abundance and root colonization were estimated in seven sampling locations in the Ceará and Paraíba States, during September of 2012. There were significant differences in soil properties, spore abundance, percentage of root colonization, and AMF diversity among sites. Altogether, 18 AMF species were identified, and spores of the genera Acaulospora, Claroideoglomus, Dentiscutata, Entrophospora, Funneliformis, Gigaspora, Glomus, Racocetra, Rhizoglomus and Scutellospora were observed. AMF species diversity and their spore abundance found in M. tenuiflora rhizosphere shown that this native plant species is an important host plant to AMF communities from Brazilian semi-arid region. We concluded that: (a) during the dry period and in semi-arid conditions, there is a high spore production in M. tenuiflora root zone; and (b) soil properties, as soil pH and available phosphorous, affect AMF species diversity, thus constituting key factors for the similarity/dissimilarity of AMF communities in the M. tenuiflora root zone among sites. PMID:26991277

  2. Conservation and restoration of degraded ecosystems in arid and semi-arid areas of northwest China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In "West Development" of China, one of the most important activities is the Natural Forest Protection Program, designed to swiftly convert the focus of management and utilization of the natural forests from a timber orientation towards forest conservation, sustainable management and environmental protection. The project covered almost all the arid and semi-arid regions in Northwest region. Accompanying this great campaign this paper studied the conservation and restoration model of degraded ecosystems in arid and semi-arid lands in Northwest China. The past practices have resulted in considerably natural forest degradation and loss through land conversion (primarily for agriculture), over-harvesting, inadequate reforestation and lack of protection. The consequences have been the loss of soil and water resources, diminished timber production capacity on a sustainable basis, and environmental losses. This paper applied Aronson's restoration model and proposed the conservation, restoration, re-allocation and preservation program for the implementation of environmental improvement and natural forest conservation.

  3. Applying animal behavior to arid rangeland mangement

    Science.gov (United States)

    Livestock production is one of many demands placed on today’s arid rangelands. Therefore, understanding plant and animal biology and their effects on biotic and abiotic landscape components is fundamental if rangelands are to remain ecologically sustainable. One limiting factor to accomplishing posi...

  4. Spatial interactions and resilience in arid ecosystems

    NARCIS (Netherlands)

    Koppel, van de J.; Rietkerk, M.

    2004-01-01

    We present a mathematical analysis of the consequences of spatial interactions between vegetation patches by means of water flow for the functioning of arid systems. Our model results suggest that spatial exchange of water improved the resilience to disturbances and increased the resistance to human

  5. Aridity and decomposition processes in complex landscapes

    Science.gov (United States)

    Ossola, Alessandro; Nyman, Petter

    2015-04-01

    Decomposition of organic matter is a key biogeochemical process contributing to nutrient cycles, carbon fluxes and soil development. The activity of decomposers depends on microclimate, with temperature and rainfall being major drivers. In complex terrain the fine-scale variation in microclimate (and hence water availability) as a result of slope orientation is caused by differences in incoming radiation and surface temperature. Aridity, measured as the long-term balance between net radiation and rainfall, is a metric that can be used to represent variations in water availability within the landscape. Since aridity metrics can be obtained at fine spatial scales, they could theoretically be used to investigate how decomposition processes vary across complex landscapes. In this study, four research sites were selected in tall open sclerophyll forest along a aridity gradient (Budyko dryness index ranging from 1.56 -2.22) where microclimate, litter moisture and soil moisture were monitored continuously for one year. Litter bags were packed to estimate decomposition rates (k) using leaves of a tree species not present in the study area (Eucalyptus globulus) in order to avoid home-field advantage effects. Litter mass loss was measured to assess the activity of macro-decomposers (6mm litter bag mesh size), meso-decomposers (1 mm mesh), microbes above-ground (0.2 mm mesh) and microbes below-ground (2 cm depth, 0.2 mm mesh). Four replicates for each set of bags were installed at each site and bags were collected at 1, 2, 4, 7 and 12 months since installation. We first tested whether differences in microclimate due to slope orientation have significant effects on decomposition processes. Then the dryness index was related to decomposition rates to evaluate if small-scale variation in decomposition can be predicted using readily available information on rainfall and radiation. Decomposition rates (k), calculated fitting single pool negative exponential models, generally

  6. CHARACTERISTICS OF ARIDITY CONDITIONS IN SOUTH DOBRUDJA

    Directory of Open Access Journals (Sweden)

    A. TISCOVSCHI

    2013-04-01

    Full Text Available Characteristics of Aridity Conditions in South Dobrudja. For most people, the arid and semi-arid lands are those where precipitation is low (less than 200 mm per year, and yet enough for supplying streams capable of temporarily carrying the debris resulted from weathering, but insufficient for encouraging the development of a vegetal cover meant to protect the soil blanket against eroding agents. The drought is a major and permanent climatic risk for the Dobrudja territory as a whole and for South Dobrudja in particular, a territory where hydrographic network is underdeveloped, streams are ephemeral, and semi-endorheic areas are well developed. When the period of moisture deficiency lasts longer, it can bring about a significant water imbalance, which results in crop losses or restrictions in water consumption, thus leading to a number of economic problems. Under the circumstances, the risk of aridity expansion is significant, this being the reason why a better water management system in Romania is urgently needed. In the last decades, the numerous specialty studies undertaken in the area have emphasized an intensification of the process of dryness, because atmospheric and pedological droughts have become more and more serious. Romania is a member of the United Nations Convention to Combat Desertification (UNCCD and the World Meteorological Organization (WMO. It actively participates within the drought management network and the Drought Management Center for Southeastern Europe, which comprises 11 countries. The scope is to work together and exchange experience with the neighboring countries that have recorded positive results and acquired a rich experience in terms of drought management. The employment of appropriate pluvial indices in identifying the areas prone to aridity may prove to be convenient tool for finding practical solutions meant to mitigate the impact of this phenomenon on the local communities living in South Dobrudja.

  7. Aridity under conditions of increased CO2

    Science.gov (United States)

    Greve, Peter; Roderick, Micheal L.; Seneviratne, Sonia I.

    2016-04-01

    A string of recent of studies led to the wide-held assumption that aridity will increase under conditions of increasing atmospheric CO2 concentrations and associated global warming. Such results generally build upon analyses of changes in the 'aridity index' (the ratio of potential evaporation to precipitation) and can be described as a direct thermodynamic effect on atmospheric water demand due to increasing temperatures. However, there is widespread evidence that contradicts the 'warmer is more arid' interpretation, leading to the 'global aridity paradox' (Roderick et al. 2015, WRR). Here we provide a comprehensive assessment of modeled changes in a broad set of dryness metrics (primarily based on a range of measures of water availability) over a large range of realistic atmospheric CO2 concentrations. We use an ensemble of simulations from of state-of-the-art climate models to analyse both equilibrium climate experiments and transient historical simulations and future projections. Our results show that dryness is, under conditions of increasing atmospheric CO2 concentrations and related global warming, generally decreasing at global scales. At regional scales we do, however, identify areas that undergo changes towards drier conditions, located primarily in subtropical climate regions and the Amazon Basin. Nonetheless, the majority of regions, especially in tropical and mid- to northern high latitudes areas, display wetting conditions in a warming world. Our results contradict previous findings and highlight the need to comprehensively assess all aspects of changes in hydroclimatological conditions at the land surface. Roderick, M. L., P. Greve, and G. D. Farquhar (2015), On the assessment of aridity with changes in atmospheric CO2, Water Resour. Res., 51, 5450-5463

  8. Designing of zero energy office buildings in hot arid climate

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Gwad, Mohamed

    2011-07-01

    The designing of office buildings by using large glass areas to have a transparent building is an attractive approach in the modern office building architecture. This attitude increases the energy demand for cooling specially in the hot arid region which has long sun duration time, while the use of small glazing areas increases the energy demand for lighting. The use of uncontrolled natural ventilation increases the rate of hot ambient air flow which increases the building energy demand for cooling. At the same time, the use of mechanical ventilation to control the air change rate may increase the energy demand for fans. Some ideas such as low energy design concept are introduced for improving the building energy performance and different rating systems have been developed such as LEED, BREEAM and DGNB for evaluating building energy performance system. One of the new ideas for decreasing the dependence on fossil fuels and improving the use of renewable energy is the net zero-energy building concept in which the building generates enough renewable energy on site to equal or exceed its annual energy use. This work depends on using the potentials of mixing different energy strategies such as hybrid ventilation strategy, passive night cooling, passive chilled ceiling side by side with the integrating of photovoltaic modules into the building facade to produce energy and enrich the architectural aesthetics and finally reaching the Net Zero Energy Building. There are different definitions for zero energy buildings, however in this work the use of building-integrated Photovoltaic (BIPV) to provide the building with its annual energy needs is adopted, in order to reach to a Grid-Connected Net-Zero Energy Office Building in the hot arid desert zone represented by Cairo, Egypt. (orig.)

  9. Water pulses and biogeochemical cycles in arid and semiarid ecosystems.

    Science.gov (United States)

    Austin, Amy T; Yahdjian, Laura; Stark, John M; Belnap, Jayne; Porporato, Amilcare; Norton, Urszula; Ravetta, Damián A; Schaeffer, Sean M

    2004-10-01

    The episodic nature of water availability in arid and semiarid ecosystems has significant consequences on belowground carbon and nutrient cycling. Pulsed water events directly control belowground processes through soil wet-dry cycles. Rapid soil microbial response to incident moisture availability often results in almost instantaneous C and N mineralization, followed by shifts in C/N of microbially available substrate, and an offset in the balance between nutrient immobilization and mineralization. Nitrogen inputs from biological soil crusts are also highly sensitive to pulsed rain events, and nitrogen losses, particularly gaseous losses due to denitrification and nitrate leaching, are tightly linked to pulses of water availability. The magnitude of the effect of water pulses on carbon and nutrient pools, however, depends on the distribution of resource availability and soil organisms, both of which are strongly affected by the spatial and temporal heterogeneity of vegetation cover, topographic position and soil texture. The 'inverse texture hypothesis' for net primary production in water-limited ecosystems suggests that coarse-textured soils have higher NPP than fine-textured soils in very arid zones due to reduced evaporative losses, while NPP is greater in fine-textured soils in higher rainfall ecosystems due to increased water-holding capacity. With respect to belowground processes, fine-textured soils tend to have higher water-holding capacity and labile C and N pools than coarse-textured soils, and often show a much greater flush of N mineralization. The result of the interaction of texture and pulsed rainfall events suggests a corollary hypothesis for nutrient turnover in arid and semiarid ecosystems with a linear increase of N mineralization in coarse-textured soils, but a saturating response for fine-textured soils due to the importance of soil C and N pools. Seasonal distribution of water pulses can lead to the accumulation of mineral N in the dry season

  10. Problems and prospects in the utilisation of animal traction in semi-arid West Africa: Evidence from Niger

    OpenAIRE

    Williams, T. O.

    1998-01-01

    Sustained adoption of animal traction for crop cultivation in the semi-arid zone of West Africa has been slow despite deliberate attempts by governments, development agencies and research organizations. to promote its use among small-scale farmers. The low adoption rates are partly due to demand and supply constraints, combined with the absence of certain preconditions (e.g appropriate climatic and biophysical attributes, and farming practices). On the demand side, factors like the short term...

  11. Efficiency of water and fertilizer use in semi-arid regions

    International Nuclear Information System (INIS)

    The proceedings contain 14 papers considering problems on soil and soil water, irrigation, and the use of fertilizers in semi-arid zones. Research projects in these fields are discussed and results obtained so far are reported (tables and diagrams on the behaviour of water and fertilizers in soils). The use of radioisotope techniques is mentioned briefly. Finally, some future ''first priority'' research areas are identified and recommendations for further research programs are given. These programs aim at reducing the hazards of crop failure and at increasing production under dry farming conditions

  12. On the relationship between environmental aridization of the Loess Plateau and soil water in loess

    Institute of Scientific and Technical Information of China (English)

    杨文治; 邵明安; 彭新德; 夏卫生

    1999-01-01

    The similarity between loess palaeo-environment and geographic distribution of modern bioclimatic zones is taken as a starting point; the relationship between the environmental aridization and soil water in loess is discussed from the point view of the soil water energy status and their soil water physical characteristics of modern loessial soils on the Loess Plateau. The soil water content becomes less and less from southeast to northwest, which not only provides favorable conditions for dust production by wind of loess origin, but also reveals that there is obviously a directional change in the environmental drought intensity of the Loess Plateau.

  13. Sediment yield assessment by EPM and PSIAC models using GIS data in semi-arid region

    Institute of Scientific and Technical Information of China (English)

    Ali Bagherzadeh; Mohammad Reza Mansouri Daneshvar

    2011-01-01

    Among land degradation processes,soil erosion is the most serious threat to soil and water conservation in semi-arid regions.At the present study,the sedimentation hazard and the erosion zonation were investigated at Kardeh watershed,north-east of Iran by Erosion Potential Method (EPM) and Pacific Sonth-west Inter Agency Committee (PSIAC) models,in combination with the geographical information system (GIS) data,satellite data and field observations.According to our investigation the study area can be categorized into heavy,moderate and slight erosion zones with the total sediment yield of 147859 and 148078 m3/a estimated by EPM and PSIAC models,respectively.The sub-basins located at the middle and south parts of the watershed are highly eroded due to the geology formation and soil erodibility conditions,while the sub-basins at the north parts are moderately eroded because of the intensive land cover.The amounts of the sediment yield in most areas are found to be consistent between the EPM and PSIAC models (R2 = 0.95).Our data suggest the applicability of both empirical models in evaluating the sediment yield in arid and semi-arid watersheds.

  14. 半干旱沙区流动沙丘与丘间低地过渡带的植被空间变化过程1)%Vegetation Processes of Transition Zones betwe n Active Dunes and Interdune Lowlands in Semi-arid Dune Are-as

    Institute of Scientific and Technical Information of China (English)

    闫守刚; 许清涛; 曹凤伟

    2014-01-01

    We studied the transition zones between active sand dunes and interdune lowlands , chronological orders that the plants of different ecological groups invaded transition zones between windward slopes of active sand dunes , and the effects of transition zone ’ s dynamics on vegetation patterns in active dune-interdune lowlands .The sand burial of active sand dunes leaded to the disappearing of parts of limnocryptophyte-meadow plants from interdune lowlands , eolian erosion of ac-tive sand dunes resulted in the invading of psammophytes into transition zones between windward slopes of active sand dunes and interdune lowlands with a typical vegetation succession in active sand dune fields .The roles of Phragmites com-munis and Salix gordejevii to revegetations of active sand dunes were more than those of Agriophyllum sqau rrosum and Arte-misia wudanica.The plant species of transition zones between windward slopes of active sand dunes and interdune lowlands were more than those of active sand dunes , greatly fewer than those of interdune lowlands with a typical edge effect in ac-tive sand dune fields .%以流动沙丘—丘间低地过渡带为研究对象,研究了不同生态组群植物侵入迎风坡过渡带的时间顺序,分析了过渡带变化对流动沙丘—丘间低地单元植被格局的影响。结果表明:(1)流动沙丘区的沙埋导致背风坡过渡带部分沼泽—草甸植物退出丘间低地,风蚀导致典型沙生植物侵入迎风坡过渡带,从而在丘间低地呈现出一种特有的植被空间动态变化过程;(2)芦苇和黄柳对于迎风坡过渡带植被恢复的作用大于沙蓬和乌丹蒿;(3)流动沙丘迎风坡—丘间低地过渡带植物种类比流动沙丘的多、但远比丘间低地少,具有流动沙丘区特有的边缘效应。

  15. Analysis list: ARID1A [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ARID1A Liver + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID1A.1.tsv http://dbar...chive.biosciencedbc.jp/kyushu-u/hg19/target/ARID1A.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/AR...ID1A.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID1A.Liver.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Liver.gml ...

  16. Analysis list: ARID1B [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ARID1B Liver + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID1B.1.tsv http://dbar...chive.biosciencedbc.jp/kyushu-u/hg19/target/ARID1B.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/AR...ID1B.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID1B.Liver.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Liver.gml ...

  17. Analysis list: ARID3B [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ARID3B Others + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID3B.1.tsv http://dbar...chive.biosciencedbc.jp/kyushu-u/hg19/target/ARID3B.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/AR...ID3B.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID3B.Others.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Others.gml ...

  18. Analysis list: ARID2 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ARID2 Liver + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID2.1.tsv http://dbar...chive.biosciencedbc.jp/kyushu-u/hg19/target/ARID2.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/AR...ID2.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID2.Liver.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Liver.gml ...

  19. Verification of watershed vegetation restoration policies, arid China

    Science.gov (United States)

    Zhang, Chengqi; Li, Yu

    2016-07-01

    Verification of restoration policies that have been implemented is of significance to simultaneously reduce global environmental risks while also meeting economic development goals. This paper proposed a novel method according to the idea of multiple time scales to verify ecological restoration policies in the Shiyang River drainage basin, arid China. We integrated modern pollen transport characteristics of the entire basin and pollen records from 8 Holocene sedimentary sections, and quantitatively reconstructed the millennial-scale changes of watershed vegetation zones by defining a new pollen-precipitation index. Meanwhile, Empirical Orthogonal Function method was used to quantitatively analyze spatial and temporal variations of Normalized Difference Vegetation Index in summer (June to August) of 2000-2014. By contrasting the vegetation changes that mainly controlled by millennial-scale natural ecological evolution with that under conditions of modern ecological restoration measures, we found that vegetation changes of the entire Shiyang River drainage basin are synchronous in both two time scales, and the current ecological restoration policies met the requirements of long-term restoration objectives and showed promising early results on ecological environmental restoration. Our findings present an innovative method to verify river ecological restoration policies, and also provide the scientific basis to propose future emphasizes of ecological restoration strategies.

  20. Verification of watershed vegetation restoration policies, arid China

    Science.gov (United States)

    Zhang, Chengqi; Li, Yu

    2016-07-01

    Verification of restoration policies that have been implemented is of significance to simultaneously reduce global environmental risks while also meeting economic development goals. This paper proposed a novel method according to the idea of multiple time scales to verify ecological restoration policies in the Shiyang River drainage basin, arid China. We integrated modern pollen transport characteristics of the entire basin and pollen records from 8 Holocene sedimentary sections, and quantitatively reconstructed the millennial-scale changes of watershed vegetation zones by defining a new pollen-precipitation index. Meanwhile, Empirical Orthogonal Function method was used to quantitatively analyze spatial and temporal variations of Normalized Difference Vegetation Index in summer (June to August) of 2000–2014. By contrasting the vegetation changes that mainly controlled by millennial-scale natural ecological evolution with that under conditions of modern ecological restoration measures, we found that vegetation changes of the entire Shiyang River drainage basin are synchronous in both two time scales, and the current ecological restoration policies met the requirements of long-term restoration objectives and showed promising early results on ecological environmental restoration. Our findings present an innovative method to verify river ecological restoration policies, and also provide the scientific basis to propose future emphasizes of ecological restoration strategies.

  1. Verification of watershed vegetation restoration policies, arid China

    Science.gov (United States)

    Zhang, Chengqi; Li, Yu

    2016-01-01

    Verification of restoration policies that have been implemented is of significance to simultaneously reduce global environmental risks while also meeting economic development goals. This paper proposed a novel method according to the idea of multiple time scales to verify ecological restoration policies in the Shiyang River drainage basin, arid China. We integrated modern pollen transport characteristics of the entire basin and pollen records from 8 Holocene sedimentary sections, and quantitatively reconstructed the millennial-scale changes of watershed vegetation zones by defining a new pollen-precipitation index. Meanwhile, Empirical Orthogonal Function method was used to quantitatively analyze spatial and temporal variations of Normalized Difference Vegetation Index in summer (June to August) of 2000–2014. By contrasting the vegetation changes that mainly controlled by millennial-scale natural ecological evolution with that under conditions of modern ecological restoration measures, we found that vegetation changes of the entire Shiyang River drainage basin are synchronous in both two time scales, and the current ecological restoration policies met the requirements of long-term restoration objectives and showed promising early results on ecological environmental restoration. Our findings present an innovative method to verify river ecological restoration policies, and also provide the scientific basis to propose future emphasizes of ecological restoration strategies. PMID:27470948

  2. Optimizing conjunctive use of surface water and groundwater for irrigation in arid and semi-arid areas: an integrated modeling approach

    Science.gov (United States)

    Wu, Xin; Wu, Bin; Zheng, Yi; Tian, Yong; Liu, Jie; Zheng, Chunmiao

    2015-04-01

    , the optimization suggests increase of pumping percentage in areas with significant GW recharge and shallow water table and adjacent to the main river channel. Temporally, the optimization suggests increase of pumping percentage during dry seasons, and decrease during flooding seasons. The groundwater storage zone could work as inartificial reservoirs because of the fierce interactions between SW and GW to help achieve spatial and temporal reallocation without loss from evaporation. Moreover, the results of different scenarios reveal that, sustainability of saturated zone for the midstream part could be promoted dramatically by cutting down irrigation demand. The study results are of significant importance to the water resources management in arid and semi-arid agricultural areas.

  3. A PROPOSED NEW VEGETATION INDEX, THE TOTAL RATIO VEGETATION INDEX (TRVI), FOR ARID AND SEMI-ARID REGIONS

    OpenAIRE

    H. Fadaei; Suzuki, R.; Sakai, T; Torii, K.

    2012-01-01

    Vegetation indices that provide important key to predict amount vegetation in forest such as percentage vegetation cover, aboveground biomass, and leaf-area index. Arid and semi-arid areas are not exempt of this rule. Arid and semi-arid areas of northeast Iran cover about 3.4 million ha and are populated by two main tree species, the broadleaf Pistacia vera (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environ...

  4. Remote Sensing Parameterization of Land Surface Heat Fluxes over Arid and Semi-arid Areas

    Institute of Scientific and Technical Information of China (English)

    马耀明; 王介民; 黄荣辉; 卫国安; MassimoMENENTI; 苏中波; 胡泽勇; 高峰; 文军

    2003-01-01

    Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based on satellite remote sensing and field observations is proposed and tested for deriving the regional land surface heat fluxes over inhomogeneous landscapes. As a case study, the method is applied to the Dunhuang experimental area and the HEIFE (Heihe River Field Experiment, 1988-1994) area. The Dunhuang area is selected as a basic experimental area for the Chinese National Key Programme for Developing Basic Sciences: Research on the Formation Mecbanism and Prediction Theory of Severe Climate Disaster in China (G1998040900, 1999-2003). The four scenes of Landsat TM data used in this study are 3 June 2000,22 August 2000, and 29 January 2001 for the Dunhuang area and 9 July 1991 for the HEIFE area. The regional distributions of land surface variables, vegetation variables, and heat fluxes over inhomogeneous landscapes in arid and semi-arid areas are obtained in this study.

  5. Correction: Independent transitions between monsoonal and arid biomes revealed by systematic revison of a complex of Australian geckos (Diplodactylus; Diplodactylidae.

    Directory of Open Access Journals (Sweden)

    Paul M Oliver

    Full Text Available How the widespread expansion and intensification of aridity through the Neogene has shaped the Austral biota is a major question in Antipodean biogeography.Lineages distributed across wide aridity gradients provide opportunities to examine the timing, frequency, and direction of transitions between arid and mesic regions.Here, we use molecular genetics and morphological data to investigate the systematics and biogeography of a nominal Australian gecko species(Diplodactylus conspicillatus sensu lato with a wide distribution spanning most of the Australian Arid Zone (AAZ and Monsoonal Tropics (AMT. Our data support a minimum of seven genetically distinct and morphologically diagnosable taxa; we thus redefine the type species, ressurrect three names from synonymy, and describe three new species. Our inferred phylogeny suggests the history and diversification of lineages in the AAZ and AMT are intimately linked, with evidence of multiple independent interchanges since the late Miocene. However, despite this shared history, related lineages in these two regions also show evidence of broadly contrasting intra-regional responses to aridification; vicarance and speciation in older and increasingly attenuated mesic regions, versus a more dynamic history including independent colonisations and recent range expansions in the younger AAZ.

  6. Independent Transitions between Monsoonal and Arid Biomes Revealed by Systematic Revison of a Complex of Australian Geckos (Diplodactylus; Diplodactylidae.

    Directory of Open Access Journals (Sweden)

    Paul M Oliver

    Full Text Available How the widespread expansion and intensification of aridity through the Neogene has shaped the Austral biota is a major question in Antipodean biogeography. Lineages distributed across wide aridity gradients provide opportunities to examine the timing, frequency, and direction of transitions between arid and mesic regions. Here, we use molecular genetics and morphological data to investigate the systematics and biogeography of a nominal Australian gecko species (Diplodactylus conspicillatus sensu lato with a wide distribution spanning most of the Australian Arid Zone (AAZ and Monsoonal Tropics (AMT. Our data support a minimum of seven genetically distinct and morphologically diagnosable taxa; we thus redefine the type species, ressurrect three names from synonymy, and describe three new species. Our inferred phylogeny suggests the history and diversification of lineages in the AAZ and AMT are intimately linked, with evidence of multiple independent interchanges since the late Miocene. However, despite this shared history, related lineages in these two regions also show evidence of broadly contrasting intra-regional responses to aridification; vicarance and speciation in older and increasingly attenuated mesic regions, versus a more dynamic history including independent colonisations and recent range expansions in the younger AAZ.

  7. Analysis of behaviour patterns and thermal responses to a hot-arid climate in rural China.

    Science.gov (United States)

    Yan, Haiyan; Yang, Liu; Zheng, Wuxing; He, Wenfang; Li, Daoyi

    2016-07-01

    Climate can greatly affect building design, life style and thermal perception for all groups of people; however, this phenomenon has not yet been rigorously evaluated in China's hot-arid climate. The aim of this paper is to present the results of a thermal comfort survey by evaluating the influence of the hot-arid climate upon the behavioural patterns and thermal comfort responses of 160 residents in 65 traditional vernacular houses in Turfan, China, in 2011. In this survey, there were 206 sets of effective data, and the features of the traditional residential buildings and the human behaviour patterns in Turfan were described and analysed. The results showed that the diversified courtyards and shade spaces were the most obvious features of traditional houses in Turfan. People here typically spend most of their time in one of two spaces for eating, resting, and entertaining. It was found that the preferred temperature was 26.5°C. The preferred air velocity occurred at 0.62m/s. A suitable air velocity range of 0.15-1.24m/s was suggested in Turfan. Moreover, the neutral temperature of the local people was 30.1°C (tg or to). The upper limits of the 80% acceptable zone by using the direct and indirect acceptability method were 32.7 and 33.8°C, respectively. The neutral temperature and upper limit of the acceptable zone in Turfan were higher than those of the adaptive standards. Attention should be paid to the role of thermal comfort in influencing building design by using simple passive cooling strategies. The above results are believed to be potentially valuable for the design and evaluation of residential buildings located in hot-arid climate.

  8. Disposal of high-level nuclear waste above the water table in arid regions

    Science.gov (United States)

    Roseboom, Eugene H.

    1983-01-01

    Locating a repository in the unsaturated zone of arid regions eliminates or simplifies many of the technological problems involved in designing a repository for operation below the water table and predicting its performance. It also offers possible accessibility and ease of monitoring throughout the operational period and possible retrieval of waste long after. The risks inherent in such a repository appear to be no greater than in one located in the saturated zone; in fact, many aspects of such a repository's performance will be much easier to predict and the uncertainties will be reduced correspondingly. A major new concern would be whether future climatic changes could produce significant consequences due to possible rise of the water table or increased flux of water through the repository. If spent fuel were used as a waste form, a second new concern would be the rates of escape of gaseous iodine-129 and carbon-14 to the atmosphere.

  9. Uses of tree legumes in semi-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.

    1980-01-01

    Uses of tree legumes in semi-arid and arid regions are reviewed. This review is divided into sections according to the following general use categories: fuels; human food; livestock food; to increase yields of crops grown beneath their canopies;and control of desertification. (MHR)

  10. CHARACTERISTICS AND CONSTRUCTION OF LANDSCAPE???ECOLOGY IN ARID REGIONS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper analyzes the characteristics of the landscape structures and landacape ecological processes in arid regions of China. Landscape structure is simplicity and homogeneity with the pattern of desert-oasis-river and canal corridor. The spatial distribution of landscape heterogeneity mosaics is relatively dependent on water resources. In arid regions,the landscape changes rapidly and extensively because of the sensitive landscape ecosystems and fragile regional ecosystems.For the sustainable development of arid regions, the theories and methods for the eco-environmental construction and the strategies of ecological construction in the arid regions were proposed in the view of landscape ecology. Keynote subjects of landscape ecology were also discussed. The paper points out that protecting and increasing landscape diversity and heterogeneity are critical to control ecological safety in arid regions.

  11. Analysis list: ARID3A [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ARID3A Blood,Liver + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/AR...ID3A.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID3A.5.tsv http://dbarchive.biosciencedb...c.jp/kyushu-u/hg19/target/ARID3A.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID3A.Blood.tsv,http://dbarchive.biosci...encedbc.jp/kyushu-u/hg19/colo/ARID3A.Liver.tsv http://dbarchive.bioscience...dbc.jp/kyushu-u/hg19/colo/Blood.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Liver.gml ...

  12. ANNUAL REPORT FOR ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 87016 CO-PRECIPITATION OF TRACE METALS IN GROUNDWATER AND VADOSE ZONE CALCITE: IN SITU CONTAINMENT AND STABILIZATION OF STRONTIUM-90 AND OTHER DIVALENT METALS AND RADIONUCLIDES AT ARID WESTERN DOE SITES

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W.; Fujita, Yoshiko; Ferris, F. Grant; Cosgrove, Donna M.; Colwell, F. S.

    2003-06-15

    Radionuclide and metal contaminants such as 90Sr are present beneath U.S. Department of Energy (DOE) lands in both the groundwater (e.g., 100-N area at Hanford, WA) and vadose zone (e.g., Idaho Nuclear Technology and Engineering Center at the Idaho National Engineering and Environmental Laboratory). In situ containment and stabilization of these contaminants is a cost-effective treatment strategy. However, implementing in situ containment and stabilization approaches requires definition of the mechanisms that control contaminant sequestration. We are investigating the in situ immobilization of radionuclides or contaminant metals (e.g., 90Sr) by their facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Our facilitated approach, shown schematically in Figure 1, relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity. Subsurface urea hydrolysis is catalyzed by the urease enzyme, which may be either introduced with the urea or produced in situ by ubiquitous subsurface urea hydrolyzing microorganisms. Because the precipitation process tends to be irreversible and many western aquifers are saturated with respect to calcite, the coprecipitated metals and radionuclides will be effectively removed from the aqueous phase over the long-term. Another advantage of the ureolysis approach is that the ammonium ions produced by the reaction can exchange with radionuclides sorbed to subsurface minerals, thereby enhancing the availability of the radionuclides for re-capture in a more stable solid phase (co-precipitation rather than adsorption).

  13. Arid Climate Landscape Evolution and the Pediment Problem

    Science.gov (United States)

    Strudley, M. W.; Murray, A. B.; Haff, P. K.

    2003-12-01

    Although widely disseminated throughout many different climatic environments, pediments, or gently sloping, laterally extensive surfaces characterized by a thin veneer of alluvium covering bedrock, are particularly well developed in granitic desert locales such as the Mojave and Colorado Deserts in southern California and the Sonoran Desert in western Arizona. These features form a transitional zone within the piedmont of many exposed batholithic mountainous bodies, separating a zone of bare bedrock erosion in the steep mountain mass from a depositional zone in the alluvial basin. Well developed pediments in granitic environments commonly contain bedrock outcroppings (tors or inselbergs) that may remain uncovered indefinitely and sharp slope discontinuities at the piedmont junction separating the pediment surface from the mountain mass. Pediments have been the focus of debate in geomorphic circles for over half a century. While some geomorphologists have proposed that pediments and their associated tor fields represent unearthed relict landforms, others propose unique modes of sediment transport that form and maintain the beveled form of pediment surfaces. We hypothesize that a simple relationship between bedrock weathering and alluvial thickness could explain this range of enigmatic features and phenomena, a relationship that Anderson (2002) incorporates in his proposed explanation for high alpine surfaces and tors. Field observations suggest that the transformation of bedrock to regolith is most rapid with a finite covering of regolith. This weathering rule, combined with a simple set of sediment transport rules provides a mechanism through which pediment surfaces are produced. We examine the development of pediment surfaces and associated features using a 3D numerical, distributed-parameter landscape evolution model incorporating the most pertinent landscape development processes acting in arid regions. Temporally and spatially variable rainfall (storm size

  14. The current bioenergy production potential of semi-arid and arid regions in sub-Saharan Africa

    NARCIS (Netherlands)

    Wicke, B.; Smeets, E.M.W.; Watson, H.; Faaij, A.P.C.

    2011-01-01

    This article assesses the current technical and economic potential of three bioenergy production systems (cassava ethanol, jatropha oil and fuelwood) in semi-arid and arid regions of eight sub-Saharan African countries. The results indicate that the availability of land for energy production ranges

  15. The Mojave vadose zone: a subsurface biosphere analogue for Mars.

    Science.gov (United States)

    Abbey, William; Salas, Everett; Bhartia, Rohit; Beegle, Luther W

    2013-07-01

    If life ever evolved on the surface of Mars, it is unlikely that it would still survive there today, but as Mars evolved from a wet planet to an arid one, the subsurface environment may have presented a refuge from increasingly hostile surface conditions. Since the last glacial maximum, the Mojave Desert has experienced a similar shift from a wet to a dry environment, giving us the opportunity to study here on Earth how subsurface ecosystems in an arid environment adapt to increasingly barren surface conditions. In this paper, we advocate studying the vadose zone ecosystem of the Mojave Desert as an analogue for possible subsurface biospheres on Mars. We also describe several examples of Mars-like terrain found in the Mojave region and discuss ecological insights that might be gained by a thorough examination of the vadose zone in these specific terrains. Examples described include distributary fans (deltas, alluvial fans, etc.), paleosols overlain by basaltic lava flows, and evaporite deposits.

  16. Development of an arid site closure plan

    International Nuclear Information System (INIS)

    This document describes the development of a prototype plan for the effective closure and stabilization of an arid low-level waste disposal site. This plan will provide demonstrated closure techniques for a trench in a disposal site at Los Alamos. The accuracy of modeling soil water storage by two hydrologic models, CREAMS and HELP, was tested by comparing simulation results with field measurements of soil moisture in eight experimental landfill cover systems having a range of well-defined soil profiles and vegetative covers. Regression analysis showed that CREAMS generally represented soil moisture more accurately than HELP simulations. Precautions for determining parameter values for model input and for interpreting simulation results are discussed. A specific example is presented showing how the field-validated hydrologic models can be used to develop a final prototype closure plan. 15 refs., 13 figs., 3 tabs

  17. Characterization of magnetically enhanced buried soil layer in arid environment

    Science.gov (United States)

    Petrovsky, E.; Grison, H.; Kapicka, A.; Silva, P. F.; Font, E.

    2011-12-01

    Magnetic susceptibility (MS) of soils, reflecting the presence of magnetite/maghemite, can be used in several environmental applications. Magnetic topsoil mapping is often used to outline areas polluted by atmospherically deposited dust. However, in these studies, the magnetically enhanced layer is usually shallow, some 5-6 cm under the surface. In our contribution, we present the case when the magnetic susceptibility is enhanced in deeper soil layers. Investigated soils are mostly sandy soils, from several localities in Portugal, in a zone with arid climate. Sample profiles were collected always in forests or forest stands with pines, cork oaks or eucalyptus trees in two areas: around the city of Sines (on the coast south of Lisbon) and around the city of Abrantes (inland, north-east of Lisbon). Both areas are presumably affected by one major source of pollution - power plant. Surface magnetic susceptibility measurements were performed by Bartington MS2D loop; values vary from 10 to 300 x 10-5 SI units. Vertical distribution of magnetic susceptibility was measured already in situ using the SM400 (ZHInstruments) on profiles about 40cm in length. Mass-specific MS was determined using Bartington MS2B dual frequency meter and Agico MFK1. Nine vertical profiles were selected for detailed analyses including the ARM, IRM and hysteresis measurements. Distinctly enhanced magnetic layers were detected in deeper horizons. This enhancement can be ascribed to several mechanisms. Migration of magnetic particles seems to be probable, as observed in our model experiments with sand columns. In coastal areas, the enhanced layer could be due to tsunami deposits, as described in other areas. Finally, in particular at sites close to power plants, the construction works followed by surface remediation have to be also considered as one of the possible mechanisms.

  18. Spatial pattern of a plant community in a wetland ecosystem in a semi-arid region in northwestern China

    Institute of Scientific and Technical Information of China (English)

    Kebin ZHANG; Rui LI; Yunfang LIU; Baitian WANG; Xiaohui YANG; Ruiping HOU

    2008-01-01

    The spatial distribution characteristics of plant communities in a wetland-dry grassland ecosystem in arid and semi-arid regions in northwestern China and the main factors affecting the distribution pattern were studied. The Siertan wetland in the Haba Lake Nature Reserve was the study area. Four transect lines, each about 1 km long, were set up in the growing season along the biotope gradient in four directions: east, northeast, west and northwest. Attributes measured include frequency of occurrence, height, density, coverage, biomass and envir-onmental soil factors. The data were analyzed using a two-way indicative species analysis (TWINSPAN), detrended correspondence analysis (DCA) and Spear-man correlation coefficients. On this basis, the vegetation in the Siertan wetland was classified into three types and 14 associations. The first vegetation type was halophytic marsh vegetation, mainly distributed in the wetland zone. This type largely contains halophyte and hygric plants and its representative association is Phragmites communis + Kalidiumfoliatum. The second type was meadow vegeta-tion, distributed in the ecotone. The meadow vegetation species are mainly mesophytic and their representative association is Nitraria tangutorum+ Pennisetum flacci-dum. The third vegetation type is grassland vegetation, which mainly consists of mesophytic and xerophytes, dis-tributed in the arid grassland zone. The representative association of the third vegetation type is the association of Anaeurolepidium secalium + Saussurea runcinata. Correlation analysis between the axes of DCA and envir-onmental soil factors shows that soil moisture content, organic matter, soil salt content and total nitrogen are the main environmental factors affecting the pattern of vegetation distribution along the biotope gradients from wetland to arid grassland. Other factors affecting the vegetation are microtopography and grazing pressure. Additionally, we have reported modifications and

  19. Geothermal technoecosystems and water cycles in arid lands. Information paper

    Energy Technology Data Exchange (ETDEWEB)

    Duffield, C.

    1976-01-01

    Arid lands resource information paper No. 2, 'Exploration and Exploitation of Geothermal Resources in Arid and Semiarid Lands,' first issued in 1973, is now out-of-print. The intent of the present paper was to revise that earlier literature review with its annotated bibliography, by recognizing the unusual developments in this field in the interim, with new geothermal fields discovered, new demands for geothermal energy as an alternative source to more conventional sources, and a number of new publications reflecting accelerated research. The extensive bibliography accompanying this paper was produced by ALIS, and includes over one hundred references prepared by the Office of Arid Lands Studies.

  20. Long-term aridity changes in the western United States.

    Science.gov (United States)

    Cook, Edward R; Woodhouse, Connie A; Eakin, C Mark; Meko, David M; Stahle, David W

    2004-11-01

    The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records. Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Medieval Warm Period. If elevated aridity in the western United States is a natural response to climate warming, then any trend toward warmer temperatures in the future could lead to a serious long-term increase in aridity over western North America.

  1. Hydrodynamic caracterisation of an heterogeneous aquifer system under semi-arid climate

    Science.gov (United States)

    Drias, T.; Toubal, A. Ch

    2009-04-01

    The studied zone is a part of the Mellegne's (North-East of Algeria) under pound, this zone is characterised by its semi-arid climate. The water bearing system is formed by the plio-quaternairy alluviums resting on a marley substratuim of age Eocene. The geostatiscitcs approach of the hydrodynamics parameters (Hydrolic load, transmisivity) allowed the study of their spatial distrubution (casting) by the method of Krigeage by blocks and the identification of zones with water-bearing potentialities. In this respect, the zone of Ain Chabro which, is situated in the South of the plain shows the best values of the transmisivity...... The use of a bidimensinnel model in the differences ended in the permanent regime allowed us to establish the global balence sheet (overall assessment) of the tablecloth and to refine the transmisivity field. These would vary more exactley between 10-4 to 10-2 m²/s. The method associating the probability appraoch of Krigeage to that determining the model has facilited the wedging of the model and clarified the inflitration value. Keys words: hydrodynamics, geostatiscitcs, Modeling, Chabro, Tébessa.

  2. Arid Lands--A Study in Ecological Disaster

    Science.gov (United States)

    Eckholm, Erik

    1977-01-01

    Reports that over-grazing and unsound agricultural practices are increasing the world-wide amount of uninhabitable land. Cites some practices which have been used to successfully reclaim arid land areas. (CP)

  3. Recycled Urban Wastewater for Irrigation of Jatropha curcas L. in Abandoned Agricultural Arid Land

    Directory of Open Access Journals (Sweden)

    María Dorta-Santos

    2014-10-01

    Full Text Available In a global context in which obtaining new energy sources is of paramount importance, the production of biodiesel from plant crops is a potentially viable alternative to the use of fossil fuels. Among the species used to produce the raw material for biodiesel, Jatropha curcas L. (JCL has enjoyed increased popularity in recent years, due partly to its ability to grow in degraded zones and under arid and semi-arid conditions. The present study evaluates the potential for JCL production under irrigation with non-conventional water resources in abandoned agricultural soils of the island of Fuerteventura (Canary Islands, Spain, which is one of the most arid parts of the European Union. JCL growth and productivity are compared during the first 39 months of cultivation in two soil types (clay-loam and sandy-loam and with two irrigation water qualities: recycled urban wastewater (RWW and desalinated brackish water (DBW. The results indicate that JCL growth (in terms of plant height and stem diameter was significantly influenced both by soil type and water quality, with better development observed in the sandy-loam soil under RWW irrigation. Productivity, measured as cumulative seed production, was not affected by soil type but was affected by water quality. Production under RWW irrigation was approximately seven times greater than with DBW (mean ~2142 vs. 322 kg·ha−1. The higher nutrient content, especially P, K and Mg, and lower B content of the RWW were found to be key factors in the greater productivity observed under irrigation with this type of water.

  4. Aridity changes in the Tibetan Plateau in a warming climate

    International Nuclear Information System (INIS)

    Desertification in the Tibetan Plateau (TP) has drawn increasing attention in the recent decades. It has been postulated as a consequence of increasing climate aridity due to the observed warming. This study quantifies the aridity changes in the TP and attributes the changes to different climatic factors. Using the ratio of precipitation to potential evapotranspiration (P/PET) as an aridity index, we used observed meteorological records at 83 stations in the TP to calculate PET using the Penman–Monteith algorithm and the ratio. Spatial and temporal changes of P/PET in 1979–2011 were analyzed. Results show that stations located in the arid and semi-arid northwestern TP are becoming significantly wetter, and half of the stations in the semi-humid eastern TP are becoming drier, though not significantly, in the recent three decades. The aridity change patterns are significantly correlated with the change patterns of precipitation, sunshine duration and diurnal temperature range. Temporal correlations between the annual P/PET ratio and other meteorological variables confirm the significant correlation between aridity and the three variables, with precipitation being the dominant driver of P/PET changes at the interannual time scale. Annual PET are insignificantly but negatively correlated with P/PET in the cold season. In the warm season, however, the correlation between PET and P/PET is significant at the confidence level of 99.9% when the cryosphere near the surface melts. Significant correlation between annual wind speed and aridity occurs in limited locations and months. Consistency in the climatology pattern and linear trends in surface air temperature and precipitation calculated using station data, gridded data, and nearest grid-to-stations for the TP average and across sub-basins indicate the robustness of the trends despite the large spatial heterogeneity in the TP that challenge climate monitoring. (letter)

  5. Late glacial aridity in southern Rocky Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Davis, O.K.; Pitblado, B.L. [Univ. of Arizona, Tucson, AZ (United States)

    1995-09-01

    While the slopes of the present-day Colorado Rocky Mountains are characterized by large stands of subalpine and montane conifers, the Rockies of the late glacial looked dramatically different. Specifically, pollen records suggest that during the late glacial, Artemisia and Gramineae predominated throughout the mountains of Colorado. At some point between 11,000 and 10,000 B.P., however, both Artemisia and grasses underwent a dramatic decline, which can be identified in virtually every pollen diagram produced for Colorado mountain sites, including Como Lake (Sangre de Cristo Mountains), Copley Lake and Splains; Gulch (near Crested Butte), Molas Lake (San Juan Mountains), and Redrock Lake (Boulder County). Moreover, the same pattern seems to hold for pollen spectra derived for areas adjacent to Colorado, including at sites in the Chuska Mountains of New Mexico and in eastern Wyoming. The implications of this consistent finding are compelling. The closest modem analogues to the Artemisia- and Gramineae-dominated late-glacial Colorado Rockies are found in the relatively arid northern Great Basin, which suggests that annual precipitation was much lower in the late-glacial southern Rocky Mountains than it was throughout the Holocene.

  6. Analyzing Landscape Trends on Agriculture, Introduced Exotic Grasslands and Riparian Ecosystems in Arid Regions of Mexico

    Directory of Open Access Journals (Sweden)

    Romeo Mendez-Estrella

    2016-08-01

    Full Text Available Riparian Zones are considered biodiversity and ecosystem services hotspots. In arid environments, these ecosystems represent key habitats, since water availability makes them unique in terms of fauna, flora and ecological processes. Simple yet powerful remote sensing techniques were used to assess how spatial and temporal land cover dynamics, and water depth reflect distribution of key land cover types in riparian areas. Our study area includes the San Miguel and Zanjon rivers in Northwest Mexico. We used a supervised classification and regression tree (CART algorithm to produce thematic classifications (with accuracies higher than 78% for 1993, 2002 and 2011 using Landsat TM scenes. Our results suggest a decline in agriculture (32.5% area decrease and cultivated grasslands (21.1% area decrease from 1993 to 2011 in the study area. We found constant fluctuation between adjacent land cover classes and riparian habitat. We also found that water depth restricts Riparian Vegetation distribution but not agricultural lands or induced grasslands. Using remote sensing combined with spatial analysis, we were able to reach a better understanding of how riparian habitats are being modified in arid environments and how they have changed through time.

