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. Leaf protein concentrate as food supplement from arid zone plants.

    Science.gov (United States)

    Rathore, Mala

    2010-06-01

    In arid and semi-arid areas where prevalence of droughts and famines is a recurring feature, forest cover can in general make valuable contributions to food security and provide income to the rural poor. Protein and calorie malnutrition is widespread in these areas leading to high child mortality rate. Plant species can play an important role in overcoming this by being used as a source of leaf protein concentrate (LPC), a highly nutritious food. LPC should be considered seriously as it can serve as an additional protein source in the case of non-ruminants and man, especially in drought prone areas. The use of LPC in developing countries as an alternative protein source to fishmeal in broiler diet holds tremendous promise as it can substantially lower high cost of fishmeal and eventually the acute shortage of animal protein supply. Potential tropical plants for LPC production have been evaluated and selected for further research by United States Department of Agriculture. The present study was aimed to determine the potential of arid zone plants for preparation of LPC. Extraction characteristics of the several plant species have been studied and the quality of LPC prepared from them was investigated. Different fractions, chloroplastic and cytoplasmic proteins, were analyzed for their crude protein contents. Analysis of LPC shows considerable differences in their protein contents, which was found to range from 13.7 to 88.9%. Based on this, Achyranthes aspera and Tephrosia purpurea were found to be the best suited plants for LPC preparation.

  3. 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.

  4. Antibacterial and Antifungal Potential of some Arid Zone Plants.

    Science.gov (United States)

    Jain, S C; Pancholi, B; Singh, R; Jain, R

    2010-07-01

    Sequential extracts of some medicinally important arid zone plants of Rajasthan, viz. Lepidagathis trinervis Nees., Polycarpea corymbosa Lam. and Sericostoma pauciflorum Stocks. ex Wight. were tested against six bacterial (Gram +ve and Gram -ve) and five fungal strains using agar well diffusion method. Ethyl acetate extract of L. trinervis showed maximum activity against Bacillus subtilis, Enterobactor aerogenes, Pseudomonas aeruginosa, Aspergillus flavus and Trichophyton rubrum (inhibition zone 16.00±0.81, 13.33±0.66, 14.33±1.85, 14.30±0.34 and 23.00±0.00 mm) at varied minimum inhibitory concentrations of 82, 20, 41, 41 and 20 μg/ml, respectively.

  5. Antibacterial and antifungal potential of some arid zone plants

    Directory of Open Access Journals (Sweden)

    Jain S

    2010-01-01

    Full Text Available Sequential extracts of some medicinally important arid zone plants of Rajasthan, viz. Lepidagathis trinervis Nees., Polycarpea corymbosa Lam. and Sericostoma pauciflorum Stocks. ex Wight. were tested against six bacterial (Gram +ve and Gram -ve and five fungal strains using agar well diffusion method. Ethyl acetate extract of L. trinervis showed maximum activity against Bacillus subtilis, Enterobactor aerogenes, Pseudomonas aeruginosa, Aspergillus flavus and Trichophyton rubrum (inhibition zone 16.00±0.81, 13.33±0.66, 14.33±1.85, 14.30±0.34 and 23.00±0.00 mm at varied minimum inhibitory concentrations of 82, 20, 41, 41 and 20 μg/ml, respectively.

  6. Impacts of Climate Anomalies on the Vegetation Patterns in the Arid and Semi-Arid Zones of Uzbekistan

    Science.gov (United States)

    Dildora, Aralova; Toderich, Kristina; Dilshod, Gafurov

    2016-08-01

    Steadily rising temperature anomalies in last decades are causing changes in vegetation patterns for sensitive to climate change in arid and semi-arid dryland ecosystems. After desiccation of the Aral Sea, Uzbekistan has been left with the challenge to develop drought and heat stress monitoring system and tools (e.g., to monitor vegetation status and/crop pattern dynamics) with using remote sensing technologies in broad scale. This study examines several climate parameters, NDVI and drought indexes within geostatistical method to predict further vegetation status in arid and semi-arid zones of landscapes. This approaches aimed to extract and utilize certain variable environmental data (temperature and precipitation) for assessment and inter-linkages of vegetation cover dynamics, specifically related to predict degraded and recovered zones or desertification process in the drylands due to scarcity of water resources and high risks of climate anomalies in fragile ecosystem of Uzbekistan.

  7. 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

  8. 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.

  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. 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.

  11. L'économie de la gestion des risques en zone semi-aride

    NARCIS (Netherlands)

    Dijk, van J.W.M.; Tielekes, E.; Schlecht, E.; Hiernaux, P.

    2001-01-01

    Toute forme de gestion ou d'aménagement des ressources fourragères pour les éleveurs dans la zone semi-aride au Sahel commence obligatoirement par l'appréciation d'un certain nombre de variables et notamment leur variabilité dans l'espace et dans le temps. Cette variabilité est la source d'une vaste

  12. Molecular phylogeography and systematics of the arid-zone members of the Egernia whitii (Lacertilia: Scincidae) species group.

    Science.gov (United States)

    Chapple, David G; Keogh, J Scott; Hutchinson, Mark N

    2004-12-01

    We assembled a molecular phylogeny for the arid-zone members of the Egernia whitii species group to test Pianka's [Zoogeography and speciation of Australian desert lizards: an ecological perspective, Copeia (1972) 127-145] hypothesis that habitat specificity to the three major arid-zone vegetation communities is the primary cause of lizard speciation within the arid interior of Australia. This hypothesis predicts that species should exhibit phylogeographic structuring concordant with the major arid-zone vegetation types. Sequence data were obtained from four of the five arid-zone members of the E. whitii species group, and from across the ranges of the ecologically generalized E. inornata and E. multiscutata and the more specialized E. striata. We targeted a fragment (696 base pair (bp)) of the mitochondrial genome comprising the 3' half of the ND4 gene. We analysed the data using parsimony, maximum likelihood and Bayesian methods. Our phylogeny confirms the monophyly of the arid-zone members of the species group, although the phylogenetic relationships among species were not fully resolved. Although our topology does not support the recognition of the existing subspecies within E. multiscutata, there is a substantial phylogeographic break between South Australian/Victorian (Clade 1) and Western Australian (Clade 2) populations. We found considerable phylogeographic structure within E. inornata, with six major clades identified. However, these clades were not concordant with the distribution of habitat types in the arid-zone. Phylogeographic structure was also observed in the more specialized E. striata, although our analysis revealed close phylogenetic affinities between the sympatric species E. striata and E. kintorei. Shimodaira-Hasegawa topology tests were equivocal in regard to whether the phylogeographic structure within E. striata was in accordance with Pianka's predictions. Although our data failed to provide strong support for the suggestion that

  13. 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.

  14. Untangling a species complex of arid zone grasses (Triodia) reveals patterns congruent with co-occurring animals.

    Science.gov (United States)

    Anderson, Benjamin M; Barrett, Matthew D; Krauss, Siegfried L; Thiele, Kevin

    2016-08-01

    The vast Australian arid zone formed over the last 15million years, and gradual aridification as well as more extreme Pliocene and Pleistocene climate shifts have impacted the evolution of its biota. Understanding the evolutionary history of groups of organisms or regional biotas such as the Australian arid biota requires clear delimitation of the units of biodiversity (taxa). Here we integrate evidence from nuclear (ETS and ITS) and chloroplast (rps16-trnK spacer) regions and morphology to clarify taxonomic boundaries in a species complex of Australian hummock grasses (Triodia) to better understand the evolution of Australian arid zone plants and to evaluate congruence in distribution patterns with co-occurring organisms. We find evidence for multiple new taxa in the T. basedowii species complex, but also incongruence between data sets and indications of hybridization that complicate delimitation. We find that the T. basedowii complex has high lineage diversity and endemism in the biologically important Pilbara region of Western Australia, consistent with the region acting as a refugium. Taxa show strong geographic structure in the Pilbara, congruent with recent work on co-occurring animals and suggesting common evolutionary drivers across the biota. Our findings confirm recognition of the Pilbara as an important centre of biodiversity in the Australian arid zone, and provide a basis for future taxonomic revision of the T. basedowii complex and more detailed study of its evolutionary history and that of arid Australia.