  7. Human Thermal Comfort and Heat Stress in an Outdoor Urban Arid Environment: A Case Study

    Directory of Open Access Journals (Sweden)

    A. M. Abdel-Ghany

    2013-01-01

    Full Text Available To protect humans from heat stress risks, thermal comfort and heat stress potential were evaluated under arid environment, which had never been made for such climate. The thermal indices THI, WBGT, PET, and UTCI were used to evaluate thermal comfort and heat stress. RayMan software model was used to estimate the PET, and the UTCI calculator was used for UTCI. Dry and wet bulb temperatures (Td, Tw, natural wet bulb temperature (Tnw, and globe temperature (Tg were measured in a summer day to be used in the calculation. The results showed the following. (i The thermal sensation and heat stress levels can be evaluated by either the PET or UTCI scales, and both are valid for extremely high temperature in the arid environment. (ii In the comfort zone, around 75% of individuals would be satisfied with the surrounding environment and feel comfortable during the whole day. (iii Persons are exposed to strong heat stress and would feel uncomfortable most of the daytime in summer. (iv Heat fatigue is expected with prolonged exposure to sun light and activity. (v During the daytime, humans should schedule their activities according to the highest permissible values of the WBGT to avoid thermal shock.

  8. Keeping Sediment and Nutrients out of Streams in Arid/Semi-Arid Regions: Application of Low Impact Development/Green Infrastructure Practices

    Science.gov (United States)

    Yongping, Yuan

    2015-04-01

    Climatic and hydrological characteristics in the arid/semi-arid areas create unique challenges to soil, water and biodiversity conservation. These areas are environmentally sensitive, but very valuable for the ecosystems services they provide to society. Some of these areas are experiencing the fastest urbanization and now face multiple water resource challenges. Low Impact Development (LID)/Green Infrastructure (GI) practices are increasingly popular for reducing stormwater and nonpoint source pollution in many regions around the world. However, streamflow in the arid/semi-arid regions is largely dependent on seasonal, short term, and high intensity rainfall events. LID has not been very common in the arid/semi-arid regions due to a lack of performance evaluation, as well as the perception that LID may not be very useful for regions with little annual precipitation. This study focused on investigating the hydrologic and pollutant removal performance of LID/GI systems in arid/semi-arid climates. Ten types of practices were found in use in the Western/Southwestern U.S.: rainwater harvest systems, detention ponds, retention ponds, bioretention, media filters, porous pavements, vegetated swales/buffer/strips, green roofs, infiltration trenches, and integrated LIDs. This study compared the performance of these practices in terms of their effectiveness at pollutant removal and cost-effectiveness. This analysis provides insight into the future implementation of LID/GI in the arid/semi-arid areas. Key words: LID/GI, arid/semi-arid, effectiveness of pollutant removal, cost-effectiveness analysis

  9. UNESCO's G-WADI Program - Developing and Delivering Tools for Improved Water Management in Semi-arid and Arid Lands

    Science.gov (United States)

    Woodard, G. C.; Imam, B.; Sorooshian, S.

    2007-12-01

    UNESCO's Water and Development Information for Arid Lands - A Global Network (G-WADI) aims to strengthen the capacity to manage the water resources of arid and semi-arid areas around the globe through a network of international and regional cooperation. Six centers, including SAHRA headquartered at the University of Arizona and CHRS at UC-Irvine, are cooperating to improve water resource management by sharing knowledge and tools. Specific objectives include: improved understanding of the special characteristics of hydrological systems and water management needs in arid areas, through shared data and experiences; capacity building of individuals and institutions; raising awareness of advanced technologies for data provision, data assimilation, and system analysis; and promoting integrated basin management and the use of appropriate decision support tools. SAHRA coordinates G-WADI's information dissemination via G-WADI's web site and publications. Web-based resources include Global Water News Watch and the subscription service, Water News Tracker, plus access to remotely sensed precipitation data from HyDIS. Information on use of isotopes and chemical tracers is also featured. Materials and outcomes from various workshops and short courses on modeling, water harvesting, and impacts of climate change also are provided. While the intent is to benefit water resource managers in semi- arid and arid developing countries, the collaboration among international water centers, and perspectives and traditional knowledge gained from users, has benefitted U.S. researchers in many ways.

  10. Aquaculture and mangrove ecosys of temproductivity in arid and semi-arid Balochistan coastal environments

    International Nuclear Information System (INIS)

    A survey of coastal shrimp-pond operations, and the structure and functioning of coastal mangrove forest ecosystems with particular reference to Ecuador, indicates that certain physical parameters may be good predictors of key biological processes. The most important factors are those associated with the regional water balance, tidal and surface water circulation patterns, and the physicochemical properties of the underlying soils. One important conclusion to emerge from the analyses is that at both regional and local levels, well-developed and productive mangrove forest areas often represent the least desirable sites for the construction and operation of commercial shrimp ponds. In certain regards semi-arid and arid coastal environments where mangroves are poorly developed, shrimp ponds that are constructed on barren mud flats and inland salt pans appear to have the potential to produce higher yields of shrimp with fewer management problems and at a relatively lower production cost. The data and research results from coast of Baluchistan and elsewhere are briefly summarized to suggest why productive mangrove ecosystems to not make the best areas in which to obtain maximum shrimp-pond yields. (author)

  11. Predictability and prediction of summer rainfall in the arid and semi-arid regions of China

    Science.gov (United States)

    Xing, Wen; Wang, Bin

    2016-09-01

    Northwest China (NWC) is an arid and semi-arid region where climate variability and environmental changes are sensitive to precipitation. The present study explores sources and limits of predictability of summer precipitation over NWC using the predictable mode analysis (PMA) of percentage of rainfall anomaly data. Two major modes of NWC summer rainfall variability are identified which are tied to Eurasian continental scale precipitation variations. The first mode features wet northern China corresponding to dry central Siberia and wet Mongolia, which is mainly driven by tropical Pacific sea surface temperature anomalies (SSTA). The second mode features wet western China reflecting wet Central Asia and dry Ural-western Siberia, which strongly links to Indian Ocean SSTA. Anomalous land warming over Eurasia also provides important precursors for the two modes. The cross-validated hindcast results demonstrate these modes can be predicted with significant correlation skills, suggesting that they may be considered as predictable modes. The domain averaged temporal correlation coefficient (TCC) skill during 1979 to 2015 using 0-month (1-month) lead models is 0.39 (0.35), which is considerably higher than dynamical models' multi-model ensemble mean skill (-0.02). Maximum potential attainable prediction skills are also estimated and discussed. The result illustrates advantage of PMA in predicting rainfall over dry land areas and large room for dynamical model improvement. However, secular changes of predictors need to be detected continuously in order to make practical useful prediction.

  12. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Emmanuel Mavhura

    2015-02-01

    Full Text Available Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to examine the rainfall variability in the study area and the drought-coping mechanisms employed by smallholder famers respectively. The results show that there are various strategies used by smallholder farmers to cope with the impact of drought. These strategies include drought-tolerant crop production, crop variety diversification, purchasing cereals through asset sales, non-governmental organisations’ food aid and gathering wild fruit. However, consecutive droughts have resulted in high food insecurity and depletion of household assets during droughts. Smallholder farmers in the valley have also resorted to a number of measures taken before, during and after the drought. Still, these strategies are not robust enough to cope with this uncertainty

  13. Combating Poverty by Irrigation from Large Dams in Arid Countries: A Case Study of Minab Dam, Iran

    Directory of Open Access Journals (Sweden)

    ALI ASGHAR IRAJ POOR

    2010-10-01

    Full Text Available A set of indicators for sustainable development were identified to be employed in developing countries. The selected indicators provided a good understanding of social and engineering outputs of a water resources project. Results of the study revealed that there are significant positive impacts of dam construction but they were not same as the targeted objectives envisaged in the feasibility report of the project. It means that after construction of the dam and irrigation system, development didn?t match with the targeted goals of the project. This study argues the world-wide controversy against construction of dam in arid zone which is ill-founded and based on a few short term, mitigable negative impacts, ignoring many positive long term inputs alleviating chronic poverty in arid regions. The study meticulously looks into the pre dam bio-physical and socio-economic conditions in one of the arid region of Iran under the area commanded by Minab dam. This dam was constructed in Hormozgan province of Iran in 1983 and its irrigation system was completed in 1986 which was followed by progressive expansion of irrigated agriculture which almost doubled in year 2006. Literacy rate has increased from 41% (pre-project to 74% in 2006. Similarly, significant improvements were observed in health care, sanitation, education, and other disciplines.

  14. Surficial weathering of iron sulfide mine tailings under semi-arid climate

    Science.gov (United States)

    Hayes, Sarah M.; Root, Robert A.; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

    2014-01-01

    Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering under semi-arid climate at an EPA Superfund Site in semi-arid central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130–140 and 100–120 g kg−1, respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even

  15. Surficial weathering of iron sulfide mine tailings under semi-arid climate.

    Science.gov (United States)

    Hayes, Sarah M; Root, Robert A; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

    2014-09-15

    Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering under semi-arid climate at an EPA Superfund Site in semi-arid central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130-140 and 100-120 g kg(-1), respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even in

  16. Dependence of juvenile reef fishes on semi-arid hypersaline estuary microhabitats as nurseries.

    Science.gov (United States)

    Sales, N S; Dias, T L P; Baeta, A; Pessanha, A L M

    2016-07-01

    The differences between fish assemblages in three microhabitat types, in relation to vegetation and sediment characteristics of a hypersaline estuary located in an semi-arid zone in north-eastern Brazil, were investigated. Fishes were collected using a beach seine during the rainy and dry seasons in 2012. A total of 78 species were recorded, with the most common families being Gerreidae, Lutjanidae and Tetraodontidae. The majority of species were represented by juveniles, with Eucinostomus argenteus, Ulaema lefroyi and Sphoeroides greeleyi being the dominant species. The fish assemblage structures differed significantly among microhabitat types, with the narrow intertidal flat adjacent to the mangrove fringe supporting the most diverse fish fauna. In addition, only 27 species were common to all of the microhabitats. The results support the hypothesis that hypersaline estuaries serve as important nursery areas for various reef fish species, due to the structural complexity provided by their macroalgae beds and mangroves.

  17. Shallow Horizontal GCHP Effectiveness in Arid Climate Soils

    Science.gov (United States)

    North, Timothy James

    Ground coupled heat pumps (GCHPs) have been used successfully in many environments to improve the heating and cooling efficiency of both small and large scale buildings. In arid climate regions, such as the Phoenix, Arizona metropolitan area, where the air condi-tioning load is dominated by cooling in the summer, GCHPs are difficult to install and operate. This is because the nature of soils in arid climate regions, in that they are both dry and hot, renders them particularly ineffective at dissipating heat. The first part of this thesis addresses applying the SVHeat finite element modeling soft-ware to create a model of a GCHP system. Using real-world data from a prototype solar-water heating system coupled with a ground-source heat exchanger installed in Menlo Park, California, a relatively accurate model was created to represent a novel GCHP panel system installed in a shallow vertical trench. A sensitivity analysis was performed to evaluate the accuracy of the calibrated model. The second part of the thesis involved adapting the calibrated model to represent an ap-proximation of soil conditions in arid climate regions, using a range of thermal properties for dry soils. The effectiveness of the GCHP in the arid climate region model was then evaluated by comparing the thermal flux from the panel into the subsurface profile to that of the prototype GCHP. It was shown that soils in arid climate regions are particularly inefficient at heat dissipation, but that it is highly dependent on the thermal conductivity inputted into the model. This demonstrates the importance of proper site characterization in arid climate regions. Finally, several soil improvement methods were researched to evaluate their potential for use in improving the effectiveness of shallow horizontal GCHP systems in arid climate regions.

  18. Zoning Districts, Zoning, Published in 2002, Freelance.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Zoning Districts dataset, was produced all or in part from Hardcopy Maps information as of 2002. It is described as 'Zoning'. Data by this publisher are often...

  19. Impact of debris dams on hyporheic interaction along a semi-arid stream

    Science.gov (United States)

    Lautz, Laura K.; Siegel, Donald I.; Bauer, Robert L.

    2006-01-01

    Hyporheic exchange increases the potential for solute retention in streams by slowing downstream transport and increasing solute contact with the substrate. Hyporheic exchange may be a major mechanism to remove nutrients in semi-arid watersheds, where livestock have damaged stream riparian zones and contributed nutrients to stream channels. Debris dams, such as beaver dams and anthropogenic log dams, may increase hyporheic interactions by slowing stream water velocity, increasing flow complexity and diverting water to the subsurface.Here, we report the results of chloride tracer injection experiments done to evaluate hyporheic interaction along a 320 m reach of Red Canyon Creek, a second order stream in the semi-arid Wind River Range of Wyoming. The study site is part of a rangeland watershed managed by The Nature Conservancy of Wyoming, and used as a hydrologic field site by the University of Missouri Branson Geologic Field Station. The creek reach we investigated has debris dams and tight meanders that hypothetically should enhance hyporheic interaction. Breakthrough curves of chloride measured during the field experiment were modelled with OTIS-P, a one-dimensional, surface-water, solute-transport model from which we extracted the storage exchange rate and cross-sectional area of the storage zone As for hyporheic exchange. Along gaining reaches of the stream reach, short-term hyporheic interactions associated with debris dams were comparable to those associated with severe meanders. In contrast, along the non-gaining reach, stream water was diverted to the subsurface by debris dams and captured by large-scale near-stream flow paths. Overall, hyporheic exchange rates along Red Canyon Creek during snowmelt recession equal or exceed exchange rates observed during baseflow at other streams.

  20. Preliminary study of radioactive waste disposal in the vadose zone

    Energy Technology Data Exchange (ETDEWEB)

    1978-09-01

    To investigate the characteristics of the vadose zone with respect to radioactive waste disposal, the mechanics of unsaturated flow in arid regions and the geohydrology of four areas with a deep water table were studied. The studies indicated that (1) arid sites with a water table deeper than 200 m can be found in at least three distinct geologic settings in the western United States, (2) the physics of unsaturated flow in soils and rock with interstitial porosity at low water contents, particularly under thermal gradients, is not yet completely understood, and (3) under certain conditions unsaturated flow can be so slow that analytic modeling of an unflawed repository is unnecessary to prove effective containment.

  1. Preliminary study of radioactive waste disposal in the vadose zone

    International Nuclear Information System (INIS)

    To investigate the characteristics of the vadose zone with respect to radioactive waste disposal, the mechanics of unsaturated flow in arid regions and the geohydrology of four areas with a deep water table were studied. The studies indicated that (1) arid sites with a water table deeper than 200 m can be found in at least three distinct geologic settings in the western United States, (2) the physics of unsaturated flow in soils and rock with interstitial porosity at low water contents, particularly under thermal gradients, is not yet completely understood, and (3) under certain conditions unsaturated flow can be so slow that analytic modeling of an unflawed repository is unnecessary to prove effective containment

  2. [CIRCULATION OF DIROFILARIA REPENS (RAILLIET ET HENRY, 1911) IN THE ARID ZONE OF SOUTHERN RUSSIA].

    Science.gov (United States)

    Varlamova, A I; Arkhipov, I A

    2016-01-01

    The prevalence of dirofilariasis was studied in dogs from the urban and rural areas in Southern Russia. The high prevalence of Dirofilaria repens infection were established among the dogs in the Republic of Kalmykia. The blood samples from 328 dogs were tested; D. repens infection was detected in 23.6 and 15.5% of the rural and urban dogs, respectively. The highest prevalence of D. repens infection was noted in of 4-6-year-old dogs. Dogs aged 0, 1-3, 4-6 7-9, and more 10 years were infected in 0, 26.3, 33.3, 29.4, and 28.5% of cases, respectively.

  3. Inexplicable inefficiency of avian molt? Insights from an opportunistically breeding arid-zone species, Lichenostomus penicillatus.

    Directory of Open Access Journals (Sweden)

    Bethany J Hoye

    Full Text Available The majority of bird species studied to date have molt schedules that are not concurrent with other energy demanding life history stages, an outcome assumed to arise from energetic trade-offs. Empirical studies reveal that molt is one of the most energetically demanding and perplexingly inefficient growth processes measured. Furthermore, small birds, which have the highest mass-specific basal metabolic rates (BMR(m, have the highest costs of molt per gram of feathers produced. However, many small passerines, including white-plumed honeyeaters (WPHE; Lichenostomus penicillatus, breed in response to resource availability at any time of year, and do so without interrupting their annual molt. We examined the energetic cost of molt in WPHE by quantifying weekly changes in minimum resting metabolic rate (RMR(min during a natural-molt period in 7 wild-caught birds. We also measured the energetic cost of feather replacement in a second group of WPHEs that we forced to replace an additional 25% of their plumage at the start of their natural molt period. Energy expenditure during natural molt revealed an energy conversion efficiency of just 6.9% (±0.57 close to values reported for similar-sized birds from more predictable north-temperate environments. Maximum increases in RMR(min during the molt of WPHE, at 82% (±5.59 above individual pre-molt levels, were some of the highest yet reported. Yet RMR(min maxima during molt were not coincident with the peak period of feather replacement in naturally molting or plucked birds. Given the tight relationship between molt efficiency and mass-specific metabolic rate in all species studied to date, regardless of life-history pattern (Efficiency (%  = 35.720 x 10(-0.494BMRm; r² = 0.944; p  =  or < 0.0001, there appears to be concomitant physiological costs entrained in the molt period that is not directly due to feather replacement. Despite these high total expenditures, the protracted molt period of WPHE significantly reduces these added costs on a daily basis.

  4. The use of medicinal plants in the trans-himalayan arid zone of Mustang district, Nepal

    Directory of Open Access Journals (Sweden)

    Chaudhary Ram P

    2010-04-01

    Full Text Available Abstract Background This study documents the use of medicinal plants from the Mustang district of the north-central part of Nepal. Traditional botanical medicine is the primary mode of healthcare for most of the population of this district and traditional Tibetan doctors (Amchi serve as the local medical experts. Methods Field research was conducted in 27 communities of the Mustang district in Nepal from 2005-2007. We sampled 202 interviewees, using random and snowball sampling techniques. After obtaining prior informed consent, we collected data through semi-structured interviews and participant-observation techniques. Voucher specimens of all cited botanic species were deposited at TUCH in Nepal. Results We recorded the traditional uses of 121 medicinal plant species, belonging to 49 vascular plant and 2 fungal families encompassing 92 genera. These 121 species are employed to treat a total of 116 ailments. We present data on 58 plant species previously unknown for their medicinal uses in the Mustang district. Of the medicinal plants reported, the most common growth form was herbs (73% followed by shrubs, trees, and climbers. We document that several parts of individual plant species are used as medicine. Plant parts were generally prepared using hot or cold water as the 'solvent', but occasionally remedies were prepared with milk, honey, jaggery, ghee and oil. Amchis recommended different types of medicine including paste, powder, decoction, tablet, pills, infusion, and others through oral, topical, nasal and others routes of administration. Conclusions The traditional pharmacopoeia of the Mustang district incorporates a myriad of diverse botanical flora. Traditional knowledge of the remedies is passed down through oral traditions and dedicated apprenticeships under the tutelage of senior Amchi. Although medicinal plants still play a pivotal role in the primary healthcare of the local people of Mustang, efforts to ensure the conservation and sustainable use of medicinal species are necessary.

  5. A new agro-climatic classification for crop suitability zoning in northern semi-arid Ethiopia

    NARCIS (Netherlands)

    Araya, A.; Keesstra, S.D.; Stroosnijder, L.

    2010-01-01

    The agro-climatic resources of Giba catchment in northern Ethiopia were assessed and characterized. The objectives were (i) to ascertain the suitability of the climate for growing teff (Eragrostis tef) and barley (Hordeum vulgare); (ii) to determine the onset and length of the growing period (LGP),

  6. Benthic Macrofaunal Assemblage in the Arid Zone Mangroves of Gulf of Kachchh - Gujarat

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The total benthic macrofauna consisting of 62 species in 5 groups, viz. crustaceans (18), gastropods (17), bivalves (16), polychaetes (9) and fishes (2), was recorded in western Kachchh mangroves near Gujarat. The population densities of benthic macrofauna ranged from 424 to 2393 ind.m-2, the diversity ranged from 1.84 to 2.45 bits ind.-1, the richness varied between 0.82 and 0.98, and the evenness varied between 0.64 and 0.81. Two maximum diversity values were recorded during winter and summer. The salinity ranged from 34 to 44, temperature varied between 17 and 37 ℃, and the acidity ranged from 7 to 8.9.

  7. SEROLOGICAL EVIDENCE OF RECENT DENGUE VIRUS INFECTION AMONG FEBRILE CHILDREN IN A SEMI ARID ZONE

    Directory of Open Access Journals (Sweden)

    Faneye Adedayo

    2013-01-01

    Full Text Available Presence of Dengue virus has been established in Nigeria; owing to the severity of this disease and its attendant complications we investigated the presence of this virus serologically in febrile Nigerian children under 5 years of age from Ilorin. Blood samples were tested from 130 children under the age of 5 years for the presence of IgM antibodies against all the Dengue virus serotypes using ELISA Kit by IVD research, Inc® California USA. A prevalence rate of 40(30.8% was recorded, with male children having a higher rate of 30(44.1% while female children recorded 10(16.1%. Age range distribution was highest in group 3>5 years with 10(62.5% and lowest in age group <1 with 12(16.2%. Our findings in this study indicate potential endemicity of this virus infection in some parts of Nigeria. We therefore recommend further studies into circulating serotypes in human populations and urgent preventive and control measures of this emerging infectious disease.

  8. Deficit irrigation in semi-arid zone irrigation projects: Case studies in Turkey

    International Nuclear Information System (INIS)

    Results of several field experiments on deficit irrigation programmes in Turkey are discussed. Deficit irrigation of sugarbeet with water stress imposed during ripening stage saved nearly 22% water, yet with not significant yield decrease. An experiment, conducted in Trakya Region, the European part of Turkey, and aimed at studying water production functions of sunflower (i.e. yield vs water consumption), revealed that water stress imposed at either head forming or seed filling stages influences yield the least, and 40% savings of irrigation water supply compared with traditional practices in the region can be achieved without significant yield reduction. Water stress imposed at vegetative and flowering stages of corn had the most detrimental effect on yield. The results showed that deficit irrigation can be a feasible option under limited supply of irrigation if stress occurs during yield formation stage. A three year experiment on irrigation programmes of cotton was conducted to test if irrigation schedules could be modified (changed) to increase field water use efficiency and thereby increase effective use of restricted irrigation water supply during dry seasons. The results showed that a 20-day irrigation interval, resulting 3 to 4 irrigations, would give optimum cotton yield with approximately 26% savings in irrigation water, when compared with general practices commonly used in the area. Under severe shortage of water supply, the irrigation interval can even be extended to 30 days, which would result to 30 to 35% overall yield reduction but 50% savings in water use. A four year field experiment aiming at developing deficit irrigation strategies for soybean showed that soybean was the most sensitive to water stress during flowering and pod filling stages, and irrigation during these stages would ensure high yields. (author). 35 refs, 5 figs, 3 tabs

  9. Dust-Metal Sources in an Urbanized Arid Zone: Implications for Health-Risk Assessments.

    Science.gov (United States)

    García-Rico, Leticia; Meza-Figueroa, Diana; Gandolfi, A Jay; Del Río-Salas, Rafael; Romero, Francisco M; Meza-Montenegro, Maria Mercedes

    2016-04-01

    The available information concerning metal pollution in different dust sources and the health effects in children remains limited in Mexico. This study focuses on Hermosillo, which is an urbanized area located in the Sonoran Desert in which soil resuspension and dust emission processes are common. The metal content of arsenic (As), chromium (Cr), manganese (Mn), and lead (Pb) were determined in three dust sources (playgrounds, roofs, and roads), each representing different exposure media (EM) for these elements. The metal levels in dust were found in the order of Mn > Cr > Pb > As with the highest metal content found in road dust. Despite the similar average metal distributions, principal component analysis shows a clear separation of the three EM with playground dust related to Cr and Mn and road dust to As and Pb. However, the geoaccumulation index results indicate that dust samples are uncontaminated to moderately polluted, except for Pb in road dust, which is considerably high. In addition, the enrichment factor suggests an anthropogenic origin for all of the studied metals except for Mn. In this context, the hazard index (HI) for noncarcinogenic risk is >1 in this population and thus represents a potential health risk. The spatial distribution for each metal on EM and the HI related to the marginality index could represent a more accurate decision-making tool in risk assessment studies.

  10. Similar burrow architecture of three arid-zone scorpion species implies similar ecological function

    Science.gov (United States)

    Adams, Amanda M.; Marais, Eugene; Turner, J. Scott; Prendini, Lorenzo; Pinshow, Berry

    2016-08-01

    Many animals reside in burrows that may serve as refuges from predators and adverse environmental conditions. Burrow design varies widely among and within taxa, and these structures are adaptive, fulfilling physiological (and other) functions. We examined the burrow architecture of three scorpion species of the family Scorpionidae: Scorpio palmatus from the Negev desert, Israel; Opistophthalmus setifrons, from the Central Highlands, Namibia; and Opistophthalmus wahlbergii from the Kalahari desert, Namibia. We hypothesized that burrow structure maintains temperature and soil moisture conditions optimal for the behavior and physiology of the scorpion. Casts of burrows, poured in situ with molten aluminum, were scanned in 3D to quantify burrow structure. Three architectural features were common to the burrows of all species: (1) a horizontal platform near the ground surface, long enough to accommodate the scorpion, located just below the entrance, 2-5 cm under the surface, which may provide a safe place where the scorpion can monitor the presence of potential prey, predators, and mates and where the scorpion warms up before foraging; (2) at least two bends that might deter incursion by predators and may reduce convective ventilation, thereby maintaining relatively high humidity and low temperature; and (3) an enlarged terminal chamber to a depth at which temperatures are almost constant (±2-4 °C). These common features among the burrows of three different species suggest that they are important for regulating the physical environment of their inhabitants and that burrows are part of scorpions' "extended physiology" ( sensu Turner, Physiol Biochem Zool 74:798-822, 2000).

  11. In the Arid Zone: Drying out Educational Resources for English Language Learners through Policy and Practice

    Science.gov (United States)

    DaSilva Iddings, Ana Christina; Combs, Mary Carol; Moll, Luis

    2012-01-01

    This article presents a variety of issues related to the effects of restrictive language and educational policies that ultimately limits important resources for English language learners (i.e., services, funding, time, and information). The authors spotlight the state of Arizona as an unfortunate case of language control through policies, which…

  12. Aerosol measurements in a semi-arid zone (Beer-Sheva) using nuclear methods

    International Nuclear Information System (INIS)

    The aims of the research were: 1) to qualitatively and quantitatively determine the elemental composition of the aerosols in Beer-Sheva area and to measure the TSP in it, 2) to determine the aerosol size distribution, 3) to find the relation between the elemental composition of the aerosols and their diameter, 4) to determine correlations between the natural aerosols and the specific meteorological conditions of the Beer-Sheva area, 5) to determine the industrial pollution of the area. Between June 1977 and May 1978, 41 aerosol samples were measured for determination of their TSP mass concentration. The main methods used to analyse the aerosols were the Instrumental Neutron Activation Analysis and the X-Ray Fluorescence. The aerosols were examined and analysed during normal meteorological conditions, during and/or after rainfall, during and/or after Hamsin and after sandstorm conditions. Comparison of the TSP of Beer-Sheva area to to the mean TSP of world large cities shows that the normal TSP in Beer-Seva area is relatively high. Since Beer-Sheva is a small town (1977 population 110000), it can be concluded that the relatively high TSP is primarily due to the natural conditions prevailing in the Negev desert

  13. Integrated Water Resources Planning and Management in Arid/Semi-arid Regions: Data, Modeling, and Assessment

    Science.gov (United States)

    Gupta, H.; Liu, Y.; Wagener, T.; Durcik, M.; Duffy, C.; Springer, E.

    2005-12-01

    Water resources in arid and semi-arid regions are highly sensitive to climate variability and change. As the demand for water continues to increase due to economic and population growth, planning and management of available water resources under climate uncertainties becomes increasingly critical in order to achieve basin-scale water sustainability (i.e., to ensure a long-term balance between supply and demand of water).The tremendous complexity of the interactions between the natural hydrologic system and the human environment means that modeling is the only available mechanism for properly integrating new knowledge into the decision-making process. Basin-scale integrated models have the potential to allow us to study the feedback processes between the physical and human systems (including institutional, engineering, and behavioral components); and an integrated assessment of the potential second- and higher-order effects of political and management decisions can aid in the selection of a rational water-resources policy. Data and information, especially hydrological and water-use data, are critical to the integrated modeling and assessment for water resources management of any region. To this end we are in the process of developing a multi-resolution integrated modeling and assessment framework for the south-western USA, which can be used to generate simulations of the probable effects of human actions while taking into account the uncertainties brought about by future climatic variability and change. Data are being collected (including the development of a hydro-geospatial database) and used in support of the modeling and assessment activities. This paper will present a blueprint of the modeling framework, describe achievements so far and discuss the science questions which still require answers with a particular emphasis on issues related to dry regions.

  14. Ground-Water Recharge in the Arid and Semiarid Southwestern United States

    Science.gov (United States)

    Stonestrom, David A.; Constantz, Jim; Ferre, Ty P.A.; Leake, Stanley A.

    2007-01-01

    , and distinct modes of recharge in the Colorado Plateau and Basin and Range subregions. The chapters in this professional paper present (first) an overview of climatic and hydrogeologic framework (chapter A), followed by a regional analysis of ground-water recharge across the entire study area (chapter B). These are followed by an overview of site-specific case studies representing different subareas of the geographically diverse arid and semiarid southwestern United States (chapter C); the case studies themselves follow in chapters D?K. The regional analysis includes detailed hydrologic modeling within the framework of a high-resolution geographic-information system (GIS). Results from the regional analysis are used to explore both the distribution of ground-water recharge for mean climatic conditions as well as the influence of two climatic patterns?the El Ni?o-Southern Oscillation and Pacific Decadal Oscillation?that impart a high degree of variability to the hydrologic cycle. Individual case studies employ a variety of geophysical and geochemical techniques to investigate recharge processes and relate the processes to local geologic and climatic conditions. All of the case studies made use of naturally occurring tracers to quantify recharge. Thermal and geophysical techniques that were developed in the course of the studies are presented in appendices. The quantification of ground-water recharge in arid settings is inherently difficult due to the generally low amount of recharge, its spatially and temporally spotty nature, and the absence of techniques for directly measuring fluxes entering the saturated zone from the unsaturated zone. Deep water tables in arid alluvial basins correspond to thick unsaturated zones that produce up to millennial time lags between changes in hydrologic conditions at the land surface and subsequent changes in recharge to underlying ground water. Recent advances in physical, chemical, isotopic, and modeling techniques have foster

  15. Actinobacteria from arid and desert habitats: diversity and biological activity

    Directory of Open Access Journals (Sweden)

    Joachim eWink

    2016-01-01

    Full Text Available Abstract The lack of new antibiotics in the pharmaceutical pipeline guides more and more researchers to leave the classical isolation procedures and to look in special niches and ecosystems. Bioprospecting of extremophilic Actinobacteria through mining untapped strains and avoiding resiolation of known biomolecules is among the most promising strategies for this purpose. With this approach, members of acidtolerant, alkalitolerant, psychrotolerant, thermotolerant, halotolerant and xerotolerant Actinobacteria have been obtained from respective habitats. Among these, little survey exists on the diversity of Actinobacteria in arid areas, which are often adapted to relatively high temperatures, salt concentrations, and radiation. Therefore, arid and desert habitats are special ecosystems which can be recruited for the isolation of uncommon Actinobacteria with new metabolic capability.At the time of this writing, members of Streptomyces, Micromonospora, Saccharothrix, Streptosporangium, Cellulomonas, Amycolatopsis, Geodermatophilus, Lechevalieria, Nocardia and Actinomadura are reported from arid habitats. However, metagenomic data present dominant members of the communities in desiccating condition of areas with limited water availability that are not yet isolated. Furthermore, significant diverse types of polyketide synthase (PKS and nonribosomal peptide synthetase (NRPS genes are detected in xerophilic and xerotolerant Actinobacteria and some bioactive compounds are reported from them. Rather than pharmaceutically active metabolites, molecules with protection activity against drying such as Ectoin and Hydroxyectoin with potential application in industry and agriculture have also been identified from xerophilic Actinobacteria. In addition, numerous biologically active small molecules are expected to be discovered from arid adapted Actinobacteria in the future. In the current survey, the diversity and biotechnological potential of Actinobacteria

  16. Evidence for extreme floods in arid subtropical northwest Australia during the Little Ice Age chronozone (CE 1400-1850)

    Science.gov (United States)

    Rouillard, A.; Skrzypek, G.; Turney, C.; Dogramaci, S.; Hua, Q.; Zawadzki, A.; Reeves, J.; Greenwood, P.; O'Donnell, A. J.; Grierson, P. F.

    2016-07-01

    Here we report a ∼2000-year sediment sequence from the Fortescue Marsh (Martuyitha) in the eastern Pilbara region, which we have used to investigate changing hydroclimatic conditions in the arid subtropics of northwest Australia. The Pilbara is located at the intersection of the tropical Indian and Pacific Oceans and its modern rainfall regime is strongly influenced by tropical cyclones, the Intertropical Convergence Zone (ITCZ) and the Indo-Pacific Warm Pool. We identified four distinct periods within the record. The most recent period (P1: CE ∼1990-present) reveals hydroclimatic conditions over recent decades that are the most persistently wet of potentially the last ∼2000 years. During the previous centuries (P2: ∼CE 1600-1990), the Fortescue Marsh was overall drier but likely punctuated by a number of extreme floods, which are defined here as extraordinary, strongly episodic floods in drylands generated by rainfall events of high volume and intensity. The occurrence of extreme floods during this period, which encompasses the Little Ice Age (LIA; CE 1400-1850), is coherent with other southern tropical datasets along the ITCZ over the last 2000 years, suggesting synchronous hydroclimatic changes across the region. This extreme flood period was preceded by several hundred years (P3: ∼CE 700-1600) of less vigorous but more regular flows. The earliest period of the sediment record (P4: ∼CE 100-700) was the most arid, with sedimentary and preservation processes driven by prolonged drought. Our results highlight the importance of developing paleoclimate records from the tropical and sub-tropical arid zone, providing a long-term baseline of hydrological conditions in areas with limited historical observations.

  17. Workshop on environmental changes of arid regions convenes in Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Hosted by the CAS Institute of Geology and Geophysics and the local government, the International Workshop on Environmental Changes and Sustainable Development in Arid and Semi-arid Regions was held recently in Alashan Left Banner, Inner Mongolia.

  18. Global synthesis of groundwater recharge in semiarid and arid regions

    Science.gov (United States)

    Scanlon, Bridget R.; Keese, Kelley E.; Flint, Alan L.; Flint, Lorraine E.; Gaye, Cheikh B.; Edmunds, W. Michael; Simmers, Ian

    2006-10-01

    Global synthesis of the findings from 140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40-374 000 km2) range from 0.2 to 35 mm year-1, representing 0.1-5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to 720 m year-1, results from focussed recharge beneath ephemeral streams and lakes and preferential flow mostly in fractured systems. System response to climate variability and land use/land cover (LU/LC) changes is archived in unsaturated zone tracer profiles and in groundwater level fluctuations. Inter-annual climate variability related to El Niño Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Niños (1977-1998) relative to periods dominated by La Niñas (1941-1957). Enhanced recharge related to ENSO is also documented in Argentina. Climate variability at decadal to century scales recorded in chloride profiles in Africa results in recharge rates of 30 mm year-1 during the Sahel drought (1970-1986) to 150 mm year-1 during non-drought periods. Variations in climate at millennial scales in the SW US changed systems from recharge during the Pleistocene glacial period (10 000 years ago) to discharge during the Holocene semiarid period. LU/LC changes such as deforestation in Australia increased recharge up to about 2 orders of magnitude. Changes from natural grassland and shrublands to dryland (rain-fed) agriculture altered systems from discharge (evapotranspiration, ET) to recharge in the SW US. The impact of LU

  19. New crops for arid lands. [Jojoba; Buffalo gourd; Bladderpod; Gumweed

    Energy Technology Data Exchange (ETDEWEB)

    Hinman, C.W.

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential of arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required.

  20. Impact and consequences of evapotranspiration changes on water resources availability in the arid Zhangye Basin, China

    NARCIS (Netherlands)

    Jin, X.; Schaepman, M.E.; Clevers, J.G.P.W.; Su, Z.

    2009-01-01

    Evapotranspiration (ET) plays an important role in the hydrological cycle and it is essential to estimate ET accurately for the evaluation of available water resources. This is most important in arid and semi-arid regions. In this paper, the long-term changes in daily ET in the semi-arid Zhangye Bas

  1. Utilisation Of Micro-Finance Institutions’ Funds By Borrowers In Arid And Semi-Arid Lands In Kenya

    OpenAIRE

    Nzioki, Paul M.; Taragon, Geoffrey; Kalio, A. M.

    2013-01-01

    Despite a lot of efforts in terms of resource mobilisation in Arid and Semi-Arid Lands (ASAL) , the poverty levels are still very high and the defaulted loans from the four Micro-Finance Institutions (MFIs) in Maralal town amounts KES 15 million. The study sought to establish whether economic characteristics of entrepreneurs and whether literacy levels affect application and usage of borrowed funds in the ASAL regions of Africa. The study was limited to Maralal Town, one of the main towns in ...

  2. The biogeophysical effect of large-scale afforestation in semi-arid regions

    Science.gov (United States)

    Yosef, Gil; Avissar, Roni; Walko, Robert; Medvigy, David; Yakir, Dan

    2015-04-01

    Forestation in the semi-arid region can significantly influence the surface energy budget and, in turn, the local atmospheric circulations. Such effects could be particularly important in regions under the influence of monsoon regimes, such as the Sahel and North Australia. In these regions, summer solar heating leads first to migration of the equatorial through and the tropical convergence zones (ITCZ) and to the monsoon rain. And second, to a meridional surface temperature gradient that generates low-level easterly jet that acts as a barrier to the penetration of the precipitation into the semi arid areas. In this study we tested the hypothesis that large-scale afforestation in these semi-regions can result in changes in local and regional atmospheric circulation and, consequently, in the precipitation and potential changes in land cover and land use. The GCM OLAM was used to performing high-resolution simulations (50km horizontal grid scale and 50 vertical layers) of afforestation scenarios in the Sahel and North Australia. These areas (Sahel 2.6 E6 km2 and North Australia 2.1 E6 km2) were afforested with a mature pine forest, using the extensive data form the long-term semi-arid Yatir forest in Israel as a reference forest for surface parameterization. The regional effect of the afforestation was analyzed for the following parameters; Surface energy budget, temperature, Easterly jet stream location and intensity, above forest atmospheric instability, water recycling and precipitation. Afforestation in the Sahel resulted in large increase of the surface net radiation (45 W m-2), mainly as a result of decrease in albedo (43 W m-2), decrease of incoming short wave radiation (21 W m-2) and increase of downward long wave radiation (13 W m-2) due to higher clouds cover, and decrease in long wave upward radiation (10 W m-2), as a result of the lower surface temperature. Increasing soil moisture because of the new forest is expressed into higher evapotranspiration, i

  3. Local facilitation, bistability and transitions in arid ecosystems

    NARCIS (Netherlands)

    Kefi, S.; Rietkerk, M.; Baalen, van M.; Loreau, M.

    2007-01-01

    Arid ecosystems are liable to undergo sudden discontinuous transitions from a vegetated to a desert state as a result of human pressure and climate change. A predictive framework about the conditions under which such transitions occur is lacking. Here, we derive and analyze a general model describin

  4. Extreme climatic events shape arid and semiarid ecosystems

    NARCIS (Netherlands)

    Holmgren, M.; Stapp, P.; Dickman, C.; Gracia, C.; Graham, S.

    2006-01-01

    Climatic changes associated with the El Nino Southern Oscillation (ENSO) can have a dramatic impact on terrestrial ecosystems worldwide, but especially on arid and semiarid systems, where productivity is strongly limited by precipitation. Nearly two decades of research, including both short-term exp

  5. Evaporation as the transport mechanism of metals in arid regions.

    Science.gov (United States)

    Lima, Ana T; Safar, Zeinab; Loch, J P Gustav

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust.

  6. Documentation of Arid Land Soilscapes in Southwestern Europe

    Science.gov (United States)

    José Ibáñez, Juan; Pérez-Gómez, Rufino; Oyonarte, Cecilio; Brevik, Eric C.

    2016-04-01

    There have been no studies to date that have proven the existence of soil assemblages typical of arid lands in Europe. This study was carried out in Almería province, a representative territory of the SE part of the Iberian Peninsula which is the driest part of Europe, to determine if soils characteristic of arid lands were present. The study made use of mathematical tools previously developed in biodiversity and pedodiversity analysis, such as richness, entropy indices, abundance distribution models, diversity-area relationships and nested subset analysis to analyse the spatial distribution of soils. The study demonstrated that the soil types or pedotaxa are typical of mountainous arid lands. Shallow and weakly developed soils (e.g. Leptosols, Regosols, Arenosols), Calcisols, Gypsisols and Solonchaks cover most of the study area, and pedodiversity analysis demonstrates that the pedotaxa spatial patterns follow the same regularities as in other areas, environments and scales. In view of the fact that the class of landscapes identified in this study are unique in Europe, the Tarbernas desert and other arid lands sites of the study area merit preservation as part of the European geological, geomorphological, and pedological heritage.

  7. Agave Lechuguilla as a Potential Biomass Source in Arid Areas

    Directory of Open Access Journals (Sweden)

    Ahmad Houri

    2016-03-01

    Full Text Available Biomass productivity presents a challenging problem in arid and semi-arid areas.  Despite a large need for energy in the form of solid biomass, liquid fuel or needs for animal feed, these regions remain largely unproductive.  A convenient way to overcome this challenge is to utilize plants with high water-use efficiency.  Agave lechuguilla is an example of a highly productive (3.8 tons ha-1 yr-1 desert plant that holds the potential for producing biomass with minimal water resources.  For this purpose, a global suitability map has been developed showing areas where this plant can be planted, and its productivity was assessed.  A Maxent model was used and was further refined by excluding protected areas and used lands (urban, agriculture, etc...  Productivity assessment provides a good way forward for prioritizing the regional utilization of this plant.   This study provides an initial analysis for the use of arid and semi-arid regions for biomass production.  Results indicate the potential generation of 93.8 million tons per year of dry biomass if the suitable areas were fully utilized.  The analytical method can be readily applied to other potential plant species to optimize the use of certain areas.

  8. Evaporation as the transport mechanism of metals in arid regions

    NARCIS (Netherlands)

    Lima, A.T.; Safar, Z.; Loch, J.P.G.

    2014-01-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evapora

  9. Trends and responses to global change of China's arid regions

    Institute of Scientific and Technical Information of China (English)

    Weixi YANG

    2009-01-01

    Ⅰ analyzed and elaborated the trends in and responses to global change in arid regions of China, from the perspective of nine variables, i.e., temperature, precipitation, river runoff, melting glaciers, water level of lakes, wind power and evaporation, vegetation, oases, and desertification. The climate and hydrology data Ⅰ citedrepresent many years of observations. Ⅰ conclude that, since the 1980s, the climate in arid regions of China has clearly changed with rising temperatures and precipitation in most areas. Wind power and the number of galestorm days have continuously decreased, which resulted in an improvement of humid conditions and increases in river discharge and water levels of lakes. Simultaneously, vegetation also has improved and the process of deserti-fication has essentially been arrested. Although there are some unfavorable developments, such as decreased river flows or flow interruptions and downstream oases have suffered from degradation, these incidental cases should not distract our attention from the generally favorable trends during the middle and late 20th century. These discordant phenomena are not consequences of climate change but rather of unsuitable human activities. Despitea substantial increase in precipitation, the level of the original precipitation was so small that any increase in precipitation was still small. As a result, none of the fundamental conditions such as a scarcity of water resources and precipitation nor the landscape of drought-ridden deserts in the arid regions will change. The vulnerability of the eco-environmental system in the arid regions will not change fundamentally either in the near future.

  10. Simulation of water use and herbage growth in arid regions

    NARCIS (Netherlands)

    Keulen, van H.

    1975-01-01

    The and and semi-arid regions of the world, totalling about 30% of the land surface of the earth, are predominantly used for extensive grazing, as low and erratic rainfall presents too high a risk for arable farming. The population that can be sustained by the animal products -meat, milk or wool- is

  11. Evaporation as the transport mechanism of metals in arid regions

    KAUST Repository

    Lima, Ana T.

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust. © 2014 Elsevier Ltd.

  12. Seepage weathering impacts on erosivity of arid stream banks: A new conceptual model

    Science.gov (United States)

    Nachshon, Uri

    2016-05-01

    Field observations have indicated the formation of horizontal, pipe shape cavities, along gully and dry stream channel banks in the semi-arid region of the northern Negev Desert, Israel. Piping is a well-known phenomenon in humid regions due to subsurface water flow and seepage weathering. However, in dry environments where rain events are scarce and subsurface water flow is rare, it is proposed here that capillary flow of saline water in the vadose zone leads to similar processes. It is suggested that where saline and shallow ground water persists, capillary flow may result in salt accumulation and precipitation at the top of the capillary fringe, consequently rendering this zone to be more susceptible to erosion. A conceptual model is presented and field observations, laboratory experiments, and a physically-based model are used to prove the feasibility of the proposed conceptual model and to explain why salts accumulate at the top of the capillary fringe, even though evaporation acts all along the vertical stream channel or gully banks. It is suggested that the low evaporative flux, in comparison to the liquid water flux, disables salt accumulation along the profile to the top of the capillary fringe where the liquid water flux is minimal. The presented findings strengthen the conceptual model, but thorough field studies are needed to estimate the impact of the proposed mechanism on erosion processes on a field scale.

  13. Mechanisms, timing and quantities of recharge to groundwater in semi-arid and tropical regions

    International Nuclear Information System (INIS)

    Groundwater being exploited in many and and semi-arid regions at the present day was recharged during former humid episodes of the Pleistocene or Holocene and, in contrast, the amounts derived from modem recharge are small generally small and variable. Geochemical and isotopic techniques provide the most effective way to calculate modem recharge and to investigate recharge history, since physically- based water-balance methods are generally inapplicable in semiarid regions. Examples from Africa (Senegal, Niger, Nigeria, Sudan as well as Cyprus) show that direct recharge rates may vary from zero to around 40% of mean rainfall, dependent primarily on the soil depth and the lithology. Spatial variability presents a real problem in any recharge investigation but results from Senegal show that unsaturated zone profiles may be extrapolated using the chemistry of shallow groundwater. Unsaturated-zone studies show that there are limiting conditions to direct recharge through soil, but that present day replenishment of aquifers takes place via wadis and channels. In the Butana area of central Sudan the regional groundwater was also recharged during a mid-Holocene wet phase and is now in decline. The only current recharge sources, which can be recognised distinctly using stable isotopes, are Nile baseflow and ephemeral wadi floods. (author)

  14. Arid land plants: promising new tools for economic development and basic research

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.

    1980-01-01

    An overview is presented of arid land plant development stressing products and plant physiological and ecological concepts unique to arid land plants. Integration of new arid land crops into polyculture management systems is suggested utilizing specialized plant functions, e.g., drought resistance, resistance to salinity, ability to fix nitrogen, frost tolerance and capability to produce a cash crop. Impacts on arid land plant productivity on political systems of developing countries are discussed and recommendations are presented for overcoming institutional constraints facing arid land plant development. (MHR)

  15. Spatial pattern of nitrogen isotopes as an indicator of ecosystem responses to rainfall in semi-arid and arid grasslands

    Science.gov (United States)

    WANG, C.; Bai, E.; Liu, D.; Fang, T. Y.; Jiang, P.; Han, G. X.

    2013-12-01

    Nitrogen (N) is an essential element for plant growth, however, whether it is a limiting factor of plant growth in water-limited areas is still not clear. Here we examined spatial variations of plant and soil stable N isotopes along a 3200 km precipitation gradient and proposed a conceptual model to explain ecosystem responses to increasing precipitation in arid and semi-arid grasslands in China. Soil δ15N increased with increasing MAP in areas with MAP areas with 200 mm 200 mm. In areas with MAP nutrient cycling in arid and semi-arid areas. If future climate change leads to drier climate in dryland, the uncoupled plant and microbial response may cause more N losses and higher ecosystem vulnerability. 3 Soil organic carbon (Soil C, a), total nitrogen (Soil N, b), C/N (c) and δ15N (d) of study sites along a MAP gradient. Relationship between MAP and foliar δ15N (a) and root δ15N (b).

  16. Increased aridity in southwestern Africa during the last-interglacial warmest periods

    Directory of Open Access Journals (Sweden)

    D. H. Urrego

    2013-07-01

    Full Text Available We use pollen analysis of marine sediments from core MD96-2098 to produce a paleoenvironmental record spanning from 190 to 24.7 ka (thousand years before present from southern Africa. Our interpretations of the pollen record are supported by an analysis of present day pollen spectra for the region. We apply canonical correspondence analysis (CCA and detrended correspondence analysis (DCA on pollen spectra from terrestrial surface samples to investigate pollen spectra-climate relationships. We identify pollen taxa that are suitable indicators for the different South African biomes, and assess in detail the distribution and potential interpretation of Poaceae pollen signals in marine sediments along the southwestern African coast. The pollen record from MD96-2098 documented major increases of Poaceae pollen percentages, that are interpreted as expansions of semi-arid southwestern African biomes (i.e. the Nama-Karoo and fine-leaved savannas during Marine Isotope Stage (MIS 5e, 5c and 5a substages. These expansions coincided with minima in precession and global ice volume. They likely resulted from a combination of reduced Benguela upwelling; expanded subtropical high pressure and reduced austral-summer precipitation due to a northward shift of the Intertropical Convergence Zone (ITCZ; and a southern displacement of the westerlies and decreased austral-winter precipitation. During glacial isotopic stages MIS 6, 4 and 3, Fynbos expanded at the expense of semi-arid biomes. Stage and substage transitions were characterised by small but rapid increases in Podocarpus indicating a humidity increase. Increased millennial-scale variability in the vegetation and climate of southern Africa is also suggested for the last 100 ka.

  17. Quantitative assessment and analysis on the dynamic change of ecological capital in arid areas

    Institute of Scientific and Technical Information of China (English)

    CHEN Xi; ZHANG Qing; ZHOU Kefa; SUN Li

    2006-01-01

    Ecological capital is the summation of the direct value of biological resources and the ecological service function value of ecosystems. Under the support of RS, GPS and GIS, in this paper the RS-based quantitative measurement model of assessing ecological capital is developed based on the traditional ecology theory and the research on the value of ecological capital per unit area by using the ecological parameters including Landsat TM data,CBERS satellite data, meteorological data, MODIS satellite data, land cover data and field-measured data. A case study on the spatiotemporal distribution of ecological capital in Changji Hui Autonomous Prefecture in 1990, 1995 and 2003 is carried out, and the dynamic change of ecological capital in the prefecture is measured and compared with GDP. The maps of the spatial distribution of ecological capital in the study area are charted, and the characteristics of spatial distribution of ecological capital are analyzed.The results show that the values of ecological capital in the prefecture in 1990, 1995 and 2003 were 1.47368×1011, 1.661 60×1011 and 1.77895×1011yuan RMB (hereafter referred to as yuan) respectively, and that in spatial distribution, the ecological capital decreases from the alpine zones to the plains and from the oases to the deserts, which accords with the zonal distribution of vegetation in arid areas.The measured results can more objectively reflect the ecological capital and its spatial distribution in arid areas, provide an ideal foundation for further study in the future, and can also be combined with the study on service functions of ecosystems and the regional planning as an important basis of regional planning.

  18. Experimental Study on Isotope Fractionation of Soil water in Arid Environments

    Science.gov (United States)

    Horita, J.; Lin, Y.

    2015-12-01

    Soil water dynamics within a thick vadose (unsaturated) zone is a key component in the hydrologic cycle in arid regions. The partitioning of precipitation and soil water into fluxes of percolation to the subsurface, surface runoff and evapotranspiration at the land-atmosphere-vegetation interface is accompanied by characteristic δ2H and δ18O values of water. The isotopic composition of the transpiration flux is very similar to soil water, since the uptake by plant roots is usually not associated with isotope fractionation. The isotopic composition of evaporation flux from unsaturated soils, which becomes an important flux in arid regions, has extensively been modeled by the Craig-Gordon model with the assumption that equilibrium isotopic fractionation between adsorbed/pored condensed water within soils and water vapor is identical to that between bulk liquid water and vapor. To test this critical assumption, we have conducted laboratory experiments on equilibrium isotope fractionation between adsorbed water in mesoporous silica (15nm pore, as soil analog) and the vapor. Firstly, the adsorption/desorption isotherms of H2O and N2 in the silica are determined at 30°C and liq-N2 temperature, respectively, and large hysteresis loops were observed. Secondly, the isotope fractionation factors between condensed water in the silica pores and the vapor (18αsilica water-vapor and 2αsilica water-vapor for oxygen and hydrogen isotopes, respectively) were determined at 30°C along the adsorption curve from near saturation pressure (p/po=1). We found that 18αsilica water-vapor values are smaller than that between free liquid-vapor (1.0088) and progressively decreased from1.0083 at p/po= 0.9 to 1.0054 at p/po=0.5, establishing a trend very similar to the isotherm curve. The corresponding 2αsilica water-vapor values are also smaller than that of free liquid-vapor system (1.0740) and decreased from 1.0651 at p/po=0.9 to 1.0295 at p/po=0.5. Our experimental results challenge

  19. Agave: a biofuel feedstock for arid and semi-arid environments

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Stephen; Martin, Jeffrey; Simpson, June; Wang, Zhong; Visel, Axel

    2011-05-31

    Efficient production of plant-based, lignocellulosic biofuels relies upon continued improvement of existing biofuel feedstock species, as well as the introduction of newfeedstocks capable of growing on marginal lands to avoid conflicts with existing food production and minimize use of water and nitrogen resources. To this end, specieswithin the plant genus Agave have recently been proposed as new biofuel feedstocks. Many Agave species are adapted to hot and arid environments generally unsuitable forfood production, yet have biomass productivity rates comparable to other second-generation biofuel feedstocks such as switchgrass and Miscanthus. Agavesachieve remarkable heat tolerance and water use efficiency in part through a Crassulacean Acid Metabolism (CAM) mode of photosynthesis, but the genes andregulatory pathways enabling CAM and thermotolerance in agaves remain poorly understood. We seek to accelerate the development of agave as a new biofuelfeedstock through genomic approaches using massively-parallel sequencing technologies. First, we plan to sequence the transcriptome of A. tequilana to provide adatabase of protein-coding genes to the agave research community. Second, we will compare transcriptome-wide gene expression of agaves under different environmentalconditions in order to understand genetic pathways controlling CAM, water use efficiency, and thermotolerance. Finally, we aim to compare the transcriptome of A.tequilana with that of other Agave species to gain further insight into molecular mechanisms underlying traits desirable for biofuel feedstocks. These genomicapproaches will provide sequence and gene expression information critical to the breeding and domestication of Agave species suitable for biofuel production.

  20. Phosphorus transformations along a large-scale climosequence in arid and semiarid grasslands of northern China

    Science.gov (United States)

    Feng, Jiao; Turner, Benjamin L.; Lü, Xiaotao; Chen, Zhenhua; Wei, Kai; Tian, Jihui; Wang, Chao; Luo, Wentao; Chen, Lijun

    2016-09-01

    The Walker and Syers model of phosphorus (P) transformations during long-term soil development has been verified along many chronosequences but has rarely been examined along climosequences, particularly in arid regions. We hypothesized that decreasing aridity would have similar effects on soil P transformations as time by increasing the rate of pedogenesis. To assess this, we examined P fractions in arid and semiarid grassland soils (0-10 cm) along a 3700 km aridity gradient in northern China (aridity between 0.43 and 0.97, calculated as 1 - [mean annual precipitation/potential evapotranspiration]). Primary mineral P declined as aridity decreased, although it still accounted for about 30% of the total P in the wettest sites. In contrast, the proportions of organic and occluded P increased as aridity decreased. These changes in soil P composition occurred in parallel with marked shifts in soil nutrient stoichiometry, with organic carbon:organic P and nitrogen:organic P ratios increasing with decreasing aridity. These results indicate increasing abundance of P relative to carbon or nitrogen along the climosequence. Overall, our results indicate a broad shift from abiotic to biotic control on P cycling at an aridity value of approximately 0.7 (corresponding to about 250 mm mean annual rainfall). We conclude that the Walker and Syers model can be extended to climosequences in arid and semiarid ecosystems and that the apparent decoupling of nutrient cycles in arid soils is a consequence of their pedogenic immaturity.

  1. Unsaturated zone 14CO2: implications for groundwater dating

    Science.gov (United States)

    Wood, C.; Cook, P. G.; Harrington, G. A.; Meredith, K.; Kipfer, R.

    2013-12-01

    Quantitative interpretation of the carbon-14 activity (14C) of dissolved inorganic carbon (DIC) in groundwater requires an understanding of the various chemical and physical processes that can vary the initial 14C activity from that of the original atmospheric source (carbon dioxide, CO2). Such processes include radioactive decay, carbonate mineral dissolution, isotope exchange, decay of organic matter and molecular diffusion. Many geochemical correction models exist to account for some of these processes (e.g., Fontes and Garnier, 1979). However in most existing correction schemes, it is assumed that the 14C activity of CO2 in the unsaturated zone is in equilibrium with the atmosphere (i.e., 14C:12C is the same as the atmospheric ratio). This assumption is rarely tested and in several cases has been found to be inappropriate (eg. Bacon and Keller, 1998; Walvoord et al., 2005). Not accounting for the influence of unsaturated zone processes on 14C may lead to problems in determining residence time and estimating fluxes from measured 14C data in groundwater. In this study we examined carbon isotope processes in deep unsaturated zone profiles (up to 30m in depth) in arid central Australia. At five sites, multi-level samples of unsaturated zone gas and groundwater were collected for 14C analysis. Chlorofluorocarbon (CFC-11 and CFC-12) samples were also collected in unsaturated zone gas. At all sites we observed a decrease in the 14C activity of unsaturated zone gas with depth, from approximately 107 pmC near the ground surface to 50 - 80 pmC immediately above the water table. The measured 14C data was reproduced in a one-dimensional model using Hydrus, with CFC concentrations used to help constrain the gas transport parameters. Modelling showed that the decrease in 14C could be explained by CO2 production from different sources at different depths in the unsaturated zone (e.g. plant root respiration at shallower depths, oxidation of dead organic matter at greater

  2. Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

    Science.gov (United States)

    Tian, Y.; Wu, B.; Zheng, Y.

    2013-12-01

    In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

  3. Root Apex Transition Zone as Oscillatory Zone

    Directory of Open Access Journals (Sweden)

    Frantisek eBaluska

    2013-10-01

    Full Text Available Root apex of higher plants shows very high sensitivity to environmental stimuli. The root cap acts as the most prominent plant sensory organ; sensing diverse physical parameters such as gravity, light, humidity, oxygen and critical inorganic nutrients. However, the motoric responses to these stimuli are accomplished in the elongation region. This spatial discrepancy was solved when we have discovered and characterized the transition zone which is interpolated between the apical meristem and the subapical elongation zone. Cells of this zone are very active in the cytoskeletal rearrangements, endocytosis and endocytic vesicle recycling, as well as in electric activities. Here we discuss the oscillatory nature of the transition zone which, together with several other features of this zone, suggest that it acts as some kind of command centre. In accordance with the early proposal of Charles and Francis Darwins, cells of this root zone receive sensory information from the root cap and instruct the motoric responses of cells in the elongation zone.

  4. Rapid warming and drought negatively impact population size and reproductive dynamics of an avian predator in the arid southwest.

    Science.gov (United States)

    Cruz-McDonnell, Kirsten K; Wolf, Blair O

    2016-01-01

    Avian communities of arid ecosystems may be particularly vulnerable to global climate change due to the magnitude of projected change for desert regions and the inherent challenges for species residing in resource limited ecosystems. How arid-zone birds will be affected by rapid increases in air temperature and increased drought frequency and severity is poorly understood because avian responses to climate change have primarily been studied in the relatively mesic northern temperate regions. We studied the effects of increasing air temperature and aridity on a Burrowing Owl (Athene cunicularia) population in the southwestern United States from 1998 to 2013. Over 16 years, the breeding population declined 98.1%, from 52 pairs to 1 pair, and nest success and fledgling output also declined significantly. These trends were strongly associated with the combined effects of decreased precipitation and increased air temperature. Arrival on the breeding grounds, pair formation, nest initiation, and hatch dates all showed significant delays ranging from 9.4 to 25.1 days over 9 years, which have negative effects on reproduction. Adult and juvenile body mass decreased significantly over time, with a loss of 7.9% mass in adult males and 10.9% mass in adult females over 16 years, and a loss of 20.0% mass in nestlings over 8 years. Taken together, these population and reproductive trends have serious implications for local population persistence. The southwestern United States has been identified as a climate change hotspot, with projections of warmer temperatures, less winter precipitation, and an increase in frequency and severity of extreme events including drought and heat waves. An increasingly warm and dry climate may contribute to this species' decline and may already be a driving force of their apparent decline in the desert southwest. PMID:26367541

  5. How Sustainable are Engineered Rivers in Arid Lands?

    Directory of Open Access Journals (Sweden)

    Jurgen Schmandt

    2013-06-01

    Full Text Available Engineered rivers in arid lands play an important role in feeding the world’s growing population. Each continent has rivers that carry water from distant mountain sources to fertile soil downstream where rainfall is scarce. Over the course of the last century most rivers in arid lands have been equipped with large engineering structures that generate electric power and store water for agriculture and cities. This has changed the hydrology of the rivers. In this paper we discuss how climate variation, climate change, reservoir siltation, changes in land use and population growth will challenge the sustainability of engineered river systems over the course of the next few decades. We use the Rio Grande in North America, where we have worked with Mexican and American colleagues, to describe our methodology and results. Similar work is needed to study future water supply and demand in engineered rivers around the world.

  6. Uranium isotopes in carbonate aquifers of arid region setting

    DEFF Research Database (Denmark)

    Alshamsi, Dalal M.; Murad, Ahmed A.; Aldahan, Ala;

    2013-01-01

    Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations in the so......Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations...... in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for 235U and 238 U at 3–39 ng L-1 (average: 18 ng L-1...

  7. On coordinated development of oasis and environment in arid area

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based upon the formation and evolution of oasis and the factors restricting the coordinated development of oasis economy and environment, this paper presents a goal of the development in coordination. It suggests that the sustainable survival and development of oasis could be ensured only if the oasis-desert and water source ecology are managed in a combined way to form a macro system. In light with the above mentioned, the approach to the development of economy and environment of oasis in arid area should depend upon the establishment of an oasis ecological and economic system, which suits the arid environment and promotes the efficiency of resource configuration, stabilizes economic increment and benefits ecological development.

  8. Domesticated proboscidea parviflora: a potential oilseed crop for arid lands

    Energy Technology Data Exchange (ETDEWEB)

    Berry, J.; Bretting, P.K.; Nabhan, G.P.; Weber, C.

    1981-01-01

    Wild and domesticated Proboscidea parviflora were evaluated as oilseed crops for arid lands through chemical and biological analyses. Domesticated plants grown in the Sonoran desert bore seed containing 35-40 per cent oil and 23-27 per cent protein. Yield per hectare was estimated at 1000 kg of oil and 675 kg of protein, quantities which compare favourably with other crops. An ephemeral life cycle and certain characteristics of the fruit and seed allow this plant to grow in xeric habitats unsuitable for many other plants. Several Proboscidea species hybridize with P. parviflora and could be used in future crop breeding. Rapid germination and higher oil and protein content of seed make the domesticated P. parviflora superior to the wild form as a crop. Domesticated P. parviflora thus shows promise as an oilseed crop for the Sonoran Desert and possibly for other arid regions. (Refs. 22).

  9. Arid lands plants as feedstocks for fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, J.J.

    1983-01-01

    The purpose of this paper is to review the recent research on arid-adapted plants that have potential as producers of fuels or chemicals. The major focus will be on plant species that appear to have commercial value. Research on guayule (Parthenium argentatum) and jojoba (Simmondsia chinensis) will be mentioned only briefly, since these plants have been discussed extensively in the literature, and excellent reviews are already in existence. In this review the literature on arid-adapted plants that have potential uses for solid fuels, liquid fuels, and chemical feedstocks is summarized, followed by an overview of the research directions and types of development that are needed in order for bio-energy production systems to reach the commercial stage. 127 references.

  10. Expanding the phenotypic spectrum of ARID1B-mediated disorders and identification of altered cell-cycle dynamics due to ARID1B haploinsufficiency

    DEFF Research Database (Denmark)

    Sim, J. C. H.; White, S. M.; Fitzpatrick, E.;

    2014-01-01

    patient-derived and ARID1B knockdown fibroblasts after serum starvation demonstrated delayed cell cycle re-entry associated with reduced cell number in the S-1 phase. Based on the patient's distinctive phenotype, we ascertained four additional patients and identified heterozygous de novo ARID1B frameshift...

  11. Importance and Use of Plants in Evaluating Water Flow and Contaminant Transport in Arid Environments

    Science.gov (United States)

    Andraski, B. J.; Sandstrom, M. W.; Michel, R. L.; Radyk, J. C.; Stonestrom, D. A.; Johnson, M. J.; Mayers, C. J.

    2002-12-01

    Improved understanding of soil-plant-atmosphere interactions is critical to water-resource and waste management decisions. Multiple-year field studies of soil-water movement at the Amargosa Desert Research Site (ADRS; http://nevada.usgs.gov/adrs/) near Beatty, Nevada identified plants as the primary control on the near-surface water balance and showed that the boundary conditions imposed by plant activity in the uppermost soil layer results in episodic, deep drying well below the root zone during periods of below-average precipitation. The results help to explain the evidence for negligible recharge and upward flow that has been inferred from environmental-tracer and soil-physics based studies of undisturbed, arid sites. The findings have contributed to the development of new conceptual models that incorporate the influence of desert vegetation in analyses of paleo- to present-day water fluxes in deep unsaturated zones. Studies at the ADRS are also using plants to investigate the transport of contaminants away from a closed low-level radioactive waste disposal area. Soil-gas sampling results indicated that tritium has moved as much as 300 m from the disposal area, and that transport primarily occurs in the gas phase with preferential transport through coarse-textured sediment layers. The need for an efficient means of gathering plume-scale data led to the development of a method that uses plant water to identify the presence and distribution of tritium. The method entails field sampling and solar distillation of foliage to collect plant water, followed by laboratory filtration and adsorption of scintillation-interfering constituents on a graphite-based, solid-phase-extraction (SPE) column. The method was evaluated using an evergreen shrub (creosote bush; Larrea tridentata (DC.) Cov.). Tritium concentrations in plant water determined with the distillation-SPE method did not differ significantly from those determined with the standard (and more laborious) toluene

  12. Evolutionary shifts in habitat aridity predict evaporative water loss across squamate reptiles.

    Science.gov (United States)

    Cox, Christian L; Cox, Robert M

    2015-09-01

    Aridity is an important determinant of species distributions, shaping both ecological and evolutionary diversity. Lizards and snakes are often abundant in deserts, suggesting a high potential for adaptation or acclimation to arid habitats. However, phylogenetic evidence indicates that squamate diversity in deserts may be more strongly tied to speciation within arid habitats than to convergent evolution following repeated colonization from mesic habitats. To assess the frequency of evolutionary transitions in habitat aridity while simultaneously testing for associated changes in water-balance physiology, we analyzed estimates of total evaporative water loss (EWL) for 120 squamate species inhabiting arid, semiarid, or mesic habitats. Phylogenetic reconstructions revealed that evolutionary transitions to and from semiarid habitats were much more common than those between arid and mesic extremes. Species from mesic habitats exhibited significantly higher EWL than those from arid habitats, while species from semiarid habitats had intermediate EWL. Phylogenetic comparative methods confirmed this association between habitat aridity and EWL despite phylogenetic signal in each. Thus, the historical colonization of arid habitats by squamates is repeatedly associated with adaptive changes in EWL. This physiological convergence, which may reflect both phenotypic plasticity and genetic adaptation, has likely contributed to the success of squamates in arid environments.

  13. Wind power variations under humid and arid meteorological conditions

    International Nuclear Information System (INIS)

    Highlights: • It indicates the role of weather parameters’ roles in the wind energy calculation. • Meteorological variables are more significant in arid regions for wind power. • It provides opportunity to take into consideration air density variability. • Wind power is presented in terms of the wind speed, temperature and pressure. - Abstract: The classical wind power per rotor area per time is given as the half product of the air density by third power of the wind velocity. This approach adopts the standard air density as constant (1.23 g/cm3), which ignores the density dependence on air temperature and pressure. Weather conditions are not taken into consideration except the variations in wind velocity. In general, increase in pressure and decrease in temperature cause increase in the wind power generation. The rate of increase in the pressure has less effect on the wind power as compared with the temperature rate. This paper provides the wind power formulation based on three meteorological variables as the wind velocity, air temperature and air pressure. Furthermore, from the meteorology point of view any change in the wind power is expressed as a function of partial changes in these meteorological variables. Additionally, weather conditions in humid and arid regions differ from each other, and it is interesting to see possible differences between the two regions. The application of the methodology is presented for two meteorology stations in Istanbul, Turkey, as representative of the humid regions and Al-Madinah Al-Monawwarah, Kingdom of Saudi Arabia, for arid region, both on daily record bases for 2010. It is found that consideration of air temperature and pressure in the average wind power calculation gives about 1.3% decrease in Istanbul, whereas it is about 13.7% in Al-Madinah Al-Monawwarah. Hence, consideration of meteorological variables in wind power calculations becomes more significant in arid regions

  14. Semi-arid development: competitiveness factors in biodiesel productive chain

    OpenAIRE

    Breno Barros Telles do Carmo; Dmontier Pinheiro Aragão; Heráclito Lopes Jaguaribe Pontes; Bruno Magalhães Ribeiro; Marcos Ronaldo Albertin

    2009-01-01

    The new global market competitiveness considerer the competition between productive chains (PC) or supply chains, not just between enterprises. In this case, it can be observed collaboration and cooperation enterprises that dispute with others productives chain. The PC competitiveness can be impaired if is subject by inhibitors factors, that can impairer the performance. This paper analyses these competitiveness factors inhibitors in biodiesel productive chain (CPB) in semi-arid area: exporte...

  15. Water and Carbon Fluxes in a Semi-Arid Region Floodplain: Multiple Approaches to Constrain Estimates of Seasonal- and Depth Dependent Fluxes at Rifle, Colorado

    Science.gov (United States)

    Tokunaga, T. K.; Wan, J.; Dong, W.; Kim, Y.; Williams, K. H.; Conrad, M. E.; Christensen, J. N.; Bill, M.; Faybishenko, B.; Hobson, C.; Dayvault, R.; Long, P. E.; Hubbard, S. S.

    2014-12-01

    The importance of floodplains as links between watersheds and rivers highlights the need to understand water and carbon fluxes within floodplain profiles, from their surface soil, through the vadose zone and underlying groundwater. Here, we present results of field and laboratory measurements conducted to quantify fluxes at a remediated uranium/vanadium mill tailings site on a floodplain at Rifle, Colorado. This semi-arid site has a vegetated, locally derived fill soil that replaced the original milling-contaminated soil to a depth of about 1.5 m. The fill soil overlies about 4.5 m of native sandy and cobbly alluvium containing the shallow aquifer. The aquifer generally drains into the Colorado River and is underlain by low permeability Wasatch Formation shale. Within this system, key issues being investigated include water and carbon fluxes between the vadose zone and aquifer, and CO2 fluxes through the vadose zone soil out to the atmosphere. Magnitudes of these fluxes are typically low, thus challenging to measure, yet increasingly important to quantify given the expansion of arid and semi-arid regions under changing climate. The results of field investigations demonstrated that the annual water table rise and fall are driven by snowmelt runoff into the Colorado River in late spring to early summer. Tensiometer data indicate that net recharge from the deeper part of the vadose zone into groundwater occurs later in summer, after water table decline. The effectiveness of summer evapotranspiration in limiting groundwater recharge is reflected in water potentials decreasing to as low as -3 MPa within the upper 1.5 m of the vadose zone. Examination of the historical precipitation record further indicates that net recharge only occurs in years with above-average precipitation during winter and spring. These short intervals of net recharge also facilitate C transport into groundwater because of higher organic C concentrations in the vadose zone. Fluxes of CO2 measured

  16. A Feasibility Study of Geologic Water Storage in Arid Regions

    Science.gov (United States)

    Fairley, J. P.; Preuit, T.

    2001-05-01

    An important control on the carrying capacity of arid and semi-arid regions is the ability to develop and maintain a reliable water supply for domestic and agricultural use. In the semi-arid highlands of southern Peru, the pre-Columbian Incas developed a technique of collecting and storing basin yields by controlling the discharge boundary of an existing aquifer. This water resource management strategy has been dubbed "Geologic Water Storage" (Fairley, in review). Yield from at least one such system near Cuzco, Peru, has provided a reliable source of irrigation water for rural farmers to the present day. The geologic water storage systems of southern Peru suggested the possibility of developing a similar system to water stock in rural Idaho. Annual precipitation in Idaho is about one-third that of southern Peru, and obtaining an adequate stock water supply is often problematic. The application of a simple lumped capacitance model to a selected basin in central Idaho showed that it may be physically and economically feasible to modify the basin characteristics to prolong water availability at the site. A more detailed study of this problem, that includes field characterization of the site, is necessary to substantiate the model results. If further studies and field trials confirm the viability of geologic water storage, this approach may find applications in many rural and developing areas, both nationally and internationally.

  17. Saline dust storms and their ecological impacts in arid regions

    Institute of Scientific and Technical Information of China (English)

    Jilili; Abuduwaili

    2010-01-01

    In many arid and semiarid regions,saline playas represent a significant source of unconsoli-dated sediments available for aeolian transport,and severe saline dust storms occur frequently due to human disturbance.In this study,saline dust storms are reviewed systematically from the aspects of con-cept,general characteristics,conditions of occurrence,distribution and ecological impact.Our researches showed that saline dust storms are a kind of chemical dust storm originating in dry lake beds in arid and semiarid regions;large areas of unconsolidated saline playa sediments and frequent strong winds are the basic factors to saline dust storm occurrence;there are differentiation characteristics in deposition flux and chemical composition with wind-blown distance during saline dust storm diffusion;and saline dust storm diffusion to some extent increases glacier melt and results in soil salinization in arid regions.An under-standing of saline dust storms is important to guide disaster prevention and ecological rehabilitation.

  18. Characteristics of the volatile organic compounds -- Arid Integrated Demonstration Site

    International Nuclear Information System (INIS)

    The Volatile Organic Compounds -- Arid Integrated Demonstration Program (VOC-Arid ID) is targeted at demonstration and testing of technologies for the evaluation and cleanup of volatile organic compounds and associated contaminants at arid DOE sites. The initial demonstration site is an area of carbon tetrachloride (CCl4) contamination located near the center of the Hanford Site. The movement of CCl4 and other volatile organic contaminants in the subsurface is very complex. The problem at the Hanford Site is further complicated by the concurrent discharge of other waste constituents including acids, lard oil, organic phosphates, and transuranic radionuclides. In addition, the subsurface environment is very complex, with large spatial variabilities in hydraulic properties. A thorough understanding of the problem is essential to the selection of appropriate containment, retrieval, and/or in situ remedial technologies. The effectiveness of remedial technologies depends on knowing where the contaminants are, how they are held up in a given physical and chemical subsurface environment; and knowing the physical, chemical, and microbiological changes that are induced by the various remedial technologies

  19. Hydrogeological investigation of shallow aquifers in an arid data-scarce coastal region (El Daba'a, northwestern Egypt)

    Science.gov (United States)

    Yousif, Mohamed; van Geldern, Robert; Bubenzer, Olaf

    2016-02-01

    Hydrogeological investigations in arid regions are particularly important to support sustainable development. The study area, El Daba'a in northwestern Egypt, faces scarce water resources as a result of reported climate change that particularly affects the southern Mediterranean coast and increases stress on the local groundwater reserves. This change in climate affects the area in terms of drought, over-pumping and unregulated exploration of groundwater for irrigation purposes. The hydrogeological investigation is based on a multidisciplinary data-layer analysis that includes geomorphology, geology, slope, drainage lines, soil type, structural lineaments, subsurface data, stable isotopes, and chemical analyses. The study area contains Pleistocene and middle Miocene marine limestone aquifers. Based on lithology and microfacies analysis, the middle Miocene aquifer is subdivided into two water-bearing zones. The area is affected by sets of faults and anticline folds, and these structures are associated with fractures and joints that increase permeability and facilitate the recharge of groundwater. Stable isotope data indicate that groundwater of both the Pleistocene and middle Miocene aquifers is recharged by modern precipitation. The high salinity values observed in some groundwater wells that tap both aquifers could be attributed to leaching and dissolution processes of marine salts from the aquifers' marine limestone matrix. In addition, human activities can also contribute to an increase in groundwater salinity. A future water exploration strategy, based on the results from the multidisciplinary data-layer analysis, is proposed for the area. The derived scientific approach is transferable to other arid coastal areas with comparable conditions.

  20. Disconnected runoff contributing areas: Evidence provided by ancient watershed management systems in arid north-eastern Marmarica (NW-Egypt)

    Science.gov (United States)

    Vetter, T.; Rieger, A.-K.; Nicolay, A.

    2014-05-01

    This study presents the importance of disconnectivity in dryland area runoff demonstrated by manmade water harvesting structures dated to Greco-Roman times. Located on the coastal strip of some 20 km width along the Mediterranean coast of modern northwestern Egypt covering the north-eastern part of the region known in antiquity as Marmarica, the area receives winterly rainfalls of up to 140 mm. Further south, precipitation decreases quickly and desert conditions become more pronounced. Bedrocks are predominantly calcareous, soils are loamy, stony, calcareous, and shallow, except in relief sinks with sedimentary deposits. The land rises from the coast up to 230 m a.s.l. on the Marmarica Plateau in a sequence of zonal northsloping plains and scarps the northern parts of which are dissected and drained by wadis. Agriculturally suitable areas comprise some 9% of the coastal zone and adjacent tablelands. Overland flow controls the discharge dynamics and is the main source of wadi runoff and hence agricultural water supply. The land use pattern is scattered because cropping areas depend mainly on suitability of soils and the generation of runoff harvest, which are closely interrelated because of the arid water and sediment regime. The patchiness of runoff generation increases further south where aridity is higher and topography inhibits greater drainage patterns. The abundance of cisterns, many of them originally Greco-Roman, is strong evidence that tableland overland flows occur and are frequently disconnected from larger drainage systems.

  1. Land use change and carbon cycle in arid and semi-arid lands of East and Central Asia

    Institute of Scientific and Technical Information of China (English)

    Togtohyn; Chuluun; Dennis; Ojima

    2002-01-01

    Dramatic changes in land use have occurred in arid and semi-arid landsof Asia during the 20th century. Grassland conversion into croplands and ecosystem degradation is widespread due to the high growth rate of human population and political reforms of pastoral systems. Rangeland degradation made many parts of this region vulnerable to environmental and political changes. The collapse of the livestock sector in some states of central Asia, expansion of livestock inChina and intensive degradation of grasslands in China are examples of the responses of pastoral systems to these changes over the past decades. Carbon dynamics in this region is highly variable in space and time. Land use/cover changes with widespread reduction of forest and grasslands increased carbon emission from the region.

  2. Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia)

    OpenAIRE

    Jonathan Deborde; Cyril Marchand; Nathalie Molnar; Luc Della Patrona; Tarik Meziane

    2015-01-01

    In mangrove ecosystems, strong reciprocal interactions exist between plant and substrate. Under semi-arid climate, Rhizophora spp. are usually predominant, colonizing the seashore, and Avicennia marina develops at the edge of salt-flats, which is the highest zone in the intertidal range. Along this zonation, distribution and speciation of C, Fe, S, N, and P in sediments and pore-waters were investigated. From the land-side to the sea-side of the mangrove, sediments were characterized by I/ in...

  3. Spatiotemporal analysis and trends of aridity of Iberian Peninsula (1960-2010)

    Science.gov (United States)

    Paniagua, Luis L.; García, Abelardo; Moral, Francisco J.; Rebollo, Francisco J.

    2016-04-01

    In this study the aridity of the Iberian Peninsula was analysed, taking into account 45 stations in Spain and Portugal from 1960 to 2010. The De Martonne Index was considered. The goal of this study was to explore the spatial distribution and to determine monotonic trends and shift changes in annual aridity by using the Mann-Kendall test and the Seńs estimator. The spatially interpolated maps of the aridity indice were generated using the ordinary kriging algorithm in a geographic information system (GIS) environment. A great variability for Martonne Index was found, gathering from semiarid climates to extremely humid, although the former being the dominant type. 41 temporal series showed decreasing tendencies, 15 of them significant, belonging to all climate types, which indicates a increase in aridity during the research period. A shift in the aridity tendency has been observed around 1979, and a period of greater aridity started since.

  4. VOC-Arid Integrated Demonstration guide to preparation of demonstration documents

    International Nuclear Information System (INIS)

    This guide has been prepared by Demonstration Operations of the Volatile Organic Compound-Arid Integrated Demonstration (VOC-Arid ID). Its purpose is to describe demonstration documents, designate responsibilities for these documents, and guide the Principal Investigator (PI) and others in their preparation. The main emphasis of this guide is to describe the documentation required of the PI. However, it does cover some of the responsibilities of other members of the VOC-Arid ID team. The VOC-Arid ID is one of several US Department of Energy (DOE) integrated demonstrations designed to support the demonstration of emerging environmental management and restoration technologies. The principal objective of the VOC-Arid ID is to identify, develop, and demonstrate new and innovative technologies for environmental restoration at arid or semiarid sites containing volatile organic compounds with or without associated contamination (e.g., radionuclides and metals)

  5. Microbial reduction of hexavalent Chromium under vadose zone conditions

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, D S.(unknown); Brockman, Fred J.(BATTELLE (PACIFIC NW LAB)); Bowman, Robert (VISITORS); Kieft, Thomas L.(BATTELLE (PACIFIC NW LAB))

    2003-01-01

    Hexavalent chromium[Cr(VI)] is a common constituent of wastes associated with nuclear reactor operation and fuel processing. Improper disposal at facilities in arid and semi-arid regions has led to contamination of underlying vadose zones and aquifers. The objectives of this study were to assess the potential for immobilizing Cr(VI) contamination using a native microbial community to reduce soluble Cr(VI) to insoluble Cr(III) under conditions similar to those found in the vadose zone, and to evaluate the potential for enhancing biological reduction of Cr(VI) through the addition of nutrients. Batch microcosm and unsaturated flow column experiments were performed. Native microbial communities in subsurface sediments with no prior Cr(VI) exposure were shown to be capable of Cr(VI) reduction. In both the batch and column experiments, Cr(VI) reduction and loss from the aqueous phase were enhanced by adding high levels of both nitrate (NO3-) and organic carbon (molasses). Nutrient amendments resulted in up to 87% Cr(VI) reduction in unsaturated batch experiments. Molasses and nitrate additions to 15-cm length unsaturated flow columns receiving 65 mg L-1 Cr(VI) resulted in microbially mediated reduction and immobilization of 10% of the Cr during a 45-day experiment. All of the immobilized Cr was in the form of Cr (III), as shown by XANES analysis. This suggests that biostimulation of microbial Cr(VI) reduction in vadose zones by nutrient amendment is a promising strategy; and that immobilization of close to 100% of Cr contamination could be achieved in a thick vadose zone with longer flow paths and longer contact times than in this experiment.

  6. Hydrochemical Differentiation of Salinisation Process of the Water in Endoreic Semi-Arid Basin: Case of Rémila Basin, Algeria

    Directory of Open Access Journals (Sweden)

    Houha Belgacem

    2008-01-01

    Full Text Available The aim of this study is to determine and treat a hierarchical basis of the various mechanisms responsible for the space variation of the water quality in a endoreic semi-arid basin. The water chemistry showed a large variability in space and time. The total dissolved solid (TDS in water increases from upstream to downstream due to the effect of the arid climate, but also due to the water-rock interactions and the anthropic polution of surface water. The water chemistry changes progressively from bicarbonate calcic upstream to sulphated and chlorinated calcic in the median zone to chlorinate sodic in the Sebkha. Thermodynamic modelling showed the major role of evaporation in the evolution of the water chemistry. The result indicated calcite precipitation then gypsum precipitation as well as cations exchanges reactions. Statistical approach allowed to arrange processes that responsible for the hydrochemical variability according to their important. The increase of water salinity is due mainly to the aridity process. The differentiation between salty surface water (Sebkha and deeper water (Chott is the second process. The combined of the geochemical and statistical methods allowed to identify the main

  7. Application of Dempster-Shafer theory, spatial analysis and remote sensing for groundwater potentiality and nitrate pollution analysis in the semi-arid region of Khuzestan, Iran.

    Science.gov (United States)

    Rahmati, Omid; Melesse, Assefa M

    2016-10-15

    Effective management and sustainable development of groundwater resources of arid and semi-arid environments require monitoring of groundwater quality and quantity. The aim of this paper is to develop a reasonable methodological framework for producing the suitability map for drinking water through the geographic information system, remote sensing and field surveys of the Andimeshk-Dezful, Khozestan province, Iran as a semi-arid region. This study investigated the delineation of groundwater potential zone based on Dempster-Shafer (DS) theory of evidence and evaluate its applicability for groundwater potentiality mapping. The study also analyzed the spatial distribution of groundwater nitrate concentration; and produced the suitability map for drinking water. The study has been carried out with the following steps: i) creation of maps of groundwater conditioning factors; ii) assessment of groundwater occurrence characteristics; iii) creation of groundwater potentiality map (GPM) and model validation; iv) collection and chemical analysis of water samples; v) assessment of groundwater nitrate pollution; and vi) creation of groundwater potentiality and quality map. The performance of the DS was also evaluated using the receiver operating characteristic (ROC) curve method and pumping test data to ensure its generalization ability, which eventually, the GPM showed 87.76% accuracy. The detailed analysis of groundwater potentiality and quality revealed that the 'non acceptable' areas covers an area of about 1479km(2) (60%). The study will provide significant information for groundwater management and exploitation in areas where groundwater is a major source of water and its exploration is critical to support drinking water need.

  8. Outcrop Groundwater Prospecting, Drilling, and Well Construction in Hard Rocks in Semi-arid Regions

    OpenAIRE

    Chambel, António

    2014-01-01

    This chapter presents some recommendations for prospecting, drilling and well construction in hard rocks in semi-arid regions. Considering that these conditions are present in many countries where technology is not always available, the chapter concentrates on the most basic and simple methods to plan where best to drill and maximize success through the direct observation of rock types, weathering and fracturing. The advantage for the geologist and hydrogeologist in an arid or semi-arid envir...

  9. Spatial distribution and comparison of aridity indices in Extremadura, southwestern Spain

    Science.gov (United States)

    Moral, Francisco J.; Rebollo, Francisco J.; Paniagua, Luis L.; García-Martín, Abelardo; Honorio, Fulgencio

    2015-09-01

    In semi-arid lands with warm climates, aridity is a real hazard, with the threat of desertification because of greater precipitation variability and prolonged droughts. Aridity indices can be used to identify areas prone to desertification. The present study aimed to analyse the spatial distribution of aridity in Extremadura, southwestern Spain, using three indices: the De Martonne aridity index (I DM), the Pinna combinative index (I P), and the Food and Agriculture Organization (FAO) aridity index (I F). Temperature, precipitation, and evapotranspiration data from 90 weather stations located throughout Extremadura and 27 along boundaries with at least 30-year length (within the 1980-2011 period) were used to compute each index at each station. The statistical properties of each aridity index were assessed, and later, they were mapped by means of an integrated geographic information system (GIS) and a multivariate geostatistical (regression-kriging) algorithm in which exhaustive secondary information on elevation was incorporated. Annual and seasonal I DM and I F, and annual I P-kriged maps were generated. According to annual I DM, the semi-arid and Mediterranean conditions are predominant in the region, covering about 70 % of the territory, while about 94 % of the areas are classified as dry and semi-dry Mediterranean based on annual I P and about 86 % are classified as semi-arid and dry categories based on annual I F. The most vulnerable to aridity are the natural regions located to the west, the south, and the southeast of Extremadura, especially during summer, when arid conditions are found across the region. Although the three aridity indices were highly correlated, displaying similar spatial patterns, I DM was preferred because it can better discriminate different climate conditions in Extremadura.

  10. Analysis and evaluation of tillage on an alfisol ina semi-arid tropical region of India

    OpenAIRE

    Klaij, M C

    1983-01-01

    Tillage field experiments were conducted on Alfisols in a semi-arid tropical environment in India. The research was conducted within the framework of the Farming Systems Research Program of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).To put the experiments into perspective, a general review is given in chapter 2 on the environment of the semi-arid tropics, its problems and the research related to agricultural production. Rainfed agriculture has failed to pro...

  11. ARID1A immunohistochemistry improves outcome prediction in invasive urothelial carcinoma of urinary bladder.

    Science.gov (United States)

    Faraj, Sheila F; Chaux, Alcides; Gonzalez-Roibon, Nilda; Munari, Enrico; Ellis, Carla; Driscoll, Tina; Schoenberg, Mark P; Bivalacqua, Trinity J; Shih, Ie-Ming; Netto, George J

    2014-11-01

    AT-rich interactive domain 1A (ARID1A) is tumor suppressor gene that interacts with BRG1 adenosine triphosphatase to form a SWI/SNF chromatin remodeling protein complex. Inactivation of ARID1A has been described in several neoplasms, including epithelial ovarian and endometrial carcinomas, and has been correlated with prognosis. In the current study, ARID1A expression in urothelial carcinoma (UC) of the bladder and its association with clinicopathological parameters and outcome are addressed. Five tissue microarrays were constructed from 136 cystectomy specimens performed for UC at our institution. Nuclear ARID1A staining was evaluated using immunohistochemistry. An H-score was calculated as the sum of the products of intensity (0-3) multiplied by extent of expression (0%-100%). Average H-score per case was used for statistical analysis. ARID1A expression was categorized in low and high using Youden index to define the cut point. ARID1A expression significantly increased from normal to noninvasive UC to invasive UC. For both tumor progression and cancer death, Youden index yielded an H-score of 288 as the optimal cut point for ARID1A expression. Low ARID1A expression showed a tendency for lower risk of tumor progression and cancer mortality. Adding ARID1A expression to pathologic features offers a better model for predicting outcome than pathologic features alone. Low ARID1A expression was more frequently seen in earlier stage disease. There was a tendency for low ARID1A expression to predict better outcome. More importantly, the findings indicate that adding ARID1A expression to pathologic features increases the goodness of fit of the predictive model. PMID:25175170

  12. Organic Matter and Water Addition Enhance Soil Respiration in an Arid Region

    OpenAIRE

    Liming Lai; Jianjian Wang; Yuan Tian; Xuechun Zhao; Lianhe Jiang; Xi Chen; Yong Gao; Shaoming Wang; Yuanrun Zheng

    2013-01-01

    Climate change is generally predicted to increase net primary production, which could lead to additional C input to soil. In arid central Asia, precipitation has increased and is predicted to increase further. To assess the combined effects of these changes on soil CO2 efflux in arid land, a two factorial manipulation experiment in the shrubland of an arid region in northwest China was conducted. The experiment used a nested design with fresh organic matter and water as the two controlled par...

  13. Abacus for the determination of the groundwater evaporation in arid areas. Case of the region of Ouargla-Algeria

    Science.gov (United States)

    El Fergougui, Myriam Marie; Boutoutaou, Djamel

    2016-07-01

    One of the possible remedies to control the inputs of salts toward the surface would be by diminishing the groundwater; because areas set on values in arid zones of the region of Ouargla are based upon excessively mineralized groundwater whose level is near the ground surface (0 to 1.5 m). The improvement and stabilization of yields of any cultural practices in these areas can only take place if the salty groundwater is maintained (drained) to a depth of 1.6m. The results of work carried on the determination of the groundwater evaporation in Ouargla show that the evaporation essentially depends on: The climate that reigns above the ground of the groundwater situated on the band from 0 to 0.6 m. The climate and soil texture according the groundwater located in the layer from 0.6 to 1.6 m. The depth of the groundwater when this latter is located beyond 1.6 m.