  15. 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.

  16. 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

  17. 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.

  18. Prevalence of peste des petits ruminants in the arid zone in the Republic of Niger

    Directory of Open Access Journals (Sweden)

    Souaibou Farougou

    2013-03-01

    Full Text Available The study aimed to determine the prevalence of peste des petits ruminants in the arid zone (Niamey, Tillabéry and Tahoua of the Republic of Niger. A serological survey was conducted and 519 serum samples were collected from 253 unvaccinated sheep and 266 unvaccinated goats. The sample included 340 female animals (168 sheep and 172 goats and 160 kids and lambs (78 lambs and 82 kids. A competitive enzyme-linked immunosorbent assay yielded an overall seroprevalence of 45.0%. The prevalence in sheep was 42.0% compared with 47.9% in goats. The seroprevalence observed amongst small ruminants in Tahoua (49.8% and Tillabéry (46.6% was significantly higher (p = 0.001 than that observed in animals from Niamey (25.1%. It was also higher (p = 0.04 in sheep younger than two years (51.8% than in adults (37.6%. Conversely, the seroprevalence showed no significant difference between male animals (35.8% in sheep; 50.1% in goats and female animals (45.1% in sheep; 46.4% in goats. The prevalence of the disease observed amongst the sheep and goat populations confirms the continued danger of this disease in the areas studied. It is therefore necessary to develop strategies such as improving livestock services, providing effective vaccines and implementing a vaccination programme for an effective control of the disease in sub-Saharan Africa.

  19. 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.

  20. 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.

  1. 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)

  2. Environmental resilience of rangeland ecosystems: assessment drought indices and vegetation trends on arid and semi-arid zones of Central Asia

    Science.gov (United States)

    Aralova, Dildora; Toderich, Kristina; Jarihani, Ben; Gafurov, Dilshod; Gismatulina, Liliya; Osunmadewa, Babatunde A.; Rahamtallah Abualgasim, Majdaldin

    2016-10-01

    The Central Asian (CA) rangelands is a part of the arid and semi-arid ecological zones and spatial extent of drylands in CA (Tajikistan, Kazakhstan, Uzbekistan, Kyrgyzstan, and Turkmenistan) is vast. Projections averaged across a suite of climate models, as measured between 1950-2012 by Standardised Precipitation-Evapotranspiration Index (SPEI) estimated a progressively increasing drought risks across rangelands (Turkmenistan, Tajikistan and Uzbekistan) especially during late summer and autumn periods, another index: Potential Evapotranspiration (PET) indicated drought anomalies for Turkmenistan and partly in Uzbekistan (between 1950-2000). On this study, we have combined a several datasets of drought indices ( SPIE, PET, temperature_T°C and precipitation_P) for better estimation of resilience/non-resilience of the ecosystems after warming the temperature in the following five countries, meanwhile, warming of climate causing of increasing rating of degradations and extension of desertification in the lowland and foothill zones of the landscape and consequently surrounding experienced of a raising balance of evapotranspiration (ET0). The study concluded, increasing drought anomalies which is closely related with raising (ET0) in the lowland and foothill zones of CA indicated on decreasing of NDVI indices with occurred sandy and loamy soils it will resulting a loss of vegetation diversity (endangered species) and raising of wind speeds in lowlands of CA, but on regional level especially towards agricultural intensification (without rotation) it indicated no changes of greenness index. It was investigated to better interpret how vegetation feedback modifies the sensitivity of drought indices associated with raising tendency of air temperature and changes of cold and hot year seasons length in the territory of CA.

  3. 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.

  4. 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.

  5. 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.)

  6. Energy use pattern in production agriculture of a typical village in arid zone - Part III

    Energy Technology Data Exchange (ETDEWEB)

    Singh, H. E-mail: hsingh11@rediffmail.com; Mishra, D.; Nahar, N.M

    2004-09-01

    India has 31.71 Mha of hot arid areas, of which 61.8% is in Western Rajasthan, commonly known as the 'Thar Desert'. A detailed study of the energy use pattern in production agriculture for a representative village, Pemasar, district Bikaner of zone II (200 mm/yr {<=} annual rainfall < 300 mm/yr) has been conducted. Out of the total geographical area (945.7 ha) of the village, 693.6 ha is cultivable land. The main crops grown in the village are cluster bean, moth bean, groundnut, green gram (Kharif), wheat, mustard, gram, barley and rocket salad (Rabi). In general, Kharif crops are grown as rain fed crops, but due to low rainfall in the zone and the presence of the Indira Gandhi Canal, even Kharif crops are raised under irrigated conditions. However, the area covered under irrigation is meagre as the availability of canal water is very much limited and uncertain. Operation wise, the total energy consumed for rain fed Kharif crops is minimum (1187.6 MJ/ha) for moth bean and maximum (1261.9 MJ/ha) for cluster bean, while for irrigated crops, it is minimum (2847.3 MJ/ha) for moth bean, and maximum (12,809.6 MJ/ha) for groundnut. The average specific energy for cultivation of cluster bean (rain fed), cluster bean (irrigated), moth bean (rain fed), moth bean (irrigated) and groundnut were 11.7, 7.5, 7.7, 7.4 and 11.2 MJ/ha, respectively. Operation wise, the energy consumed for Rabi crops is minimum (3855.6 MJ/ha) for rocket salad followed by 4779.4 MJ/ha for mustard, 4845.2 MJ/ha for gram and maximum (7953.2 MJ/ha) for wheat. The average specific energy for cultivation of wheat, gram, mustard and rocket salad were 11.4, 16.5, 13.2 and 13.7 MJ/ha, respectively. The average values of estimated energy ratio for cluster bean (rain fed), cluster bean (irrigated), moth bean (rain fed), moth bean (irrigated) and groundnut were 2.1, 0.5, 3.4, 3.5 and 3.0, respectively. This suggests that the moth bean crop is more remunerating to the farmers in Kharif as compared to

  7. Variations of the aerosol concentration and chemical composition over the arid steppe zone of Southern Russia in summer

    Science.gov (United States)

    Artamonova, M. S.; Gubanova, D. P.; Iordanskii, M. A.; Lebedev, V. A.; Maksimenkov, L. O.; Minashkin, V. M.; Obvintsev, Y. I.; Chketiani, O. G.

    2016-12-01

    Variations in the surface aerosol over the arid steppe zone of Southern Russia have been measured. The parameters of atmospheric aerosol (mass concentration, both dispersed and elemental compositions) and meteorological parameters were measured in Tsimlaynsk raion (Rostov oblast). The chemical composition of aerosol particles in the atmospheric surface layer has been determined, and the coefficients of enrichment of elements with respect to clarkes in the Earth's crust have been calculated. It is shown that, in summer, arid aerosols are transported from both alkaline and sandy soils of Kalmykia to the air basin over the observation zone. Aerosol particles in the surface air layer over this region have been found to contain the products of combustion of oil, coal, and ethylized fuel. These combustion products make a small contribution to the total mass concentration of atmospheric aerosol; however, they are most hazardous to the health of people because of their sizes and heavy-metal contents. A high concentration of submicron sulfur-containing aerosol particles of chemocondensation nature has been recorded. Sources of aerosol of both natural and anthropogenic origins in southern Russia are discussed.

  8. Functional traits drive the contribution of solar radiation to leaf litter decomposition among multiple arid-zone species.