  14. An integrated assessment of the impact of precipitation and groundwater on vegetation growth in arid and semiarid areas

    CERN Document Server

    Zhu, Lin; Dai, Zhenxue; Xu, Tingbao; Su, Xiaosi

    2014-01-01

    Increased demand for water resources together with the influence of climate change has degraded water conditions which support vegetation in many parts of the world, especially in arid and semiarid areas. This study develops an integrated framework to assess the impact of precipitation and groundwater on vegetation growth in the Xiliao River Plain of northern China. The integrated framework systematically combines remote sensing technology with water flow modeling in the vadose zone and field data analysis. The vegetation growth is quantitatively evaluated with the remote sensing data by the Normalized Difference Vegetation Index (NDVI) and the simulated plant water uptake rates. The correlations among precipitation, groundwater depth and NDVI are investigated by using Pearson correlation equations. The results provide insights for understanding interactions between precipitation and groundwater and their contributions to vegetation growth. Strong correlations between groundwater depth, plant water uptake and...

  15. Generalized Fibonacci zone plates

    CERN Document Server

    Ke, Jie; Zhu, Jianqiang

    2015-01-01

    We propose a family of zone plates which are produced by the generalized Fibonacci sequences and their axial focusing properties are analyzed in detail. Compared with traditional Fresnel zone plates, the generalized Fibonacci zone plates present two axial foci with equal intensity. Besides, we propose an approach to adjust the axial locations of the two foci by means of different optical path difference, and further give the deterministic ratio of the two focal distances which attributes to their own generalized Fibonacci sequences. The generalized Fibonacci zone plates may allow for new applications in micro and nanophotonics.

  16. Shanghai's Development Zones

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Since the early 1980s,development zones began appearing in China.Their Success largely stems from the preferential policies they offer and the safe investment environment they work hard to create.As zones have personalities themselves,it is essential to look beyond the pamphlets and published information and get down to the nittygritty.Shanghai has more State designated Economic and Technology Development Zones than any other city in China.In the following article,we have chosen development zones located around Shanghai and conducted a comparison.

  17. Estimation of soil moisture-thermal infrared emissivity relation in arid and semi-arid environments using satellite observations

    Science.gov (United States)

    Grazia Blasi, Maria; Masiello, Guido; Serio, Carmine; Venafra, Sara; Liuzzi, Giuliano; Dini, Luigi

    2016-04-01

    The retrieval of surface parameters is very important for various aspects concerning the climatological and meteorological context. At this purpose surface emissivity represents one of the most important parameters useful for di fferent applications such as the estimation of climate changes and land cover features. It is known that thermal infrared (TIR) emissivity is aff ected by soil moisture, but there are very few works in literature on this issue. This study is aimed to analyze and fi nd a relation between satellite soil moisture data and TIR emissivity focusing on arid and semi-arid environments. These two parameters, together with the land surface temperature, are fundamental for a better understanding of the physical phenomena implied in the soil-atmosphere interactions and the surface energy balance. They are also important in several fi elds of study, such as climatology, meteorology, hydrology and agriculture. In particular, there are several studies stating a correlation between soil moisture and the emissivity at 8-9 μ m in desertic soils, which corresponds to the quartz Reststrahlen, a feature which is typical of sandy soils. We investigated several areas characterized by arid or semi-arid environments, focusing our attention on the Dahra desert (Senegal), and on the Negev desert (Israel). For the Dahra desert we considered both in situ, provided by the International Soil Moisture Network, and satellite soil moisture data, from ASCAT and AMSR-E sensors, for the whole year 2011. In the case of the Negev desert soil moisture data are derived from ASCAT observations and we computed a soil moisture index from a temporal series of SAR data acquired by the Cosmo-SkyMed constellation covering a period of six months, from June 2015 to November 2015. For both cases soil moisture data were related to the retrieved TIR emissivity from the geostationary satellite SEVIRI in three di erent spectral channels, at 8.7 μm, 10.8 μ m and 12 μ m. A Kalman lter

  18. Groundwater potentiality mapping of hard-rock terrain in arid regions using geospatial modelling: example from Wadi Feiran basin, South Sinai, Egypt

    Science.gov (United States)

    Arnous, Mohamed O.

    2016-04-01

    Identifying a good site for groundwater exploitation in hard-rock terrains is a challenging task. In Sinai, Egypt, groundwater is the only source of water for local inhabitants. Interpretation of satellite data for delineation of lithological units and weathered zones, and for mapping of lineament density and their trends, provides a valuable aid for the location of groundwater promising areas. Complex deformational histories of the wide range of lithological formations add to the difficulty. Groundwater prospect mapping is a systematic approach that considers the major controlling factors which influence the aquifer and quality of groundwater. The presented study aims to delineate, identify, model and map groundwater potential zones in arid South Sinai using remote sensing data and a geographic information system (GIS) to prepare various hydromorphogeological thematic maps such as maps of slope, drainage density, lithology, landforms, structural lineaments, rainfall intensity and plan curvature. The controlling-factor thematic maps are each allocated a fixed score and weight, computed by using a linear equation approach. Furthermore, each weighted thematic map is statistically computed to yield a groundwater potential zone map of the study area. The groundwater potential zones thus obtained were divided into five categories (very poor, poor, moderate, good and very good) and were validated using the relation between the zone and the spatial distribution of productive wells and of previous geophysical investigations from a literature review. The results show the groundwater potential zones in the study area, and create awareness for better planning and management of groundwater resources.

  19. Groundwater potentiality mapping of hard-rock terrain in arid regions using geospatial modelling: example from Wadi Feiran basin, South Sinai, Egypt

    Science.gov (United States)

    Arnous, Mohamed O.

    2016-09-01

    Identifying a good site for groundwater exploitation in hard-rock terrains is a challenging task. In Sinai, Egypt, groundwater is the only source of water for local inhabitants. Interpretation of satellite data for delineation of lithological units and weathered zones, and for mapping of lineament density and their trends, provides a valuable aid for the location of groundwater promising areas. Complex deformational histories of the wide range of lithological formations add to the difficulty. Groundwater prospect mapping is a systematic approach that considers the major controlling factors which influence the aquifer and quality of groundwater. The presented study aims to delineate, identify, model and map groundwater potential zones in arid South Sinai using remote sensing data and a geographic information system (GIS) to prepare various hydromorphogeological thematic maps such as maps of slope, drainage density, lithology, landforms, structural lineaments, rainfall intensity and plan curvature. The controlling-factor thematic maps are each allocated a fixed score and weight, computed by using a linear equation approach. Furthermore, each weighted thematic map is statistically computed to yield a groundwater potential zone map of the study area. The groundwater potential zones thus obtained were divided into five categories (very poor, poor, moderate, good and very good) and were validated using the relation between the zone and the spatial distribution of productive wells and of previous geophysical investigations from a literature review. The results show the groundwater potential zones in the study area, and create awareness for better planning and management of groundwater resources.

  20. Targeting EZH2 methyltransferase activity in ARID1A mutated cancer cells is synthetic lethal

    Science.gov (United States)

    Biter, Benjamin G.; Aird, Katherine M.; Garipov, Azat; Li, Hua; Amatangelo, Michael; Kossenkov, Andrew V.; Schultz, David C.; Liu, Qin; Shih, Ie-Ming; Conejo-Garcia, Jose R.; Speicher, David W.; Zhang, Rugang

    2015-01-01

    ARID1A, a chromatin remodeler, shows one of the highest mutation rates across many cancer types. Notably, ARID1A is mutated in over 50% of ovarian clear cell carcinomas, which currently has no effective therapy. To date, clinically applicable targeted cancer therapy based on ARID1A mutational status has not been described. Here we show that inhibition of the EZH2 methyltransferase acts in a synthetic lethal manner in ARID1A mutated ovarian cancer cells. ARID1A mutational status correlates with response to the EZH2 inhibitor. We identified PIK3IP1 as a direct ARID1A/EZH2 target, which is upregulated by EZH2 inhibition and contributes to the observed synthetic lethality by inhibiting PI3K/AKT signaling. Significantly, EZH2 inhibition causes regression of ARID1A mutated ovarian tumors in vivo. Together, these data demonstrate for the first time a synthetic lethality between ARID1A mutation and EZH2 inhibition. They indicate that pharmacological inhibition of EZH2 represents a novel treatment strategy for ARID1A mutated cancers. PMID:25686104

  1. Late Pleistocene-Holocene morphosedimentary architecture, Spiti River, arid higher Himalaya

    Science.gov (United States)

    Srivastava, Pradeep; Ray, Yogesh; Phartiyal, Binita; Sharma, Anupam

    2013-03-01

    The Spiti River drains the rain shadow zone of western Himalaya. In the present study, the fluvial sedimentary record of Spiti valley was studied to understand its responses to tectonics and climate. Geomorphic changes along the river enable to divide the river into two segments: (i) upper valley with a broad, braided channel where relict sedimentary sequences rise 15-50 m high from the riverbed and (ii) lower valley with a narrow, meandering channel that incises into bedrock, and here, the fluvio-lacustrine sediments reside on a bedrock bench located above the riverbed. The transition between these geomorphic segments lies along the river between Seko-Nasung and Lingti villages (within Tethyan Himalaya). Lithofacies analyses of the sedimentary sequences show six different lithofacies. These can be grouped into three facies associations, viz. (A) a glacial outwash; (B) sedimentation in a channel and in an accreting bar under braided conditions; and (C) formation of lake due to channel blockage by landslide activities. Seventeen optically stimulated luminescence ages derived from ten sections bracketed the phases of river valley aggradation between 14-8 and 50-30 ka. These aggradation phases witnessed mass wasting, channel damming and lake formation events. Our record, when compared with SW monsoon archives, suggests that the aggradation occurred during intensified monsoon phase of MIS 3/4 and that proceeded the Last Glacial Maxima. Thus, the study reports monsoon modulated valley aggradation in the NW arid Himalaya.

  2. Soils of floodplains in arid regions of Inner Asia (the Zavkhan River, Mongolia)

    Science.gov (United States)

    Ubugunov, L. L.; Ubugunova, V. I.

    2012-03-01

    The environmental conditions of soil formation and the diversity and classification position of soils developing on the Zavkhan River floodplain are considered, and the morphogenetic and agrochemical properties of these soils are characterized. It is shown that the conditions of soil formation on the floodplain of the Zavkhan River are specified by the mountainous topography, the effect of the large Mongol Els sand massif, the character of the alluviation processes, the groundwater level and salinity, and the regime of floods. The position of the floodplain in the system of altitudinal zones largely dictates the character of the soil cover pattern. In terms of the new Russian soil classification system, the soils studied belong to three trunks, four orders, and seven types: stratified humus alluvial soils, light-humus alluvial soils, light-humus quasigley alluvial soils, light-humus stratozems, and solonchaks. The soils of floodplain ecosystems in arid regions are characterized by low fertility. For their efficient use for pasturing and crop growing, the ecologically balanced differentiated application of manure, mineral fertilizers (NPK), and some microelements is required.

  3. Human-Wildlife Conflicts in Arid Areas of Western India: Strategies for Mutual Co-Existence

    Directory of Open Access Journals (Sweden)

    Darshana Patel

    2014-04-01

    Full Text Available The study has been carried out in the North Gujarat region of Gujarat state, Western India which represents unique habitats from arid regions to dry deciduous forests with annual rainfall ranging from 25-125 cms. Human-wildlife conflicts are intensifying owing to increase in human population and destruction of wildlife habitats. In the present study we characterized and classified the conflicts, identified zones with acute conflicts and evaluated the economic loss to the local villagers due to such humanwildlife conflicts. Sampling methods mainly included village surveys for interviewing locals who are affected by wildlife damage. The information was overlaid on the existing digital land use data to identify landscape characteristics associated with wildlife occupancy in the region. The result depicts that 80% of total damage in seasonal crop is caused by wild ungulates. Wild animals like Blue bull, Wild boar and Porcupine are reported as a chief crop raider. The Leopard is the only big cat occurring in the region reported to cause human injury and livestock predation. Sloth bear attacks on human are very common in some part of the study area. Conflicts are more severe around unprotected forests while high intensity of conflicts was recorded on the fringes of the forests

  4. Evaluation of Warm Season Turfgrass under Different Irrigation Regimes in Arid Region

    Directory of Open Access Journals (Sweden)

    Abdullah Mohd Hassan ALSHEHHI

    2010-09-01

    Full Text Available Turfgrasses play a very important role in enhancing quality of life in modern urban living. Water quantity is the most important challenge worldwide in establishing and maintaining quality turf. The present study was aimed to test the performance of three warm season turfgrasses under four water levels for plantation in arid zones. Pits (48 measuring 1m length x 1m width x 0.6 m depth were planted with four replications of Common Bermuda grass (Cynodon dactylon, Tifway Bermuda grass (Cynodon dactylon x transvaalensis and Seashore Paspalum grass (Paspalum vaginatum in complete randomized design (CRD. Irrigation was done daily with 15 l/plot during the first 4 weeks (establishment period and four irrigation levels (5, 10, and 15, 20 l/lot were maintained in the following 8 weeks (treatment period. Physical parameters (canopy temperatures, ambient temperature, leaf area, shoot production and relative water content were measured once in two week as well as the visual quality (shoot color, shoot density and shoot uniformity was assessed, however, chlorophyll analysis was done in the end of the study. It was found that temperature has significant effect on performance of turfgrasses. Canopy temperature was higher than ambient temperature in the three turfgrasses but it has different level in each variety. Five liter of water per day per square meter gave acceptable turf quality when ambient temperature ranged from 20 to 33�C. Seashore paspalum performed best followed by Tifway Bermuda grass and common Bermuda grass respectively.

  5. Spatial changes of Extended De Martonne climatic zones affected by climate change in Iran

    Science.gov (United States)

    Rahimi, Jaber; Ebrahimpour, Meisam; Khalili, Ali

    2013-05-01

    In order to better understand the effect associated with global climate change on Iran's climate condition, it is important to quantify possible shifts in different climatic types in the future. To this end, monthly mean minimum and maximum temperature, and precipitation from 181 synoptic meteorological stations (average 1970-2005) have been collected from the meteorological organization of Iran. In this paper, to study spatial changes of Iran's climatic zones affected by climate changes, Extended De Martonne's classification (originally formulated by De Martonne and extended by Khalili (1992)) was used. Climate change scenarios were simulated in two future climates (average conditions during the 2050s and the 2080s) under each of the SRES A1B and A2, for the CSIRO-MK3, HadCM3, and CGCM3 climate models. Coarse outputs of GCMs were downscaled by delta method. We produced all maps for three time periods (one for the current and two for the future) according to Extended De Martonne's classification. Finally, for each climatic zone, changes between the current and the future were compared. As the main result, simulated changes indicate shifts to warmer and drier zones. For example, in the current, extra arid-cold ( A1.1m2) climate is covering the largest area of the country (21.4 %), whereas in both A1B and A2 scenarios in the 2050s and the 2080s, extra arid-moderate ( A1.1m3) and extra arid-warm ( A1.1m4) will be the climate and will occupy the largest area of the country, about 21 and 38 %, respectively. This analysis suggests that the global climate change will have a profound effect on the future distribution of severe aridity in Iran.

  6. ZoneLib

    DEFF Research Database (Denmark)

    Jessen, Jan Jacob; Schiøler, Henrik

    2006-01-01

    We present a dynamic model for climate in a livestock building divided into a number of zones, and a corresponding modular Simulink library (ZoneLib). While most literature in this area consider air flow as a control parameter we show how to model climate dynamics using actual control signals for...

  7. Meaningful traits for grouping plant species across arid ecosystems.

    Science.gov (United States)

    Bär Lamas, Marlene Ivonne; Carrera, A L; Bertiller, M B

    2016-05-01

    Grouping species may provide some degree of simplification to understand the ecological function of plants on key ecosystem processes. We asked whether groups of plant species based on morpho-chemical traits associated with plant persistence and stress/disturbance resistance reflect dominant plant growth forms in arid ecosystems. We selected twelve sites across an aridity gradient in northern Patagonia. At each site, we identified modal size plants of each dominant species and assessed specific leaf area (SLA), plant height, seed mass, N and soluble phenol concentration in green and senesced leaves at each plant. Plant species were grouped according with plant growth forms (perennial grasses, evergreen shrubs and deciduous shrubs) and plant morphological and/or chemical traits using cluster analysis. We calculated mean values of each plant trait for each species group and plant growth form. Plant growth forms significantly differed among them in most of the morpho-chemical traits. Evergreen shrubs were tall plants with the highest seed mass and soluble phenols in leaves, deciduous shrubs were also tall plants with high SLA and the highest N in leaves, and perennial grasses were short plants with high SLA and low concentration of N and soluble phenols in leaves. Grouping species by the combination of morpho-chemical traits yielded 4 groups in which species from one growth form prevailed. These species groups differed in soluble phenol concentration in senesced leaves and plant height. These traits were highly correlated. We concluded that (1) plant height is a relevant synthetic variable, (2) growth forms adequately summarize ecological strategies of species in arid ecosystems, and (3) the inclusion of plant morphological and chemical traits related to defenses against environmental stresses and herbivory enhanced the potential of species grouping, particularly within shrubby growth forms. PMID:26897637

  8. Semi-arid development: competitiveness factors in biodiesel productive chain

    Directory of Open Access Journals (Sweden)

    Breno Barros Telles do Carmo

    2009-04-01

    Full Text Available The new global market competitiveness considerer the competition between productive chains (PC or supply chains, not just between enterprises. In this case, it can be observed collaboration and cooperation enterprises that dispute with others productives chain. The PC competitiveness can be impaired if is subject by inhibitors factors, that can impairer the performance. This paper analyses these competitiveness factors inhibitors in biodiesel productive chain (CPB in semi-arid area: exported product, market knowledge, competitiveness position, opportunities to aggregate value in chain, cooperation between enterprises, enterprises way of thinking and paternalism by government. It was done this analyses to compare CPB with the world.

  9. Aerosol radiative effects over global arid and semi-arid regions based on MODIS Deep Blue satellite observations

    Science.gov (United States)

    Hatzianastassiou, Nikolaos; Papadimas, Christos D.; Gkikas, Antonis; Matsoukas, Christos; Sayer, Andrew M.; Hsu, N. Christina; Vardavas, Ilias

    2014-05-01

    Aerosols are a key parameter for several atmospheric processes related to weather and climate of our planet. Specifically, the aerosol impact on Earth's climate is exerted and quantified through their radiative effects, which are induced by their direct, indirect and semi-direct interactions with radiation, in particular at short wavelengths (solar). It is acknowledged that the uncertainty of present and future climate assessments is mainly associated with aerosols and that a better understanding of their physico-chemical, optical and radiative effects is needed. The contribution of satellites to this aim is important as a complementary tool to climate and radiative transfer models, as well as to surface measurements, since space observations of aerosol properties offer an extended spatial coverage. However, such satellite based aerosol properties and associated model radiation computations have suffered from unavailability over highly reflecting surfaces, namely polar and desert areas. This is also the case for MODIS which, onboard the Terra and Aqua satellites, has been providing high quality aerosol data since 2000 and 2002, respectively. These data, more specifically the aerosol optical depth (AOD) which is the most important optical property used in radiative and climate models, are considered to be of best quality. In order to address this problem, the MODIS Deep Blue (DB) algorithm has been developed which enables the retrieval of AOD above arid and semi-arid areas of the globe, including the major deserts. In the present study we make use of the FORTH detailed spectral radiative transfer model (RTM) with MODIS DB AOD data, supplemented with single scattering albedo (SSA) and asymmetry parameter (AP) aerosol data from the Global Aerosol DataSet (GADS) to estimate the aerosol DREs over the arid and semi-arid regions of the globe. The RTM is run using surface and atmospheric data from the ISCCP-D2 dataset and the NCEP global reanalysis project and computes the

  10. Factors affecting carbon-14 activity of unsaturated zone CO2 and implications for groundwater dating

    Science.gov (United States)

    Wood, Cameron; Cook, Peter G.; Harrington, Glenn A.; Meredith, Karina; Kipfer, Rolf

    2014-11-01

    Unsaturated zone processes may influence the carbon-14 (14C) activity of infiltrating groundwater and thus introduce error in derived groundwater residence times. However unsaturated zone 14C activities are rarely measured and there is little understanding of how they may vary spatially in a groundwater basin. In this study we measured 14C activity in unsaturated zone gas at five sites with different watertable depths (8.2-31.5 m) in the arid Ti Tree Basin, central Australia. We observed a relatively uniform decrease in 14C activity of unsaturated zone gas with depth at most sites, with variation in unsaturated zone depths leading to variation in 14C activities directly above the watertable at each site (ranging from 54 to 106 percent Modern Carbon (pMC)). Through modelling we show that the profiles are influenced by CO2 production at different depths from sources with different isotopic ratios, including production of ‘modern' CO2 in the root zone and production of ‘old' CO2 above the watertable. Scenario modelling showed that these processes are independent of recharge when recharge is low (0-10 mm y-1) but that higher recharge rates (>100 mm y-1) result in more advective transport of atmospheric CO2 to the watertable. The variation in 14C above the watertable was more sensitive to watertable depth and shallow and deep CO2 production rates. These findings offer insight into how unsaturated zone 14C activities may vary spatially and provide guidance as to when 14C depletion in unsaturated zone CO2 may become important for groundwater dating, particularly in arid settings.

  11. Ecosystem restoration at the Arid-Semiarid Interface in Israel's Northern Negev

    Science.gov (United States)

    Mor-Mussery, Amir; Leu, Stefan; Bar-Kutiel, Pua

    2016-04-01

    The interface between the arid and semi-arid zones in Southern Israel (as elsewhere in the world) is heavily degraded. Thousands of years of overexploitation by wood cutting, farming and grazing have left the area at 10 - 30% of their nominal biological productivity, void of any trees and shrubs, and generally low in biodiversity. Degradation is an ongoing process in Israel's open areas, whereby overgrazing and continuous soil tilling for field crops, and contour trenching for planting of exotic tree species are the main drivers for ongoing soil degradation. The results of those activities are further loss of productivity, soil organic matter and soil nutrients, and massive soil erosion. In the framework of several research projects and a large ecosystem restoration project (http://www.sustainabilitylabs.org/ecosystem-restoration/) we have analyzed in detail the drivers of degradation by field studies accompanied by GIS analyses. Various approaches for soil restoration have been attempted and documented. Fencing of and protection from grazing has a rapid impact on the amount of standing biomass left both in rocky slopes, and degraded loess plains, leading to increased plant biodiversity, and initiating rapid growth in harvester ant activity. This ant activity seems to provide an important positive feedback on enhancing soil fertility and biological productivity, and we postulate a recovery mechanisms whereby enhanced food availability to ants and similar soil dwelling herbivores enhances soil nutrient pools, soil organic matter, soil aeration and soil water infiltration to result in a cycle of ongoing productivity improvements and ecosystem recovery. Alternative, faster and more expensive methods of restoration tested are overlaying of degraded soils using compost or manure, a method immediately restoring 5 - 10 fold higher biological productivity, which was being maintained for at least 10 years and appears permanent unless renewed degradation should occur. We

  12. Spatial variation in the storages and age-related dynamics of forest carbon sequestration in different climate zones-evidence from black locust plantations on the Loess Plateau of China.

    Directory of Open Access Journals (Sweden)

    Taijun Li

    Full Text Available Knowledge about the long-term influences of climate change on the amount of potential carbon (C sequestration in forest ecosystems, including age-related dynamics, remains unclear. This study used two similar age-sequences of black locust forests (Robinia pseudoacacia L. in the semi-arid and semi-humid zones of China's Loess Plateau to assess the variation in C stocks and age-related dynamics. Our results demonstrated that black locust forests of the semi-humid zone stored significantly more C than did forests in the semi-arid zone, across the chronosequence (p < 0.001. The C carrying capacity of the plantations was measured at 166.4 Mg C ha-1 (1 Mg = 106 g in the semi-humid zone, while the semi-arid zone had a capacity of only 79.4 Mg C ha-1. Soil organic C (SOC increased continuously with stand age in the semi-arid zone (R2 = 0.84, p = 0.010. However, in the semi-humid zone, SOC declined sharply by 47.8% after the initial stage (5 to 10 y. The C stock in trees increased continuously with stand age in the semi-humid zone (R2 = 0.83, p = 0.011, yet in the semi-arid zone, it decreased dramatically from 43.0 Mg C ha-1 to 28.4 Mg C ha-1 during the old forest stage (38 to 56 y. The shift from being a net C sink to a net C source occurred at the initial stage in the semi-humid zone versus at the old forest stage in the semi-arid zone after reforestation. Surprisingly, with the exception of the initial and later stages (55 y, the patterns of C allocation among trees, soils, understory and litter were not statistically different between the two climate zones. Our results suggest that climate factors can alter the potential amount and age-related dynamics of forest C sequestration.

  13. Is aridity a high-order control on the hydro-geomorphic response of burned landscapes?

    Science.gov (United States)

    Sheridan, Gary; Van der Sant, Rene; Nyman, Petter; Lane, Patrick

    2015-04-01

    Fire results in hydro-geomorphic changes that are spatially variable and difficult to predict. In this study we compile 294 infiltration measurements, ten other soil, catchment runoff and erosion datasets, and a year of new data from 15 natural runoff plots across an aridity gradient from the eastern Victorian uplands in SE Australia. The results show that aridity (a function of the long term mean precipitation and net radiation) is associated with low post-fire infiltration capacities, increasing the chance of surface runoff, and strongly increasing the chance of debris flows. Runoff plots from the wettest site (aridity = 1.1) had an average runoff ratio of 0.3% compared with 33.6% for the most arid sites (aridity = 2.4). Post-fire debris flows were only observed in the more arid locations within the Victorian uplands, and resulted in erosion rates more than two orders of magnitude greater than non-debris flow processes. We therefore argue that in south eastern Australia aridity is a high-order control on the magnitude of post-wildfire hydro-geomorphic processes. The results from this Australian study may also help to provide insight into the landscape controls on post fire debris flows elsewhere. Aridity is a landscape-scale parameter that is mappable at a high resolution and therefore is a useful predictor of the spatial variability of the magnitude of post-fire hydro-geomorphic responses.

  14. A methodology to assess and evaluate rainwater harvesting techniques in (semi-) arid regions

    NARCIS (Netherlands)

    Adham, Ammar; Riksen, Michel; Ouessar, Mohamed; Ritsema, Coen J.

    2016-01-01

    Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologie

  15. Conservation tillage of rainfed maize in semi-arid Zimbabwe: A review

    NARCIS (Netherlands)

    Nyakudya, I.W.; Stroosnijder, L.

    2015-01-01

    Food security in Sub-Saharan Africa, particularly in semi-arid tropics (41% of the region; 6 months of dry season) is threatened by droughts, dry spells and infertile soils. In Zimbabwe, 74% of smallholder farming areas are located in semi-arid areas mostly in areas with soils of low fertility and w

  16. An overview of biodegradation of LNAPLs in coastal (semi)-arid environment

    NARCIS (Netherlands)

    Yadav, B.K.; Hassanizadeh, S.M.

    2011-01-01

    Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these o

  17. Analysis and evaluation of tillage on an alfisol ina semi-arid tropical region of India

    NARCIS (Netherlands)

    Klaij, M.C.

    1983-01-01

    Tillage field experiments were conducted on Alfisols in a semi-arid tropical environment in India. The research was conducted within the framework of the Farming Systems Research Program of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).To put the experiments into per

  18. Impact of grazing on range plant community components under arid Mediterranean climate in northern Syria

    NARCIS (Netherlands)

    Niane, A.A.

    2013-01-01

    Keywords: Rotational grazing, full protection, continuous grazing species richness, species diversity, soil seed bank, Bayesian methods, Salsola vermiculata, seed longevity, rangeland management, Syria.   Rangelands represent 70% of the semi-arid and arid Mediterranean land mass. It is a n

  19. Differences in the ARID-1 alpha expressions in squamous and adenosquamous carcinomas of uterine cervix.

    Science.gov (United States)

    Solakoglu Kahraman, Dudu; Diniz, Gulden; Sayhan, Sevil; Ayaz, Duygu; Uncel, Melek; Karadeniz, Tugba; Akman, Tulay; Ozdemir, Aykut

    2015-10-01

    AT-rich interactive domain 1A (ARID1A) is a tumor suppressor gene involved in chromatin remodeling which encodes ARID1A (BAF250a) protein. Recent studies have shown the loss of ARID1A expression in several types of tumors. This retrospective study was designed to evaluate the differences in tissue expressions of ARID1A in a spectrum of cervical neoplasms. Cervical intraepithelial neoplasms, invasive squamous or adenosquamous carcinomas were identified in 100 patients recently diagnosed as cervical neoplasms based on pathology databases. In this series, there were 29 low- and 29 high-grade cervical intraepithelial neoplasms, 27 squamous cell carcinomas, and 15 adenosquamous carcinomas. Mean age of the patients was 47.8 ± 13 years (20-80 years). It was determined that the expression of ARID1A was statistically significantly down-regulated in adenosquamous carcinomas when compared with non-invasive or invasive squamous cell carcinomas (p = 0.015). Lower levels of the ARID1A expression were detected in cases with adenosquamous carcinomas (60%), low- or high-grade squamous intraepithelial lesion (SIL) (31%), and squamous cell carcinomas (18.5%). Our findings have demonstrated the presence of a correlation between ARID1A expression and adenomatous differentiation of uterine squamous cell carcinomas. Therefore, ARID1A gene may suggestively have a role in the pathogenesis of cervical adenosquamous carcinomas.

  20. Expansive Soil Properties in a Semi-Arid Region

    Directory of Open Access Journals (Sweden)

    MuawiaA. Dafalla

    2012-11-01

    Full Text Available The expansive soils in semi-arid regions are of great concern to design and geotechnical engineers. Range and variations of geotechnical properties of soils are very useful for appropriate design. Saudi Arabia; a semi arid region attracted the attention of researchers and practicing engineers over the last three decades following the rapid urbanizations in different parts of the country. Advanced testing equipments were made available for this study. The research group conducted joint visits with high officials from different municipality authorities to survey the problem and study the extent of damage to various structures. The areas visited included Al Ghatt, Al Zulfi, Al Hofuf, Um Al Sahik, Al Qatif, Tabuk, Tayma and Al Qaleeba. Single and two storey buildings, boundary walls, pavements and asphalt roads suffered significant damage in many parts of the visited locations. This paper presents the outcome of survey and a general review of previous works carried out for swelling clays in Saudi Arabia. Engineering properties for typical soil formation are presented.

  1. Feasibility of groundwater recharge dam projects in arid environments

    Science.gov (United States)

    Jaafar, H. H.

    2014-05-01

    A new method for determining feasibility and prioritizing investments for agricultural and domestic recharge dams in arid regions is developed and presented. The method is based on identifying the factors affecting the decision making process and evaluating these factors, followed by determining the indices in a GIS-aided environment. Evaluated parameters include results from field surveys and site visits, land cover and soils data, precipitation data, runoff data and modeling, number of beneficiaries, domestic irrigation demand, reservoir objectives, demography, reservoirs yield and reliability, dam structures, construction costs, and operation and maintenance costs. Results of a case study on more than eighty proposed dams indicate that assessment of reliability, annualized cost/demand satisfied and yield is crucial prior to investment decision making in arid areas. Irrigation demand is the major influencing parameter on yield and reliability of recharge dams, even when only 3 months of the demand were included. Reliability of the proposed reservoirs as related to their standardized size and net inflow was found to increase with increasing yield. High priority dams were less than 4% of the total, and less priority dams amounted to 23%, with the remaining found to be not feasible. The results of this methodology and its application has proved effective in guiding stakeholders for defining most favorable sites for preliminary and detailed design studies and commissioning.

  2. Microclimates of the arid lands ecology reserve, 1968--1975

    Energy Technology Data Exchange (ETDEWEB)

    Thorp, J. M.; Hinds, W. T.

    1977-04-01

    The climatology of the Hanford Reservation Arid Lands Ecology (ALE) Reserve does not end, of course, with this report. As this goes to press the arid lands of eastern Washington are experiencing the driest winter in 65 years of record. Even without including this winter's (1976-77) data in our summaries here, we have been fortunate to have had a very dry winter (1972-73) and a very wet winter (1973-74) occur within our first 8 years of climatological measurements on the Reserve. Our primary purpose with this report has been to analyze the first 8 years of climatological measurements from the ALE Reserve and to identify persistent spatial variations between stations or groups of stations. From these variations we have been able to recognize several distinct, but related microclimates occurring within the Reserve. Secondly, we have shown that significant correlations exist between each microclimate on the Reserve and that of the Hanford Meteorological Station nearby. These correlations, coupled with the 30-year weather record at the HMS and possibly with the 32-year (1912-1944) record at the Hanford townsite, allow ALE Reserve temperature and precipitation estimates to be made for years prior to the ALE climatology program.

  3. Glacial aridity in central Indonesia coeval with intensified monsoon circulation

    Science.gov (United States)

    Konecky, Bronwen; Russell, James; Bijaksana, Satria

    2016-03-01

    The Last Glacial Maximum was cool and dry over the Indo-Pacific Warm Pool (IPWP), a key region driving global oceanic-atmospheric circulation. Both low- and high-latitude teleconnections with insolation, ice sheets, and sea level have been suggested to explain the pervasive aridity observed in paleoecological and geomorphic data. However, proxies tracking the H- and O-isotopic composition of rainfall (e.g., speleothems, sedimentary biomarkers) suggest muted aridity or even wetter conditions than the present, complicating interpretations of glacial IPWP climate. Here we use multiproxy reconstructions from lake sediments and modern rainfall isotopic measurements from central Indonesia to show that, contrary to the classical "amount effect," intensified Australian-Indonesian monsoon circulation drove lighter H- and O-isotopic composition of IPWP rainfall during the LGM, while at the same time, dry conditions prevailed. Precipitation isotopes are particularly sensitive to the apparent increase in monsoon circulation and perhaps also decreased moisture residence time implied by our data, explaining contrasts among proxy records while illuminating glacial IPWP atmospheric circulation, a key target for climate models.

  4. Sustainable Small-Scale Agriculture in Semi-Arid Environments

    Directory of Open Access Journals (Sweden)

    Scott Ingram

    2011-03-01

    Full Text Available For at least the past 8000 years, small-scale farmers in semi-arid environments have had to mitigate shortfalls in crop production due to variation in precipitation and stream flow. To reduce their vulnerability to a shortfall in their food supply, small-scale farmers developed short-term strategies, including storage and community-scale sharing, to mitigate inter-annual variation in crop production, and long-term strategies, such as migration, to mitigate the effects of sustained droughts. We use the archaeological and paleoclimatic records from A.D. 900-1600 in two regions of the American Southwest to explore the nature of variation in the availability of water for crops, and the strategies that enhanced the resilience of prehistoric agricultural production to climatic variation. Drawing on information concerning contemporary small-scale farming in semi-arid environments, we then suggest that the risk coping and mitigation strategies that have endured for millennia are relevant to enhancing the resilience of contemporary farmers' livelihoods to environmental and economic perturbations.

  5. Soil microbial responses to nitrogen addition in arid ecosystems

    Directory of Open Access Journals (Sweden)

    Robert L Sinsabaugh

    2015-08-01

    Full Text Available The N cycle of arid ecosystems is influenced by low soil organic matter, high soil pH and extremes in water potential and temperature that lead to open canopies and development of biological soil crusts (biocrusts. We investigated the effects of N amendment on soil microbial dynamics in a Larrea tridentata-Ambrosia dumosa shrubland site in southern Nevada USA. Sites were fertilized with a NO3-NH4 mix at 0, 7, and 15 kg ha-1 yr-1 from March 2012 to March 2013. In March 2013, biocrust (0-0.5 cm and bulk soils (0-10 cm were collected beneath Ambrosia canopies and in the interspaces between plants. Biomass responses were assessed as bacterial and fungal SSU rRNA gene copy number and chlorophyll a concentration. Metabolic responses were measured by five ecoenzyme activities (EEA and rates of N transformation. By most measures, nutrient availability, microbial biomass and process rates were greater in soils beneath the shrub canopy compared to the interspace between plants, and greater in the surface biocrust horizon compared to the deeper 10 cm soil profile. Most measures responded positively to experimental N addition. Effect sizes were generally greater for bulk soil than biocrust. Results were incorporated into a meta-analysis of arid ecosystem responses to N.

  6. Impact of rhizobial populations and their host legumes on microbial activity in soils of arid regions in Tunisia

    International Nuclear Information System (INIS)

    Nitrogen fixing legumes and their microsymbionts are a fundamental contributor to soil fertility and prevent their degradation in arid and semi arid ecosystems. In Tunisia, few data are available on the contribution of these legumes in microbial activity in the arid soil. In this objective, a study was undertaken on five leguminous species from different arid regions to evaluate their ability to regenerate microbiological processes of the soil: Genista saharea, Genista microcephala, Acacia tortilis sspr raddiana, Retama raetam and Prosopis stephaniana. (Author)

  7. Impact of rhizobial populations and their host legumes on microbial activity in soils of arid regions in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Fterich, A.; Mahdhi, M.; Mars, M.

    2009-07-01

    Nitrogen fixing legumes and their microsymbionts are a fundamental contributor to soil fertility and prevent their degradation in arid and semi arid ecosystems. In Tunisia, few data are available on the contribution of these legumes in microbial activity in the arid soil. In this objective, a study was undertaken on five leguminous species from different arid regions to evaluate their ability to regenerate microbiological processes of the soil: Genista saharea, Genista microcephala, Acacia tortilis sspr raddiana, Retama raetam and Prosopis stephaniana. (Author)

  8. Predicting changes in hydrologic retention in an evolving semi-arid alluvial stream

    Science.gov (United States)

    Harvey, J.W.; Conklin, M.H.; Koelsch, R.S.

    2003-01-01

    Hydrologic retention of solutes in hyporheic zones or other slowly moving waters of natural channels is thought to be a significant control on biogeochemical cycling and ecology of streams. To learn more about factors affecting hydrologic retention, we repeated stream-tracer injections for 5 years in a semi-arid alluvial stream (Pinal Creek, Ariz.) during a period when streamflow was decreasing, channel width increasing, and coverage of aquatic macrophytes expanding. Average stream velocity at Pinal Creek decreased from 0.8 to 0.2 m/s, average stream depth decreased from 0.09 to 0.04 m, and average channel width expanded from 3 to 13 m. Modeling of tracer experiments indicated that the hydrologic retention factor (Rh), a measure of the average time that solute spends in storage per unit length of downstream transport, increased from 0.02 to 8 s/m. At the same time the ratio of cross-sectional area of storage zones to main channel cross-sectional area (As/A) increased from 0.2 to 0.8 m2/m2, and average water residence time in storage zones (ts) increased from 5 to 24 min. Compared with published data from four other streams in the US, Pinal Creek experienced the greatest change in hydrologic retention for a given change in streamflow. The other streams differed from Pinal Creek in that they experienced a change in streamflow between tracer experiments without substantial geomorphic or vegetative adjustments. As a result, a regression of hydrologic retention on streamflow developed for the other streams underpredicted the measured increases in hydrologic retention at Pinal Creek. The increase in hydrologic retention at Pinal Creek was more accurately predicted when measurements of the Darcy-Weisbach friction factor were used (either alone or in addition to streamflow) as a predictor variable. We conclude that relatively simple measurements of channel friction are useful for predicting the response of hydrologic retention in streams to major adjustments in channel

  9. Biomarker evidence for increasing aridity in south-central India over the Holocene

    Science.gov (United States)

    Sarkar, S.; Wilkes, H.; Prasad, S.; Brauer, A.; Basavaiah, N.; Strecker, M. R.; Sachse, D.

    2012-12-01

    Summer monsoonal rainfall has played an important role in the development and sustenance of the largely agro-based economy in the Indian subcontinent in the recent past. A better understanding of past variations in monsoonal rainfall can therefore lead to an assessment of its potential impact on early human societies. However, our knowledge of spatiotemporal patterns of past monsoon strength, as inferred from proxy records, is limited due to the lack of high-resolution paleo-hydrological records from continental archives. Here, we reconstruct centennial-scale hydrological variability associated with changes in the intensity of the Indian Summer Monsoon based on a record of lipid biomarker abundances and compound-specific stable isotopic composition of a 10-m-long sediment core from saline-alkaline Lonar Lake, situated in the core 'monsoon zone' of south-central India. We identified three periods of distinct hydrology over the Holocene in south-central India. The period between 10.4 and 6.5 ka BP was characterized by a relatively high abundance of land-plant biomarkers, such as long-chain n-alkanes. The composition of these leaf-wax n-alkanes (weighted average of concentration of different chain-length n-alkanes, expressed as the ACL index) and their negative δ13C (-30‰ to -33 ‰) indicate the dominance of woody C3 vegetation in the catchment, and negative δD (-170‰ to -175‰) values argue for a wet period due to an intensified monsoon. Rapid fluctuations in abundance of both terrestrial and aquatic biomarkers between 6.5 and 4 ka BP indicate an unstable lake ecosystem, culminating in a transition to arid conditions. Higher ACL values and a pronounced shift to more positive δ13C values (up to -22‰) of leaf-wax n-alkanes over this period indicate a change of dominant vegetation to C4 grasses. Along with a 40‰ increase in leaf wax n-alkane δD values, which likely resulted from less rainfall and/or higher plant evapotranspiration, we interpret this period

  10. BLM Solar Energy Zones

    Data.gov (United States)

    Bureau of Land Management, Department of the Interior — Priority development areas for utility-scale solar energy facilities as identified in the Solar PEIS Record of Decision. An additional Solar Energy Zone identified...

  11. Phase zone photon sieve

    Institute of Scientific and Technical Information of China (English)

    Jia Jia; Xie Chang-Qing

    2009-01-01

    A novel diffractive optical element, named phase zone photon sieve (PZPS), is presented. There are three kinds of phase plates in PZPSs: PZPS1, PZPS2, and PZPS3. Each of the PZPSs has its own structure and is made on quartz substrate by etching. The three PZPSs have stronger diffraction peak intensity than a photon sieve (PS) when the margin pinhole and zone line width are kept the same. The PZPS3 can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate. We have given the design method for and the simulation of PZPS and PS. PZPS has potential applications in optical maskless lithography.

  12. : Seizure onset zone imaging

    OpenAIRE

    David, Olivier; Blauwblomme, Thomas; Job, Anne-Sophie; Chabardès, Stéphan; Hoffmann, Dominique,; Minotti, Lorella; Kahane, Philippe

    2011-01-01

    International audience Stereo-electroencephalography is used to localize the seizure onset zone and connected neuronal networks in surgical candidates suffering from intractable focal epilepsy. The concept of an epileptogenicity index has been proposed recently to represent the likelihood of various regions being part of the seizure onset zone. It quantifies low-voltage fast activity, the electrophysiological signature of seizure onset usually assessed visually by neurologists. Here, we re...

  13. Urban spring phenology in the middle temperate zone of China: dynamics and influence factors

    Science.gov (United States)

    Liang, Shouzhen; Shi, Ping; Li, Hongzhong

    2016-04-01

    Urbanization and its resultant urban heat island provide a means for evaluating the impact of climate warming on vegetation phenology. To predict the possible response of vegetation phenology to rise of temperature, it is necessary to investigate factors influencing vegetation phenology in different climate zones. The start of growing season (SOS) in seven cities located in the middle temperate humid, semi-humid, semi-arid, and arid climate zones in China was extracted based on satellite-derived normalized difference vegetation index (NDVI) data. The dynamics of urban SOS from 2000 to 2009 and the correlations between urban SOS and land surface temperatures (LST), precipitation, and sunshine duration, respectively, were analyzed. The results showed that there were no obvious change trends for urban SOS, and the heat island induced by urbanization can make SOS earlier in urban areas than that in adjacent rural areas. And the impact of altitude on SOS was also not negligible in regions with obvious altitude difference between urban and adjacent rural areas. Precipitation and temperature were two main natural factors influencing urban SOS in the middle temperate zone, but their impacts varied with climate zones. Only in Harbin city with lower sunshine duration in spring, sunshine duration had more significant impact than temperature and precipitation. Interference of human activities on urban vegetation was non-negligible, which can lower the dependence of urban SOS on natural climatic factors.

  14. Improvement of Surface Albedo Simulations over Arid Regions

    Institute of Scientific and Technical Information of China (English)

    BAO Yan; L(U) Shihua; ZHANG Yu; MENG Xianhong; YANG Shengpeng

    2008-01-01

    To improve the simulation of the surface radiation budget and related thermal processes in arid regions, three sophisticated surface albedo schemes designed for such regions were incorporated into the Biosphere-Atmosphere Transfer Scheme (BATS). Two of these schemes are functions of the solar zenith angle (SZA), where the first one has one adjustable parameter defined as SZA1 scheme, and the second one has two empir-ical parameters defined as SZA2 scheme. The third albedo scheme is a function of solar angle and soil water that were developed based on arid-region observations from the Dunhuang field experiment (DHEX) (defined as DH scheme). We evaluated the performance of the original and newly-incorporated albedo schemes within BATS using the in-situ data from the Oasis System Energy and Water Cycle Field Experiment that was carried out in JinTa, Gansu arid area (JTEX). The results indicate that a control run by the original version of the BATS generates a constant albedo, while the SZA1 and SZA2 schemes basically can reproduce the observed diurnal cycle of surface albedo, although these two schemes still underestimate the albedo when SZA is high in the early morning and late afternoon, and overestimate it when SZA is low during noontime. The SZA2 scheme has a better overall performance than the SZA1 scheme. In addition, BATS with the DH scheme slightly improves the albedo simulation in magnitude as compared to that from the control run, but a diurnal cycle of albedo is not produced by this scheme. The SZAl and SZA2 schemes significantly increase the surface absorbed solar radiation by nearly 70 W m~2, which further raises the ground temperature by 6 K and the sensible heat flux by 35 W m~2. The increased solar radiation, heat flux, and temperature are more consistent with the observations that those from the control run. However, a significant improvement in these three variables is not found in BATS with the DH scheme due to the neglect of the diurnal cycle of

  15. Cave Monitoring to Determine the Controls on δ18O From a Modern Speleothem Record in Semi-arid SE Australia.

    Science.gov (United States)

    Markowska, M.; Baker, A.; Andersen, M. S.; Jex, C.; Cuthbert, M. O.; Rau, G. C.; Graham, P. W.; Rutlidge, H.; Marjo, C.; Treble, P. C.