    Science.gov (United States)

    Pan, Xu; Song, Yao-Bin; Liu, Guo-Fang; Hu, Yu-Kun; Ye, Xue-Hua; Cornwell, William K; Prinzing, Andreas; Dong, Ming; Cornelissen, Johannes H C

    2015-08-18

    In arid zones, strong solar radiation has important consequences for ecosystem processes. To better understand carbon and nutrient dynamics, it is important to know the contribution of solar radiation to leaf litter decomposition of different arid-zone species. Here we investigated: (1) whether such contribution varies among plant species at given irradiance regime, (2) whether interspecific variation in such contribution correlates with interspecific variation in the decomposition rate under shade; and (3) whether this correlation can be explained by leaf traits. We conducted a factorial experiment to determine the effects of solar radiation and environmental moisture for the mass loss and the decomposition constant k-values of 13 species litters collected in Northern China. The contribution of solar radiation to leaf litter decomposition varied significantly among species. Solar radiation accelerated decomposition in particular in the species that already decompose quickly under shade. Functional traits, notably specific leaf area, might predict the interspecific variation in that contribution. Our results provide the first empirical evidence for how the effect of solar radiation on decomposition varies among multiple species. Thus, the effect of solar radiation on the carbon flux between biosphere and atmosphere may depend on the species composition of the vegetation.

  9. 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

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

    OpenAIRE

    W. R.J. Dean; S. J. Milton; P.J. O'Farrell; P. M.L. Anderson

    2009-01-01

    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 droug...

  11. 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.

  12. Transport of elemental mercury in the unsaturated zone from a waste disposal site in an arid region

    Science.gov (United States)

    Walvoord, M.A.; Andraski, B.J.; Krabbenhoft, D.P.; Striegl, R.G.

    2008-01-01

    Mercury contained in buried landfill waste may be released via upward emission to the atmosphere or downward leaching to groundwater. Data from the US Geological Survey's Amargosa Desert Research Site (ADRS) in arid southwestern Nevada reveal another potential pathway of Hg release: long-distance (102 m) lateral migration of elemental Hg (Hg0) through the unsaturated zone. Gas collected from multiple depths from two instrumented boreholes that sample the entire 110-m unsaturated zone thickness and are located 100 and 160 m away from the closest waste burial trench exhibit gaseous Hg concentrations of up to 33 and 11 ng m-3, respectively. The vertical distribution of gaseous Hg in the borehole closest to the disposal site shows distinct subsurface peaks in concentration at depths of 1.5 and 24 m that cannot be explained by radial diffusive transport through a heterogeneous layered unsaturated zone. The inability of current models to explain gaseous Hg distribution at the ADRS highlights the need to advance the understanding of gas-phase contaminant transport in unsaturated zones to attain a comprehensive model of landfill Hg release.

  13. 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.

  14. An effect of spatial resolution of remotely sensed data for vegetation analysis over an arid zone

    Science.gov (United States)

    Oguro, Y.; Tsuchiya, K.; Setoguchi, R.

    1997-05-01

    One of the recent trends in the development of an optical sensor of earth observation satellite is a great importance of spatial resolution and the order of 1 - 2 meter resolution sensor is under development. To cope with this trend analyses are made on the effect of extremely fine spatial resolution of land cover classification accuracy utilizing spatial resolution of 20 cm and 1 meter aerial multi-sensor data of an arid reddish land where desertification is taking place in small spatial scale. Applied methods are supervised classification with combination of multi-level slice(pallarelpiped classification) and the Mahalanobis distance. The result of analysis indicates that the difference is within several percentage for 3 categories of bare land, vegetation and shadow. It was also found that small dried sparse grass land which can be recognized in 20 cm resolution image is difficult to extract in 1 meter resolution image.

  15. 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.

  16. 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.

  17. 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.

  18. Performance of Jatropha curcas L. in Semi-arid Zone: Seed Germination, Seedling Growth and Early Field Growth

    Directory of Open Access Journals (Sweden)

    Sharif AHAMAD

    2013-05-01

    Full Text Available There is a lack of information on basic agronomic properties of Jatropha curcas L. (jatropha cultivation on the marginal lands in the semi-arids. Evaluation of agronomic performance of identified elite strains of J. curcas in marginal lands would be of paramount importance for addressing gap areas in their agronomic properties and subsequently for harnessing their optimum economic potentials. The present study undertook the task of analysing the growth performance of a high oil bearing elite strain of J. curcas–DARL-2 in degraded land in semi-arid zone of Deccan Plateau, India. While undertaking the assessment of growth performance of elite strain DARL-2, two other native (wild strains (namely AHN-1 and AHN-2 of J. curcas were also considered so that a comparative evaluation could be carried out. The role of gypsum was also investigated on J. curcas in the nursery stage as well its carry over effects on growth performance of transplanted trees in the field. Two types of substrates, gypsum-treated soil (GS and untreated soil (SL were used for growing seedlings of all the three jatropha strains. Seedlings (120-days-old of DARL-2 exhibited greater plant height, collar diameter and number of branches but root length was greater in the local strains. In the second year of field transplantation, DARL-2 strain exhibited significantly (p<0.05 greater plant height and number of branches/plant. No carry over effects of gypsum treatment were observed in field transplanted plants as none of the growth parameters significantly varied among the substrate types.

  19. 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.

  20. 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

  1. 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.

  2. Ajustement de la courbe de lactation de la chèvre locale dans les zones arides Tunisiennes

    Directory of Open Access Journals (Sweden)

    Ilyes Mekki

    2011-10-01

    Full Text Available Les performances laitières de la chèvre locale dans les zones arides tunisiennes dépendent des capacités génétiques de l’effet des conditions du milieu et du mode de conduite des troupeaux. L’objectif de cette étude est d’analyser les performances laitières de la chèvre locale en fonction de ces facteurs à travers l’ajustement de la courbe de lactation. De telles connaissances sont indispensables pour planifier la gestion raisonnable de cette ressource animale rustique dans des conditions naturelles difficiles. Les données utilisées pour cette étude sont issues de 10 campagnes de contrôle laitier réalisé au niveau d’un troupeau caprin expérimental conduit dans les régions arides. Suite à l’élaboration des données, l’application des procédures de régression non linéaire a identifié le modèle de Wood comme le plus adaptée pour l’ajustement de la courbe de lactation de la chèvre locale. Ce modèle a été appliqué pour estimer les paramètres de la lactation individuelle et l’étude des facteurs de variation. Les résultats d’ajustements des données montrent que la lactation de la chèvre locale évolue après la mise bas selon une trajectoire assez aplatie. Les performances de la chèvre locale sont assez réduites et similaires à celles observées pour des populations élevées dans des zones difficiles tunisiennes de point de vue climatique et pastorale. La moyenne de production initiale observée est de 720 g/j, le pic de lactation est observé au 17ème jour lorsqu’une chèvre produit en moyenne 980g/j. La réduction des potentialités laitières de la chèvre locale illustre les effets du processus de sélection naturelle qui a favorisé l’adaptation aux conditions difficiles des régions arides. Les résultats contribuent à la caractérisation de la chèvre locale et à la planification de son amélioration comme étant une ressource génétique locale et rustique.

  3. 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.

  4. 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.

  5. 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

  6. Tritium plume dynamics in the shallow unsaturated zone in an arid environment

    Science.gov (United States)

    Maples, S.R.; Andraski, B.J.; Stonestrom, D.A.; Cooper, C.A.; Pohll, G.; Michel, R.L.