    2015-12-01

    Cave monitoring provides a crucial link between hydrological and climate processes and how they may in turn effect speleothem δ18O calcite composition. This is particularly important in arid environments where potential evapotranspiration (PET) exceeds precipitation (P) and may dominate the δ18O signature. In this study we investigate climate-karst-cave interactions driving the δ18O variability in modern drip water samples from Cathedral Cave in semi-arid SE Australia and use this information to interpret a modern sub-annually resolved speleothem record. Over a two-year monitoring campaign we established that mean composition of δ18O in modern drip waters was enriched by up to 2.9‰, relative to the weighted mean annual rainfall. Furthermore, fluctuations in δ18O over time were controlled by two processes (1) evaporation in the unsaturated zone, resulting in heavier values, and (2) recharge during infiltration events, resulting in isotopically lighter values. Large soil moisture deficits in the soil zone must therefore be surpassed to initiate infiltration, resulting in relatively infrequent (0-3 per year) infiltration events. A series of infiltration experiments were conducted to elucidate water flow delivery mechanisms and water residence times. We found that the hydrological pathways and resulting mixing processes that occurred in the unsaturated zone determined the isotopic variability in the drip water δ18O between individual drip sites, and that potential storage in the unsaturated zone is generally greater than 6 months. We establish that the δ18O record in speleothems from this cave do not exclusively record rainfall composition or amount but are overlaid with an evaporative signal that is strongly affected by the time since the last infiltration event, local hydrogeology, cave climate and disequilibrium during calcite deposition. This hypothesis was tested by reconstructing the δ18O proxy record in a speleothem growing for ~50 years in the

  16. Pipeline monitoring with interferometry in non-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    McCardle, Adrian; Rabus, Bernhard; Ghuman, Parwant [MacDonald Dettwiler, Richmond, BC (Canada); Freymueller, Jeff T. [University of Alaska, Fairbanks (United States)

    2005-07-01

    Interferometry has become a proven technique for accurately measuring ground movements caused by subsidence, landslides, earthquakes and volcanoes. Using space borne sensors such as the ERS, ENVISAT and RADARSAT satellites, ground deformation can be monitored on a millimeter level. Traditionally interferometry has been limited to arid areas however new technology has allowed for successful monitoring in vegetated regions and areas of changing land-cover. Analysis of ground movement of the Trans-Alaskan pipeline demonstrates how these techniques can offer pipeline engineers a new tool for observing potential dangers to pipeline integrity. Results from Interferometric Point Target Analysis were compared with GPS measurements and speckle tracking interferometry was demonstrated to measure a major earthquake. (author)

  17. 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.

  18. Performance of pearl millet hybrids under arid conditions

    Directory of Open Access Journals (Sweden)

    V.K. Manga, and Arun Kumar

    2011-09-01

    Full Text Available Sixteen male-sterile lines of pearl millet (Pennisetum glaucum (L. R. Br. found promising at CAZRI, Jodhpur were crossed with nine diverse restorers from different sources in this region, in a line x tester fashion to develop 144 hybrid combinations, with the objective to identify suitable A lines, R lines and hybrid combinations for arid Rajasthan. These hybrids were evaluated at three different locations in western Rajasthan (Tinwari, Pali and Jodhpur during the rainy season of 2003. Eighteen promising hybrids based upon their performance over locations during 2003, were again evaluated in larger plots during the rainy season of 2004. Considering grain yield over all the five locations during the two seasons 2003 and 2004, ten high yielding hybrids were identified. Among these hybrids grain yield ranged from 1932 kg/ha to 2293 kg/ha, and flowering time from 43 to 48 days. The highest yielding hybrid was ICMA 96111 x RIB-3135-18 followed by ICMA 98333 x RIB-3135-18, ICMA 98222 x CZI 9621, ICMA 98004 x RIB-3135-18, ICMA 97555 x RIB-3135-18 and ICMA 95555 x H 77/833-2. It was observed that the restorer lines RIB-3135-18, CZI 9621, H77/833-2, CZI 1676-2, MIR 97171 and ICMR 356 gave high yielding hybrids. Similarly male sterile lines, ICMA 98222, ICMA 97555 and ICMA 98004 were involved in promising hybrid combinations. The hybrid ICMA 98222 x CZI 9621, which was one of the top five high yielding hybrids, ranked first in a multilocation trial conducted during the rainy season of 2005, at Jodhpur, Bawal, Durgapura and Bikaner, representing extreme arid conditions. This hybrid again recorded 12.8% and 6.6% higher grain yield over national checks GHB 538 and ICMH 356 respectively in Initial hybrid trial 2007, and was promoted to the Advance Hybrid and Population Trial for Kharif 2008.

  19. Rainfall partitioning by desert shrubs in arid regions

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We measured the rainfall partitioning among throughfall, stemflow, and interception by desert shrubs in an arid region of China, and analyzed the influence of rainfall and canopy characteristics on this partitioning and its ecohydrological effects. The percent-ages of total rainfall accounted for by throughfall, stemflow, and interception ranged from 78.85±2.78 percent to 86.29±5.07 per-cent, from 5.50±3.73 percent to 8.47±4.19 percent, and from 7.54±2.36 percent to 15.95±4.70 percent, respectively, for the four shrubs in our study (Haloxylon ammodendron, Elaeagnus angustifolia, Tamarix ramosissima, and Nitraria sphaerocarpa). Rain-fall was significantly linearly correlated with throughfall, stemflow, and interception (P < 0.0001). The throughfall, stemflow, and interception percentages were logarithmically related to total rainfall (P < 0.01), but were quadratically related to the maximum 1-hour rainfall intensity (P < 0.01). The throughfall and stemflow percentages increased significantly with increasing values of the rainfall characteristics, whereas the interception percentage generally decreased (except for average wind speed, air temperature, and canopy evaporation). Regression analysis suggested that the stemflow percentage increased significantly with increasing crown length, number of branches, and branch angle (R2 = 0.92, P < 0.001). The interception percentage increased significantly with increasing LAI (leaf area index) and crown length, but decreased with increasing branch angle (R2 = 0.96, P < 0.001). The mean funnelling percentages for the four shrubs ranged from 30.27±4.86 percent to 164.37±6.41 percent of the bulk precipitation. Much of the precipitation was funnelled toward the basal area of the stem, confirming that shrub stemflow conserved in deep soil layers may be an available moisture source to support plant survival and growth under arid conditions.

  20. Time Profile of Three Semi-Arid Ecosystems in Africa

    Science.gov (United States)

    Anyamba, A.; Damoah, R.; Small, J. L.; Tucker, C. J.

    2015-12-01

    We examine the spatio-temporal variability of rainfall and satellite derived-vegetation index of three endorheic semi-arid ecosystems in Africa: Lake Chad (in the Sahel region), Okavango and Etosha (Southern Africa) to infer the nature and trends of the variability during the satellite data instrumental record. We utilize African Rainfall Climatology Precipitation Estimates (1983-2014) and Normalized Difference Vegetation Index (NDVI) derived from the Advanced Very High Resolution Radiometer (AVHRR: 1981-2014) and Moderate Resolution Imaging Spectroradiometer (MODIS: 2001:2014) to examine the aspects of the annual cycle and interannual variability using both time series plots and time-space diagrams. With respect to Lake Chad region, the first two decades of the series (1981-2000) show predominantly dryer than long-term average conditions with the periods 1989, 1992 and 1996/1997 as the signature drought periods coinciding with the desiccation of the Sahel region during the 1980s to early 1990s decades. The period 2000 to present is dominated by above average rainfall and NDVI with 2003, 2007 and 2012 being the most pronounced wet/greener years. The southern African ecosystems (Okavango and Etosha) show more or less a similar temporal pattern to that of Lake Chad basin, however, the wet periods are more amplified and persistent especially 2000, 2006, 2010 and 2014, with corresponding above average NDVI departures. The amplified nature of wet and dry periods present in the southern African ecosystem time series are consistent with the El Niño Southern Oscillation teleconnection patterns. Overall these three ecosystems serve as detectable fingerprints of changing climate conditions and ecosystems in these arid regions.

  1. Spatial analysis of the annual and seasonal aridity trends in Extremadura, southwestern Spain

    Science.gov (United States)

    Moral, Francisco J.; Paniagua, Luis L.; Rebollo, Francisco J.; García-Martín, Abelardo

    2016-09-01

    The knowledge of drought (or wetness) conditions is necessary not only for a rational use of water resources but also for explaining landscape and ecology characteristics. An increase in aridity in many areas of the world is expected because of climate change (global warming). With the aim of analysing annual and seasonal aridity trends in Extremadura, southwestern Spain, climate data from 81 locations within the 1951-2010 period were used. After computing the De Martonne aridity index at each location, a geographic information system (GIS) and multivariate geostatistics (regression kriging) were utilised to map this index throughout the region. Later, temporal trends were analysed using the Mann-Kendall test, and the Sen's estimator was utilised to estimate the magnitude of trends. Maps of aridity trends were generated by ordinary kriging algorithm, providing a visualisation of detected annual and seasonal tendencies. An increase in aridity, as the De Martonne aridity index decreased, was apparent during the study period, mainly in the more humid locations of the north of the region. An increase of the seasonal De Martonne aridity index was also found, but it was only statistically significant in some locations in spring and summer, with the highest decreasing rate in the north of Extremadura. Change year detection was achieved using cumulative sum graphs, obtaining that firstly the change point occurred in spring, in the mid-1970s, later in the annual period in the late 1970s and finally in summer at the end of the 1980s.

  2. Various ARID1A expression patterns and their clinical significance in gastric cancers.

    Science.gov (United States)

    Kim, Young-Bae; Ham, In-Hye; Hur, Hoon; Lee, Dakeun

    2016-03-01

    AT-rich interactive domain 1A (ARID1A) is frequently mutated in gastric cancers, and loss of ARID1A expression is considered a poor prognostic factor in various cancers. However, in practice, ARID1A shows various expression patterns, and our understanding of its significance is limited. We performed immunohistochemistry for ARID1A, MLH1, and pS6 using whole tissue blocks of 350 gastric cancers and classified the ARID1A expression as follows: retained (63.7%), reduced (17.7%), complete loss (14.9%), and partial loss (3.7%). Complete/partial loss was more common in poorly differentiated histology (P hazard ratio [HR], 1.732; P = .015) and OS (HR, 1.751; P = .013). Worse DFS (HR, 2.672; P = .005) and OS (HR, 2.531; P = .002) were also noted in the group with partial loss. High expression of pS6 was observed more frequently in groups showing altered ARID1A expression patterns (P understanding ARID1A with implications for future research and therapeutics. PMID:26826411

  3. Evolution of a Permian Arid Lake System, Upper Pedra de Fogo Formation, Western Border of the Parnaiba Basin

    Directory of Open Access Journals (Sweden)

    Luiz Saturnino de Andrade

    2014-12-01

    Full Text Available Stratigraphic and facies analysis in the Filadélfia region, TO, BR, at the western of the Parnaíba Basin, allowed redefine the paleoenvironment of the upper portion of the Pedra de Fogo Formation of Permian age. The studied deposits are a series of approximately 100 m thick, predominantly siliciclastic, with subordinate carbonates and evaporites, where were defined 21 sedimentary facies that could be grouped into six facies associations (AF: AF1 Lacustrine with ephemeral river deposits; AF2 Storm wave-influenced lake deposits; AF3 Continental sabkha deposits; AF4 Central lake deposits; AF5 Eolian dunes field deposits; and AF6 Lake/oasis deposits with inunditos. These associations indicate that during Permian, an extensive lacustrine arid system developed adjacent to eolian dunes fields and continental sabkha, as well as with contributions from ephemeral rivers. Fluvial incursions into lakes propitiated the formation of suspension lobes and sheet flows (AF1. Sabkha plains (AF3 were formed in the marginal portions of the lake that eventually were influenced by storms waves (AF2, while central zone were site of intense pelitic deposition (AF4. The low supply of eolian sand in this system resulted in the formation of restricted dune fields (AF5, with development of interdune lakes (oasis, where proliferating giant ferns, sporadically flooded by ephemeral rivers (AF6. The facies associations data, corroborated by the paleogeography of the region during the Late Permian, indicate that settling of the top part of the Pedra de Fogo Formation was laid during a hot and arid climate.

  4. Diversification of plant species in arid Northwest China: species-level phylogeographical history of Lagochilus Bunge ex Bentham (Lamiaceae).

    Science.gov (United States)

    Meng, Hong-Hu; Zhang, Ming-Li

    2013-09-01

    Lagochilus occurs in the arid zones across temperate steppe and desert regions of Northwest China. Cooling with strong dessication in the Pleistocene, along with rapid uplift of mountain ranges peripheral to the Qinghai-Tibet Plateau, appear to have had major impacts on the genetic structure of the flora. To understand the evolutionary history of Lagochilus and the divergence related to these past shifts of habitats among these regions, we sequenced the plastid intergenic spacers, psbA-trnH and trnS-trnG from populations throughout the known distributions of ten species of the genus. We investigated species-level phylogeographical patterns within Lagochilus. Phylogenetic trees were constructed using Neighbor-joining and Bayesian inference. The divergence times of major lineages were estimated with BEAST and IMa. Genetic structure and demographic history were inferred by AMOVA, neutrality tests, mismatch distribution, and Bayesian skyline plot analyses. The results showed that most chloroplast haplotypes were species-specific, and that the phylogeny of Lagochilus is geographically structured. The estimated Bayesian chronology and IMa suggested that the main divergence events for species between major eastern and western portions of the Chinese desert occurred at the Plio-/Pleistocene boundary (ca. 2.1-2.8 Ma ago), and likely coinciding with the formation of these deserts in Northwest China. The regional demographic expansions, in the western region at ca. 0.39 Ma, and in the eastern at ca. 0.06 Ma, or across all regions at ca. 0.26 Ma, showed the response to aridification accompanied by cooling of the Pleistocene sharply increased aridity in the Chinese deserts, which reflects a major influence of geologic and climatic events on the evolution of species of Lagochilus. We suggest that diversification is most likely the result of the past fragmentation due to aridification; the expansion of the range of species along with the deserts was an adaptation to dry and cold

  5. Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia.

    Science.gov (United States)

    Zhu, Binq-Qi; Wang, Yue-Ling

    2016-01-01

    Understanding the source and recharge of ground waters is of great significance to our knowledge in hydrological cycles in arid environments over the world. Northern Xinjiang in northwestern China is a significant repository of information relating to the hydrological evolution and climatic changes in central Asia. In this study, two multivariate statistical techniques, hierarchical cluster analysis (HCA) and principal component analysis (PCA), were used to assess the ground water recharge and its governing factors, with the principal idea of exploring the above techniques to utilize all available hydrogeochemical variables in the quality assessment, which are not considered in the conventional techniques like Stiff and Piper diagrams. Q-mode HCA and R-mode PCA were combined to partition the water samples into seven major water clusters (C1-C7) and three principal components (PC1-PC3, PC1 salinity, PC2 hydroclimate, PC3 contaminant). The water samples C1 + C4 were classified as recharge area waters (Ca-HCO3 water), C2 + C3 as transitional zone waters (Ca-Mg-HCO3-SO4 water), and C5 + C6 + C7 as discharge area waters (Na-SO4 water). Based on the Q-mode PCA scores, three groups of geochemical processes influencing recharge regimes were identified: geogenic (i.e., caused by natural geochemical processes), geomorphoclimatic (caused by topography and climate), and anthropogenic (caused by ground water contamination). It is proposed that differences in recharge mechanism and ground water evolution, and possible bedrock composition difference, are responsible for the chemical genesis of these waters. These will continue to influence the geochemistry of the northern Xinjiang drainage system for a long time due to its steady tectonics and arid climate. This study proved that the chemistry differentiation of ground water can effectively support the identification of ground water recharge and evolution patterns.

  6. Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia.

    Science.gov (United States)

    Zhu, Binq-Qi; Wang, Yue-Ling

    2016-01-01

    Understanding the source and recharge of ground waters is of great significance to our knowledge in hydrological cycles in arid environments over the world. Northern Xinjiang in northwestern China is a significant repository of information relating to the hydrological evolution and climatic changes in central Asia. In this study, two multivariate statistical techniques, hierarchical cluster analysis (HCA) and principal component analysis (PCA), were used to assess the ground water recharge and its governing factors, with the principal idea of exploring the above techniques to utilize all available hydrogeochemical variables in the quality assessment, which are not considered in the conventional techniques like Stiff and Piper diagrams. Q-mode HCA and R-mode PCA were combined to partition the water samples into seven major water clusters (C1-C7) and three principal components (PC1-PC3, PC1 salinity, PC2 hydroclimate, PC3 contaminant). The water samples C1 + C4 were classified as recharge area waters (Ca-HCO3 water), C2 + C3 as transitional zone waters (Ca-Mg-HCO3-SO4 water), and C5 + C6 + C7 as discharge area waters (Na-SO4 water). Based on the Q-mode PCA scores, three groups of geochemical processes influencing recharge regimes were identified: geogenic (i.e., caused by natural geochemical processes), geomorphoclimatic (caused by topography and climate), and anthropogenic (caused by ground water contamination). It is proposed that differences in recharge mechanism and ground water evolution, and possible bedrock composition difference, are responsible for the chemical genesis of these waters. These will continue to influence the geochemistry of the northern Xinjiang drainage system for a long time due to its steady tectonics and arid climate. This study proved that the chemistry differentiation of ground water can effectively support the identification of ground water recharge and evolution patterns. PMID:26718947

  7. Tropical Warm Semi-Arid Regions Expanding Over Temperate Latitudes In The Projected 21st Century

    Science.gov (United States)

    Rajaud, A.; de Noblet, N. I.

    2015-12-01

    Two billion people today live in drylands, where extreme climatic conditions prevail, and natural resources are limited. Drylands are expected to expand under several scenarios of climatic change. However, relevant adaptation strategies need to account for the aridity level: it conditions the equilibrium tree-cover density, ranging from deserts (hyper-arid) to dense savannas (sub-humid). Here we focus on the evolution of climatically defined warm semi-arid areas, where low-tree density covers can be maintained. We study the global repartition of these regions in the future and the bioclimatic shifts involved. We adopted a bioclimatological approach based on the Köppen climate classification. The warm semi-arid class is characterized by mean annual temperatures over 18°C and a rainfall-limitation criterion. A multi-model ensemble of CMIP5 projections for three representative concentration pathways was selected to analyze future conditions. The classification was first applied to the start, middle and end of the 20th and 21st centuries, in order to localize past and future warm semi-arid regions. Then, time-series for the classification were built to characterize trends and variability in the evolution of those regions. According to the CRU datasets, global expansion of the warm semi-arid area has already started (~+13%), following the global warming trend since the 1900s. This will continue according to all projections, most significantly so outside the tropical belt. Under the "business as usual" scenario, the global warm semi-arid area will increase by 30% and expand 12° poleward in the Northern Hemisphere, according to the multi-model mean. Drying drives the conversion from equatorial sub-humid conditions. Beyond 30° of latitude, cold semi-arid conditions become warm semi-arid through warming, and temperate conditions through combined warming and drying processes. Those various transitions may have drastic but also very distinct ecological and sociological

  8. Aridity/humidity status of land surface in China during the last three decades

    Institute of Scientific and Technical Information of China (English)

    WU Shaohong; YIN Yunhe; ZHENG Du; YANG Qinye

    2005-01-01

    To clarify aridity/humidity status of land surface is helpful for studying environmental background and regional differences, seeking causes of environmental change, and providing a scientific basis for researches on climate change in the future. In this paper, the authors calculated potential evapotranspiration of China using data from 616 meteorological stations during the period of 1971-2000 with the Penman-Monteith model recommanded by FAO in 1998. Vysothkii's model was used to calculate aridity/humidity index. Then the calculated results of stations were interpolated to land surface using ArcGIS. Results show that the annual average potential evapotranspiration is 400-1500 mm in the whole country, 600-800 mm in most parts of it; and 350-1400 mm in growing season (April-Octobor), which is nearly 200 mm less than the annual average. According to the aridity/humidity indexes of 1.0, 1.5 and 4.0, the aridity/humidity status is categorized to four types, namely, humid, subhumid, semiarid and arid. A majority of stations (76%) are more humid in growing season than the annual average. Results of comprisons between the distribution map of aridity/humidity index with that of precipitation and vegetation indicate a good consistence of aridity/humidity status with natural environment. Therefore potential evapotranspiration calculated with modified FAO's Penman-Monteith model in combination with aridity/humidity index that considers water balance can more reasonably explain the actual land surface aridity/humidity status of China.

  9. Impacts of groundwater extraction on salinization risk in a semi-arid floodplain

    Science.gov (United States)

    Alaghmand, S.; Beecham, S.; Hassanli, A.

    2013-12-01

    In the lower River Murray in Australia, a combination of a reduction in the frequency, duration and magnitude of natural floods, rising saline water tables in floodplains, and excessive evapotranspiration have led to an irrigation-induced groundwater mound forcing the naturally saline groundwater onto the floodplain. It is during the attenuation phase of floods that these large salt accumulations are likely to be mobilised and discharged into the river. This has been highlighted as the most significant risk in the Murray-Darling Basin and the South Australian Government and catchment management authorities have subsequently developed salt interception schemes (SIS). The aim of these schemes is to reduce the hydraulic gradient that drives the regional saline groundwater towards the River Murray. This paper investigates the interactions between a river (River Murray in South Australia) and a saline semi-arid floodplain (Clark's floodplain) that is significantly influenced by groundwater lowering due to a particular SIS. The results confirm that groundwater extraction maintains a lower water table and a higher amount of fresh river water flux to the saline floodplain aquifer. In terms of salinity, this may lead to less solute stored in the floodplain aquifer. This occurs through three mechanisms, namely extraction of the solute mass from the system, reducing the saline groundwater flux from the highland to the floodplain and changing the floodplain groundwater regime from a losing to a gaining one. It is shown that groundwater extraction is able to remove some of the solute stored in the unsaturated zone and this can mitigate the floodplain salinity risk. A conceptual model of the impact of groundwater extraction on floodplain salinization has been developed.

  10. The yearly amount and characteristics of deep-buried phreatic evaporation in hyper-arid areas

    Science.gov (United States)

    Li, H.; Wang, W.; Zhan, H.; Qiu, F.; Wu, F.; Zhang, G.

    2015-12-01

    Water scarcity is the primary cause of land deterioration, so finding new available water resources is crucial to ecological restoration. We investigated a hyper-arid Gobi location in the Dunhuang Mogao Grottoes in this work wherein the burial depth of phreatic water is over 200 m. An air-conditioner was used in a closed greenhouse to condense and measure the yearly amount of phreatic evaporation (PE) from 2010 to 2015. The results show that the annual quantity of PE is 4.52 mm, and that the PE has sinusoidal characteristics. The average PE is 0.0183 mm d-1 from March to November. Accordingly, by monitoring the annual changes in soil-air temperature and humidity to a depth of 5.0 m, we analyzed the water migration mechanism in the heterothermozone (subsurface zone of variable temperature). The results show that, from March to November, the temperature and absolute humidity (AH) increase. This is due to the flow of solar heat entering the soil - the soil subsequently releases moisture and the soil is in a state of increasing AH so that evaporation occurs. From November to March, the temperature decreases. Now, the soil absorbs water vapor and AH is in a state of decline. Thus, it is temperature alternation in the heterothermozone - due to solar heat transfer - that provides the main driving power for PE. When it drives water vapor to move downwards in the heterothermozone, a small part is reversed upwards and evaporates. Solar radiation intensity dominates the annual sinusoidal PE characteristics.

  11. The yearly amount and characteristics of deep-buried phreatic evaporation in hyper-arid areas

    Directory of Open Access Journals (Sweden)

    H. Li

    2015-12-01

    Full Text Available Water scarcity is the primary cause of land deterioration, so finding new available water resources is crucial to ecological restoration. We investigated a hyper-arid Gobi location in the Dunhuang Mogao Grottoes in this work wherein the burial depth of phreatic water is over 200 m. An air-conditioner was used in a closed greenhouse to condense and measure the yearly amount of phreatic evaporation (PE from 2010 to 2015. The results show that the annual quantity of PE is 4.52 mm, and that the PE has sinusoidal characteristics. The average PE is 0.0183 mm d-1 from March to November. Accordingly, by monitoring the annual changes in soil–air temperature and humidity to a depth of 5.0 m, we analyzed the water migration mechanism in the heterothermozone (subsurface zone of variable temperature. The results show that, from March to November, the temperature and absolute humidity (AH increase. This is due to the flow of solar heat entering the soil – the soil subsequently releases moisture and the soil is in a state of increasing AH so that evaporation occurs. From November to March, the temperature decreases. Now, the soil absorbs water vapor and AH is in a state of decline. Thus, it is temperature alternation in the heterothermozone – due to solar heat transfer – that provides the main driving power for PE. When it drives water vapor to move downwards in the heterothermozone, a small part is reversed upwards and evaporates. Solar radiation intensity dominates the annual sinusoidal PE characteristics.

  12. Antibody Reactivity of B Cells in Lupus Patients with Increased Disease Activity and ARID3a Expression

    Directory of Open Access Journals (Sweden)

    Julie M. Ward

    2015-11-01

    Full Text Available Earlier studies showed that the DNA-binding protein, Bright/ARID3a bound to a subset of human and mouse immunoglobulin heavy chain promoters where it enhanced expression. Indeed, mice with transgenic expression of ARID3a in all B lymphocytes have expanded MZ B cells and produce anti-nuclear antibodies (ANAs. Consistent with our findings in mice, we observed that human systemic lupus erythematosus (SLE patients had expanded numbers of peripheral blood ARID3a+ B cells that were associated with increased disease activity (p = 0.0038. We hypothesized that ARID3a+ naïve B cells would eventually produce autoantibodies, explaining associations between ARID3a expression and disease activity in lupus. Unlike healthy controls, ARID3a was expressed in the naïve B cell population in SLE patients, and we hypothesized that these might represent expansions of autoreactive cells. Therefore, monoclonal antibodies were generated from single-sorted naïve B cells derived from patients with normal (ARID3aN and high (ARID3aH numbers of ARID3a+ B cells. We found that ARID3a expression did not correlate with autoantibody expression. Furthermore, measures of antigen specificities of autoreactive antibodies did not reveal skewing toward particular proteins. These data suggest that the association of increased disease activity in SLE with numbers of ARID3a+ B lymphocytes may be mediated by an antibody-independent mechanism.

  13. Passive diffusion sampling of sulfur dioxide in India: Impact assessment on arid areas

    Institute of Scientific and Technical Information of China (English)

    S. Kumar; M. Mohan; R. Datta

    2002-01-01

    Environmental constraints have drastically limited options of sustainable developmentand have severely offset many developmental schemes. In this paper, possibilities of acidic depo-sition, as a counter measure of desertification, are analyzed. Seasonal data of ambient sulfur di-oxide, pH of rain water and soil acidity are collected for over an year and analyzed. Arid environ-ment of surrounding areas of Delhi is considered and analyzed. Though ambient sulfur depositionis well below critical level, it might not be truly indicative of plant survival in arid areas. Results maybe useful in arid area afforestation, and polluting industries relocation, which holds tremendouspotential vis-a-vis sustainable development.

  14. Zones of emotional labour

    DEFF Research Database (Denmark)

    Strøbæk, Pernille Solveig

    2011-01-01

    The paper suggests that due to the difficult nature of their work public family law caseworkers are to be included in the definition of emotional labour even though they are omitted by Hochschild. Based upon a review of the structures involved in emotional labour an explorative qualitative study is...... put forth among 25 Danish public family law caseworkers. The study points to personal, professional, and social zones of emotional labour through which the caseworkers carry out their work. Emotional labour zones mark emotion structures that may be challenging due to complex emotional intersections...

  15. Grid zone drone

    OpenAIRE

    McCarthy, Clive; Cooper, Graham; Field, James; Thayne, Martyn; Vickers, Richard

    2014-01-01

    From 16th – 19th October 2014, co_LAB presented its newest creation, Grid Zone Drone, at Kinetica – an international exhibition providing a global platform for galleries, curatorial groups, design studios and artists working with new media art. 2014 marked the third consecutive year that the University of Lincoln has been represented at the global art fair. Grid Zone Drone represents a continuation of the group’s research into ‘drone culture’, and explores the detachment of the drone withi...

  16. Validation of MODIS and Deep Blue aerosol optical depth retrievals in an arid/semi-arid region of northwest China

    Institute of Scientific and Technical Information of China (English)

    Xia Li; Xiangao Xia; Shengli Wang; Jietai Mao; Yan Liu

    2012-01-01

    The global aerosol optical depth (AOD or τ) has been retrieved using the Dark Target algorithm (the C004 and C005 products) and the Deep Blue algorithm (DB product).Few validations have thus far been performed in arid/semi-arid regions,especially in northwest China.The ground-based remote sensing of AOD from sun photometers at four sites in Xinjiang during the years 2002-2003 is used to validate aerosol products,including C004,C005 and DB of the Moderate Resolution Imaging Spectroradiometer (MODIS).The results show substantial improvement in the C005 aerosol product over the C004 product.The average correlation coefficient of regression with ground measurements increased from 0.59 to 0.69,and the average offset decreased from 0.28 to 0.13.The slopes of the linear regressions tended to be close to unity.The percentage of AODs falling within the retrieval errors of 30% (or △τ =±0.1 ± 0.2τ)increased from 16.1% to 45.6%.The best retrievals are obtained over an oasis region,whereas the worst are obtained over urban areas.Both the MODIS C004 and C005 products overestimate AOD,which is likely related to improper assumptions of the aerosol model and of the estimation of surface reflectance.An encouraging result has been derived with regard to validation of the DB AOD.Overall,the average offset,slope and correlation coefficient of regression with sun-photometer measurements are -0.04,0.88 and 0.85,respectively.Approximately 73% of the DB AOD retrievals fall within the expected error of 30%.Underestimation of the AOD by the DB products is observed.The aerosol model and estimations of surface reflectance in this region require further improvements.

  17. Changes of AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China.

    Directory of Open Access Journals (Sweden)

    Yajun Hu

    Full Text Available Arbuscular mycorrhizal (AM fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT, soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools.

  18. Changes of AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China.

    Science.gov (United States)

    Hu, Yajun; Rillig, Matthias C; Xiang, Dan; Hao, Zhipeng; Chen, Baodong

    2013-01-01

    Arbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD) in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT), soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC) and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC) and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools.

  19. Ecosystem Services Evaluation and Its Spatial Characteristics in Central Asia’s Arid Regions: A Case Study in Altay Prefecture, China

    Directory of Open Access Journals (Sweden)

    Qi Fu

    2015-06-01

    Full Text Available Ecosystem services are important foundations to realize the sustainable development of economy and society. The question of how to quantitatively evaluate ecosystem services in a scientific way is a hot topic among international researchers. Studying the spatial characteristics of ecosystem services in arid regions can provide the theoretical and practical basis for coordinating a sustainable man-land relationship. Altay Prefecture of China, a typical arid region in Central Asia, was taken as the study area. It is on the Silk Road economic belt, which is a key region in the program of developing Western China. Three ecosystem services: water yield, soil conservation, and net primary productivity were quantitatively evaluated. The results show that (1 the spatial distribution pattern has a distinct characteristic of zonality; (2 mountain zone and mountain-oasis ecotone are the hotspots of ecosystem services; and (3 the correlation between water yield and net primary productivity shows a gradual increasing trend as altitude decreases. Objective analysis from the aspect of mechanism is given by discussing the causes of this particular pattern. It is found that altitude and slope have great influence on spatial distributions of ecosystem services, zones with the most amount of services are distributed in 1.5–2 km-altitude and 15–25°-slope. Different human activities in different regions and spatial distance decay of ecosystem services also contribute to the formation of spatial pattern. Thus, overgrazing, logging and mining are prohibited in mountain zones and mountain-oasis ecotones. Scholars are encouraged to focus on desert-ecosystem services in the future.

  20. Hydrogeologic and Hydrochemical Studies in a Semi-arid Watershed in Northern Mexico

    Science.gov (United States)

    Kretzschmar, T.; Vazquez, R.; Hinojosa, A.

    2006-12-01

    Within the Baja California panhandle exist quite a significant number of valleys which hydrogeology conditions are of great importance for the communities of the region. The Guadalupe Valley for example, located 30 km Northeast of Ensenada, hosts an important wine industry which presents a mayor factor for agriculture and tourism in Baja California. The irrigation is carried out basically by groundwater extracted from quaternary sediments filling this post-Miocene depression. Besides the intensive usage of the water by the wine industry in the Guadalupe Valley, the local waterworks installed in 1985 a gallery of 10 wells extracting around 320 l/s or 30 % of the total water extraction in the valley to supply the city of Ensenada with drinking water. A total of more than 500 wells with a combined annual consumption of about 28 Mio m3 are at the moment active in the valley. In the arid portions of northern Mexico Mountain front recharge presents an important recharge source for the alluvial aquifers. Other important sources directly related to precipitation are direct infiltration, recharge by surface water runoff in the arroyos as well as by active fault systems. The principal recharge sources for the Guadalupe Valley aquifer are the Sierra Juárez and the Guadalupe River. To be able to address the state of equilibrium of aquifer, recharge estimates for the watershed were calculated determining the runoff/infiltration relationships obtained by curve number determinations combined with the interpretation of satellite images. These results were integrated into an evaluation and hydrologic modeling of the hydrologic data pointing towards differences of up to over 50 percent in the recharge estimation in comparison to earlier studies carried out in the area. Furthermore hydrochemical and isotopic studies were carried out to show the effects of the excessive ground water extraction on the water quality of the aquifer. The hydrochemical data indicate that intense use of

  1. DNS zones revisited

    NARCIS (Netherlands)

    Wanrooij, van Ward; Pras, Aiko; Delgado Kloos, Carlos

    2005-01-01

    Recent research [Pap04b] suggests DNS reliability and performance is not up to the levels it should be due to misconfigurations. This paper checks the configuration of nameserver zones against additional requirements, recommendations and best-practices. It shows that almost one in four domains fails

  2. Integrating management objectives and grazing strategies on semi-arid rangelands

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Rangelands account for almost half of Nebraska's 24 million acres. Much of these expansive natural resource areas are in the semi-arid climatic region of Nebraska...

  3. Karst characterization in a semi-arid region using gravity, seismic, and resistivity geophysical techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Barnhart, Kevin Scott

    2013-10-01

    We proposed to customize emerging in situ geophysical monitoring technology to generate time-series data during sporadic rain events in a semi-arid region. Electrodes were to be connected to wireless \

  4. Human Constraints to Sustainable Agriculture in the Arid Regions of South Africa.

    Science.gov (United States)

    Duvel, G. H.; Botha, A. J.

    1999-01-01

    Interviews with 79 South African farmers in arid regions showed that their conservation practices were influenced by such human factors as needs, perceptions, and knowledge. Direct influence on adoption behaviors was recommended to encourage sustainable agriculture practices. (SK)

  5. Arid land irrigation in the United States Pacific Northwest for 2001

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the extent of arid land irrigation in the Pacific Northwest region of the United...

  6. A brief introduction to Physical Geography of Arid Land in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A book, Physical Geography of Arid Land in China, mainly edited by Prof. Xi CHEN from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences has been published by Science Press in July of 2010.

  7. Energy and water budgets of larks in a life history perspective : Parental effort varies with aridity

    NARCIS (Netherlands)

    Tieleman, BI; Williams, JB; Visser, GH

    2004-01-01

    We compared physiological, demographic, and ecological variables of larks to gain insights into life history variation along an aridity gradient, incorporating phylogenetic relationships in analyses when appropriate. Quantifying field metabolic rate (FMR). and water influx rate (WIR) of parents feed

  8. Evaporation Intensity of Bare Soil in Northwest Arid Inland Basin%西北干旱内陆盆地区裸土蒸发强度

    Institute of Scientific and Technical Information of China (English)

    乔冈; 王文科

    2014-01-01

    Owing to the vadose zone evaporation water from the ground surface,finding out the bare soil evaporation rule has important meaning to study some vadose zone water and underwater evaporation problems.To find out the rule of bare soil evaporation intensity in northwest arid inland basin,we analyze the vadose zone cross section water flow features with weather data and calculate the bare soil evaporation intensity adopting the finite-difference method through developing some bare soil water content and vadose zone pressure monitoring site experiments.Express as a result:According to vertical transportation different status of some vadose zone water,the cross section in the bare soil area vadose zone is divided into the vadose zone water upward to transfer zone and the vadose zone water downward to move zone.The extreme limit evaporation depth is 1.2 m in the bare soil zone of Northwest arid inland basin.Subjecting to the external space weather evaporation ability and the vadose zone water upward to transfer ability,the bare soil evaporation inside the basin appears in the second half month of April to the second half month of September,among which the bare soil evaporation quantity in the second half month of April to May is the biggest,and the evaporation intensity reaches to 0.56 mm/d on the average.The percentage of the bare soil evaporation intensity only equivalent to surface evaporation intensity on the average of 3.5%,as biggest as 6.7%.%鉴于包气带蒸发的水分是从地表散失,故查明裸土蒸发规律对研究包气带水分蒸发、潜水蒸发问题具有重要意义。为了查明西北干旱内陆盆地区裸土蒸发强度规律,通过开展裸土含水率观测、包气带负压观测等野外原位试验,结合气象资料,对包气带剖面流场特征进行分析,采用有限差分法对裸土蒸发强度进行计算。结果表明:依据包气带水分在垂向上迁移的不同状态,将裸土区包气带剖面划分为

  9. Epidemiology of ixodid ticks in cattle population of various agro-climatic zones of Punjab, India

    Institute of Scientific and Technical Information of China (English)

    Nirbhay Kumar Singh; Shitanshu Shekhar Rath

    2013-01-01

    Objective:To determine the epidemiology of ixodid ticks in bovines of different agro-climatic zones ofPunjab state,India.Methods:A total of4459 cattle of all age groups and sex were examined from eighteen districts of five major agro-climatic zones ofPunjab state, India.Results:The overall prevalence of ixodid ticks,Rhipicephalus microplus(R. microplus), Hyalomma anatolicum anatolicum(H. a. anatolicum) and mixed infestation were58.06%,50.16%, 11.34% and3.45%, respectively.Amongthe various agro-climatic zones highest prevalence rate ofR. microplus andH. a. anatolicumwere recorded in submountain undulating region(79.36%) and western region(20.40%), respectively indicating thatR. microplus prefers a hot and humid environment whereas, arid and semi arid conditions suit better forH. a. anatolicum.The overall prevalence of ixodid ticks was highest in monsoon season(83.74%), followed by summer(69.01%) and least in winters(31.64%) and a significant variation(P1year age group(55.02%) and the difference was statistically significant(P<0.01). Also a significantly higher(P<0.01) infestation rates of ixodid ticks was observed in males. Conclusions:The findings of the current study would provide a basis for evolving effective control strategy for the management of ticks in bovines of the region.

  10. Drought or humidity oscillations? The case of coastal zone of Lebanon

    Science.gov (United States)

    Shaban, Amin; Houhou, Rola

    2015-10-01

    There is discrepancy in classifying Lebanon according to the different climatic zones; however, it is often described as a semi-arid region. Lately, Lebanon has been witnessing climatic oscillations in the meteorological parameters. The impact of these oscillations on water sector has been reflected also on energy-food nexus. Yet, there are a number of studies obtained to identify the climate of Lebanon, and they show contradictory results; especially these studies elaborated different datasets and applied diverse methods which often modeled only on large-scale regions. Therefore, the analysis of climatic data depended on complete and long-term climatic records that can be applied to assess the existing climatic status of Lebanon, as well as to assure whether Lebanon is under drought, humidity or it is oscillating between both. This study utilized considerable datasets, from different sources including the remotely sensed systems (e.g. TRMM). These datasets were interpolated and analyzed statistically according to De Martonne Aridity Index. Aiming to affirm the climatic attribute of Lebanon; however, ten climatic stations were investigated. They are with representative geographic setting and diverse time series in the coastal zone of Lebanon were investigated. Even though, Lebanon is known as a semi-arid region, yet results in this study show that the studied zone does not evidence any drought, since around 70% of the investigated years are characterized by semi-humid to humid climate. This climatic figure is well pronounced since rainfall rate exceeds 900 mm, average temperature rate is about 19 °C, and snow remains for a couple of months annually.

  11. A Methodology to Assess and Evaluate Rainwater Harvesting Techniques in (Semi-) Arid Regions

    OpenAIRE

    Ammar Adham; Michel Riksen; Mohamed Ouessar; Coen J Ritsema

    2016-01-01

    Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for determining suitable sites and techniques for RWH. However, limited attention has been given to the evaluation of RWH structure performance. The aim of this research was to design a scientifical...

  12. Understanding runoff processes in a semi-arid environment through isotope and hydrochemical hydrograph separations

    OpenAIRE

    Camacho Suarez, V. V.; Saraiva Okello, A. M. L.; Wenninger, J.W.; Uhlenbrook, S.

    2015-01-01

    The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamflow variability, high evaporation rates, and deep groundwater reservoirs may increase the complexity of hydrological process dyna...

  13. Understanding runoff processes in a semi-arid environment through isotope and hydrochemical hydrograph separations

    OpenAIRE

    V. V. Camacho; Saraiva Okello, A. M. L.; Wenninger, J.W.; Uhlenbrook, S.

    2015-01-01

    The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamflow variability, high evaporation rates, and deep groundwater reservoirs increase the complexity of hydrologica...

  14. REUSE OF TREATED WASTEWATER IN AGRICULTURE: SOLVING WATER DEFICIT PROBLEMS IN ARID AREAS (REVIEW)

    OpenAIRE

    Faissal AZIZ; Farissi, Mohamed

    2014-01-01

    In the arid and semiarid areas, the availability and the management of irrigation water have become priorities of great importance. The successive years of drought, induced by climate change and population growth, increasingly reduced the amount of water reserved for agriculture. Consequently, many countries have included wastewater reuse as an important dimension of water resources planning. In the more arid areas wastewater is used in agriculture, releasing high resource of water supplies. ...

  15. Impact of grazing on range plant community components under arid Mediterranean climate in northern Syria

    OpenAIRE

    Niane, A.A.

    2013-01-01

    Keywords: Rotational grazing, full protection, continuous grazing species richness, species diversity, soil seed bank, Bayesian methods, Salsola vermiculata, seed longevity, rangeland management, Syria.   Rangelands represent 70% of the semi-arid and arid Mediterranean land mass. It is a natural habitat for millions of people whose livelihood depends on animal husbandry. The revolutionary developments in the animal husbandry and veterinary medicines resulted in exponential increases in h...

  16. Geochemical Weathering Increases Lead Bioaccessibility in Semi-Arid Mine Tailings

    OpenAIRE

    Hayes, Sarah M.; Webb, Sam M.; Bargar, John R.; O'Day, Peggy A; Maier, Raina M.; Chorover, Jon

    2012-01-01

    Mine tailings can host elevated concentrations of toxic metal(loid)s that represent a significant hazard to surrounding communities and ecosystems. Eolian transport, capable of translocating small (micrometer-sized) particles, can be the dominant mechanism of toxic metal dispersion in arid or semi-arid landscapes. Human exposure to metals can then occur via direct inhalation or ingestion of particulates. The fact that measured doses of total lead (Pb) in geomedia correlate poorly with blood P...

  17. Empowerment Zones and Enterprise Districts - MDC_EnterpriseZone

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Polygon feature class of Miami Dade County Enterprise Zones. Enterprise Zones are special areas in the county where certain incentives from the State are available...

  18. Functional Analysis of In-frame Indel ARID1A Mutations Reveals New Regulatory Mechanisms of Its Tumor Suppressor Functions

    Directory of Open Access Journals (Sweden)

    Bin Guan

    2012-10-01

    Full Text Available AT-rich interactive domain 1A (ARID1A has emerged as a new tumor suppressor in which frequent somatic mutations have been identified in several types of human cancers. Although most ARID1A somatic mutations are frame-shift or nonsense mutations that contribute to mRNA decay and loss of protein expression, 5% of ARID1A mutations are in-frame insertions or deletions (indels that involve only a small stretch of peptides. Naturally occurring in-frame indel mutations provide unique and useful models to explore the biology and regulatory role of ARID1A. In this study, we analyzed indel mutations identified in gynecological cancers to determine how these mutations affect the tumor suppressor function of ARID1A. Our results demonstrate that all in-frame mutants analyzed lost their ability to inhibit cellular proliferation or activate transcription of CDKN1A, which encodes p21, a downstream effector of ARID1A. We also showed that ARID1A is a nucleocytoplasmic protein whose stability depends on its subcellular localization. Nuclear ARID1A is less stable than cytoplasmic ARID1A because ARID1A is rapidly degraded by the ubiquitin-proteasome system in the nucleus. In-frame deletions affecting the consensus nuclear export signal reduce steady-state protein levels of ARID1A. This defect in nuclear exportation leads to nuclear retention and subsequent degradation. Our findings delineate a mechanism underlying the regulation of ARID1A subcellular distribution and protein stability and suggest that targeting the nuclear ubiquitin-proteasome system can increase the amount of the ARID1A protein in the nucleus and restore its tumor suppressor functions.

  19. Richness, diversity and evenness of vegetation upon rehabilitation of gypsum mine spoiled lands in the Indian arid zone

    Science.gov (United States)

    Kumar, S.; Sharma, K.D.; Sharma, U.K.; Gough, L.P.

    1998-01-01

    Richness, diversity and evenness of vegetation, after rehabilitation of gypsum mine spoils at Barmer were investigated in plots protected and planted one year and four years ago. There were four water harvesting treatments, viz., half-moon terraces, micro-catchments with 5% slope, ridge and furrow and control, wherein, indigenous and exotic trees and shrubs were planted at 5 ?? 5 m spacing. Sampling of the planted and natural vegetation, using quadrats and transacts, revealed much less species richness in unplanted control as compared to all treatments and in all the years. The species richness that increased initially (within one year) gradually declined over time (during four year), though the extent varied in different treatments. The water harvesting treatment showing maximum initial increase in richness also showed maximum decline over time, though decline was more in annual species. Two perennial species increased in richness with time. This was further proved from the trends in diversity and evenness indices. It was concluded that natural successional process was accelerated by rehabilitation providing stability to the habitat.