    2014-01-01

    The spatiotemporal variability of a tritium plume in the shallow unsaturated zone and the mechanisms controlling its transport were evaluated during a 10-yr study. Plume movement was minimal and its mass declined by 68%. Upward-directed diffusive-vapor tritium fluxes and radioactive decay accounted for most of the observed plume-mass declines. Effective isolation of tritium (3H) and other contaminants at waste-burial facilities requires improved understanding of transport processes and pathways. Previous studies documented an anomalously widespread (i.e., theoretically unexpected) distribution of 3H (>400 m from burial trenches) in a dry, sub-root-zone gravelly layer (1–2-m depth) adjacent to a low-level radioactive waste (LLRW) burial facility in the Amargosa Desert, Nevada, that closed in 1992. The objectives of this study were to: (i) characterize long-term, spatiotemporal variability of 3H plumes; and (ii) quantify the processes controlling 3H behavior in the sub-root-zone gravelly layer beneath native vegetation adjacent to the facility. Geostatistical methods, spatial moment analyses, and mass flux calculations were applied to a spatiotemporally comprehensive, 10-yr data set (2001–2011). Results showed minimal bulk-plume advancement during the study period and limited Fickian spreading of mass. Observed spreading rates were generally consistent with theoretical vapor-phase dispersion. The plume mass diminished more rapidly than would be expected from radioactive decay alone, indicating net efflux from the plume. Estimates of upward 3H efflux via diffusive-vapor movement were >10× greater than by dispersive-vapor or total-liquid movement. Total vertical fluxes were >20× greater than lateral diffusive-vapor fluxes, highlighting the importance of upward migration toward the land surface. Mass-balance calculations showed that radioactive decay and upward diffusive-vapor fluxes contributed the majority of plume loss. Results indicate that plume losses

  7. Antimicrobial activities of endophytic fungi obtained from the arid zone invasive plant Opuntia dillenii and the isolation of equisetin, from endophytic Fusarium sp.

    OpenAIRE

    Ratnaweera, Pamoda B.; de Silva, E. Dilip; Williams, David E.; Andersen, Raymond J

    2015-01-01

    Background Opuntia dillenii is an invasive plant well established in the harsh South-Eastern arid zone of Sri Lanka. Evidence suggests it is likely that the endophytic fungal populations of O. dillenii assist the host in overcoming biotic and abiotic stress by producing biologically active metabolites. With this in mind there is potential to discover novel natural products with useful biological activities from this hitherto poorly investigated source. Consequently, an investigation of the an...

  8. 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.

  9. Tritium Plume Dynamics in the Shallow Unsaturated Zone Adjacent to an Arid Waste Disposal Facility

    Science.gov (United States)

    Maples, S.; Andraski, B. J.; Stonestrom, D. A.; Cooper, C. A.; Michel, R. L.; Pohll, G. M.

    2012-12-01

    Previous studies at the U.S. Geological Survey's Amargosa Desert Research Site (ADRS) in southern Nevada have documented two plumes of tritiated water-vapor (3HHOg) adjacent to a closed, commercial low-level radioactive waste disposal facility. Wastes were disposed on-site from 1962-92. Tritium has moved long distances (> 400 m) through a shallow (1-2-m depth) dry gravelly layer—orders of magnitude further than anticipated by standard transport models. Geostatistical methods, spatial moment analyses and tritium flux calculations were applied to assess shallow plume dynamics. A grid-based plant-water sampling method was utilized to infer detailed, field-scale 3HHOg concentrations at 5-yr intervals during 2001-11. Results indicate that gravel-layer 3HHOg mass diminished faster than would be expected from radioactive decay (~70% in 10 yr). Both plumes exhibited center-of-mass stability, suggesting that bulk-plume movement is minimal during the period of study. Nonetheless, evidence of localized lateral advancement along some margins, combined with increases in the spatial covariance of concentration distribution, indicates intra-plume mass redistribution is ongoing. Previous studies have recognized that vertical movement of tritiated water from sub-root-zone gravel into the root-zone contributes to atmospheric release via evapotranspiration. Estimates of lateral and vertical tritium fluxes during the study period indicate (1) vertical tritiated water fluxes were dominated by diffusive-vapor fluxes (> 90%), and (2) vertical diffusive-vapor fluxes were roughly an order of magnitude greater than lateral diffusive-vapor fluxes. This behavior highlights the importance of the atmosphere as a tritium sink. Estimates of cumulative vertical diffusive-vapor flux and radioactive decay with time were comparable to observed declines in total shallow plume mass with time. This suggests observed changes in plume mass may (1) be attributed, in considerable part, to these removal

  10. 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.

  11. Plant species effects on soil nutrients and chemistry in arid ecological zones.

    Science.gov (United States)

    Johnson, Brittany G; Verburg, Paul S J; Arnone, John A

    2016-09-01

    The presence of vegetation strongly influences ecosystem function by controlling the distribution and transformation of nutrients across the landscape. The magnitude of vegetation effects on soil chemistry is largely dependent on the plant species and the background soil chemical properties of the site, but has not been well quantified along vegetation transects in the Great Basin. We studied the effects of plant canopy cover on soil chemistry within five different ecological zones, subalpine, montane, pinyon-juniper, sage/Mojave transition, and desert shrub, in the Great Basin of Nevada all with similar underlying geology. Although plant species differed in their effects on soil chemistry, the desert shrubs Sarcobatus vermiculatus, Atriplex spp., Coleogyne ramosissima, and Larrea tridentata typically exerted the most influence on soil chemistry, especially amounts of K(+) and total nitrogen, beneath their canopies. However, the extent to which vegetation affected soil nutrient status in any given location was not only highly dependent on the species present, and presumably the nutrient requirements and cycling patterns of the plant species, but also on the background soil characteristics (e.g., parent material, weathering rates, leaching) where plant species occurred. The results of this study indicate that the presence or absence of a plant species, especially desert shrubs, could significantly alter soil chemistry and subsequently ecosystem biogeochemistry and function.

  12. Energy use pattern in production agriculture of a typical village in arid zone. Pt. 3

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-09-01

    India has 31.71 Mha of hot and areas, of which 61.8% is in Western Rajasthan, commonly known as the ''Thar Desert''. A detailed study of the energy use pattern in production agriculture for a representative village, Pemasar, district Bikaner of zone II (200 mm/yr {<=} annual rainfall < 300 mm/yr) has been conducted. Out of the total geographical area (945.7 ha) of the village, 693.6 ha is cultivable land. The main crops grown in the village are cluster bean, moth bean, groundnut, green gram (Kharif), wheat, mustard, gram, barley and rocket salad (Rabi). In general, Kharif crops are grown as rain fed crops, but due to low rainfall in the zone and the presence of the Indira Gandhi Canal, even Kharif crops are raised under irrigated conditions. However, the area covered under irrigation is meagre as the availability of canal water is very much limited and uncertain. Operation wise, the total energy consumed for rain fed Kharif crops is minimum (1187.6 MJ/ha) for moth bean and maximum (1261.9 MJ/ha) for cluster bean, while for irrigated crops, it is minimum (2847.3 MJ/ha) for moth bean, and maximum (12,809.6 MJ/ha) for groundnut. The average specific energy for cultivation of cluster bean (rain fed), cluster bean (irrigated), moth bean (rain fed), moth bean (irrigated) and groundnut were 11.7, 7.5, 7.7, 7.4 and 11.2 MJ/ha, respectively. Operation wise, the energy consumed for Rabi crops is minimum (3855.6 MJ/ha) for rocket salad followed by 4779.4 MJ/ha for mustard, 4845.2 MJ/ha for gram and maximum (7953.2 MJ/ha) for wheat. The average specific energy for cultivation of wheat, gram, mustard and rocket salad were 11.4, 16.5, 13.2 and 13.7 MJ/ha, respectively. The average values of estimated energy ratio for cluster bean (rain fed), cluster bean (irrigated), moth bean (rain fed), moth bean (irrigated) and groundnut were 2.1, 0.5, 3.4, 3.5 and 3.0, respectively. This suggests that the moth bean crop is more remunerating to the farmers in Kharif as

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. Evaporation and concentration gradients created by episodic river recharge in a semi-arid zone aquifer: Insights from Cl-, δ18O, δ2H, and 3H

    Science.gov (United States)

    Meredith, K. T.; Hollins, S. E.; Hughes, C. E.; Cendón, D. I.; Chisari, R.; Griffiths, A.; Crawford, J.

    2015-10-01

    This study has significantly advanced our understanding of the origin of groundwater recharge in a semi-arid zone region of the Darling River catchment, Australia. The generally accepted hypothesis in arid zone environments in Australia that river water forms the primary groundwater recharge source has proven difficult to monitor. This is due to the time lags between large floods, the remoteness and expense of studying these hydrologically complex systems in detail. In addition, the highly episodic nature of dryland rivers complicates the interpretation of the groundwater signal. A range of hydrochemical tracers (chloride, oxygen-18, deuterium and tritium) measured in rain, river water, soil water and groundwater were used in this multi-year study to trace the pathways of groundwater recharge under wet and dry climatic conditions. The evaporation and Cl concentrations observed in the unsaturated zone confirmed that small volumetric inputs from periodic rainfall were not the major recharge mechanism. Sampling which included an overbank flooding event in March 2012 provided firm evidence for groundwater originating from high flow episodic river recharge. The use of long-term environmental data to understand how economically important water resources respond to climate change with increasing temperatures is considered essential for future sustainability.

  18. 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.

  19. 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

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

    OpenAIRE

    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...

  1. Effects of land use/land cover and climate changes on surface runoff in a semi-humid and semi-arid transition zone in northwest China

    Science.gov (United States)

    Yin, Jing; He, Fan; Jiu Xiong, Yu; Qiu, Guo Yu

    2017-01-01

    Water resources, which are considerably affected by land use/land cover (LULC) and climate changes, are a key limiting factor in highly vulnerable ecosystems in arid and semi-arid regions. The impacts of LULC and climate changes on water resources must be assessed in these areas. However, conflicting results regarding the effects of LULC and climate changes on runoff have been reported in relatively large basins, such as the Jinghe River basin (JRB), which is a typical catchment (> 45 000 km2) located in a semi-humid and arid transition zone on the central Loess Plateau, northwest China. In this study, we focused on quantifying both the combined and isolated impacts of LULC and climate changes on surface runoff. We hypothesized that under climatic warming and drying conditions, LULC changes, which are primarily caused by intensive human activities such as the Grain for Green Program, will considerably alter runoff in the JRB. The Soil and Water Assessment Tool (SWAT) was adopted to perform simulations. The simulated results indicated that although runoff increased very little between the 1970s and the 2000s due to the combined effects of LULC and climate changes, LULC and climate changes affected surface runoff differently in each decade, e.g., runoff increased with increased precipitation between the 1970s and the 1980s (precipitation contributed to 88 % of the runoff increase). Thereafter, runoff decreased and was increasingly influenced by LULC changes, which contributed to 44 % of the runoff changes between the 1980s and 1990s and 71 % of the runoff changes between the 1990s and 2000s. Our findings revealed that large-scale LULC under the Grain for Green Program has had an important effect on the hydrological cycle since the late 1990s. Additionally, the conflicting findings regarding the effects of LULC and climate changes on runoff in relatively large basins are likely caused by uncertainties in hydrological simulations.

  2. 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

    2016-11-01

    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).

  3. 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).

  4. Climate variability, precipitation trends, and impacts on surface processes in humid to arid climate transition zones of the NW Argentine Andes (24° S, 65° W)

    Science.gov (United States)

    Castino, Fabiana; Bookhagen, Bodo; Strecker, Manfred

    2015-04-01

    In the Andes of NW Argentina the distribution and amount of rainfall and associated surface processes are intimately correlated with pronounced topographic gradients and relief contrasts that intercept easterly moisture-bearing winds related to the South American Monsoon System. These conditions have led to a pronounced elevation-dependent distribution of rainfall, which involves areally limited transition zones between the humid eastern flanks of the orogen (eastern foreland and eastern flanks of the E Cordillera) and the arid orogen interior (Puna Plateau). At interannual scales rainfall patterns in this area can be modulated by different atmospheric disturbances, such as the South Atlantic Convergent Zone and the El Niño Southern Oscillation, resulting in drought or flooding events. During the last two decades, field observations document fluvial aggradation in many intermontane valleys along the eastern flanks of the orogen. This may be related to changing overall climatic conditions, impacting hillslope erosion processes at high elevation, but contemporaneously overwhelming the fluvial system and reducing transport capacity, leading to transient sediment storage. We analyzed rainfall trends in the humid to arid climatic transition zone in the NW Argentine Andes over different time periods to characterize the spatiotemporal variability of rainfall patterns during the last five decades. We relied on both daily ground station (40 stations, 1956-2012) and three-hourly remote sensing rainfall data (3B42 V7 TRMM data, 1998-2014). Seasonal total anomalies analysis shows a complex rainfall pattern, reflected both in station data and remote sensing observations with clear positive (negative) statistically significant trends in the northern Puna Plateau and in the northern part of the foreland basin (southern part of the eastern foreland basin) of up to +20mm/yr (-20mm/yr). Quantile regression of three-hourly and daily data furthermore shows that, on average

  5. 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.

  6. 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.

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

    Science.gov (United States)

    Perrin, J. L.; Raïs, N.; Chahinian, N.; Moulin, P.; Ijjaali, M.

    2014-03-01

    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 network. The Oued Fez and the Sebou River are characterised by severe pollution downstream from the city of Fez, particularly TN (mainly NH4 and Norg), TP (mainly Ppart) and TCr. The most polluted sites are those directly under the influence of domestic and industrial waste water inputs, particularly tannery effluents. Obviously, the concentrations measured at these locations are above all environmental quality standards. Pollutant loads are very heavy in the Sebou River and can contaminate the river course for kilometres. Moreover, as the water of the Sebou River is used for the irrigation of vegetables, serious problems of public health could arise. A better understanding of contaminant dynamics and self-purifying processes in these rivers will help implement actions and steps aimed at improving water quality in the Sebou River, which is the primary water supply source in Morocco and is used for agricultural and industrials purposes as well as for drinking water.

  8. 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

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

    OpenAIRE

    2006-01-01

    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 ma...

  10. 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.

  11. 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.

  12. Tritium Fluxes through the Shallow Unsaturated Zone adjacent to a Radioactive Waste Disposal Facility in an Arid Environment

    Science.gov (United States)

    Maples, S.; Andraski, B. J.; Stonestrom, D. A.; Cooper, C. A.; Pohll, G.

    2011-12-01

    Studies at the U.S. Geological Survey's Amargosa Desert Research Site (ADRS) in southern Nevada have documented long-distance (>400-m) tritium (3H) transport adjacent to a commercial, low-level radioactive waste disposal facility. Transport at this scale is orders of magnitude greater than anticipated; however, lateral 3H fluxes through the shallow unsaturated zone (UZ) have not been investigated in detail. The objective of this study is to estimate and compare lateral and vertical tritiated water-vapor (3HHOg) fluxes in the shallow UZ and their relation to the observed plume migration. Previous studies have recognized two distinct plumes of 3H emanating from the facility. Shallow (0.5 and 1.5-m depth) soil-water vapor samples were collected yearly along 400-m long transects through both plumes from 2003-09. Within the south plume, 3H concentrations at 1.5-m depth have decreased by 44 ± 0.3% during this period, and plume advancement there has effectively ceased (i.e., rate of advance equals rate of decay). During the same period, the west plume showed a net decrease in concentration of 34 ± 0.9% within 100-m of the facility; however, plume advancement is observed at the leading edge of the plume, and concentrations 200-300-m from the facility show an increase in 3H concentration of 64 ± 28.4%. Lateral and vertical diffusive fluxes within both plumes were calculated using 3HHOg concentrations from 2006. Lateral 3HHOg diffusive fluxes within both plumes have been estimated 25-300-m from the facility at 1.5-m depth. Mean lateral 3HHOg diffusive fluxes are 10-14 g m-2 yr-1 within the south plume, and 10-13 g m-2 yr-1 within the west plume. Mean lateral fluxes in the south plume are an order of magnitude lower than in the west plume. This behavior corresponds with the observed relative immobility of the south plume, while the elevated west plume fluxes agree with the plume advancement seen there. Shallow, upward directed, mean vertical 3HHOg fluxes 25-300-m from the

  13. 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.