  20. Performance of Yankasa RAM lambs fed graded levels of RMW and SBMR combination in the semi-arid zone, Nigeria

    Directory of Open Access Journals (Sweden)

    M.G. Garba

    2012-11-01

    Full Text Available This experiment was conducted at Bayero University Kano, to determine the performance of Yankasa ram lambs fed complete diet containing graded levels of SBMR and RMW at 5, 10, 15 and 20% representing treatments B, C, D and E, respectively. Treatment A served as the control with 0% inclusion of both SBMR and RMW. Twenty entire males Yankasa ram lambs with an average weight of 14.3 ±0.03kg were used for the study. Results obtained revealed that incorporation of RMW and SBMR in the diets of growing Yankasa ram lambs up to 20% gave impressive output. Although significant differences were not recorded (P>0.05 between all the treatments in respect of average daily gain (ADG, diet C (10% inclusion recorded the highest mean. The Dry matter, Crude fibre and Crude protein digestibility significantly (P

  1. Floral biology of Commiphora wightii – a data deficient medicinal plant distributed in the arid zones of India

    Directory of Open Access Journals (Sweden)

    Aarti Harshadbhai Kawane

    2015-02-01

    Full Text Available Abstract: Commiphora wightii commonly known as Guggul is an important medicinal plant that contains oleo gum resin which is used as antiarthritic, hypocholesterolaemic and hypolipidaemic agents. It is an apomictic species native to India (Gujarat, Rajasthan and Pakistan. Due to over exploitation, it is enlisted under the ‘data deficient’ category in the IUCN Red Data Book. However, very little information is available about its reproductive biology. Knowledge of reproductive biology of any plant species is crucial for its genetic improvement and planning for effective conservation and management of genetic resources. The present paper reports our findings on the flower opening pattern, pollen grain viability, stigma receptivity, flowering behaviour and fruit set in C. wightii. The study showed that flowers do not open in the night hours and maximum flower opening occurs in the morning hours up to 8.00 am. Maximum stigma receptivity was observed on the first day of flower opening. Polymorphism in pollen grain size was observed and a significant difference in pollen grain size was observed between hermaphrodite and male accessions. Maximum number of pollen grains is produced by hermaphrodite accessions. Pollen viability ranged from 35.07 to 60.85 % among the accessions. Flowering studied in 37 accessions showed wide variability among the accessions. Peak flowering was observed from November to April. Based on data on peak flowering time, the accessions were grouped into profusely, medium and shy flowering types. The fruit set percentage was very low among the accessions; it remained between zero and 5%.

  2. Study of Self-Purification Capacity in the Semi- Arid Zones: Case of Wadi Cheliff, (Northern Algeria

    Directory of Open Access Journals (Sweden)

    Mokadem Maamar

    2014-12-01

    Full Text Available The aim of this paper was to study and predict the self-purification capacity of wadi Cheliff (in the section Oum Drou –Chlef. This was done primarily by measuring the Dissolved Oxygen (DO downstream of a pre-selected pollution discharge point on wadi Cheliff and then predicting the same using the modified Streeter-Phelps equations. Twelve sampling stations are chosen, on a section of approximately 8.5 km of the wadi Cheliff (Oum Drou - Chlef, to collect data with knowing the Biochemical Oxygen Demand (BOD, pH, stream velocity, stream depth and distance. Predicted DO deficit trend lines were first fitted by retaining the original re-aeration coefficient component, k2, of the modified Streeter-Phelps equation (United States Geological Survey equation and subsequently by substituting it with our reaeration coefficient model. It was found that the latter displayed better predictive capacity. Results also demonstrated that the self-purification capacity of the river which is already limited by the relatively low DO saturation level is further threatened by the wastes being discharged into it at varying intervals. Some of these wastes are non-biodegradable which slows down the self-purification processes of the wadi. To preserve the underground layers of the area and to ensure a water of good quality for the irrigation, the Wadi Cheliff must be, necessarily, to protect from any pollution.

  3. Validation of the CORINE land cover database in a pilot zone under semi-arid conditions in La Mancha (Spain)

    OpenAIRE

    Mañas, Martín de Santa Olalla; Soria, Cabañero; Ramírez, Artigao

    2003-01-01

    El programa CORINE (iniciado en 1985) ha creado un Sistema de Información referido a los países de la Unión Europea, que suministra datos administrativos, geográficos, de usos del suelo, cubierta vegetal, así como diferentes parámetros ambientales (CORINE, 1994). La base de datos CORINE de cobertura terrestre (land cover)  ofrece una valiosa información acerca de las distintas cubiertas del suelo en el área cartografiada. Actualmente, toda la Península Ibérica se encuentra accesible en esta b...

  4. Methanic fermentation of Euphorbia tirucalli, a rich and renewable vegetal biomass of the Sahel and arid zones

    Energy Technology Data Exchange (ETDEWEB)

    Sow, D. [Dakar Univ. (Senegal); Depeyre, D.; Isambert, A. [Ecole Centrale des Arts et Manufactures, 92 - Chatenay-Malabry (France)

    1994-12-31

    A rich and renewable vegetal biomass is existing in Senegal. In fact Euphorbia tirucalli is a latex plant well adapted to sahelian climatic conditions, spread all along the country. In this work, methanic fermentation experimentations are made with this plant in a specific continuous fermentor named Transpaille. A 120 l biodigester was tested at 37 deg C with a piece-broken plant. The registered volumic efficiency is 0.80 l/l.d. With this interesting result, the same experiment was made with real operating conditions on a village digester in a farm. With a bioreactor of 12 m{sup 3}, incubated at ambient temperature, the obtained volumic efficiency is 0.61 l/l.d. The produced biogas of this experiment was used for food cooking and for farm milk cooling. This work shows that a vulgarization policy of the biogas way in rural conditions in Senegal is now possible with Euphorbia tirucalli. (authors). 19 refs., 6 figs., 2 tabs.

  5. Agricultural sustainability in the semi-arid Near East

    Directory of Open Access Journals (Sweden)

    F. Hole

    2007-05-01

    Full Text Available Agriculture began in the eastern Mediterranean Levantine Corridor about 11000 years ago toward the end of the Younger Dryas when aridity had diminished wild food resources. During the subsequent Climatic Optimum, agricultural villages spread rapidly but subsequent climatic changes on centennial to millennial scales resulted in striking oscillations in settlement, especially in marginal areas. Natural climate change thus alternately enhanced and diminished the agricultural potential of the land. Growing populations and more intensive land us, both for agriculture and livestock, have led to changes in the structure of vegetation, hydrology, and land quality. Over the millennia, political and economic interventions, warfare and incursions by nomadic herding tribes all impacted sustainability of agriculture and the ability of the land to supports its populations. In much of the region today, agricultural land use is not sustainable given existing technology and national priorities. The Near Eastern case is instructive because of the quality of information, the length of the record, and the pace of modern change.

  6. Synthetic socioeconomic based domestic wastewater hydrographs for small arid communities

    KAUST Repository

    Elnakar, H.

    2012-06-04

    A model was developed to predict synthetic socioeconomic based domestic wastewater hydrographs for the small arid communities. The model predicts the flow hydrograph for random weekdays and weekends based on the specific socioeconomic characteristics of the community. The main socioeconomic characteristics are the composition of the community, the different user behaviours in using water appliances, and the unit discharges of such appliances. Use patterns of water appliances are assumed to vary for the various members of the community and the type of day. Each community is composed of several social categories such as the employee, working woman, stay home woman, stay home child, students etc. The use patterns account for the stochastic nature of use in terms of number of uses, duration of the use and times of use in the day. Randomly generated hydrographs are generated for weekdays and weekends along with synthetic hydrographs of non-exceedance. The model was verified for a small residential compound in Sharm El Shiekh - Egypt using 11 days of flow measurements performed in summer. The synthetic hydrographs based on assumed water use patterns of the various members of the community compared reasonably with the measured hydrographs. Synthetic hydrographs can be derived for a community under consideration to reflect its socioeconomic conditions and thus can be used to generate probability based peaking factors to be used in the design of sewerage systems pumping facilities, and treatment plants. © 201 WIT Press.

  7. Water harvesting techniques for small communities in arid areas.

    Science.gov (United States)

    Yuen, E; Anda, M; Mathew, K; Ho, G

    2001-01-01

    Limited water resources exist in numerous remote indigenous settlements around Australia. Indigenous people in these communities are still living in rudimentary conditions while their urban counterparts have full amenities, large scale water supplies and behavioral practices which may not be appropriate for an arid continent but are supported by extensive infrastructure in higher rainfall coastal areas. As remote indigenous communities continue to develop, their water use will increase, and in some cases, costly solutions may have to be implemented to augment supplies. Water harvesting techniques have been applied in settlements on a small scale for domestic and municipal purposes, and in the large, broadacre farm setting for productive use of the water. The techniques discussed include swales, infiltration basins, infiltration trenches and "sand dam" basins. This paper reviews the applications of water harvesting relevant to small communities for land rehabilitation, landscaping and flood control. Landscaping is important in these communities as it provides shelter from the sun and wind, reduces soil erosion and hence reduced airborne dust, and in some cases provides food and nutrition. Case studies of water harvesting systems applied in the Pilbara Region, Western Australia for landscaping around single dwellings in Jigalong and Cheeditha, in a permaculture garden in Wittenoon and at a college and carpark in Karratha are described.

  8. Comparison modeling for alpine vegetation distribution in an arid area.

    Science.gov (United States)

    Zhou, Jihua; Lai, Liming; Guan, Tianyu; Cai, Wetao; Gao, Nannan; Zhang, Xiaolong; Yang, Dawen; Cong, Zhentao; Zheng, Yuanrun

    2016-07-01

    Mapping and modeling vegetation distribution are fundamental topics in vegetation ecology. With the rise of powerful new statistical techniques and GIS tools, the development of predictive vegetation distribution models has increased rapidly. However, modeling alpine vegetation with high accuracy in arid areas is still a challenge because of the complexity and heterogeneity of the environment. Here, we used a set of 70 variables from ASTER GDEM, WorldClim, and Landsat-8 OLI (land surface albedo and spectral vegetation indices) data with decision tree (DT), maximum likelihood classification (MLC), and random forest (RF) models to discriminate the eight vegetation groups and 19 vegetation formations in the upper reaches of the Heihe River Basin in the Qilian Mountains, northwest China. The combination of variables clearly discriminated vegetation groups but failed to discriminate vegetation formations. Different variable combinations performed differently in each type of model, but the most consistently important parameter in alpine vegetation modeling was elevation. The best RF model was more accurate for vegetation modeling compared with the DT and MLC models for this alpine region, with an overall accuracy of 75 % and a kappa coefficient of 0.64 verified against field point data and an overall accuracy of 65 % and a kappa of 0.52 verified against vegetation map data. The accuracy of regional vegetation modeling differed depending on the variable combinations and models, resulting in different classifications for specific vegetation groups.

  9. Agricultural sustainability in the semi-arid Near East

    Directory of Open Access Journals (Sweden)

    F. Hole

    2006-07-01

    Full Text Available Agriculture began in the eastern Mediterranean Levantine Corridor about 11 000 years ago toward the end of the Younger Dryas when aridity had diminished wild food resources. During the subsequent Climatic Optimum, agricultural villages spread rapidly but subsequent climatic changes on centennial to millennial scales resulted in striking oscillations in settlement, especially in marginal areas. Natural climate change thus alternately enhanced and diminished the agricultural potential of the land. Growing populations and more intensive land use, both for agriculture and livestock, have led to changes in the structure of vegetation, hydrology, and land quality. Over the millennia, political and economic interventions, warfare and incursions by nomadic herding tribes all impacted sustainability of agriculture and the ability of the land to support its populations. In much of the region today, agricultural land use is not sustainable given existing technology and national priorities. The Near Eastern case is instructive because of the quality of information, the length of the record, and the pace of modern change.

  10. Comparison modeling for alpine vegetation distribution in an arid area.

    Science.gov (United States)

    Zhou, Jihua; Lai, Liming; Guan, Tianyu; Cai, Wetao; Gao, Nannan; Zhang, Xiaolong; Yang, Dawen; Cong, Zhentao; Zheng, Yuanrun

    2016-07-01

    Mapping and modeling vegetation distribution are fundamental topics in vegetation ecology. With the rise of powerful new statistical techniques and GIS tools, the development of predictive vegetation distribution models has increased rapidly. However, modeling alpine vegetation with high accuracy in arid areas is still a challenge because of the complexity and heterogeneity of the environment. Here, we used a set of 70 variables from ASTER GDEM, WorldClim, and Landsat-8 OLI (land surface albedo and spectral vegetation indices) data with decision tree (DT), maximum likelihood classification (MLC), and random forest (RF) models to discriminate the eight vegetation groups and 19 vegetation formations in the upper reaches of the Heihe River Basin in the Qilian Mountains, northwest China. The combination of variables clearly discriminated vegetation groups but failed to discriminate vegetation formations. Different variable combinations performed differently in each type of model, but the most consistently important parameter in alpine vegetation modeling was elevation. The best RF model was more accurate for vegetation modeling compared with the DT and MLC models for this alpine region, with an overall accuracy of 75 % and a kappa coefficient of 0.64 verified against field point data and an overall accuracy of 65 % and a kappa of 0.52 verified against vegetation map data. The accuracy of regional vegetation modeling differed depending on the variable combinations and models, resulting in different classifications for specific vegetation groups. PMID:27307276

  11. Using NDVI to measure precipitation in semi-arid landscapes

    Science.gov (United States)

    Birtwhistle, Amy N.; Laituri, Melinda; Bledsoe, Brian; Friedman, Jonathan M.

    2016-01-01

    Measuring precipitation in semi-arid landscapes is important for understanding the processes related to rainfall and run-off; however, measuring precipitation accurately can often be challenging especially within remote regions where precipitation instruments are scarce. Typically, rain-gauges are sparsely distributed and research comparing rain-gauge and RADAR precipitation estimates reveal that RADAR data are often misleading, especially for monsoon season convective storms. This study investigates an alternative way to map the spatial and temporal variation of precipitation inputs along ephemeral stream channels using Normalized Difference Vegetation Index (NDVI) derived from Landsat Thematic Mapper imagery. NDVI values from 26 years of pre- and post-monsoon season Landsat imagery were derived across Yuma Proving Ground (YPG), a region covering 3,367 km2 of semiarid landscapes in southwestern Arizona, USA. The change in NDVI from a pre-to post-monsoon season image along ephemeral stream channels explained 73% of the variance in annual monsoonal precipitation totals from a nearby rain-gauge. In addition, large seasonal changes in NDVI along channels were useful in determining when and where flow events have occurred.

  12. Mining the Agave Microbiome for adaptions to arid environments

    Energy Technology Data Exchange (ETDEWEB)

    Coleman-Derr, Devin; Wojke, Tanja; North, Gretchen; Partida-Martinez, Laila; DeAngeli, Kristen; Clingenpeel, Scott; Gross, Stephen; Tringe, Susannah; Visel, Axel

    2013-03-25

    A major challenge facing the biofuels industry is the identification of high-yield plant feedstocks that can be cultivated with minimal resource inputs without competing for land and water supplies with existing food crops. Recent research has demonstrated that the Agave plant, cultivated in Mexico and Southwestern United States for the production of fiber and alcohol, meets these criteria1. Agaves grow on non-arable rocky soils in regions characterized by prolonged drought and extreme temperatures, due in part to physiological adaptions that prevent excess water-loss in arid environments2. Plant-microbial symbioses can play a role in helping plants adapt to heat and drought stress, increasing the accessibility of soil nutrients, or compete with plant pathogens3. Whether agaves have similar beneficial microbe interactions in their native environment is unknown. We aim to provide a comprehensive characterization of the Agave microbiome, with the goal of identifying specific community members that may contribute to Agave biotic and abiotic stress tolerance

  13. Revision of the water-holding frogs, Cyclorana platycephala (Anura: Hylidae), from arid Australia, including a description of a new species.

    Science.gov (United States)

    Anstis, Marion; Price, Luke C; Roberts, J Dale; Catalano, Sarah R; Hines, Harry B; Doughty, Paul; Donnellan, Stephen C

    2016-01-01

    The water-holding frog, Cyclorana platycephala, occurs in the Australian arid and semi-arid zones but not in the central Australian deserts. Recent inspection of morphological variation in adults and larvae suggests that the taxon comprises three regional populations: eastern, northern and western that may each represent separate species. To assess the systematic status of these populations, we documented phylogenetic relationships using mitochondrial and nuclear DNA markers, divergence in adult and larval morphology and male advertisement call. Our molecular genetic data demonstrates that the western population of C. platycephala is not the sister taxon of eastern and northern representatives of this nominate species, as the latter two are more closely related to another morphologically distinct species, C. verrucosa. Discriminant Function Analysis of 14 morphological traits in adults and 15 in larvae showed a high degree of morphological differentiation of western versus eastern/northern C. platycephala. Calls of eastern and western populations differed in duration, pulse rate, frequency and especially in amplitude modulation pattern across the call duration. We describe the western population as a new species, whose range is contained entirely within Western Australia. In addition, we redescribe Cyclorana platycephala, quantify morphological and genetic differences between the eastern and northern populations, and conclude that these data support recognition of a single species, Cyclorana platycephala, for populations found in New South Wales, the Barkly Tablelands and south-eastern Northern Territory, Queensland and South Australia. PMID:27395600

  14. Modeling groundwater quality in an arid agricultural environment in the face of an uncertain climate: the case of Mewat District, India

    Science.gov (United States)

    Weber, M. C.; Ward, A. S.; Muste, M.

    2014-12-01

    The salinization of groundwater resources is a widespread problem in arid agricultural environments. In Mewat District (Haryana, India), groundwater salinity has rendered much of the accessible supply unfit for human consumption or agriculture. Historically, this closed basin retained fresh pockets of water at the foothills of the Aravalli Hills, where monsoonal precipitation runoff from the mountains was recharged through infiltration or facilitated by man-made structures. To date, an increasing number of pumps supply the region with fresh water for consumption and agriculture leading to shrinking the freshwater zone at an accelerated pace. The potential for increased human consumption corroborated with the effects of climate change bring uncertainty about the future of water security for the Mewat communities, most of them critically bound to the existence of local water. This study addresses the sustainability of the freshwater supply under a range of land interventions and climate scenarios, using a 2-D groundwater flow and transport model. Our results quantify potential futures for this arid, groundwater-dependent location, using numerical groundwater modeling to quantify interactions between human water use, infrastructure, and climate. Outcomes of this modeling study will inform an NGO active in the area on sustainable management of groundwater resources.

  15. Land Cover Land Use change and soil organic carbon under climate variability in the semi-arid West African Sahel (1960-2050)

    Science.gov (United States)

    Dieye, Amadou M.

    Land Cover Land Use (LCLU) change affects land surface processes recognized to influence climate change at local, national and global levels. Soil organic carbon is a key component for the functioning of agro-ecosystems and has a direct effect on the physical, chemical and biological characteristics of the soil. The capacity to model and project LCLU change is of considerable interest for mitigation and adaptation measures in response to climate change. A combination of remote sensing analyses, qualitative social survey techniques, and biogeochemical modeling was used to study the relationships between climate change, LCLU change and soil organic carbon in the semi-arid rural zone of Senegal between 1960 and 2050. For this purpose, four research hypotheses were addressed. This research aims to contribute to an understanding of future land cover land use change in the semi-arid West African Sahel with respect to climate variability and human activities. Its findings may provide insights to enable policy makers at local to national levels to formulate environmentally and economically adapted policy decisions. This dissertation research has to date resulted in two published and one submitted paper.

  16. Assessment of the Current State of Agropastoral Landscapes in Semi-Arid Areas of the Republic of Kalmykia with Application of Gis-Technologies

    Directory of Open Access Journals (Sweden)

    Mushaeva Kermen Batnasunovna

    2015-04-01

    Full Text Available The state of lands in arid areas of southern Russia is entirely dependent on the state of natural steppe, dry steppe and semi-desert ecosystems. The study of vegetation traditionally enjoys a commanding position in synecological studies, because plant communities form the framework of terrestrial ecosystems. In this paper we give a detailed geobothanical description of the test plots made as a result of field research in the semi-desert areas of Kalmykia. In addition, we obtained photo samples of soils that were subsequently processed, analyzed and entered into the database of soils and used as an identifier of rangeland degradation, located in the semi-arid zone of the country. The creation of this database will improve the quality of remote sensing in the region. In the course of computer processing of materials using GIS technology, the geoinformation analysis of land degradation in the studied territory was held, and the area of these lands according to the levels of degradation was calculated.

  17. ZONE OF COOPERATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The China-ASEAN Economic Zone is attracting more and more investors from both Southeast Asia and China Compared with other countries that have established free trade areas with ASEAN, China owns millions of unique advantages. Millions, after all, is the quantity of Chinese living in ASEAN countries. "With ties of blood, geography and commerce, business people of Chinese descent can be the best candidates to pro-

  18. Cape Verde Frontal Zone

    OpenAIRE

    Zenk, Walter; Klein, Birgit; Schröder, Michael

    1991-01-01

    The term Cape Verde Frontal Zone is introduced to characterize the southeastern corner of the subtropical gyre circulation in the North Atlantic Ocean far west of the upwelling area off the Mauretanean shelf. Two water mass fronts, one overlying the other, are identified with a quasi-synoptic set of CTD-OZ and nutrient data from November 1986. In the warm water sphere we encounter North and South Atlantic Central Water (NACWISACW) superimposed on extensions of Mediterranean outflow and Antarc...

  19. The uncomfortable comfort zone

    Directory of Open Access Journals (Sweden)

    Carlos Renato Zacharias

    2012-04-01

    Full Text Available Whenever we achieve the satisfaction of our expectations and anxiety dissolves, we feel as if we were in a comfort zone – safe, complete, free from risks and in peace with ourselves. We might even have a little taste of heaven when we feel that we have fulfilled our duty. And as a fact, scientists are entitled to this kind of reward… but not for too long! In science, to enter a comfort zone can be as pleasant as dangerous. On one hand we may have a safe ground available to develop new modes of reasoning, protocols and theories. And on the other, we may stay stuck in a conventional but fragile ground, missing opportunities to reveal novel secrets or to address edge issues. ... The community of HD researchers seems to have entered a new comfort zone when nanostructures were found in HD. Nanostructures have been raised to the level of ultimate evidence doing away with Avogadro’s limit and leading homeopathy and HD research into mainstream science. We really should enjoy this moment and collect more information about the HD phenomenon. However, we must be wary to not fall into a trap.

  20. Decreased expression of the ARID1A gene is associated with poor prognosis in primary gastric cancer.

    Directory of Open Access Journals (Sweden)

    Dan-dan Wang

    Full Text Available BACKGROUND: The ARID1A gene encodes adenine-thymine (AT-rich interactive domain-containing protein 1A, which participates in chromatin remodeling. ARID1A has been showed to function as a tumor suppressor in various cancer types. In the current study, we investigated the expression and prognosis value of ARID1A in primary gastric cancer. Meanwhile, the biological role of ARID1A was further investigated using cell model in vitro. METHODOLOGY/PRINCIPAL FINDINGS: To investigate the role of ARID1A gene in primary gastric cancer pathogenesis, real-time quantitative PCR and western blotting were used to examine the ARID1A expression in paired cancerous and noncancerous tissues. Results revealed decreased ARID1A mRNA (P = 0.0029 and protein (P = 0.0015 expression in most tumor-bearing tissues compared with the matched adjacent non-tumor tissues, and in gastric cancer cell lines. To further investigate the clinicopathological and prognostic roles of ARID1A expression, we performed immunohistochemical analyses of the 224 paraffin-embedded gastric cancer tissue blocks. Data revealed that the loss of ARID1A expression was significantly correlated with T stage (P = 0.001 and grade (P = 0.006. Consistent with these results, we found that loss of ARID1A expression was significantly correlated with poor survival in gastric cancer patients (P = 0.003. Cox regression analyses showed that ARID1A expression was an independent predictor of overall survival (P = 0.029. Furthermore, the functions of ARID1A in the proliferation and colony formation of gastric cell lines were analyzed by transfecting cells with full-length ARID1A expression vector or siRNA targeting ARID1A. Restoring ARID1A expression in gastric cancer cells significantly inhibited cell proliferation and colony formation. Silencing ARID1A expression in gastric epithelial cell line significantly enhanced cell growth rate. CONCLUSIONS/SIGNIFICANCE: Our data suggest that ARID1A may play an important role

  1. Landfill cover revegetation using organic amendments and cobble mulch in the arid southwest

    Energy Technology Data Exchange (ETDEWEB)

    AGUILAR,RICHARD; DWYER,STEPHEN F.; REAVIS,BRUCE A.; NEWMAN,GRETCHEN CARR; LOFTIN,SAMUEL R.

    2000-02-01

    biomass production in the irrigated control plots over that produced in the non-irrigated control plots. This surprising result was probably due to the cumulative effects of other factors that influenced the initial establishment and production of plants in the plots (e.g., plant species competition, seed germination delay times, differences in nutrient release and availability). Variation within individual plots, and among the three replicate plots associated with each treatment, rendered many of the recorded differences in vegetation establishment and production statistically insignificant. However, after two complete growing seasons the highest total plant foliar cover and the greatest biomass production and plant species diversity occurred in the cobble-mulched plots. These results suggest that cobble-mulch may be the desired amendment in re-vegetated arid landfill covers if the principal objectives are to quickly establish vegetation cover, stabilize the site from erosion, and increase water usage by plants, thereby reducing the potential for leaching and contaminant movement from the landfill's waste-bearing zone.

  2. Blasting of broken marble zones

    OpenAIRE

    Dambov, Risto; Stojceski, Igor; Dambov, Ilija

    2015-01-01

    On receipt of marble blocks appear deformed zones with presence of cracks and other deformities and very small cracks with different azimuth in the rocky massif. The fastest and economical way to bring this zone are removed by applying the methods of blasting. Before blasting, these tables - zones are limited by the block, making the cuts with diamond wire because explosive action may cause of surrounding quality marble blocks. Keywords: blasting, crashed zones, cracks, marble ...

  3. A Review of Applicability and Effectiveness of Low Impact Development/Green Infrastructure Practices in Arid/Semi-Arid United States

    Directory of Open Access Journals (Sweden)

    Yan Jiang

    2015-06-01

    Full Text Available Urbanized areas of the southwestern/western United States are among the fastest growing in the nation and face multiple water resource challenges. Low impact development (LID/green infrastructure (GI practices are increasingly popular technologies for managing stormwater; however, LID is often not as common in the southwest/west due to the lack of regulatory and/or economic drivers. There is also a lack of performance evaluation of these practices, particularly at the field scale. This study focused on investigating the hydrologic and pollutant removal performance of field-scale LID/GI systems in arid/semi-arid climates. Nine typical practices were reviewed: rainwater harvest system, detention pond, retention pond, bioretention, media filter, porous pavement, vegetated swale/buffer/strip, green roof, and infiltration trench, as well as integrated LIDs. We evaluate these practices by a cost-effectiveness analysis and also recommend best practices for the arid/semi-arid area. The analysis provides data support and insights for future implementation of LID/GI in the southwest/west.

  4. Simulation of water use and herbage growth in arid regions : a re-evaluation and further development of the model ‘arid crop’

    NARCIS (Netherlands)

    Keulen, van H.; Seligman, N.G.; Benjamin, R.W.

    1981-01-01

    A previously published simulation model, describing growth of annual pasture under semi-arid conditions, is re-examined and further developed on the basis of additional experimental information. Major changes introduced are connected with the partitioning of above-ground dry matter into leaves and n

  5. Date palm (Phoenix dactylifera L.) leaves as biomonitors of atmospheric metal pollution in arid and semi-arid environments

    International Nuclear Information System (INIS)

    The leaves of date palms were evaluated as a possible biomonitor of heavy metal contamination in Ma'an city, Jordan. Concentrations of (Fe), (Pb), (Zn), (Cu), (Ni), and (Cr) were determined in washed and unwashed leaves and soil samples collected from different sites with different degrees of metal contamination (urban, suburban, industrial, highway and rural sites); separate leaves were taken from outside the city to be used as a control sample. Samples collected from industrial sites were found to have high concentrations of all metals except those of Cu, Ni and Pb, which were found at high levels in the highway site samples which is associated with the road traffic. The difference between unwashed and washed samples showed that metal pollutants exist as contaminants, particularly Pb, Zn and Ni, which varied in concentration, depending on the source of the metal. - Highlights: → High metal concentration in plant samples and roadside soil was due to the heavy traffic. → The mean concentrations (C) were in the order: CFe > CPb > CZn > CNi > CCu > CCr. → Difference between unwashed and washed samples showed that pollutants exist as contaminants. - Date palm (Phoenix dactylifera L.) leaves can be used as an inexpensive biomonitor of the deposition, accumulation and distribution of heavy metal contamination in arid environments.

  6. Correlations between microbial tetraether lipids and environmental variables in Chinese soils: Optimizing the paleo-reconstructions in semi-arid and arid regions

    Science.gov (United States)

    Yang, Huan; Pancost, Richard D.; Dang, Xinyue; Zhou, Xinying; Evershed, Richard P.; Xiao, Guoqiao; Tang, Changyan; Gao, Li; Guo, Zhengtang; Xie, Shucheng

    2014-02-01

    The bacterial membrane lipid-based continental paleothermometer, the MBT/CBT or MBT‧-CBT proxy (methylation index of branched tetraethers/cyclization of branched tetraethers), results in a large temperature deviation when applied in semiarid and arid regions. Here we propose new calibration models based on the investigation of >100 surface soils across a large climatic gradient, with a particular focus on semiarid and arid regions of China, and apply them to a loess-paleosol sequence. As reported elsewhere, MBT values exhibit a much higher correlation with MAAT than with summer temperature, suggesting a minimal seasonality bias; however, MBT is apparently insensitive to temperature 20 °C. Additional complexities are apparent in alkaline and arid soils, which are characterized by different relationships to climatic parameters than those in the complete Chinese (or global) dataset. For example, MBT and CBT indices exhibit a negative correlation in alkaline and arid soils, in contrast to their positive correlation in acid soils. Moreover, the cyclization ratio of bGDGTs (CBT), previously defined as a proxy for soil pH, is apparently primarily controlled by MAAT in these alkaline soils. Thus, we propose (1) a local Chinese calibration of the MBT-CBT proxy and (2) an alternative temperature proxy for use in semiarid and arid regions based on the fractional abundances of bGDGTs; the latter has a markedly higher determination factor and lower root mean square error in alkaline soils than the Chinese local calibration and is suggested to be preferred for paleotemperature reconstruction in Chinese loess/paleosol sequences. These new bGDGT proxies have been applied to the Weinan Holocene paleosol section of the Chinese Loess Plateau (CLP). The fractional abundance calibration, when applied in the Weinan Holocene paleosol, produces a total Holocene temperature variation of 5.2 °C and a temperature for the topmost sample that is consistent with the modern temperature

  7. Dust aerosol effect on semi-arid climate over Northwest China detected from A-Train satellite measurements

    OpenAIRE

    Huang, J; Minnis, P.; Yan, H; Yi, Y.; Chen, B; Zhang, L.; J. K. Ayers

    2010-01-01

    The impact of dust aerosols on the semi-arid climate of Northwest China is analyzed by comparing aerosol and cloud properties derived over the China semi-arid region (hereafter, CSR) and the United States semi-arid region (hereafter, USR) using several years of surface and A-Train satellite observations during active dust event seasons. These regions have similar climatic conditions, but aerosol concentrations are greater over the CSR. Because the CSR is close to two major dust source regions...

  8. Energy Productivity of the High Velocity Algae Raceway Integrated Design (ARID-HV)

    Energy Technology Data Exchange (ETDEWEB)

    Attalah, Said; Waller, Peter M.; Khawam, George; Ryan, Randy D.; Huesemann, Michael H.

    2015-06-03

    The original Algae Raceway Integrated Design (ARID) raceway was an effective method to increase algae culture temperature in open raceways. However, the energy input was high and flow mixing was poor. Thus, the High Velocity Algae Raceway Integrated Design (ARID-HV) raceway was developed to reduce energy input requirements and improve flow mixing in a serpentine flow path. A prototype ARID-HV system was installed in Tucson, Arizona. Based on algae growth simulation and hydraulic analysis, an optimal ARID-HV raceway was designed, and the electrical energy input requirement (kWh ha-1 d-1) was calculated. An algae growth model was used to compare the productivity of ARIDHV and conventional raceways. The model uses a pond surface energy balance to calculate water temperature as a function of environmental parameters. Algae growth and biomass loss are calculated based on rate constants during day and night, respectively. A 10 year simulation of DOE strain 1412 (Chlorella sorokiniana) showed that the ARID-HV raceway had significantly higher production than a conventional raceway for all months of the year in Tucson, Arizona. It should be noted that this difference is species and climate specific and is not observed in other climates and with other algae species. The algae growth model results and electrical energy input evaluation were used to compare the energy productivity (algae production rate/energy input) of the ARID-HV and conventional raceways for Chlorella sorokiniana in Tucson, Arizona. The energy productivity of the ARID-HV raceway was significantly greater than the energy productivity of a conventional raceway for all months of the year.

  9. Bird migration patterns in the arid southwest-Final report

    Science.gov (United States)

    Ruth, Janet M.; Felix, Rodney K.; Dieh, Robert H.

    2010-01-01

    To ensure full life-cycle conservation, we need to understand migrant behavior en route and how migrating species use stopover and migration aerohabitats. In the Southwest, birds traverse arid and mountainous landscapes in migration. Migrants are known to use riparian stopover habitats; we know less about how migrant density varies across the Southwest seasonally and annually, and how migrants use other habitat types during migratory stopover. Furthermore, we lack information about migrant flight altitudes, speeds, and directions of travel, and how these patterns vary seasonally and annually across the Southwest. Using weather surveillance radar data, we identified targets likely dominated by nocturnally migrating birds and determined their flight altitudes, speeds, directions over ground, and variations in abundance. Migrating or foraging bats likely are present across the region in some of these data, particularly in central Texas. We found that migrants flew at significantly lower altitudes and significantly higher speeds in spring than in fall. In all seasons migrants maintained seasonally appropriate directions of movement. We detected significant differences in vertical structure of migrant densities that varied both geographically within seasons and seasonally within sites. We also found that in fall there was a greater and more variable passage of migrants through the central part of the borderlands (New Mexico and west Texas); in spring there was some suggestion of greater and more variable passage of migrants in the eastern borderlands (central and south Texas). Such patterns are consistent with the existence of at least two migration systems through western North America and the use of different migration routes in spring and fall for at least some species. Using radar data and satellite land cover data, we determined the habitats with which migrants are associated during migration stopover. There were significant differences in bird densities among

  10. Modeling and Managing Regional Aquifers in Arid Countries

    Science.gov (United States)

    Schüth, C.; Rausch, R.

    2009-12-01

    Most of the regional aquifers in arid countries were recharged many thousand years ago when the climate was much wetter than today. Therefore, most of the groundwater stored in the aquifers is fossil water. The aquifers are in a state of constant depletion as recent groundwater recharge is much smaller than the outflow. A prerequisite for the smart management of such groundwater resources is a sound understanding of the aquifer system based on reliable data and robust simulation models. Mathematical groundwater models are one of the tools available that can consider a complex array of aquifer variables and allow these variables to interact with themselves. Exploring these interactions with a model can reveal how an aquifer behaves. Once a model is working properly, it can be used to make predictions for managing groundwater resources, such as predicting how groundwater levels might respond to increased pumping or drought, testing different management scenarios etc. Furthermore, groundwater models describing regional aquifers in arid regions must be considered to be in a transient state and consider the entire extent of the aquifer. The introduction of artificial boundaries is not possible and lead to wrong estimations. Within the modeling process the reduction and estimation of uncertainties is required, which leads to the “inverse problem” in groundwater modeling. Strategies for the reduction and estimation of uncertainties are needed. Problems are (1) the ill-posedness of parameter estimation, (2) that no unique solution may exist, and (3) that measurement errors make the results unreliable. Ways out are the reduction of degrees of freedom by introducing geological ‘a priori’ knowledge as well as the joint use of head, flow and/or concentration measurements, and the estimation of uncertainty. This concept is demonstrated by examples of model development for regional aquifers on the Arabian Peninsula, e.g. ‘a priori’ knowledge is introduced into the

  11. let-7 Modulates Chromatin Configuration and Target Gene Repression through Regulation of the ARID3B Complex

    Directory of Open Access Journals (Sweden)

    Tsai-Tsen Liao

    2016-01-01

    Full Text Available Let-7 is crucial for both stem cell differentiation and tumor suppression. Here, we demonstrate a chromatin-dependent mechanism of let-7 in regulating target gene expression in cancer cells. Let-7 directly represses the expression of AT-rich interacting domain 3B (ARID3B, ARID3A, and importin-9. In the absence of let-7, importin-9 facilitates the nuclear import of ARID3A, which then forms a complex with ARID3B. The nuclear ARID3B complex recruits histone demethylase 4C to reduce histone 3 lysine 9 trimethylation and promotes the transcription of stemness factors. Functionally, expression of ARID3B is critical for the tumor initiation in let-7-depleted cancer cells. An inverse association between let-7 and ARID3A/ARID3B and prognostic significance is demonstrated in head and neck cancer patients. These results highlight a chromatin-dependent mechanism where let-7 regulates cancer stemness through ARID3B.

  12. [Relationships among leaf traits and their expression in different vegetation zones in Yanhe River basin, Northwest China].

    Science.gov (United States)

    Guo, Ru; Wen, Zhong-ming; Wang, Hong-xia; Qi, De-hui

    2015-12-01

    This article selected zonal plant communities as the research objects in different vegetation zones in Yanhe River basin. We measured six leaf traits of the dominant species and main accompanying species in each community, and then analyzed the relationships and their changes along with environmental gradients between these traits in order to understand the plant adaptation strategies to the environment changes. The results showed that the specific leaf area was significantly negatively correlated to leaf tissue density, area-based leaf nitrogen and phosphorus concentrations, and significantly positively correlated to mass-based leaf phosphorus concentration. Both the scaling relationships among these traits and plant life strategies were different among the three vegetation zones, the scaling-dependent relationship between leaf tissue density and specific leaf area was stronger in steppe and forest-steppe zones than in forest zone, but the correlations among area-based leaf nitrogen/phosphorus concentrations and specific leaf area and leaf tissue density were more significant in forest zone than in steppe zone. In the arid grassland and forest-steppe zone, plants give priority to defensive and stress resistance strategies, and in relatively moist nutrient-rich forest zone, plants give priority to fast growth and resource optimization allocation strategies. PMID:27111998

  13. VOCs in Non-Arid Soils Integrated Demonstration: Technology summary

    International Nuclear Information System (INIS)

    The Volatile Organic Compounds (VOCs) in Non-Arid Soils Integrated Demonstration (ID) was initiated in 1989. Objectives for the ID were to test the integrated demonstration concept, demonstrate and evaluate innovative technologies/systems for the remediation of VOC contamination in soils and groundwater, and to transfer technologies and systems to internal and external customers for use in fullscale remediation programs. The demonstration brought together technologies from DOE laboratories, other government agencies, and industry for demonstration at a single test bed. The Savannah River Site was chosen as the location for this ID as the result of having soil and groundwater contaminated with VOCS. The primary contaminants, trichlorethylene and tetrachloroethylene, originated from an underground process sewer line servicing a metal fabrication facility at the M-Area. Some of the major technical accomplishments for the ID include the successful demonstration of the following: In situ air stripping coupled with horizontal wells to remediate sites through air injection and vacuum extraction; Crosshole geophysical tomography for mapping moisture content and lithologic properties of the contaminated media; In situ radio frequency and ohmic heating to increase mobility, of the contaminants, thereby speeding recovery and the remedial process; High-energy corona destruction of VOCs in the off-gas of vapor recovery wells; Application of a Brayton cycle heat pump to regenerate carbon adsorption media used to trap VOCs from the offgas of recovery wells; In situ permeable flow sensors and the colloidal borescope to determine groundwater flow; Chemical sensors to rapidly quantify chlorinated solvent contamination in the subsurface; In situ bioremediation through methane/nutrient injection to enhance degradation of contaminants by methanotrophic bateria

  14. VOCs in Non-Arid Soils Integrated Demonstration: Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    The Volatile Organic Compounds (VOCs) in Non-Arid Soils Integrated Demonstration (ID) was initiated in 1989. Objectives for the ID were to test the integrated demonstration concept, demonstrate and evaluate innovative technologies/systems for the remediation of VOC contamination in soils and groundwater, and to transfer technologies and systems to internal and external customers for use in fullscale remediation programs. The demonstration brought together technologies from DOE laboratories, other government agencies, and industry for demonstration at a single test bed. The Savannah River Site was chosen as the location for this ID as the result of having soil and groundwater contaminated with VOCS. The primary contaminants, trichlorethylene and tetrachloroethylene, originated from an underground process sewer line servicing a metal fabrication facility at the M-Area. Some of the major technical accomplishments for the ID include the successful demonstration of the following: In situ air stripping coupled with horizontal wells to remediate sites through air injection and vacuum extraction; Crosshole geophysical tomography for mapping moisture content and lithologic properties of the contaminated media; In situ radio frequency and ohmic heating to increase mobility, of the contaminants, thereby speeding recovery and the remedial process; High-energy corona destruction of VOCs in the off-gas of vapor recovery wells; Application of a Brayton cycle heat pump to regenerate carbon adsorption media used to trap VOCs from the offgas of recovery wells; In situ permeable flow sensors and the colloidal borescope to determine groundwater flow; Chemical sensors to rapidly quantify chlorinated solvent contamination in the subsurface; In situ bioremediation through methane/nutrient injection to enhance degradation of contaminants by methanotrophic bateria.

  15. Adaptive wetland management in an uncertain and changing arid environment

    Directory of Open Access Journals (Sweden)

    Rebekah Downard

    2014-06-01

    Full Text Available Wetlands in the arid western United States provide rare and critical migratory bird habitat and constitute a critical nexus within larger social-ecological systems (SES where multiple changing land-use and water-use patterns meet. The Bear River Migratory Bird Refuge in Utah, USA, presents a case study of the ways that wetland managers have created adaptive management strategies that are responsive to the social and hydrological conditions of the agriculture-dominated SES within which they are located. Managers have acquired water rights and constructed infrastructure while cultivating collaborative relationships with other water users to increase the adaptive capacity of the region and decrease conflict. Historically, water management involved diversion and impoundment of water within wetland units timed around patterns of agricultural water needs. In the last 20 years, managers have learned from flood and drought events and developed a long-term adaptive management plan that specifies alternative management actions managers can choose each year based on habitat needs and projected water supply. Each alternative includes habitat goals and target wetland water depth. However, wetland management adapted to agricultural return-flow availability may prove insufficient as population growth and climate change alter patterns of land and water use. Future management will likely depend more on negotiation, collaboration, and learning from social developments within the SES than strictly focusing on water management within refuge boundaries. To face this problem, managers have worked to be included in negotiations with regional water users, a strategy that may prove instructive for other wetland managers in agriculture-dominated watersheds.

  16. Evapotranspiration And Geochemical Controls On Groundwater Plumes At Arid Sites: Toward Innovative Alternate End-States For Uranium Processing And Tailings Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Looney, Brian B.; Denham, Miles E.; Eddy-Dilek, Carol A.; Millings, Margaret R.; Kautsky, Mark

    2014-01-08

    Management of legacy tailings/waste and groundwater contamination are ongoing at the former uranium milling site in Tuba City AZ. The tailings have been consolidated and effectively isolated using an engineered cover system. For the existing groundwater plume, a system of recovery wells extracts contaminated groundwater for treatment using an advanced distillation process. The ten years of pump and treat (P&T) operations have had minimal impact on the contaminant plume – primarily due to geochemical and hydrological limits. A flow net analysis demonstrates that groundwater contamination beneath the former processing site flows in the uppermost portion of the aquifer and exits the groundwater as the plume transits into and beneath a lower terrace in the landscape. The evaluation indicates that contaminated water will not reach Moenkopi Wash, a locally important stream. Instead, shallow groundwater in arid settings such as Tuba City is transferred into the vadose zone and atmosphere via evaporation, transpiration and diffuse seepage. The dissolved constituents are projected to precipitate and accumulate as minerals such as calcite and gypsum in the deep vadose zone (near the capillary fringe), around the roots of phreatophyte plants, and near seeps. The natural hydrologic and geochemical controls common in arid environments such as Tuba City work together to limit the size of the groundwater plume, to naturally attenuate and detoxify groundwater contaminants, and to reduce risks to humans, livestock and the environment. The technical evaluation supports an alternative beneficial reuse (“brownfield”) scenario for Tuba City. This alternative approach would have low risks, similar to the current P&T scenario, but would eliminate the energy and expense associated with the active treatment and convert the former uranium processing site into a resource for future employment of local citizens and ongoing benefit to the Native American Nations.

  17. Estimates of net infiltration in arid basins and potential impacts on recharge and solute flux due to land use and vegetation change

    Science.gov (United States)

    Robertson, Wendy Marie; Sharp, John M.

    2015-03-01

    Human impacts on land use and vegetation in arid basins have, in some regions, altered infiltration, recharge, and groundwater chemistry. However, some modeling approaches currently used do not account for these effects. In the Trans-Pecos region of Texas the presence of modern water, increasing groundwater NO3- concentrations, and vadose zone cores flushed of naturally accumulated solutes belie the notion that basin groundwater is unaffected by overlying land use and vegetation change. Recharge to the Trans-Pecos basins is spatially and temporally variable, and due to human impacts it has likely changed since pre-western settlement time (circa 1850s). By using the INFIL 3.0.1 model, a spatially distributed model of net infiltration, the volume and spatial distribution of net infiltration was examined for two basins, Wild Horse/Michigan Flats and Lobo/Ryan Flats, with model simulations designed to examine the effects of irrigated agriculture and human impacts on vegetation. Model results indicate that recharge to the basins is not limited to mountain-front zones and discrete features (i.e., alluvial channels), rather, irrigation return flow contributes an estimated 6.3 × 107 m3 (408 mm) of net infiltration over 40 yrs and net infiltration on the basin floors could contribute between 7% and 11.5% of annual basin recharge. Model results also indicate that net infiltration may be higher under current vegetation regimes than in pre-western settlement conditions; the removal of thick dense grasslands in INFIL model simulations enhanced net infiltration by 48% or more. Results from distributed models (like INFIL) improve upon scientific understanding of the links between vegetation regime and hydrological processes; this is important for the sustainable management of arid basin aquifers in Texas and elsewhere.