  14. 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

  15. Facteurs décisionnels dans la gestion des ressources hydriques par les éleveurs et agro-éleveurs dans une zone semi-aride du Burkina Faso

    Directory of Open Access Journals (Sweden)

    Zongo, BIN.

    2006-01-01

    Full Text Available Decisional Factors in the Water Resources Management by the Livestock Keepers and the Agropastoralist in a Semi-arid Zone of Burkina Faso. A survey was carried out in a semi-arid zone of Burkina Faso in order to determine the factors influencing water management by allochthonous livestock keepers and native agro-pastoralists. The results of the study showed that the availability of water and grazing land as well as some other factors influence the livestock keepers on the place where to settle in a zone. The village and the geographical origin of the producers can influence the utilisation of the different types of watering points. The study shows also that easy access, easy drawing of water and proximity influence their choices. These factors explain why livestock keepers and agropastoralists used on a rather high level (56 to 94% surface water to water cattle and sheep, and boreholes (41.1 to 76.9% to water sheep and goats. Surface water attracts farmers if the distance to cover does not exceed 4 km. The factors determining the behaviours of livestock keepers and agro-pastoralists in water management were similar. The type of watering point, the distance and the animal species influence their choices. They however present differences in the levels of using watering points.

  16. 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.

  17. 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...

  18. RECOMMEND OF HIGH-YIELDING HYBRID MILLET DEVELOPMENT IN CENTRAL ARID ZONE OF NINGXIA%宁夏中部干旱带发展高产杂交谷子产业的建议

    Institute of Scientific and Technical Information of China (English)

    马力文; 刘静; 周斌; 刘维斌; 杨立文; 席国术

    2016-01-01

    Ningxia is a severe water scarcity province in China. Under the background of global warming, the drought on central arid zone has intensified, the contradiction between water supply and demand is increasingly prominent, and food production is low and long-term instability. Ecological migrants faced enormous pressure to get rid of poverty, and survival and development problems became prominent. Since 2010, Ningxia meteorological department successfully introduced a series of hybrid millet varieties in the central arid zone, carried out a large se-ries of hybrid millet experimental study, and promoted the planting areas to nearly 667hm2 . In this paper, under the very dry year of 2011 , the comparative cost-effectiveness and prospects of high-yielding hybrid millet with local mainly cultivars was analyzed. The results showed that the cultivation of hybrid millet can save water resources, re-sist heavy drought, and increase more than double yield comparing with the traditional local millet yields. Due to the high price of small grains, farmers' income was generally higher than that planting other crops. Based on the Zhang hybrid millet experiment and demonstration, combined with the distribution of agricultural climate resources, the Ningxia Zhang hybrid millet cultivated climatic suitability zoning map was obtained. Different areas suitable va-rieties for cultivation, methods and planting risks were analyzed. It recommended to actively and steadily develop hybrid millet cultivation in the central arid zone of Ningxia,strengthen hybrid millet yield cultivation and water-saving technology training, and establish millet cultivation-processing-marketing service system becoming a new way for the central arid zone farmers to get rich.%宁夏水资源严重匮乏,在全球气候变暖背景下,中部干旱带干旱有所加剧,水资源供需矛盾日益突出,粮食产量长期低而不稳,生态移民脱贫压力大,生存与发展问题突出.2010

  19. 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

    2016-01-20

    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.

  20. 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

  1. 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

  2. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kushelevsky, A.; Shani, G.; Haccoun, A. (Ben-Gurion Univ. of the Negev, Beersheba (Israel). Dept. of Nuclear Engineering)

    1983-02-01

    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 ..mu..g m-/sup 3/) were found during Sharav conditions and sandstorms (hot, dry weather, typical to this region). Low TSP levels (59 +- 28 ..mu..g m-/sup 3/) were found in the winter following rain. Usual TSP levels were found to be 140 +- 20 ..mu..g m-/sup 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.

  4. 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

  5. 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.

  6. Trace Metals in Groundwater & Vadose Zone Calcite: In Situ Containment & Stabilization of Stronthium-90 & Other Divalent Metals & Radionuclides at Arid West DOE

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W.

    2005-06-01

    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 [INTEC] at the Idaho National Laboratory [INL]). 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 (primarily calcite) in groundwater and vadose zone systems. Our facilitated approach relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by (a) increasing pH and alkalinity and (b) liberating cations from the aquifer matrix by cation exchange reactions. Subsurface urea hydrolysis is catalyzed by the urease enzyme, which is produced in situ by native 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. We are currently conducting field based activities at both the INL Vadose Zone Research Park (VZRP), an uncontaminated surrogate site for the strontium-90 contaminated vadose zone at INTEC and at the strontium-90 contaminated aquifer of 100-N area of the Hanford site.

  7. 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.

  8. Relationship between the Salt Accumulation and the Drought Resistance in Several Woody Plants in Arid Zone%干旱区木本植物盐分积累与其耐旱性的关系

    Institute of Scientific and Technical Information of China (English)

    柏新富; 朱建军; 王仲礼; 谭永芹; 刘林德

    2012-01-01

    The plants in arid zones tend to accumulate more salt because the evaporation is much higher than the rainfall in arid environment, and because the selective uptake of water by plant roots results in the rise of salt concentration in solutions in the rhizosphere. In this study, parameters such as the Na+ and K+ concentrations, as well as the water status and photosynthesis were measured and analyzed. The results showed that H. ammodendron and T. ramosissima were able to absorb and accumulate more Na+ than H. scoparium and E. angustifolia. In accordance, H. scoparium and T. ramosissima also had lower water potentials and osmotic potentials in their tissues, as well as lower transpiration and larger range of water potential for effective photosynthesis than H. scoparium and E. angustifolia. There was a negative correlation between the Na+ concentration and the water/osmotic potentials of the plants, a negative correlation between the Na+ concentration and the transpirational water loss; but a positive correlation between the Na+ concentration and the range of water potential for effective photosynthesis. It is therefore concluded that the salt accumulation could decrease the osmotic potential and water potential of plant tissues, enhance the driving force of water absorption, and reduce the transpiration of the plants, which was beneficial for the plants to retain a relatively higher photosynthesis, implying that salt accumulation in plants could enhance the drought resistance of the plant species in arid zone.%通过对干旱区4种木本植物体内Na+,K+浓度和水分、光合等指标的测定、比较,分析盐分积累与其耐旱性的关系.结果表明:梭梭和柽柳能够吸收、积累较多的Na+,而花棒和沙枣组织Na+浓度相对较低;与花棒和沙枣相比,梭梭和柽柳具有较低的组织水势和渗透势、较小的蒸腾失水量和较大光合作用有效水势范围.表现为植株水势、渗透势和蒸腾失水量与其组织Na

  9. 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.

  10. 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).

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

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W.

    2004-12-01

    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).