  18. Using multiple environmental methods to estimate groundwater discharge into an arid lake (Dakebo Lake, Inner Mongolia, China)

    Science.gov (United States)

    Su, Xiaosi; Cui, Geng; Du, Shanghai; Yuan, Wenzhen; Wang, Huang

    2016-06-01

    It is important to have both a qualitative and quantitative understanding of the hydraulic exchange between groundwater and surface water to support the development of effective management plans for sustainable use of water resources. Groundwater is a major source of surface-water recharge and plays an important role in maintaining the integrity of ecosystems, especially within wetlands in semi-arid regions. The Ordos Desert Plateau of Inner Mongolia (China) is a vulnerable ecosystem that suffers from an extreme lack of water. The hydraulic exchange between groundwater and lake water in Dakebo Lake (the largest of hundreds of lakes on the Ordos Desert Plateau) was evaluated using multiple environmental methods. Continuous monitoring of the groundwater and lake-water levels indicated that the lake was recharged vertically by groundwater. Application of hydrodynamic and temperature tracing methods to the western side of the lake indicated that the rate of groundwater discharge to the lake was about 2 × 10-6 to 3 × 10-6 m/s in spring, summer, and autumn, but that there was no recharge in winter because the hypolentic zone (HZ) was frozen. Mixing ratios of groundwater and lake water in the HZ, estimated from the 18O and 2H ratios, showed that there were spatial variations in the hydrodynamic exchange between groundwater and lake water within the HZ.

  19. Suitability of different comfort indices for the prediction of thermal conditions in tree-covered outdoor spaces in arid cities

    Science.gov (United States)

    Ruiz, María Angélica; Correa, Erica Norma

    2015-10-01

    Outdoor thermal comfort is one of the most influential factors in the habitability of a space. Thermal level is defined not only by climate variables but also by the adaptation of people to the environment. This study presents a comparison between inductive and deductive thermal comfort models, contrasted with subjective reports, in order to identify which of the models can be used to most correctly predict thermal comfort in tree-covered outdoor spaces of the Mendoza Metropolitan Area, an intensely forested and open city located in an arid zone. Interviews and microclimatic measurements were carried out in winter 2010 and in summer 2011. Six widely used indices were selected according to different levels of complexity: the Temperature-Humidity Index (THI), Vinje's Comfort Index (PE), Thermal Sensation Index (TS), the Predicted Mean Vote (PMV), the COMFA model's energy balance (S), and the Physiological Equivalent Temperature (PET). The results show that the predictive models evaluated show percentages of predictive ability lower than 25 %. Despite this low indicator, inductive methods are adequate for obtaining a diagnosis of the degree and frequency in which a space is comfortable or not whereas deductive methods are recommended to influence urban design strategies. In addition, it is necessary to develop local models to evaluate perceived thermal comfort more adequately. This type of tool is very useful in the design and evaluation of the thermal conditions in outdoor spaces, based not only to climatic criteria but also subjective sensations.

  20. Smartphones and Time Zones

    Science.gov (United States)

    Baird, William; Secrest, Jeffery; Padgett, Clifford; Johnson, Wayne; Hagrelius, Claire

    2016-09-01

    Using the Sun to tell time is an ancient idea, but we can take advantage of modern technology to bring it into the 21st century for students in astronomy, physics, or physical science classes. We have employed smartphones, Google Earth, and 3D printing to find the moment of local noon at two widely separated locations. By reviewing GPS time-stamped photos from each place, we are able to illustrate that local noon is longitude-dependent and therefore explain the need for time zones.

  1. Linking chloride mass balance infiltration rates with chlorofluorocarbon and SF6 groundwater dating in semi-arid settings: potential and limitations.

    Science.gov (United States)

    Stadler, Susanne; Osenbruck, Karsten; Duijnisveld, Wilhelmus H M; Schwiede, Martin; Bottcher, Jurgen

    2010-09-01

    In the framework of the investigation of enrichment processes of nitrate in groundwater of the Kalahari of Botswana near Serowe, recharge processes were investigated. The thick unsaturated zone extending to up to 100 m of mostly unconsolidated sediments and very low recharge rates pose a serious challenge to study solute transport related to infiltration and recharge processes, as this extends past the conventional depths of soil scientific investigations and is difficult to describe using evidence from the groundwater due to the limitations imposed by available tracers. To determine the link between nitrate in the vadose zone and in the uppermost groundwater, sediment from the vadose zone was sampled up to a depth of 15-20 m (in one case also to 65 m) on several sites with natural vegetation in the research area. Among other parameters, sediment and water were analysed to determine chloride and nitrate concentration depth profiles. Using the chloride mass balance method, an estimation of groundwater infiltration rates produced values of 0.2-4 mm a(-1). The uncertainty of these values is, however, high. Because of the extreme thickness of the vadose zone, the travel time in the unsaturated zone might reach extreme values of up to 500 years and more. For investigations using groundwater, we applied the chlorofluorocarbons CFC-113, CFC-12, sulphur hexafluoride (SF(6)) and tritium to identify potential recharge, and found indications for some advective transport of the CFCs and SF(6), which we accounted for as constituting potential active localised recharge. In our contribution, we show the potential and limitations of the applied methods to determine groundwater recharge and coupled solute transport in semi-arid settings, and compare travel time ranges derived from soil science and groundwater investigations.

  2. Parapapillary atrophy: histological gamma zone and delta zone.

    Directory of Open Access Journals (Sweden)

    Jost B Jonas

    Full Text Available BACKGROUND: To examine histomorphometrically the parapapillary region in human eyes. METHODOLOGY/PRINCIPAL FINDINGS: The histomorphometric study included 65 human globes (axial length:21-37 mm. On anterior-posterior histological sections, we measured the distance Bruch's membrane end (BME-optic nerve margin ("Gamma zone", BME-retinal pigment epithelium (RPE ("Beta zone", BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer. "Delta zone" was defined as part of gamma zone in which blood vessels of at least 50 µm diameter were not present over a length of >300 µm. Beta zone (mean length:0.35±0.52 mm was significantly (P = 0.01 larger in the glaucoma group than in the non-glaucomatous group. It was not significantly (P = 0.28 associated with axial length. Beta zone was significantly (P = 0.004 larger than the region with occluded choriocapillaris. Gamma zone (mean length:0.63±1.25 mm was associated with axial length (P50 µm diameter within gamma zone was present only in highly axially elongated globes and was not related with glaucoma. Beta zone (Bruch's membrane without RPE was correlated with glaucoma but not with globe elongation. Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.

  3. Groundwater dating with radiocarbon: application to an aquifer under semi-arid conditions in the south of Morocco (Guelmime)

    International Nuclear Information System (INIS)

    Radiocarbon dating is based on measuring the loss of the parent radionuclide (14C) in a given sample. This assumes two key features of the system. The first is that the initial concentration of the parent is known and has remained constant in the past. The second is that the system is closed to subsequent gains or losses of the parent, except through radioactive decay. But, the reaction and evolution of the carbonate system strongly dilute the initial 14C activity in dissolved inorganic carbon (DIC). The result is an artificial 'aging' of groundwater by dilution of 14C. Unravelling the relevant processes and distinguishing 14C decay from 14C dilution is an engaging geochemical problem. Several attempts to overcome these problems have been made during the past 30 years and a number of possible correction procedures have been presented by different authors. Environmental isotopes study (13C, 14C) from the aquifers of the Guelmime under semi-arid conditions provides new information on recharge zones, mixing zones and the circulation routes of water. The combination of logPCO2, the saturation index of dolomite and calcite, HCO3-, δ13C, 14C and pH along flow paths can provide an indication of open- and closed-system conditions in the Oumlaachar and Seyyad sub-basins. This approach of geochemical analysis, when combined with correction procedures, allows us to understand age and recharge in the Guelmime aquifer. 14C groundwater ages range from modern to about 2700 years in this aquifer, and indicate recharge values of 0.55-15 mm/yr

  4. Mixed crop-livestock production systems of smallholder farmers in sub-humid and semi-arid areas of Zambia

    International Nuclear Information System (INIS)

    Livestock production activities among small-scale farmers of semi-arid (Agro-ecological zone 1) and sub-humid (Agro-ecological zone 2) areas of Zambia are integrated with crop production activities in what is termed as crop/livestock farming system. This is a closed system in which production of one enterprise depends on the other. In Zambia, crop production depends on draught animals for tillage of cropping area, animal manure for fertilisation of crops while livestock depend on crop residues for dry season feeding. Good quality grass is generally available in adequate amounts to support reasonable level of livestock productivity during the rainy season. But livestock rely on low quantity and poor quality, highly fibrous perennial grass from veld and fibrous crop residues during the dry season. These resources are inadequate to support optimum livestock productivity activities. Poor nutrition results in low rates of reproduction and production as well as increased susceptibility to diseases. With the increasing human population cropping land is expanding, leading to increased production of crop residues. This has however, reduced the grazing land available for ruminant production. In Zambia large quantities of crop residues (stovers, husks and straws, legume tops and hulls, sugar cane tops, cassava leaves, potato vines, etc.) are left in the field where they are wasted each year because small-scale farmers lack the knowledge on how best to use them. There is a need to find ways to reverse this situation by adapting known and workable technologies to local conditions and by introducing new approaches for improving the use of crop residues and poor quality fibrous feeds. Efforts should also be made to enlarge feed resource base. The technologies should be simple and effective. In the presence of a dynamic market system, livestock production in a crop/livestock system could be intensified and made profitable for small-scale farmers. (author)

  5. Groundwater dating with radiocarbon: application to an aquifer under semi-arid conditions in the south of Morocco (Guelmime).

    Science.gov (United States)

    Bouhlassa, S; Aiachi, A

    2002-04-01

    Radiocarbon dating is based on measuring the loss of the parent radionuclide (14C) in a given sample. This assumes two key features of the system. The first is that the initial concentration of the parent is known and has remained constant in the past. The second is that the system is closed to subsequent gains or losses of the parent, except through radioactive decay. But, the reaction and evolution of the carbonate system strongly dilute the initial 14C activity in dissolved inorganic carbon (DIC). The result is an artificial "aging" of groundwater by dilution of 14C. Unravelling the relevant processes and distinguishing 14C decay from 14C dilution is an engaging geochemical problem. Several attempts to overcome these problems have been made during the past 30 years and a number of possible correction procedures have been presented by different authors. Environmental isotopes study (13C, 14C) from the aquifers of the Guelmime under semi-arid conditions provides new information on recharge zones, mixing zones and the circulation routes of water. The combination of logP(CO2), the saturation index of dolomite and calcite, HCO3, delta13C, 14C and pH along flow paths can provide an indication of open- and closed-system conditions in the Oumlaachar and Seyyad sub-basins. This approach of geochemical analysis, when combined with correction procedures, allows us to understand age and recharge in the Guelmime aquifer. 14C groundwater ages range from modern to about 2700 years in this aquifer, and indicate recharge values of 0.55-15 mm/yr. PMID:11999164

  6. Phylogeographic History of Atraphaxis Plants in Arid Northern China and the Origin of A. bracteata in the Loess Plateau

    Science.gov (United States)

    Xu, Zhe; Zhang, Ming-Li; Cohen, James I.

    2016-01-01

    In China, species of Atraphaxis (Polygonaceae) primarily inhabit arid zones across temperate steppe and desert regions. The complex geologic history (e.g., expansion of deserts) and extreme climate shifts of the region appear to have played an important role in shaping the phylogeography of Atraphaxis. The present study focuses on species-level phylogeographic patterns of Atraphaxis in China, with the goal of determining the impact of past environmental changes, in northern China, on the evolutionary history of the genus. Five hundred and sixty-four individuals distributed among 71 populations of 11 species of Atraphaxis from across the geographic range of the genus were studied using sequence data from two plastid spacers, psbK-psbI and psbB-psbH. The results demonstrate that most chloroplast haplotypes are species-specific, except for some present among widespread species. The phylogeny of Atraphaxis was well structured, and molecular dating analyses suggest that the main divergence events occurred during the late Pliocene and Pleistocene (5.73–0.03 million years ago). The statistical dispersal-vicariance analysis (S-DIVA) results provide evidence that phylogeographic patterns for the genus were characterized by both vicariance events and regional dispersal. The presented data suggest that the rapid expansion of deserts and climatic changes in northern China during the late Pliocene and Pleistocene have driven the diversification and spread of Atraphaxis in the region. The expansion of the Tengger Desert provided appropriate conditions for the origin of A. bracteata. Additionally, a contact zone in the north of the Hexi Corridor was identified as having played a significant role as a migratory route for species in adjacent areas. PMID:27656885

  7. Nutritional value of tree leaves for livestock from a semi-hilly arid region of India

    International Nuclear Information System (INIS)

    Samples of 13 species of forest tree leaves growing in the semi-hilly arid zone of Punjab State in India were collected at 30 day intervals over 12 months, in order to assess their nutritional value for livestock. The ground samples were pooled for four seasons: dry hot, hot humid, fall, and winter. The data were arranged in a 13 x 4 factorial design for analysis. For tannin fractionation, leaves of 12 species containing more than 3.5% total phenols were selected and data were analysed within a 12 x 12 factorial design. The chemical composition, irrespective of the season, revealed that Leucaena had the highest crude protein (CP, 220 g/kg dry matter). Globulin was the major protein fraction in most of the leaves. The lowest concentration of neutral detergent fibre (NDF) was in Morus, Acacia and Grewea spp. Fibre and lignin content increased during the fall and winter. The leaves of Grewea, Morus, Leucaena, Carrisa and Acacia were rich in Ca, P and most of the trace elements. The total phenolics ranged between 38 (Toona) and 169 g/kg DM (Anogeisus). The leaves of Anogeisus had the highest concentration of hydrolysable tannins (16.9%) whereas those of Carrisa had highest condensed tannins (4.6%). The condensed tannins (>3%) were negatively correlated to the digestibility of dry matter (DM), NDF and CP. The digestion kinetic parameters for DM, NDF and CP revealed that leaves of Morus alba, Zizyphus and Ehretia were most degradable. The minimum rumen fill values also revealed that leaves of Grewea, Azadirachta, Morus, Ehretia and Leucaena had higher potential for voluntary DM intake, especially compared to leaves of Ougeinia, Zizyphus xylopyrus, Dodonea and Carrisa. During winter, most of the leaves had a low potentially degradable fraction, with a low rate of degradation. Screening leaves by the in vitro gas production technique suggested that leaves of Melia azedarach, Azadirachta indica, Morus alba and Leucaena leucocephala were potential feeds for ruminants

  8. Simple, spatial and predictive approach for cereal yield prediction in the semi-arid areas

    Science.gov (United States)

    Toumi, Jihad; Khabba, Said; Er-Raki, Salah; Le page, Michel; Chahbi Bellakanji, Aicha; Lili Chabaane, Zohra; Ezzahar, Jamal; Zribi, Mehrez; Jarlan, Lionel

    2016-04-01

    The objective is to develop a simple, spatial and predictive approach of dry matter (DM) and grain yield (GY) of cereal in the semi-arid areas. The proposed method is based on the three efficiencies model of Monteith (1972). This approach summarizes the transformation of solar radiation to the dry matter (DM) by the climate (ɛc), interception (ɛi) and conversion (ɛconv) efficiencies. The method combines the maximum of ɛi and ɛconv (noted ɛimax and ɛconvmax) into a single parameter denoted ɛmax, calculating as a function of cumulating growing degree day (CGDD). Also, the stress coefficient ks, which affects the conversion of solar radiation to the biomass was calculated by the surface temperature or the water balance at the root zone. In addition, the expression of ks has been improved by the consideration of the results achieved by deficit irrigation (AquaCrop and STICS models) which showed that the value of ks from 0.7 to 1 didn't affect significantly the cereal production. For the partitioning of the dry matter developed, between straw and grain, the method proposed calculates a variable Harvest Index coefficient (HI). HI is deducted from CGDD and HI0max (maximal final harvest Index in the region of study). Finally, the approach calculates DM depending Satellite Information (NDVI and surface temperature Ts) and climatic data (solar radiation and air temperature). In the case of no availability of Ts, the amount of irrigation is required to calculate ks. Until now, the developed model has been calibrated and validated on the irrigated area R3, located 40 Km east of Marrakech. The evolutions of DM and GY were reproduced satisfactorily. R2 and RMSE are respectively 0.98 and 0.35 t/ha and 0.98 and 0.19 t/ha, respectively. Currently, additional tests are in progress on data relating to the Kairouan plain of Tunisia.

  9. Land-atmosphere feedbacks amplify aridity increase over land under global warming

    Science.gov (United States)

    Berg, Alexis; Findell, Kirsten; Lintner, Benjamin; Giannini, Alessandra; Seneviratne, Sonia I.; van den Hurk, Bart; Lorenz, Ruth; Pitman, Andy; Hagemann, Stefan; Meier, Arndt; Cheruy, Frédérique; Ducharne, Agnès; Malyshev, Sergey; Milly, P. C. D.

    2016-09-01

    The response of the terrestrial water cycle to global warming is central to issues including water resources, agriculture and ecosystem health. Recent studies indicate that aridity, defined in terms of atmospheric supply (precipitation, P) and demand (potential evapotranspiration, Ep) of water at the land surface, will increase globally in a warmer world. Recently proposed mechanisms for this response emphasize the driving role of oceanic warming and associated atmospheric processes. Here we show that the aridity response is substantially amplified by land-atmosphere feedbacks associated with the land surface's response to climate and CO2 change. Using simulations from the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we show that global aridity is enhanced by the feedbacks of projected soil moisture decrease on land surface temperature, relative humidity and precipitation. The physiological impact of increasing atmospheric CO2 on vegetation exerts a qualitatively similar control on aridity. We reconcile these findings with previously proposed mechanisms by showing that the moist enthalpy change over land is unaffected by the land hydrological response. Thus, although oceanic warming constrains the combined moisture and temperature changes over land, land hydrology modulates the partitioning of this enthalpy increase towards increased aridity.

  10. Karst characterization in a semi-arid region using gravity, seismic, and resistivity geophysical techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Barnhart, Kevin Scott

    2013-10-01

    We proposed to customize emerging in situ geophysical monitoring technology to generate time-series data during sporadic rain events in a semi-arid region. Electrodes were to be connected to wireless %5Cnodes%22 which can be left in the eld for many months. Embedded software would then increase sampling frequency during periods of rainfall. We hypothesized that this contrast between no-volume ow in karst passageways dur- ing dry periods and partial- or saturated-volume ow during a rain event is detectable by these Wireless Sensor Network (WSN) geophysical nodes, we call this a Wireless Resistivity Network (WRN). The development of new methodologies to characterize semi-arid karst hydrology is intended to augment Sandia National Laboratorys mission to lead e orts in energy technologies, waste disposal and climate security by helping to identify safe and secure regions and those that are at risk. Development and initial eld testing identi ed technological barriers to using WRNs for identifying semi-arid karst, exposing R&D which can be targeted in the future. Gravity, seismic, and resis- tivity surveys elucidated how each technique might e ectively be used to characterize semi-arid karst. This research brings to light the importance and challenges with char- acterizing semi-arid karst through a multi-method geophysical study. As there have been very few studies with this emphasis, this study has expanded the body of practical experience needed to protect the nations water and energy security interests.

  11. Heavy metal contamination and source in arid agricultural soil in central Gansu Province, China

    Institute of Scientific and Technical Information of China (English)

    LI Yu; GOU Xin; WANG Gang; ZHANG Qiang; SU Qiong; XIAO Guoju

    2008-01-01

    Concentrations of copper (Cu), lead (Pb), chromium (Cr), mercury (Hg), and arsenic (As) were measured in arid agricultural and irrigated agricultural soils collected in Daba Village, Shajiawuan Village, Gangou Village and Sifangwu Village, located in central Gansu Province, China. Concentrations except Hg and Pb were lower than the background values in grey calcareous soil in the selected arid agricultural soils. Pb concentration exceeded the threshold of arid agricultural soils in China by 72. 46%. These results showed that there was indeed serious pollution with Pb, a slight pollution problem for other selected metals in the irrigated agricultural soils in Daba Village. Principal component analysis (PCA) was used to assess the soil data, applying varimax rotation with Kaiser Normalization. The result showed that the irrigated factor, agricultural factor and anthropogenic factor all contributed to the relations between selected chemical properties. The main factor of accumulation of Cu, Pb, Cr, Hg and As was lithological factor in arid agricultural areas. There is a striking dissimilarity of origin of Cu, Pb, Cr, Hg and As in agricultural soil between the irrigate agriculture and arid agriculture.

  12. The relationship between anthropogenic dust and population over global semi-arid regions

    Science.gov (United States)

    Guan, Xiaodan; Huang, Jianping; Zhang, Yanting; Xie, Yongkun; Liu, Jingjing

    2016-04-01

    Although anthropogenic dust has received more attention from the climate research community, its dominant role in the production process is still not identified. In this study, we analysed the relationship between anthropogenic dust and population density/change over global semi-arid regions and found that semi-arid regions are major source regions in producing anthropogenic dust. The results showed that the relationship between anthropogenic dust and population is more obvious in cropland than in other land cover types (crop mosaics, grassland, and urbanized regions) and that the production of anthropogenic dust increases as the population density grows to more than 90 persons km-2. Four selected semi-arid regions, namely East China, India, North America, and North Africa, were used to explore the relationship between anthropogenic dust production and regional population. The most significant relationship between anthropogenic dust and population occurred in an Indian semi-arid region that had a greater portion of cropland, and the high peak of anthropogenic dust probability appeared with 220 persons km-2 of population density and 60 persons km-2 of population change. These results suggest that the influence of population on production of anthropogenic dust in semi-arid regions is obvious in cropland regions. However, the impact does not always have a positive contribution to the production of anthropogenic dust, and overly excessive population will suppress the increase of anthropogenic dust. Moreover, radiative and climate effects of increasing anthropogenic dust need more investigation.

  13. An Overview of the Semi-arid Climate and Environment Research Observatory over the Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    HUANG Jianping; ZHANG Seidou; WANG Guoyin; FENG Guanghong; YUAN Jiuyi; ZHANG Lei; ZUO Hongchao; WANG Shigong; FU Congbin; CHOU Jifan; ZHANG Wu; ZUO Jinqing; BI Jianrong; SHI Jinsen; WANG Xin; CHANG Zhoulin; HUANG Zhongwei; YANG Su

    2008-01-01

    Arid and semi-arid areas comprise about 30% of the earth's surface. Changes in climate and climate variability will likely have a significant impact on these regions. The Loess Plateau over Northwest China is a special semi-arid land surface and part of a dust aerosol source. To improve understanding and capture the direct evidence of the impact of human activity on the semi-arid climate over the Loess Plateau, the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) was established in 2005. SACOL consists of a large set of instruments and focuses on: (1) monitoring of long term tendencies in semiarid climate changes; (2) monitoring of the aerosol effect on the water cycle; (3) studies of interaction between land surface and the atmosphere; (4) improving the land surface and climate models; and (5) validation of space-borne observations. This paper presents a description of SACOL objectives, measurements, and sampling strategies. Preliminary observation results are also reviewed in this paper.

  14. On the Role of Hyper-arid Regions within the Virtual Water Trade Network

    Science.gov (United States)

    Aggrey, James; Alshamsi, Aamena; Molini, Annalisa

    2016-04-01

    Climate change, economic development, and population growth are bound to increasingly impact global water resources, posing a significant threat to the sustainable development of arid regions, where water consumption highly exceeds the natural carrying capacity, population growth rate is high, and climate variability is going to impact both water consumption and availability. Virtual Water Trade (VWT) - i.e. the international trade network of water-intensive products - has been proposed as a possible solution to optimize the allocation of water resources on the global scale. By increasing food availability and lowering food prices it may in fact help the rapid development of water-scarce regions. The structure of the VWT network has been analyzed by a number of authors both in connection with trade policies, socioeconomic constrains and agricultural efficiency. However a systematic analysis of the structure and the dynamics of the VWT network conditional to aridity, climatic forcing and energy availability, is still missing. Our goal is hence to analyze the role of arid and hyper-arid regions within the VWN under diverse climatic, demographic, and energy constraints with an aim to contribute to the ongoing Energy-Water-Food nexus discussion. In particular, we focus on the hyper-arid lands of the Arabian Peninsula, the role they play in the global network and the assessment of their specific criticalities, as reflected in the VWN resilience.

  15. Synthetic Lethal Targeting of ARID1A-Mutant Ovarian Clear Cell Tumors with Dasatinib.

    Science.gov (United States)

    Miller, Rowan E; Brough, Rachel; Bajrami, Ilirjana; Williamson, Chris T; McDade, Simon; Campbell, James; Kigozi, Asha; Rafiq, Rumana; Pemberton, Helen; Natrajan, Rachel; Joel, Josephine; Astley, Holly; Mahoney, Claire; Moore, Jonathan D; Torrance, Chris; Gordan, John D; Webber, James T; Levin, Rebecca S; Shokat, Kevan M; Bandyopadhyay, Sourav; Lord, Christopher J; Ashworth, Alan

    2016-07-01

    New targeted approaches to ovarian clear cell carcinomas (OCCC) are needed, given the limited treatment options in this disease and the poor response to standard chemotherapy. Using a series of high-throughput cell-based drug screens in OCCC tumor cell models, we have identified a synthetic lethal (SL) interaction between the kinase inhibitor dasatinib and a key driver in OCCC, ARID1A mutation. Imposing ARID1A deficiency upon a variety of human or mouse cells induced dasatinib sensitivity, both in vitro and in vivo, suggesting that this is a robust synthetic lethal interaction. The sensitivity of ARID1A-deficient cells to dasatinib was associated with G1-S cell-cycle arrest and was dependent upon both p21 and Rb. Using focused siRNA screens and kinase profiling, we showed that ARID1A-mutant OCCC tumor cells are addicted to the dasatinib target YES1. This suggests that dasatinib merits investigation for the treatment of patients with ARID1A-mutant OCCC. Mol Cancer Ther; 15(7); 1472-84. ©2016 AACR.

  16. Evidence of moisture control on the methylation of branched glycerol dialkyl glycerol tetraethers in semi-arid and arid soils

    Science.gov (United States)

    Dang, Xinyue; Yang, Huan; Naafs, B. David A.; Pancost, Richard D.; Xie, Shucheng

    2016-09-01

    The distribution of bacterial branched glycerol dialkyl glycerol tetraethers (brGDGTs) is influenced by growth temperature and pH. This results in the widespread application of the brGDGT-based MBT(‧)/CBT proxy (MBT - methylation of branched tetraethers, CBT - cyclization of branched tetraethers) in terrestrial paleo-environmental reconstructions. Recently, it was shown that the amount of precipitation could also have an impact on CBT, as well as the abundance of brGDGTs relative to that of archaeal isoprenoidal (iso)GDGTs (Ri/b) and the absolute abundance of brGDGTs, potentially complicating the use of MBT/CBT as paleothermometer. However, the full influence of hydrology, and in particular soil water content (SWC), on GDGT distributions remains unclear. Here we investigated variations in the GDGT distribution across a SWC gradient (0-61%) around Qinghai Lake in the Tibetan Plateau, an arid to semiarid region in China. Our results demonstrate that SWC affects the brGDGT distribution. In particular, we show that SWC has a clear impact on the degree of methylation of C6-methylated brGDGTs, whereas C5-methylated brGDGTs are more impacted by temperature. This results in a combined SWC and temperature control on MBT‧. In this context we propose a diagnostic parameter, the IR6ME (relative abundance of C6-methylated GDGTs) index, to evaluate the applicability of brGDGT-based paleotemperature reconstructions. Using the global dataset, expanded with our own data, MBT‧ has a significant correlation with mean annual air temperature when IR6ME MBT‧/CBT as temperature proxy. However, MBT‧ has a significant correlation with mean annual precipitation (i.e., a substantial reflection of SWC impact) when IR6ME > 0.5, implying that MBT‧ may respond to hydrological change in these regions and can be used as a proxy for MAP.

  17. The Near Zone to Far Zone Transformation (N2F)

    Energy Technology Data Exchange (ETDEWEB)

    Blackfield, Donald T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Poole, Brian R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-03-11

    N2F is a C/C++ code used to calculate the far zone electromagnetic (EM) field, given E and H near zone field data. The method used by N2F can be found in Ref. 1 and 2. N2F determines the far field EΦ and Eθ in spherical coordinates for near zone data calculated in either Cartesian or Cylindrical geometry.

  18. Risk Assessment and Zoning of Agricultural Drought Disaster in Heilongjiang Province

    Institute of Scientific and Technical Information of China (English)

    ZHENG Kai; CHEN Hong; ZHANG Li-juan; GAO Yu-hong

    2011-01-01

    In this study, we first zoned the drought degree in the years from 1971 to 2000 in Heilongjiang Province by using precipitation anomaly equation as an indicator, and analyzed the temporal distribution characteristics and laws of arid disaster in different periods. Using the method of human being habitat risk assessment, we further studied and zoned the drought disaster risk index(DDRI) of maize cultivated in 74 stations in Heilongjiang Province via GIS software. The results showed that (1) the occurrence frequency of moderate and heavy drought in Heilongjiang Province was 1970s >1990s > 1980s, and (2) the high risk area of drought disaster for maize production mainly assembled in Qiqihar and Daqing regions in west Heilongjiang Province, where agricultural drought should be highly concerned, while low risk and slight risk areas mainly distribute in middle areas and east plain areas in Heilongjiang Province. Our study provided basis for the defense of agricultural drought disaster.

  19. Empowerment Zones and Enterprise Districts - Volusia County Enterprise Zones

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Florida's Enterprise Zone Program encourages economic growth and investment in distressed areas by offering tax advantages and incentives to businesses that are...

  20. Landscaping and performance of some aesthetic plant species in hot,arid conditions of India

    Institute of Scientific and Technical Information of China (English)

    Rajesh Kumar Gupta; Pradeep Chaudhry; Rameshwar Lal Srivastava

    2012-01-01

    Abstract:Establishment of ornamental and aesthetic plants in hot,arid conditions of India is difficult due to the prevailing climatic,edaphic and biotic factors.Effect of turfgrass on the growth of ornamental plants in hot arid conditions has not been studied so far anywhere in the world.A study was conducted on the campus of Arid Forest Research Institute,Jodhpur,India to assess the performance of a few ornamental plant species in combination with turfgrass and without turfgrass with respect to different soil tilling intervals.Growth of plants was better with turfgrass than without turfgrass.We suggest adopting a soil tilling interval of 30 days to achieve optimum growth of ornamental plant species in terms of height and crown diameter.Our results can help reduce labor costs and achieving better landscapes in fewer days in hot urban conditions of Indian sub continent.

  1. Large-scale hydrological modelling in the semi-arid north-east of Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Guentner, A.

    2002-09-01

    Semi-arid areas are characterized by small water resources. An increasing water demand due to population growth and economic development as well as a possible decreasing water availability in the course of climate change may aggravate water scarcity in future in these areas. The quantitative assessment of the water resources is a prerequisite for the development of sustainable measures of water management. For this task, hydrological models within a dynamic integrated framework are indispensable tools. The main objective of this study is to develop a hydrological model for the quantification of water availability over a large geographic domain of semi-arid environments. The study area is the Federal State of Ceara in the semi-arid north-east of Brazil. Surface water from reservoirs provides the largest part of water supply. The area has recurrently been affected by droughts which caused serious economic losses and social impacts like migration from the rural regions. (orig.)

  2. REUSE OF TREATED WASTEWATER IN AGRICULTURE: SOLVING WATER DEFICIT PROBLEMS IN ARID AREAS (REVIEW

    Directory of Open Access Journals (Sweden)

    Faissal AZIZ

    2014-12-01

    Full Text Available In the arid and semiarid areas, the availability and the management of irrigation water have become priorities of great importance. The successive years of drought, induced by climate change and population growth, increasingly reduced the amount of water reserved for agriculture. Consequently, many countries have included wastewater reuse as an important dimension of water resources planning. In the more arid areas wastewater is used in agriculture, releasing high resource of water supplies. In this context, the present work is a review focusing the reuse of treated wastewater in agriculture as an important strategy for solving water deficit problems in arid areas. Much information concerning the wastewater reuse in different regions of the world and in Morocco, the different wastewater treatment technologies existing in Morocco were discussed. The review focused also the fertilizing potential of wastewater in agriculture, the role of nutrients and their concentrations in wastewater and their advantages effects on plant growth and yield.

  3. Water balance of two earthen landfill caps in a semi-arid climate

    Energy Technology Data Exchange (ETDEWEB)

    Khire, M.V. [GeoSyntec Consultants, Boca Raton, FL (United States); Benson, C.H.; Bosscher, P.J. [Univ. of Wisconsin, Madison, WI (United States)

    1997-12-31

    Water balance data are presented that were obtained from two earthen cap test sections located in a semi-arid region. The test sections were constructed on a municipal solid waste landfill in East Wenatchee, Washington, USA. One test section represents a traditional resistive barrier, and is constructed with a compacted silty clay barrier 60 cm thick and a vegetated silty clay surface layer 15 cm thick. The other test section represents a capillary barrier and has a sand layer 75 cm thick overlain by a 15-cm-thick vegetated surface layer of silt. Extensive hydrological and meteorological data have been collected since November 1992. Unsaturated hydraulic properties of soils, hydrologic parameters, and vegetation have been extensively characterized. Results of the study show that capillary barriers can be effective caps in semi-arid and arid regions. They are also cheaper to construct and can perform better than traditional resistive barriers.

  4. On predicting debris flows in arid mountain belts

    Science.gov (United States)

    Stolle, Amelie; Langer, Maria; Blöthe, Jan Henrik; Korup, Oliver

    2015-03-01

    The use of topographic metrics for estimating the susceptibility to, and reconstructing the characteristics of, debris flows has a long research tradition, although largely devoted to humid mountainous terrain. The exceptional 2010 monsoonal rainstorms in the high-altitude mountain desert of Ladakh and Zanskar, NW India, were a painful reminder of how susceptible arid regions are to rainfall-triggered flash floods, landslides, and debris flows. The rainstorms of August 4-6 triggered numerous debris flows, killing 182 people, devastating 607 houses, and more than 10 bridges around Ladakh's capital of Leh. The lessons from this disaster motivated us to revisit methods of predicting (a) flow parameters such as peak discharge and maximum velocity from field and remote sensing data, and (b) the susceptibility to debris flows from catchment morphometry. We focus on quantifying uncertainties tied to these approaches. Comparison of high-resolution satellite images pre- and post-dating the 2010 rainstorm reveals the extent of damage and catastrophic channel widening. Computations based on these geomorphic markers indicate maximum flow velocities of 1.6-6.7 m s- 1 with runout of up to ~ 10 km on several alluvial fans that sustain most of the region's settlements. We estimate median peak discharges of 310-610 m3 s- 1, which are largely consistent with previous estimates. Monte Carlo-based error propagation for a single given flow-reconstruction method returns a variance in discharge similar to one derived from juxtaposing several different flow reconstruction methods. We further compare discriminant analysis, classification tree modelling, and Bayesian logistic regression to predict debris-flow susceptibility from morphometric variables of 171 catchments in the Ladakh Range. These methods distinguish between fluvial and debris flow-prone catchments at similar success rates, but Bayesian logistic regression allows quantifying uncertainties and relationships between potential

  5. Assessment of the Consistency among Precipitation Products over Arid Regions

    Science.gov (United States)

    Ghebreyesus, Dawit; Temimi, Marouane

    2016-04-01

    This study addresses the analysis of the consistency among global precipitation products over arid regions. First, precipitation products were examined against in situ observations from the UAE network. Then, the consistency among the different products was assessed regionally over the Arabian Peninsula and the Sahara Desert. Four distinct independently-derived precipitation products, namely, Global Precipitation Climate Center (GPCC), Willmott-Matsuura 2001 (WM), Tropical Rainfall Measurement Mission (TRMM), and CPC Morphing (CMORPH) were examined. Over the UAE, in situ monthly observations from 6 stations over a time period of 11 years, from 2000 to 2010 inclusive, were used. The correlation with in situ observations, Root Mean Square Error (RMSE), and Relative Bias (rBIAS) were calculated to evaluate the precipitation products. The lowest areal averaged RMSE over all stations, ranging from 3.82mm to 9.98mm, was obtained with the GPCC indicating a higher agreement with in situ observations. The average RMSE of GPCC over the country was 6.18mm. However, the highest areal averaged RMSE, ranging from 9.44 to 19.52mm, was obtained with the WM product with average of 13.57mm. The results showed an overestimation of the observed rainfall values across all products with overall average of 42%. CMORPH product was found to be the most inconsistent products spatially across the UAE with rBIAS ranging from -47% in Al Ain to 372% in Dubai. The correlation with in situ observations was found to be higher with GPCC product ranging from 0.8450 to 0.9494. TRMM was second with an average of 0.8413, ranging from 0.7098 to 0.9248. Furthermore, Mean Relative Difference (MRD) was calculated to investigate the precision among the precipitation products. CMORPH was found to be inconsistent spatially being the lowest estimator for four stations (Adu Dhabi, Al Ain, Sharjah, Ras Al Khaimah) whereas being the highest estimator for the rest two stations (Dubai and Fujairah). Generally, the

  6. Nairu en zone heureuse

    OpenAIRE

    Reynès, Frédéric; Lemoine, Matthieu; Veroni, Paola

    2007-01-01

    Cette étude spéciale propose des estimations du niveau non inflationniste du taux de chômage (Nairu) pour la zone euro agrégée, pour la France, l’Italie et l’Allemagne. Une équation d’inflation, qui dépend de l’écart du taux de chômage au Nairu, est estimée par le filtre de Kalman. Le modèle le plus simple, qui considère le Nairu comme une marche aléatoire, a des capacités prédictives limitées. Il diagnostique un taux de chômage inférieur au Nairu à l’horizon de notre prévision. Il est con...

  7. Saturated Zone Colloid Transport

    Energy Technology Data Exchange (ETDEWEB)

    H. S. Viswanathan

    2004-10-07

    This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R{sub col} is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of R{sub col} that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, k{sub att}, and detachment rate constants, k{sub det}, of colloids to the fracture surface have been measured for the fractured volcanics, and separate R{sub col} uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant

  8. The zone of alienation

    International Nuclear Information System (INIS)

    Ten years after the nuclear disaster, people still live and die in Chernobyl. Thousands of people continue to live and work there. Roughly 500 have moved back into their old homes inside the alienation zone. Fewer than half still alive. Medical researchers in the area insist that immune systems are weakened by doses of radiation far lower than previously thought. However, an European Union sponsored study concluded that Chernobyl's toll has been exaggerated. Thus, while 760 children in the contaminated area have developed thyroid cancer, only three have died as a result. Yet in and around Chernobyl, people carry on their lives and the Ukrainian Government says it can't afford to close the plant without billions of dollars in Western aid. ills

  9. Time-domain reflectometry probing systems for the monitoring of hydrological processes in the unsaturated zone

    Science.gov (United States)

    Kallioras, A.; Khan, A.; Piepenbrink, M.; Pfletschinger, H.; Koniger, F.; Dietrich, P.; Schuth, C.

    2016-08-01

    Precise measurements of the downward movement of precipitation through the unsaturated zone, as well as return flow of moisture to the atmosphere via evaporation, have always been challenging in regard to in-situ monitoring techniques. This study investigates the profile of volumetric water-content fluctuations within the unsaturated zone through a combination of field techniques, including in-situ measurements of the volumetric porewater content at different depths using specially designed time-domain reflectometry (TDR) probes. The probes are installed through direct-push vibro-coring methods, at significant depths within the unsaturated zone, providing continuous readings of the soil-moisture content throughout the unsaturated column. The measured waveform is analyzed by using the inverse modeling approach resulting in an apparent relative dielectric permittivity profile of the surrounding medium along the TDR probe length. The approach sufficiently analyzes the mechanisms of water fluxes through significant depths within the unsaturated zone, which in turn can be used to quantify groundwater recharge at areas where the unsaturated zone hydrology plays a key role in the recharge of the underlying aquifers (such as arid and hydrologically sensitive areas). The approach was applied at an experimental field site in the Upper Rhine Valley, Germany.

  10. Climatic controls on arid continental basin margin systems

    Science.gov (United States)

    Gough, Amy; Clarke, Stuart; Richards, Philip; Milodowski, Antoni

    2016-04-01

    Alluvial fans are both dominant and long-lived within continental basin margin systems. As a result, they commonly interact with a variety of depositional systems that exist at different times in the distal extent of the basin as the basin evolves. The deposits of the distal basin often cycle between those with the potential to act as good aquifers and those with the potential to act as good aquitards. The interactions between the distal deposits and the basin margin fans can have a significant impact upon basin-scale fluid flow. The fans themselves are commonly considered as relatively homogeneous, but their sedimentology is controlled by a variety of factors, including: 1) differing depositional mechanisms; 2) localised autocyclic controls; 3) geometrical and temporal interactions with deposits of the basin centre; and, 4) long-term allocyclic climatic variations. This work examines the basin margin systems of the Cutler Group sediments of the Paradox Basin, western U.S.A and presents generalised facies models for the Cutler Group alluvial fans as well as for the zone of interaction between these fans and the contemporaneous environments in the basin centre, at a variety of scales. Small-scale controls on deposition include climate, tectonics, base level and sediment supply. It has been ascertained that long-term climatic alterations were the main control on these depositional systems. Models have been constructed to highlight how both long-term and short-term alterations in the climatic regime can affect the sedimentation in the basin. These models can be applied to better understand similar, but poorly exposed, alluvial fan deposits. The alluvial fans of the Brockram Facies, northern England form part of a once-proposed site for low-level nuclear waste decommissioning. As such, it is important to understand the sedimentology, three-dimensional geometry, and the proposed connectivity of the deposits from the perspective of basin-scale fluid flow. The developed

  11. Great Basin semi-arid woodland dynamics during the late quaternary

    Energy Technology Data Exchange (ETDEWEB)

    Wigand, P.E.; Hemphill, M.L.; Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States)] [and others

    1995-09-01

    Semi-arid woodlands have dominated the middle elevations of Great Basin mountain ranges during the Holocene where subalpine woodlands prevailed during the Pleistocene. Ancient woodrat middens, and in a few cases pollen records indicate in the late Pleistocene and early Holocene woodland history lowered elevation of subalpine woodland species. After a middle Holocene retrenchment at elevations in excess of 500 meters above today, Juniper-dominated semi-arid woodland reached its late Holocene maximum areal extent during the Neoglacial (2 to 4 ka). These records, along with others indicate contracting semi-arid woodland after the Neoglacial about 1.9 ka. Desert shrub community expansion coupled with increased precariousness of wetland areas in the southern Great Basin between 1.9 and 1.5 ka coincide with shrinking wet-lands in the west-central and northern Great Basin. Coincident greater grass abundance in northern Great Basin sagebrush steppe, reaching its maximum between 1.5 and 1.2 ka, corresponds to dramatic increases in bison remains in the archaeological sites of the northern Intermontane West. Pollen and woodrat midden records indicate that this drought ended about 1.5 ka. Succeeding ameliorating conditions resulted in the sudden northward and downward expansion of pinon into areas that had been dominated by juniper during the Neoglacial. Maximum areal extent of pinon dominated semi-arid woodland in west-central Nevada was centered at 1.2 ka. This followed by 100 years the shift in dominance from juniper to pinon in southern Nevada semi-arid woodlands. Great Basin woodlands suffered from renewed severe droughts between .5 to .6 ka. Effectively wetter conditions during the {open_quotes}Little Ice Age{close_quotes} resulted in re-expansion of semi-arid woodland. Activities related to European settlement in the Great Basin have modified prehistoric factors or imposed new ones that are affecting woodland response to climate.

  12. An Overview of Biodegradation of LNAPLs in Coastal (Semi)-arid Environment.

    Science.gov (United States)

    Yadav, Brijesh Kumar; Hassanizadeh, S Majid

    2011-09-01

    Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these organic contaminated resources is receiving increasing interests and where applicable, can serve as a cost-effective remediation alternative. The success of bioremediation greatly depends on the prevailing environmental variables, and their remediation favoring customization requires a sound understanding of their integrated behavior on fate and transport of LNAPLs under site-specific conditions. The arid and semi-arid coastal sites are characterized by specific environmental extremes; primarily, varying low and high temperatures, high salinity, water table dynamics, and fluctuating soil moisture content. An understanding of the behavior of these environmental variables on biological interactions with LNAPLs would be helpful in customizing the bioremediation for restoring problematic sites in these regions. Therefore, this paper reviews the microbial degradation of LNAPLs in soil-water, considering the influences of prevailing environmental parameters of arid and semi-arid coastal regions. First, the mechanism of biodegradation of LNAPLs is discussed briefly, followed by a summary of popular kinetic models used by researchers for describing the degradation rate of these hydrocarbons. Next, the impact of soil moisture content, water table dynamics, and soil-water temperature on the fate and transport of LNAPLs are discussed, including an overview of the studies conducted so far. Finally, based on the reviewed information, a general conclusion is presented with recommendations for future research subjects on optimizing the bioremediation technique in the field under the aforesaid environmental conditions. The present review will be useful to better understand the

  13. Theoretical critical value curve and driving force formation of ecological migration in the arid land

    Institute of Scientific and Technical Information of China (English)

    ZHU Zi'an; ZHANG Xiaolei

    2006-01-01

    The features of the fragile eco-environment of the arid land decide that its capacity of disturbance-resistance is lower. The natural desert oases in the arid land are in mosaic patches distributed in a wide Gobi desert. The population distribution is greatly dependent on water resources. The population is characterized with dispersed distribution, simple production and living style, and poverty and remoteness. The reason why the ecological migrations are carried out lies in the ecological problems. "Ecological degradation" is the main driving force of the ecological migration. Then, the strength of the driving force depends on the degree of ecological degradation. Hence, whether to carry out ecological migration depends on the extent of ecological degradation.Theoretically, the critical value curve for calculating ecological migration in the arid land is put forward through comprehensive research of relative problems of ecology, economics etc., combined with the ecological migration experience in the arid land, and based on the features of the arid environment. In this article, with this curve, the theoretical research and some practice of the ecological migration have been done from the perspective of natural behavior and governmental behavior of the driving force formation of ecological migration. It analyses the active driving force (factors) and negative forces (factors), and points out the timing and steps of implementing the ecological migration in the arid land. The theoretical curve embodies certain originality and applicability,which provides a quantitative method for evaluating 196the degree of ecological degradation and the theoretical base for implementing ecological migration projects.