  12. Trace Metals in Groundwater & Vadose Zone Calcite: In Situ Containment & Stabilization of Stronthium-90 & Other Divalent Metals & Radionuclides at Arid West DOE

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W

    2003-06-01

    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 recapture in a more stable solid phase (co-precipitation rather than adsorption). Our specific research objectives include: * Elucidation of the mechanisms and rates for the release of sorbed trace metals and their subsequent sequestration by co-precipitation in calcite induced by urea hydrolysis. * Evaluation at the field scale of the influence of

  13. 种植枸杞对干旱区荒漠缓冲带土壤质量的影响%Research on Soil Quality of Planting Lycium barbarum in Arid Desert Buffer Zone

    Institute of Scientific and Technical Information of China (English)

    牟宗江; 何学敏; 孙景鑫; 吕光辉

    2011-01-01

    [ Objective] A comparative analysis was conducted about the soil pH, organic matter, total soil N and C/N before and after planting Lycium barbarum in Arid Desert Buffer Zone of National Nature Reserve in the Ebinur Wetland and the condition of soil comprehensive quality changes was evaluated in order that the basis for protecting areas soil and water conservation and planting economic crops could be provided. [Method] Through artificial cultivation and indoor experiments, the physical and chemical properties and comprehensive quality status of soil samples before and after planting the Lycium barbarum and the surrounding natural control samples were evaluated and analyzed. [ Result ] Short - term weather changes insignificantly impacted on soil pH, total salt and total nitrogen, while the influence on surface soil organic matter was stronger; Effects of Artificial cultivation, planting and irrigation on soil physical and chemical properties were strong, such as reducing the soil pH and total salt, which was helpful to the improvement of soil salinization, while reducing soil organic matter and total nitrogen at the same time; The orders about integrated soil quality index of April, August, the experimental group and contrast group were that August test group < April < August contrast group. [ Conclusion ] Newly planted Lycium barbarum plantation played a certain role in the improvement of soil salinization in arid desert buffer zone, but exacerbated the soil poor degree. Under natural conditions, soil quality showed increasing trend from spring to summer, and Lycium barbarum cultivation reduced the soil quality to some extent.%[目的]对艾比湖湿地国家级自然保护区荒漠边缘缓冲带枸杞种植前后土壤的pH、总盐、有机质、全氮及C/N进行比较分析,评价其土壤综合质量变化情况,为保护区水土保持和经济作物种植提供依据.[方法]通过人工栽培和室内试验,对枸杞种植前后及周边自然对照土

  14. VOCs in Arid soils: Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    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.

  15. 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

  16. 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.

  17. A new approach for studying prehistoric herd management in arid areas: intra-tooth isotopic analyses of archaeological caprine from IranUne nouvelle approche pour l'étude de la gestion préhistorique des troupeaux en zones arides: analyses isotopiques intra-dentaires de caprinés archéologiques d'Iran

    Science.gov (United States)

    Bocherens, Hervé; Mashkour, Marjan; Billiou, Daniel; Pellé, Eric; Mariotti, André

    2001-01-01

    Carbon and oxygen isotopic variations in archaeological tooth enamel from Iran have been used to investigate prehistoric herd management. Oxygen isotopic variations in domestic caprines are more important than in wild equids, indicating a seasonal consumption of 18O-depleted drinking water. Since the plants consumed at the same time were partly C 4, it is presumed that the access to this 18O-depleted water was controlled by humans, and that the water came from wells or underground canalisations. This methodology is expected to provide valuable information on herd management in the past in arid areas.

  18. 新疆干旱区湖泊演化及其气候水文特征%LAKE EVOLUTION AND CLIMATIC AND HYDROLOGICAL CHANGES IN ARID ZONE OF XINJIANG

    Institute of Scientific and Technical Information of China (English)

    吴敬禄; 马龙

    2011-01-01

    新疆干旱区湖泊水资源变化受自然和人类活动的共同影响,湖泊面积收缩与扩展幅度大而频繁,引起一系列的区域环境问题.然而,不同时期或不同类型的湖泊受这两种因素影响的强度并不一致.在人类活动前,湖泊受气候因素控制,湖泊波动表现出一定的规律性.约6.5~8.0 kaBP期间,艾比湖处于近一万年来的最高水位,湖面扩展,当时湖泊流域平均降水比现代高约22%,其他地区不同类型湖泊也处于高湖面时期.随后,在中世纪早期及小冰期前后也都出现了历时百年的气候湿润时期,艾比湖、罗布泊以及博斯腾湖等都处于相对较高的水位.人类活动影响以来,以20世纪六七十年代人为活动对湖泊水资源变化的影响最为强烈.新疆平原区湖泊出现大范围萎缩,艾比湖面积比1950s减少近400km2,罗布泊、台特玛湖以及玛纳斯湖等100km2以上的大湖快速干涸,而赛里木湖等山地湖泊变化相对稳定,受人类活动影响小,与相应的气候变化较一致.从长远分析,新疆湖泊水资源变化以自然因素影响为主,人类活动对湖泊的影响充当气候效应放大器的功能,即人类活动的结果放大了气候对湖泊变化的影响,使得湖泊的变化幅度加剧、频率增加.%Both natural and artificial factors bring effects to lake water resources in the arid zone of Xinjiang. The considerable and frequent shrinkage and expansion of lakes may cause a series of regional environmental problems. However, the influence intensity of the factors on lake variations changes with time.The lake variations were mainly controlled by climatic factors before human society. During the period between 6.5 and 8.0 kaBP, the Ebinur Lake had reached the highest water level in a time span of almost ten thousand years. The average precipitation of the Ebinur drainage area was about 22%, higher than that of the present, and the lakes in other regions were also

  19. Impact de l'érosion sur l'envasement des barrages, la recharge des nappes phréatiques côtières et les intrusions marines dans la zone semi-aride méditerranéenne : cas du barrage de Boukourdane (Algérie

    Directory of Open Access Journals (Sweden)

    Tadrist, N.

    2016-01-01

    Full Text Available Impact of erosion on the silting of dams, on the recharging groundwater and on coastal marine intrusion in the Mediterranean semi-arid area: Case of Boukourdane dam (Algeria. Description of the subject. Water erosion is a particularly important issue, especially in the Mediterranean and semi-arid zone. This zone is characterized by irregular rainfall patterns, which have a considerable influence on soil loss. In mountainous areas, water erosion phenomena are accentuated by steep slopes and low ground cover. The dams draining these areas undergo siltation linked to significant erosion. The silting of the dams drastically limits their capacity and thus their operating life. When used for recharging aquifers, the resuspension of fine particles may accumulate in the recharge areas and reduce infiltration capacity by clogging soil porosity. This leads to a significant reduction of groundwater levels. Additionally, groundwater situated in the coastal zone is submitted to intensive pumping. These two phenomena make groundwater particularly sensitive to marine intrusions. Objectives. This article aims, on the one hand to quantify the rate of siltation in the case of the Boukourdane dam (northern Algeria, which is used to recharge groundwater. On the other hand, the article also shows the reduction in permeability in the capturing field with the current management of releases. Method. Solid rates were set in relation to the liquid flow and sediment concentration occasionally taken from the wadi. The relation established made it possible to evaluate the solid contributions to the dam of Boukourdane. The impact of the releases on recharging the well field was evaluated by grouping wells and the well field mushrooms using heuristic k-means. Regressions were applied to the piezometric variations of each group. Results. This dam is fed by a catchment area of 156 km². Sediment transport was estimated from empirical formulas. The specific degradation rate was

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. Changes in aridity in response to the global warming hiatus

    Science.gov (United States)

    Guan, Xiaodan; Huang, Jianping; Guo, Ruixia

    2017-02-01

    The global warming slowdown or warming hiatus, began around the year 2000 and has persisted for nearly 15 years. Most studies have focused on the interpretation of the hiatus in temperature. In this study, changes in a global aridity index (AI) were analyzed by using a newly developed dynamical adjustment method that can successfully identify and separate dynamically induced and radiatively forced aridity changes in the raw data. The AI and Palmer Drought Severity Index produced a wetting zone over the mid-to-high latitudes of the Northern Hemisphere in recent decades. The dynamical adjustment analysis suggested that this wetting zone occurred in response to the global warming hiatus. The dynamically induced AI (DAI) played a major role in the AI changes during the hiatus period, and its relationships with the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO) also indicated that different phases of the NAO, PDO, and AMO contributed to different performances of the DAI over the Northern Hemisphere. Although the aridity wetting over the mid-to-high latitudes may relieve long-term drying in certain regions, the hiatus is temporary, and so is the relief. Accelerated global warming will return when the NAO, PDO, and AMO revert to their opposite phases in the future, and the wetting zone is likely to disappear.