  14. An Overview of Biodegradation of LNAPLs in Coastal (Semi)-arid Environment.

    KAUST Repository

    Yadav, Brijesh Kumar

    2011-02-22

    Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these organic contaminated resources is receiving increasing interests and where applicable, can serve as a cost-effective remediation alternative. The success of bioremediation greatly depends on the prevailing environmental variables, and their remediation favoring customization requires a sound understanding of their integrated behavior on fate and transport of LNAPLs under site-specific conditions. The arid and semi-arid coastal sites are characterized by specific environmental extremes; primarily, varying low and high temperatures, high salinity, water table dynamics, and fluctuating soil moisture content. An understanding of the behavior of these environmental variables on biological interactions with LNAPLs would be helpful in customizing the bioremediation for restoring problematic sites in these regions. Therefore, this paper reviews the microbial degradation of LNAPLs in soil-water, considering the influences of prevailing environmental parameters of arid and semi-arid coastal regions. First, the mechanism of biodegradation of LNAPLs is discussed briefly, followed by a summary of popular kinetic models used by researchers for describing the degradation rate of these hydrocarbons. Next, the impact of soil moisture content, water table dynamics, and soil-water temperature on the fate and transport of LNAPLs are discussed, including an overview of the studies conducted so far. Finally, based on the reviewed information, a general conclusion is presented with recommendations for future research subjects on optimizing the bioremediation technique in the field under the aforesaid environmental conditions. The present review will be useful to better understand the

  15. Performance investigation of solid desiccant evaporative cooling system configurations in different climatic zones

    International Nuclear Information System (INIS)

    Highlights: • Five configurations of a DEC system are analyzed in five climate zones. • DEC system model configurations are developed in Dymola/Modelica. • Performance analysis predicted a suitable DEC system configuration for each climate zone. • Results show that climate of Vienna, Sao Paulo, and Adelaide favors the ventilated-dunkle cycle. • While ventilation cycle configuration suits the climate of Karachi and Shanghai. - Abstract: Performance of desiccant evaporative cooling (DEC) system configurations is strongly influenced by the climate conditions and varies widely in different climate zones. Finding the optimal configuration of DEC systems for a specific climatic zone is tedious and time consuming. This investigation conducts performance analysis of five DEC system configurations under climatic conditions of five cities from different zones: Vienna, Karachi, Sao Paulo, Shanghai, and Adelaide. On the basis of operating cycle, three standard and two modified system configurations (ventilation, recirculation, dunkle cycles; ventilated-recirculation and ventilated-dunkle cycles) are analyzed in these five climate zones. Using an advance equation-based object-oriented (EOO) modeling and simulation approach, optimal configurations of a DEC system are determined for each climate zone. Based on the hourly climate data of each zone for its respective design cooling day, performance of each system configuration is estimated using three performance parameters: cooling capacity, COP, and cooling energy delivered. The results revealed that the continental/micro-thermal climate of Vienna, temperate/mesothermal climate of Sao Paulo, and dry-summer subtropical climate of Adelaide favor the use of ventilated-dunkle cycle configuration with average COP of 0.405, 0.89 and 1.01 respectively. While ventilation cycle based DEC configuration suits arid and semiarid climate of Karachi and another category of temperate/mesothermal climate of Shanghai with average COP of

  16. Extreme environments in the critical zone: Linking acidification hazard of acid sulfate soils in mound spring discharge zones to groundwater evolution and mantle degassing.

    Science.gov (United States)

    Shand, Paul; Gotch, Travis; Love, Andrew; Raven, Mark; Priestley, Stacey; Grocke, Sonia

    2016-10-15

    A decrease in flow from the iconic travertine mound springs of the Great Artesian Basin in South Australia has led to the oxidation of hypersulfidic soils and extreme soil acidification, impacting their unique groundwater dependent ecosystems. The build-up of pyrite in these systems occurred over millennia by the discharge of deep artesian sulfate-containing groundwaters through organic-rich subaqueous soils. Rare iron and aluminium hydroxysulfate minerals form thick efflorescences due to high evaporation rates in this arid zone environment, and the oxidised soils pose a significant risk to local aquatic and terrestrial ecosystems. The distribution of extreme acidification hazard is controlled by regional variations in the hydrochemistry of groundwater. Geochemical processes fractionate acidity and alkalinity into separate parts of the discharge zone allowing potentially extreme environments to form locally. Differences in groundwater chemistry in the aquifer along flow pathways towards the spring discharge zone are related to a range of processes including mineral dissolution and redox reactions, which in turn are strongly influenced by degassing of the mantle along deep crustal fractures. There is thus a connection between shallow critical zone ecosystems and deep crustal/mantle processes which ultimately control the formation of hypersulfidic soils and the potential for extreme geochemical environments.

  17. Extreme environments in the critical zone: Linking acidification hazard of acid sulfate soils in mound spring discharge zones to groundwater evolution and mantle degassing.

    Science.gov (United States)

    Shand, Paul; Gotch, Travis; Love, Andrew; Raven, Mark; Priestley, Stacey; Grocke, Sonia

    2016-10-15

    A decrease in flow from the iconic travertine mound springs of the Great Artesian Basin in South Australia has led to the oxidation of hypersulfidic soils and extreme soil acidification, impacting their unique groundwater dependent ecosystems. The build-up of pyrite in these systems occurred over millennia by the discharge of deep artesian sulfate-containing groundwaters through organic-rich subaqueous soils. Rare iron and aluminium hydroxysulfate minerals form thick efflorescences due to high evaporation rates in this arid zone environment, and the oxidised soils pose a significant risk to local aquatic and terrestrial ecosystems. The distribution of extreme acidification hazard is controlled by regional variations in the hydrochemistry of groundwater. Geochemical processes fractionate acidity and alkalinity into separate parts of the discharge zone allowing potentially extreme environments to form locally. Differences in groundwater chemistry in the aquifer along flow pathways towards the spring discharge zone are related to a range of processes including mineral dissolution and redox reactions, which in turn are strongly influenced by degassing of the mantle along deep crustal fractures. There is thus a connection between shallow critical zone ecosystems and deep crustal/mantle processes which ultimately control the formation of hypersulfidic soils and the potential for extreme geochemical environments. PMID:27256909

  18. Contaminants in Vadose Zone Environments

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Dawn M.; Freshley, Mark D.; Johnson, Timothy C.; Miracle, Ann L.

    2012-11-01

    Contaminants in vadose zone environments pose a long-term source and threat to groundwater resources, human health, and the environment. Several technical, regulatory, and policy challenges and opportunities are associated with contamination in vadose zone environments, particularly in remediation. In this special issue, ten papers present novel approaches to characterize, monitor, remediate, and predict the transport and fate of contaminants in vadose zone environments.

  19. Street Prostitution Zones and Crime

    OpenAIRE

    Bisschop, Paul; Kastoryano, Stephen; Van der Klaauw, Bas

    2015-01-01

    This paper studies the effects of introducing legal street prostitution zones on both registered and perceived crime. We exploit a unique setting in the Netherlands where legal street prostitution zones were opened in nine cities under different regulation systems. We provide evidence that the opening of these zones was not in response to changes in crime. Our difference-in-difference analysis using data on the largest 25 Dutch cities between 1994 and 2011 shows that opening a legal street pr...

  20. Learning About Intervention Target Zones

    OpenAIRE

    Klein, Michael W; Karen K. Lewis

    1991-01-01

    This paper provides a framework for evaluating how market participants' beliefs about foreign exchange target zones change as they learn about central bank intervention policy. In order to examine this behavior, we first generalize the standard target zone model to allow for intra-marginal intervention. Intra-marginal intervention implies that the position of market participants' beliefs about the target zone can be determined from their beliefs about the likelihood of intervention. As an app...

  1. Race, Ethnicity, and Discriminatory Zoning

    OpenAIRE

    Allison Shertzer; Tate Twinam; Randall P. Walsh

    2014-01-01

    Zoning has been cited as a discriminatory policy tool by critics, who argue that ordinances are used to deter the entry of minority residents into majority neighborhoods through density restrictions (exclusionary zoning) and locate manufacturing activity in minority neighborhoods (environmental racism). However, identifying discrimination in these regulations is complicated by the fact that land use and zoning have been co-evolving for nearly a century in most American cities, rendering resid...

  2. Estimation of groundwater recharge in arid and semi-arid areas based on water cycle simulation%基于水循环模拟的干旱半干旱地区地下水补给评价

    Institute of Scientific and Technical Information of China (English)

    陆垂裕; 孙青言; 李慧; 盖燕如

    2014-01-01

    干旱半干旱地区的地下水补给评价在地下水的开发利用和保护中起着基础性的重要作用。本文从全区域水循环整体的角度出发,以水循环模拟与地下水数值模拟紧密耦合的综合性水文模型 MODCYCLE为工具,以处于半干旱地区的通辽市平原区为例,探索地下水在“自然-社会”二元水循环过程中的补给规律。结果表明:通辽市平原区地下水的主要补给来源为降水入渗,占总补给量的65.2%;降水入渗补给量与降水量的变化趋势基本一致,但受众多因素影响,并不呈线性关系;年均降水入渗补给量农田区107.3 mm,非农田生态区29.1 mm,且前者较后者稳定;地下水从人口分布较少的平原坨沼区向社会经济活动频繁的中部平原区侧向净流动,年均净流量为6570万m3,呈逐年下降趋势。模型反映的地下水补给规律基本符合研究区域的客观情况,可以为当地地下水管理提供参考。该评价方法为类似地区的地下水研究提供一种可以选择的方式。%Groundwater recharge evaluation in arid and semi-arid areas plays a foundational role in the ex⁃ploitation and protection of the groundwater. In this study, from the perspective of water cycle for the whole region, the law of groundwater recharge is explored in the artificial-natural dual water cycle. The in⁃tegrated hydrology model named MODCYCLE is used, which is formed by the tightly-coupling of the water cycle model and the groundwater numerical simulation. The groundwater of the plain area in Tongliao, a typical semi-arid region, is evaluated as an example. The analytical results show that (1) the precipitation recharge, 65.2 % of the total recharge, is the main supply source of groundwater;(2) the variation trends of precipitation recharge and precipitation are basically consistent, but influenced by many factors, not a linear relationship;(3) the average annual amount of

  3. Problems of Chernobyl Exclusion Zone

    International Nuclear Information System (INIS)

    The collection comprises the results of researches and design activity in the ChNPP exclusion zone, aimed at the development of technologies, equipment and devices for radioactive waste management and ChNPP accident clean-up, at studying the composition and structure of the Exclusion zone soil activity solid bearers, form transformation of the fission products of fuel fallout radionuclide composition in the ChNPP near zone, the spatial distribution of radionuclides and other radioecological issues.. Much attention is paid to medical and biological aspects of the accident influence on the flora, fauna and people's health, labour conditions and incidence of the workers of the Exclusion zone

  4. Plant functional traits and phylogenetic relatedness explain variation in associations with root fungal endophytes in an extreme arid environment

    Science.gov (United States)

    Since root endophytes may ameliorate drought stress, understanding which plants associate with endophytes is important, especially in arid ecosystems. Here we characterized the root endophytes of 42 plants from an arid region of Argentina. We related colonization by arbuscular mycorrhizal fungi (AMF...

  5. New crops for arid lands. [Bladderpod, gumweed, guayule, jojoba, and buffalo gourd

    Energy Technology Data Exchange (ETDEWEB)

    Hinman, C.W.

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential or arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required. 20 references.

  6. Oviposition-site selection by Phyllomedusa sauvagii (Anura: Hylidae): An arboreal nester inhabiting arid environments

    Science.gov (United States)

    García, Cecilia G.; Lescano, Julián N.; Leynaud, Gerardo C.

    2013-08-01

    Breeding biology in Phyllomedusa sauvagii is related to vegetation since the species encloses its eggs in leaves above water. Considering that arid environments may represent high risks of death by desiccation for amphibians with this reproductive mode, we evaluated plant characteristics associated with sites used for oviposition in semi-permanent ponds in the Arid Chaco region of Argentina. Plant characteristics were used to fit a statistical habitat selection model that allows the prediction of nest presence. Our results show that P. sauvagii needs substrate with specific features for oviposition that would help to reduce the probability of eggs and tadpoles desiccation.

  7. Impacts of Present and Future Climate Variability and Change on Agriculture and Forestry in the Arid and Semi-Arid Tropics

    International Nuclear Information System (INIS)

    The arid and semi-arid regions account for approximately 30% of the world total area and are inhabited by approximately 20% of the total world population. Issues of present and future climate variability and change on agriculture and forestry in the arid and semi-arid tropics of the world were examined and discussion under each of these issues had been presented separately for Asia, Africa and Latin America. Several countries in tropical Asia have reported increasing surface temperature trends in recent decades. Although, there is no definite trend discernible in the long-term mean for precipitation for the tropical Asian region, many countries have shown a decreasing trend in rainfall in the past three decades. African rainfall has changed substantially over the last 60 yr and a number of theoretical, modelling and empirical analyses have suggested that noticeable changes in the frequency and intensity of extreme events, including floods may occur when there are only small changes in climate. Climate in Latin America is affected by the El Nino-southern oscillation (ENSO) phases and there is a close relationship between the increase and decrease of rainfall depending upon the warm or cold phases of the phenomenon. Over land regions of Asia, the projected area-averaged annual mean warming is likely to be 1.6 ± 0.2C in the 2020s, 3.1 ± 0.3C in the 2050s, and 4.6 ± 0.4C in the 2080s and the models show high uncertainty in projections of future winter and summer precipitation. Future annual warming across Africa is projected to range from 0.2C per decade to more than 0.5C per decade, while future changes in mean seasonal rainfall in Africa are less well defined. In Latin America, projections indicate a slight increase in temperature and changes in precipitation. Impacts of climate variability and changes are discussed with suitable examples. Agricultural productivity in tropical Asia is sensitive not only to temperature increases, but also to changes in the nature

  8. Comparison of satellite microwave backscattering (ASCAT and visible/near-infrared reflectances (PARASOL for the estimation of aeolian aerodynamic roughness length in arid and semi-arid regions

    Directory of Open Access Journals (Sweden)

    C. Prigent

    2012-04-01

    Full Text Available Previous studies examined the possibility to estimate the aeolian aerodynamic roughness length from satellites, either from visible/near-infrared observations or from microwave backscattering measurements. Here we compare the potential of the two approaches and propose to merge the two sources of information to benefit from their complementary aspects, i.e. the high spatial resolution of the visible/near-infrared (PARASOL part of the A-Train and the independence from atmospheric contamination of the active microwaves (ASCAT on board MetOp. A global map of the aeolian aerodynamic roughness length at 6 km resolution is derived, for arid and semi-arid regions. It shows very good consistency with the existing information on the properties of these surfaces. The dataset is available to the community, for use in atmospheric dust transport models.

  9. Comparison of satellite microwave backscattering (ASCAT and visible/near-infrared reflectances (PARASOL for the estimation of aeolian aerodynamic roughness length in arid and semi-arid regions

    Directory of Open Access Journals (Sweden)

    C. Prigent

    2012-11-01

    Full Text Available Previous studies examined the possibility to estimate the aeolian aerodynamic roughness length from satellites, either from visible/near-infrared observations or from microwave backscattering measurements. Here we compare the potential of the two approaches and propose to merge the two sources of information to benefit from their complementary aspects, i.e. the high spatial resolution of the visible/near-infrared (6 km for PARASOL that is part of the A-Train and the independence from atmospheric contamination of the active microwaves (ASCAT on board MetOp with a lower spatial resolution of 25 km. A global map of the aeolian aerodynamic roughness length at 6 km resolution is derived, for arid and semi-arid regions. It shows very good consistency with the existing information on the properties of these surfaces. The dataset is available to the community, for use in atmospheric dust transport models.

  10. Influence of soil and climate on root zone storage capacity

    Science.gov (United States)

    de Boer-Euser, Tanja; McMillan, Hilary; Hrachowitz, Markus; Winsemius, Hessel; Savenije, Hubert

    2016-04-01

    The catchment representative root zone storage capacity (Sr), i.e. the plant available soil water, is an important parameter of hydrological systems. It does not only influence the runoff from catchments, by controlling the partitioning of water fluxes but it also influences the local climate, by providing the source for transpiration. Sr is difficult to observe at catchment scale, due to heterogeneities in vegetation and soils. Sr estimates are traditionally derived from soil characteristics and estimates of root depths. In contrast, a recently suggested method allows the determination of Sr based on climate data, i.e. precipitation and evaporation, alone (Gao et al., 2014). By doing so, the time-variable size of Sr, is explicitly accounted for, which is not the case for traditional soil based methods. The time-variable size of Sr reflects root growth and thus the vegetation's adaption to medium-term fluctuations in the climate. Thus, we tested and compared Sr estimates from this 'climate based method' with estimates from soil data for 32 catchments in New Zealand. The results show a larger range in climate derived Sr than in soil derived Sr. Using a model experiment, we show that a model using the climate derived Sr is more accurately able to reproduce a set of hydrological regime signatures, in particular for humid catchments. For more arid catchments, the two methods provide similar model results. This implies that, although soil database information has some predictive power for model soil storage capacity, climate has a similar or greater control on Sr, as climate affects the evolving hydrological functioning of the root zone at the time scale of hydrological interest. In addition, Sr represents the plant available water and thus root surface, volume and density, and is therefore a more complete descriptor of vegetation influence on water fluxes than mere root depth. On balance, the results indicate that climate has a higher explanatory power than soils for

  11. Drought-tolerant Streptomyces pactum Act12 assist phytoremediation of cadmium-contaminated soil by Amaranthus hypochondriacus: great potential application in arid/semi-arid areas.

    Science.gov (United States)

    Cao, Shumiao; Wang, Wenke; Wang, Fei; Zhang, Jun; Wang, Zhoufeng; Yang, Shenke; Xue, Quanhong

    2016-08-01

    Microbe-assisted phytoremediation provides an effective approach to clean up heavy metal-contaminated soils. However, severe drought may affect the function of microbes in arid/semi-arid areas. Streptomyces pactum Act12 is a drought-tolerant soil actinomycete strain isolated from an extreme environment on the Qinghai-Tibet Plateau, China. In this study, pot experiments were conducted to assess the effect of Act12 on Cd tolerance, uptake, and accumulation in amaranth (Amaranthus hypochondriacus) under water deficit. Inoculated plants had higher Cd concentrations (root 8.7-33.9 %; shoot 53.2-102.1 %) and uptake (root 19.9-95.3 %; shoot 110.6-170.1 %) than non-inoculated controls in Cd-treated soil. The translocation factor of Cd from roots to shoots was increased by 14.2-75 % in inoculated plants, while the bioconcentration factor of Cd in roots and shoots was increased by 10.2-64.4 and 53.9-114.8 %, respectively. Moreover, inoculation with Act12 increased plant height, root length, and shoot biomass of amaranth in Cd-treated soil compared to non-inoculated controls. Physiochemical analysis revealed that Act12 enhanced Cd tolerance in the plants by increasing glutathione, elevating superoxide dismutase and catalase activities, as well as reducing malondialdehyde content in the leaves. The drought-tolerant actinomycete strain Act12 can enhance the phytoremediation efficiency of amaranth for Cd-contaminated soils under water deficit, exhibiting potential for application in arid and semi-arid areas. PMID:27072036

  12. ESTIMATION OF EXTRACELLULAR LIPOLYTIC ENZYME ACTIVITY BY THERMOPHILIC BACILLUS SP. ISOLATED FROM ARID AND SEMI-ARID REGION OF RAJASTHAN, INDIA

    Directory of Open Access Journals (Sweden)

    Deeksha Gaur

    2012-10-01

    Full Text Available Thermophilic organisms can be defined as, micro-organisms which are adapted to survive at high temperatures. The enzymes secreted by thermophilic bacteria are capable of catalyzing biochemical reactions at high temperatures. Thermophilic bacteria are able to produce thermostable lipolytic enzymes (capable of degradation of lipid at temperatures higher than mesophilic bacteria. Therefore, the isolation of thermophilic bacteria from natural sources and their identification are quite beneficial in terms of discovering thermostable lipase enzymes. Due to great temperature fluctuation in hot arid and semi-arid region of Rajasthan, this area could serve as a good source for new thermophilic lipase producing bacteria with novel industrially important properties. The main objective of this research is the isolation and estimation of industrially important thermophilic lipase enzyme produced by thermophilic bacteria, isolated from arid and semi-arid region of Rajasthan. For this research purpose soil samples were collected from Churu, Sikar and Jhunjunu regions of Rajasthan. Total 16 bacterial strains were isolated and among only 2 thermostable lipolytic enzyme producing bacteria were charcterized. The thermostable lipolytic enzyme was estimated by qualitative and quantitative experiments. The isolates were identified as Bacillus sp. by microscopic, biochemical and molecular characterization. The optimum enzyme activity was observed at pH 8, temperature 60°C and 6% salt concentrations at 24 hrs time duration. Lipolytic enzyme find useful in a variety of biotechnological fields such as food and dairy (cheese ripening, flavour development, detergent, pharmaceutical (naproxen, ibuprofen, agrochemical (insecticide, pesticide and oleochemical (fat and oil hydrolysis, biosurfactant synthesis industries. Lipolytic enzyme can be further used in many newer areas where they can serve as potential biocatalysts.

  13. Corpus callosum abnormalities, intellectual disability, speech impairment, and autism in patients with haploinsufficiency of ARID1B

    DEFF Research Database (Denmark)

    Hansen, Christina Halgren; Kjaergaard, S; Bak, M;

    2011-01-01

    Corpus callosum abnormalities, intellectual disability, speech impairment, and autism in patients with haploinsufficiency of ARID1B. Corpus callosum abnormalities are common brain malformations with a wide clinical spectrum ranging from severe intellectual disability to normal cognitive function...... of corpus callosum (CC), intellectual disability, severe speech impairment, and autism. The chromosome 6 breakpoint truncated ARID1B which was also truncated in a recently published translocation patient with a similar phenotype. Quantitative polymerase chain reaction (Q-PCR) data showed that a primer set...... with various sized deletions encompassing ARID1B confirms that haploinsufficiency of ARID1B is associated with CC abnormalities, intellectual disability, severe speech impairment, and autism. Our findings emphasize that ARID1B is important in human brain development and function in general...

  14. Renewable energy and sustainable urban development in hot arid regions - case of Egypt : development concepts and implementation strategies for new settlements

    OpenAIRE

    Abd-Elaal; Mohammad Refaat Mohammad

    2008-01-01

    The main objective of this research is to make a connection between the hot arid regions urban development and renewable energy e.g. photovoltaics (PV), to delineate urban integrated renewable energy e.g. Urban Integrated Photovoltaics (UIPV) as a new approach for building new sustainable settlements in hot arid regions. The study assumes that applying this approach can play a major role in developing communities of the hot arid regions. Furthermore, the study claimed that developing arid re...

  15. Zone refining of plutonium metal

    International Nuclear Information System (INIS)

    The zone refining process was applied to Pu metal containing known amounts of impurities. Rod specimens of plutonium metal were melted into and contained in tantalum boats, each of which was passed horizontally through a three-turn, high-frequency coil in such a manner as to cause a narrow molten zone to pass through the Pu metal rod 10 times. The impurity elements Co, Cr, Fe, Ni, Np, U were found to move in the same direction as the molten zone as predicted by binary phase diagrams. The elements Al, Am, and Ga moved in the opposite direction of the molten zone as predicted by binary phase diagrams. As the impurity alloy was zone refined, δ-phase plutonium metal crystals were produced. The first few zone refining passes were more effective than each later pass because an oxide layer formed on the rod surface. There was no clear evidence of better impurity movement at the slower zone refining speed. Also, constant or variable coil power appeared to have no effect on impurity movement during a single run (10 passes). This experiment was the first step to developing a zone refining process for plutonium metal

  16. Instrumentation for coastal zone management

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    stream_size 11 stream_content_type text/plain stream_name Trg_Course_Coast_Zone_Manage_1993_91.pdf.txt stream_source_info Trg_Course_Coast_Zone_Manage_1993_91.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  17. Management of coastal zone vegetation

    Digital Repository Service at National Institute of Oceanography (India)

    Untawale, A.G.

    stream_size 14 stream_content_type text/plain stream_name Trg_Course_Coast_Zone_Manage_1993_22.pdf.txt stream_source_info Trg_Course_Coast_Zone_Manage_1993_22.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  18. Hourly Wind Speed Interval Prediction in Arid Regions

    Science.gov (United States)

    Chaouch, M.; Ouarda, T.

    2013-12-01

    The long and extended warm and dry summers, the low rate of rain and humidity are the main factors that explain the increase of electricity consumption in hot arid regions. In such regions, the ventilating and air-conditioning installations, that are typically the most energy-intensive among energy consumption activities, are essential for securing healthy, safe and suitable indoor thermal conditions for building occupants and stored materials. The use of renewable energy resources such as solar and wind represents one of the most relevant solutions to overcome the increase of the electricity demand challenge. In the recent years, wind energy is gaining more importance among the researchers worldwide. Wind energy is intermittent in nature and hence the power system scheduling and dynamic control of wind turbine requires an estimate of wind energy. Accurate forecast of wind speed is a challenging task for the wind energy research field. In fact, due to the large variability of wind speed caused by the unpredictable and dynamic nature of the earth's atmosphere, there are many fluctuations in wind power production. This inherent variability of wind speed is the main cause of the uncertainty observed in wind power generation. Furthermore, producing wind power forecasts might be obtained indirectly by modeling the wind speed series and then transforming the forecasts through a power curve. Wind speed forecasting techniques have received substantial attention recently and several models have been developed. Basically two main approaches have been proposed in the literature: (1) physical models such as Numerical Weather Forecast and (2) statistical models such as Autoregressive integrated moving average (ARIMA) models, Neural Networks. While the initial focus in the literature has been on point forecasts, the need to quantify forecast uncertainty and communicate the risk of extreme ramp events has led to an interest in producing probabilistic forecasts. In short term

  19. Excavation damaged zone

    Energy Technology Data Exchange (ETDEWEB)

    Popp, T.; Salzer, K.; Minkley, W. [Institut fur Gebirgsmechanik GmbH, Leipzig (Germany); Gibert, D.; Nicollin, F.; Kergosien, B. [Rennes-1 Univ., GdR FORPRO (CNRS/ANDRA GdR 788) and Geosciences Rennes (CNRS/UR1 UMR 6118) (France); Bossart, P. [Federal Office for Topography, Wabern (Switzerland); Nussbaum, C. [Institut Geotechnique SA, St-Ursanne (Switzerland); Robinet, J.C.; Nguyen, M.T. [EGC Euro-Geomat-Consulting, 45 - Orleans (France); Barnichon, J.D.; Plas, F. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Ghorbani, A.; Cosenza, P.; Florsch, N. [Pierre et Marie Curie Univ., UMR 7619 Sisyphe, 75 - Paris (France); Revil, A.; Jougnot, D. [Aix-Marseille-2, UMR 6635, CNRS-CEREGE, 13 (France); Schmutz, M. [EGID, M. de Montaigne Univ., 33 - Pessac (France); Contrucci, I.; Klein, E. [Institut National de l' Environnement Industriel et des Risques (INERIS), Ecole des Mines de Nancy, 54 - Nancy (France); Cabrera, J.; Ben-Slimane, K.; Rejeb, A.; Matray, J.M.; Savoye, S. [Institut de Radioprotection et de Surete Nucleaire (IRSN), 92 - Fontenay-aux-Roses (France); Maiolino, S. [Ecole Polytechnique, Lab. de Mecanique des Solides, UMR 7649, LMS, 91 - Palaiseau (France); CETE de Lyon/LRPC de Lyon/Meca Roches/ ERA, 69 - Bron (France); Yong, S.; Loew, S.; Fidelibus, C.; Lemy, F. [Engineering Geology, ETH Zurich, Zurich (Switzerland); Frank, E. [Swiss Federal Nuclear Safety Inspectorate (HSK), Villigen (Switzerland); Chun-Liang, Zhang; Tilmann, Rothfuchs [Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS) mbH, Braunschweig (Germany)

    2007-07-01

    This session gathers 10 articles (posters) dealing with: the influence of bedding planes to EDZ evolution and the coupled HM properties of Opalinus Clay; the electrical tomography monitoring of the EDZ during the excavation of the gallery 04 in the Mont Terri rock laboratory; the seismic endoscopy and tomography of the EDZ of the gallery 04 in the Mont Terri rock laboratory; a elastoplastic damage model for saturated and unsaturated stiffness clays: description and application to the modelling of EDZ around drifts in Callovo-Oxfordian argillites; the non-invasive monitoring of water content and microcracks in argillites using spectral induced polarization; EDZ investigations by ultrasonic borehole logging in drifts of different ages excavated in argillaceous formations of the Tournemire experimental station (Aveyron, France); the excavation damaged zones in the argillaceous Tournemire site: characterisation and failure mechanisms; the hardening-based degradation factor: influence of mean stress and stiffness; the disturbance in the EDZ in the Opalinus clay at Mont Terri; and the experimental study on self-sealing capacity of clay rocks.

  20. Volcanic Zone, New Zealand

    Directory of Open Access Journals (Sweden)

    Graham J. Weir

    2001-01-01

    Full Text Available A conceptual model of the Taupo Volcanic Zone (TVZ is developed, to a depth of 25 km, formed from three constant density layers. The upper layer is formed from eruption products. A constant rate of eruption is assumed, which eventually implies a constant rate of extension, and a constant rate of volumetric creation in the middle and bottom layers. Tectonic extension creates volume which can accomodate magmatic intrusions. Spreading models assume this volume is distributed throughout the whole region, perhaps in vertical dykes, whereas rifting models assume the upper crust is thinned and the volume created lies under this upper crust. Bounds on the heat flow from such magmatic intrusions are calculated. Heat flow calculations are performed and some examples are provided which match the present total heat output from the TVZ of about 4200 MW, but these either have extension rates greater than the low values of about 8 ± 4 mm/a being reported from GPS measurements, or else consider extension rates in the TVZ to have varied over time.

  1. Study on the glacier variation and its runoff responses in the arid region of Northwest China

    Institute of Scientific and Technical Information of China (English)

    刘潮海; 康尔泗; 刘时银; 陈建明; 刘宗香

    1999-01-01

    The glaciers in the arid region of Northwest China are viewed as an independent system, and glacier variation and mass balance fluctuation since the Little Ice Age and in the recent decades are estimated. Based on the estimation, the threshold time of glacier runoff against the backgrounds of the current and future varying climate conditions is simulated.

  2. Extensive Green Roof Species and Soilless Media Evaluations in Semi-arid Colorado

    Science.gov (United States)

    In the high elevation, semi-arid climate of Colorado, green roofs have not been scientifically tested. This research examined alternative plant species, soilless media blends and plant interactions on an existing, modular-extensive (shallow, 10 cm deep) green roof in Denver, Colo...

  3. Insertional Mutagenesis Identifies a STAT3/Arid1b/β-catenin Pathway Driving Neurofibroma Initiation

    Directory of Open Access Journals (Sweden)

    Jianqiang Wu

    2016-03-01

    Full Text Available To identify genes and signaling pathways that initiate Neurofibromatosis type 1 (NF1 neurofibromas, we used unbiased insertional mutagenesis screening, mouse models, and molecular analyses. We mapped an Nf1-Stat3-Arid1b/β-catenin pathway that becomes active in the context of Nf1 loss. Genetic deletion of Stat3 in Schwann cell progenitors (SCPs and Schwann cells (SCs prevents neurofibroma formation, decreasing SCP self-renewal and β-catenin activity. β-catenin expression rescues effects of Stat3 loss in SCPs. Importantly, P-STAT3 and β-catenin expression correlate in human neurofibromas. Mechanistically, P-Stat3 represses Gsk3β and the SWI/SNF gene Arid1b to increase β-catenin. Knockdown of Arid1b or Gsk3β in Stat3fl/fl;Nf1fl/fl;DhhCre SCPs rescues neurofibroma formation after in vivo transplantation. Stat3 represses Arid1b through histone modification in a Brg1-dependent manner, indicating that epigenetic modification plays a role in early tumorigenesis. Our data map a neural tumorigenesis pathway and support testing JAK/STAT and Wnt/β-catenin pathway inhibitors in neurofibroma therapeutic trials.

  4. Insertional Mutagenesis Identifies a STAT3/Arid1b/β-catenin Pathway Driving Neurofibroma Initiation.

    Science.gov (United States)

    Wu, Jianqiang; Keng, Vincent W; Patmore, Deanna M; Kendall, Jed J; Patel, Ami V; Jousma, Edwin; Jessen, Walter J; Choi, Kwangmin; Tschida, Barbara R; Silverstein, Kevin A T; Fan, Danhua; Schwartz, Eric B; Fuchs, James R; Zou, Yuanshu; Kim, Mi-Ok; Dombi, Eva; Levy, David E; Huang, Gang; Cancelas, Jose A; Stemmer-Rachamimov, Anat O; Spinner, Robert J; Largaespada, David A; Ratner, Nancy

    2016-03-01

    To identify genes and signaling pathways that initiate Neurofibromatosis type 1 (NF1) neurofibromas, we used unbiased insertional mutagenesis screening, mouse models, and molecular analyses. We mapped an Nf1-Stat3-Arid1b/β-catenin pathway that becomes active in the context of Nf1 loss. Genetic deletion of Stat3 in Schwann cell progenitors (SCPs) and Schwann cells (SCs) prevents neurofibroma formation, decreasing SCP self-renewal and β-catenin activity. β-catenin expression rescues effects of Stat3 loss in SCPs. Importantly, P-STAT3 and β-catenin expression correlate in human neurofibromas. Mechanistically, P-Stat3 represses Gsk3β and the SWI/SNF gene Arid1b to increase β-catenin. Knockdown of Arid1b or Gsk3β in Stat3(fl/fl);Nf1(fl/fl);DhhCre SCPs rescues neurofibroma formation after in vivo transplantation. Stat3 represses Arid1b through histone modification in a Brg1-dependent manner, indicating that epigenetic modification plays a role in early tumorigenesis. Our data map a neural tumorigenesis pathway and support testing JAK/STAT and Wnt/β-catenin pathway inhibitors in neurofibroma therapeutic trials. PMID:26904939

  5. Semi-arid Northeast Brazil: integrated modelling of regional development and global change impacts

    NARCIS (Netherlands)

    Krol, Maarten S.; Fuhr, Dagmar; Döring, Andreas; Unruh, Jon D.; Krol, Maarten S.; Kliot, Nurit

    2004-01-01

    Societies in semi-arid areas in developing regions are amongst those most vulnerable to climate variability and potentially most vulnerable to climate change. The vulnerability to climate variability emerges from a combination of the level of availability of natural resources and the human dependenc

  6. Land Use and Environmental Variability Impacts on the Phenology of Arid Agro-Ecosystems

    Science.gov (United States)

    Romo-Leon, Jose Raul; van Leeuwen, Willem J. D.; Castellanos-Villegas, Alejandro

    2016-02-01

    The overexploitation of water resources in arid environments often results in abandonment of large extensions of agricultural lands, which may (1) modify phenological trends, and (2) alter the sensitivity of specific phenophases to environmental triggers. In Mexico, current governmental policies subsidize restoration efforts, to address ecological degradation caused by abandonments; however, there is a need for new approaches to assess their effectiveness. Addressing this, we explore a method to monitor and assess (1) land surface phenology trends in arid agro-ecosystems, and (2) the effect of climatic factors and restoration treatments on the phenology of abandoned agricultural fields. We used 16-day normalized difference vegetation index composites from the moderate resolution imaging spectroradiometer from 2000 to 2009 to derive seasonal phenometrics. We then derived phenoclimatic variables and land cover thematic maps, to serve as a set of independent factors that influence vegetation phenology. We conducted a multivariate analysis of variance to analyze phenological trends among land cover types, and developed multiple linear regression models to assess influential climatic factors driving phenology per land cover analyzed. Our results suggest that the start and length of the growing season had different responses to environmental factors depending on land cover type. Our analysis also suggests possible establishment of arid adapted species (from surrounding ecosystems) in abandoned fields with longer times since abandonment. Using this approach, we were able increase our understanding on how climatic factors influence phenology on degraded arid agro-ecosystems, and how this systems evolve after disturbance.

  7. Comparison of groundwater recharge estimation methods for the semi-arid Nyamandhlovu area, Zimbabwe

    NARCIS (Netherlands)

    Sibanda, T.; Nonner, J.C.; Uhlenbrook, S.

    2009-01-01

    The Nyamandhlovu aquifer is the main water resource in the semi-arid Umguza district in Matebeleland North Province in Zimbabwe. The rapid increase in water demand in the city of Bulawayo has prompted the need to quantify the available groundwater resources for sustainable utilization. Groundwater r

  8. Regional difference of aridity/humidity conditions changeover China during the last thirty years

    Institute of Scientific and Technical Information of China (English)

    YIN Yunhe; WU Shaohong; ZHENG Du; YANG Qingye

    2005-01-01

    The meteorological data of 616 stations in China were used to calculate the potential evapotranspiration and aridity/humidity index by applying the modified FAO-Penman-Monteith model. Regional difference of trends in precipitation, potential evapotranspiration and aridity/humidity index over China and their interdecadal variations were analyzed from 1971 to 2000. The results show that all the four climatic factors trends have obvious regional difference and interdecadal variations. Annual precipitation during the 30-year period shows an increasing trend over most regions of China, with decreasing trends in potential evapotranspiration and aridity/humidity index. Most regions in China become more humid, especially significant in northern Xinjiang, eastern Tibet, western Sichuan, and northern Yunnan. The average value over China would mask the regional difference of climate change because of the complex environmental condition in China. Therefore regional difference should be analyzed to further understand climate change and its impacts. Both water supply and demand need to be considered when attempting to study regional aridity/humidity conditions.

  9. THE IMPORTANCE OF THE BIODIVERSITY OF SOIL BIOTA IN ARID ECOSYSTEMS

    Science.gov (United States)

    The importance of soil biota in maintaining ecosystem integrity is examined by a review of studies of soil processes and soil biota in arid ecosystems. In decomposition and mineralization processes, there is a temporal succession of microarthropod and nematode species. Tydeid mit...

  10. Plant-associated microbiomes in arid lands: diversity, ecology and biotechnological potential

    KAUST Repository

    Soussi, Asma

    2015-08-28

    Background: Aridification is a worldwide serious threat directly affecting agriculture and crop production. In arid and desert areas, it has been found that microbial diversity is huge, built of microorganisms able to cope with the environmental harsh conditions by developing adaptation strategies. Plants growing in arid lands or regions facing prolonged abiotic stresses such as water limitation and salt accumulation have also developed specific physiological and molecular stress responses allowing them to thrive under normally unfavorable conditions. Scope: Under such extreme selection pressures, special root-associated bacterial assemblages, endowed with capabilities of plant growth promotion (PGP) and extremophile traits, are selected by the plants. In this review, we provide a general overview on the microbial diversity in arid lands and deserts versus specific microbial assemblages associated with plants. The ecological drivers that shape this diversity, how plant-associated microbiomes are selected, and their biotechnological potential are discussed. Conclusions: Selection and recruitment of the plant associated bacterial assemblages is mediated by the combination of the bio-pedo-agroclimatic conditions and the plant species or varieties. Diversity and functional redundancy of these associated PGPR makes them very active in supporting plant improvement, health and resistance to drought, salt and related stresses. Implementing proper biotechnological applications of the arid and desert-adapted PGPR constitute the challenge to be raised.

  11. Site-specific properties and irreversible vegetation changes in semi-arid grazing systems

    NARCIS (Netherlands)

    Rietkerk, M; vandenBosch, F; vandeKoppel, J

    1997-01-01

    There is an urgent need to develop a mechanistic understanding of how site-specific properties can lead to irreversible vegetation changes. We show, by means of a bifurcation analysis of two mathematical models, how site-specific properties determine the resilience of vegetation changes in semi-arid

  12. Infiltration and planting pits for improved water management and maize yield in semi-arid Zimbabwe

    NARCIS (Netherlands)

    Nyakudya, I.W.; Stroosnijder, L.; Nyagumbo, I.

    2014-01-01

    Realising that rainwater harvesting (RWH) improves crop productivity, smallholder farmers in semi-arid Zimbabwe modified contour ridges traditionally used for rainwater management by digging infiltration pits inside contour ridge channels in order to retain more water in crop fields. However, scient

  13. Understanding hydrological variability for improved water management in the Semi-Arid Karkheh basin, Iran

    NARCIS (Netherlands)

    Masih, I.

    2011-01-01

    This study provides a hydrology based assessment of (surface) water resources and its continuum of variability and change at different spatio-temporal scales in the semi-arid Karkheh Basin, Iran, where water is scarce, competition among users is high and massive water resources development is under

  14. Uncertainty in Ecohydrological Modeling in an Arid Region Determined with Bayesian Methods.

    Science.gov (United States)

    Yang, Junjun; He, Zhibin; Du, Jun; Chen, Longfei; Zhu, Xi

    2016-01-01

    In arid regions, water resources are a key forcing factor in ecosystem circulation, and soil moisture is the critical link that constrains plant and animal life on the soil surface and underground. Simulation of soil moisture in arid ecosystems is inherently difficult due to high variability. We assessed the applicability of the process-oriented CoupModel for forecasting of soil water relations in arid regions. We used vertical soil moisture profiling for model calibration. We determined that model-structural uncertainty constituted the largest error; the model did not capture the extremes of low soil moisture in the desert-oasis ecotone (DOE), particularly below 40 cm soil depth. Our results showed that total uncertainty in soil moisture prediction was improved when input and output data, parameter value array, and structure errors were characterized explicitly. Bayesian analysis was applied with prior information to reduce uncertainty. The need to provide independent descriptions of uncertainty analysis (UA) in the input and output data was demonstrated. Application of soil moisture simulation in arid regions will be useful for dune-stabilization and revegetation efforts in the DOE. PMID:26963523

  15. Uncertainty in Ecohydrological Modeling in an Arid Region Determined with Bayesian Methods.

    Directory of Open Access Journals (Sweden)

    Junjun Yang

    Full Text Available In arid regions, water resources are a key forcing factor in ecosystem circulation, and soil moisture is the critical link that constrains plant and animal life on the soil surface and underground. Simulation of soil moisture in arid ecosystems is inherently difficult due to high variability. We assessed the applicability of the process-oriented CoupModel for forecasting of soil water relations in arid regions. We used vertical soil moisture profiling for model calibration. We determined that model-structural uncertainty constituted the largest error; the model did not capture the extremes of low soil moisture in the desert-oasis ecotone (DOE, particularly below 40 cm soil depth. Our results showed that total uncertainty in soil moisture prediction was improved when input and output data, parameter value array, and structure errors were characterized explicitly. Bayesian analysis was applied with prior information to reduce uncertainty. The need to provide independent descriptions of uncertainty analysis (UA in the input and output data was demonstrated. Application of soil moisture simulation in arid regions will be useful for dune-stabilization and revegetation efforts in the DOE.

  16. Tillage and farmyard manure efects on crusting and compacting soils at Katumani, Semi-arid Kenya

    NARCIS (Netherlands)

    Biamah, E.K.; Sterk, G.; Stroosnijder, L.

    2008-01-01

    In semi-arid Kenya, the most dominatn soil types are of limited agricultural productivity due to crusting and compaction. The occurence of soil crusting and compaction is attributed to seasonal rainfall characteristics, physical soil properties and bad tillage practices. Soil crusting and compaction

  17. Runoff controlling factors in various sized catchments in a semi-arid Mediterranean environment in Spain

    NARCIS (Netherlands)

    Wit, A.M.W. de

    2001-01-01

    Understanding land degradation in a semi-arid Mediterranean environment is very difficult because of the contributing factors: precipitation, infiltration vegetation cover and discontinuity of flow and the temporal and spatial levels of resolution at which these factors are acting. Therefore it is s

  18. The recharge process in alluvial strip aquifers in arid Namibia and implication for artificial recharge

    Science.gov (United States)

    Sarma, Diganta; Xu, Yongxin

    2016-10-01

    Alluvial strip aquifers associated with ephemeral rivers are important groundwater supply sources that sustain numerous settlements and ecological systems in arid Namibia. More than 70 % of the population in the nation's western and southern regions depend on alluvial aquifers associated with ephemeral rivers. Under natural conditions, recharge occurs through infiltration during flood events. Due to the characteristic spatial and temporal variability of rainfall in arid regions, recharge is irregular making the aquifers challenging to manage sustainably and they are often overexploited. This condition is likely to become more acute with increasing water demand and climate change, and artificial recharge has been projected as the apparent means of increasing reliability of supply. The article explores, through a case study and numerical simulation, the processes controlling infiltration, significance of surface water and groundwater losses, and possible artificial recharge options. It is concluded that recharge processes in arid alluvial aquifers differ significantly from those processes in subhumid systems and viability of artificial recharge requires assessment through an understanding of the natural recharge process and losses from the aquifer. It is also established that in arid-region catchments, infiltration through the streambed occurs at rates dependent on factors such as antecedent conditions, flow rate, flow duration, channel morphology, and sediment texture and composition. The study provides an important reference for sustainable management of alluvial aquifer systems in similar regions.

  19. Soil quality improvement for crop production in semi-arid West Africa

    NARCIS (Netherlands)

    Ouédraogo, E.

    2004-01-01

    Soil quality maintenance and crop production improvement in semi-arid West Africa require appropriate cropping technologies, which are ecologically sound and economically viable. Thus, on-farm and on-station experiments have been carried out on the central plateau and in the south of Burkina Faso Th

  20. Organic matter and water addition enhance soil respiration in an arid region.

    Directory of Open Access Journals (Sweden)

    Liming Lai

    Full Text Available Climate change is generally predicted to increase net primary production, which could lead to additional C input to soil. In arid central Asia, precipitation has increased and is predicted to increase further. To assess the combined effects of these changes on soil CO2 efflux in arid land, a two factorial manipulation experiment in the shrubland of an arid region in northwest China was conducted. The experiment used a nested design with fresh organic matter and water as the two controlled parameters. It was found that both fresh organic matter and water enhanced soil respiration, and there was a synergistic effect of these two treatments on soil respiration increase. Water addition not only enhanced soil C emission, but also regulated soil C sequestration by fresh organic matter addition. The results indicated that the soil CO2 flux of the shrubland is likely to increase with climate change, and precipitation played a dominant role in regulating soil C balance in the shrubland of an arid region.