  5. 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)

    Ferris, F. Grant; Fujita, Yoshiko; Smith, Robert W.

    2004-06-15

    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.

  6. Aridity modulates N availability in arid and semiarid Mediterranean grasslands.

    Directory of Open Access Journals (Sweden)

    Manuel Delgado-Baquerizo

    Full Text Available While much is known about the factors that control each component of the terrestrial nitrogen (N cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia, including both biotic (e.g. plant cover and abiotic (e.g. soil OC and pH. If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. Salinization of groundwater in arid and semi-arid zones: an example from Tajarak, western Iran

    Science.gov (United States)

    Jalali, Mohsen

    2007-06-01

    Study of the groundwater samples from Tajarak area, western Iran, was carried out in order to assess their chemical compositions and suitability for agricultural purposes. All of the groundwaters are grouped into two categories: relatively low mineralized of Ca-HCO3 and Na-HCO3 types and high mineralized waters of Na-SO4 and Na-Cl types. The chemical evolution of groundwater is primarily controlled by water-rock interactions mainly weathering of aluminosilicates, dissolution of carbonate minerals and cation exchange reactions. Calculated values of pCO2 for the groundwater samples range from 2.34 × 10-4 to 1.07 × 10-1 with a mean value of 1.41 × 10-2 (atm), which is above the pCO2 of the earth’s atmosphere (10-3.5). The groundwater is oversaturated with respect to calcite, aragonite and dolomite and undersaturated with respect to gypsum, anhydrite and halite. According to the EC and SAR the most dominant classes (C3-S1, C4-S1 and C4-S2) were found. With respect to adjusted SAR (adj SAR), the sodium (Na+) content in 90% of water samples in group A is regarded as low and can be used for irrigation in almost all soils with little danger of the development of harmful levels of exchangeable Na+, while in 40 and 37% of water samples in group B the intensity of problem is moderate and high, respectively. Such water, when used for irrigation will lead to cation exchange and Na+ is adsorbed on clay minerals while calcium (Ca2+) and magnesium (Mg2+) are released to the liquid phase. The salinity hazard is regarded as medium to high and special management for salinity control is required. Thus, the water quality for irrigation is low, providing the necessary drainage to avoid the build-up of toxic salt concentrations.

  13. Rapid warming accelerates tree growth decline in semi-arid forests of Inner Asia.

    Science.gov (United States)

    Liu, Hongyan; Park Williams, A; Allen, Craig D; Guo, Dali; Wu, Xiuchen; Anenkhonov, Oleg A; Liang, Eryuan; Sandanov, Denis V; Yin, Yi; Qi, Zhaohuan; Badmaeva, Natalya K

    2013-08-01

    Forests around the world are subject to risk of high rates of tree growth decline and increased tree mortality from combinations of climate warming and drought, notably in semi-arid settings. Here, we assess how climate warming has affected tree growth in one of the world's most extensive zones of semi-arid forests, in Inner Asia, a region where lack of data limits our understanding of how climate change may impact forests. We show that pervasive tree growth declines since 1994 in Inner Asia have been confined to semi-arid forests, where growing season water stress has been rising due to warming-induced increases in atmospheric moisture demand. A causal link between increasing drought and declining growth at semi-arid sites is corroborated by correlation analyses comparing annual climate data to records of tree-ring widths. These ring-width records tend to be substantially more sensitive to drought variability at semi-arid sites than at semi-humid sites. Fire occurrence and insect/pathogen attacks have increased in tandem with the most recent (2007-2009) documented episode of tree mortality. If warming in Inner Asia continues, further increases in forest stress and tree mortality could be expected, potentially driving the eventual regional loss of current semi-arid forests.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Quantifying macropore recharge: Examples from a semi-arid area

    Science.gov (United States)

    Wood, W.W.; Rainwater, K.A.; Thompson, D.B.

    1997-01-01

    The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically dosed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used us an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in arid and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered

  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. Life at the hyperarid margin: novel bacterial diversity in arid soils of the Atacama Desert, Chile

    Science.gov (United States)

    Neilson, Julia W.; Quade, Jay; Ortiz, Marianyoly; Nelson, William M.; Legatzki, Antje; Tian, Fei; LaComb, Michelle; Betancourt, Julio L.; Wing, Rod A.; Soderlund, Carol A.; Maier, Raina M.

    2012-01-01

    Nearly half the earth's surface is occupied by dryland ecosystems, regions susceptible to reduced states of biological productivity caused by climate fluctuations. Of these regions, arid zones located at the interface between vegetated semiarid regions and biologically unproductive hyperarid zones are considered most vulnerable. The objective of this study was to conduct a deep diversity analysis of bacterial communities in unvegetated arid soils of the Atacama Desert, to characterize community structure and infer the functional potential of these communities based on observed phylogenetic associations. A 454-pyrotag analysis was conducted of three unvegetated arid sites located at the hyperarid-arid margin. The analysis revealed communities with unique bacterial diversity marked by high abundances of novel Actinobacteria and Chloroflexi and low levels of Acidobacteria and Proteobacteria, phyla that are dominant in many biomes. A 16S rRNA gene library of one site revealed the presence of clones with phylogenetic associations to chemoautotrophic taxa able to obtain energy through oxidation of nitrite, carbon monoxide, iron, or sulfur. Thus, soils at the hyperarid margin were found to harbor a wealth of novel bacteria and to support potentially viable communities with phylogenetic associations to non-phototrophic primary producers and bacteria capable of biogeochemical cycling.

  2. 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.

  3. 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

  4. Feeding behavior and physiological responses of sheep grazing in the semi-arid

    Directory of Open Access Journals (Sweden)

    Carolyny Batista Lima

    2014-01-01

    Full Text Available Sheep farming is an important social and economic support for the population living in semi-arid zones. These climatic conditions in these regions - a high radiant heat load, especially - may require adjustments in physiology and behavior of the animal to enable their survival. The increased respiratory rate and rectal temperature, with seeking behavioral patterns reduced grazing time and increased idle time are recurrent in the literature as the main physiological and behavioral responses of sheep grazing in high radiant heat load environments. The presence of shadow, natural or artificial, can encourage and facilitate thermolysis physiological adjustments sheep without harm, predominantly, your metabolism. Thus, the objective of compiling information on the main patterns of behavior, as well as major physiological responses of sheep grazing in semi-arid zones.

  5. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, J. [Univ. of Nevada, Las Vegas, NV (United States)

    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.

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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.

  12. Cultural innovation and megafauna interaction in the early settlement of arid Australia

    Science.gov (United States)

    Hamm, Giles; Mitchell, Peter; Arnold, Lee J.; Prideaux, Gavin J.; Questiaux, Daniele; Spooner, Nigel A.; Levchenko, Vladimir A.; Foley, Elizabeth C.; Worthy, Trevor H.; Stephenson, Birgitta; Coulthard, Vincent; Coulthard, Clifford; Wilton, Sophia; Johnston, Duncan

    2016-11-01

    Elucidating the material culture of early people in arid Australia and the nature of their environmental interactions is essential for understanding the adaptability of populations and the potential causes of megafaunal extinctions 50-40 thousand years ago (ka). Humans colonized the continent by 50 ka, but an apparent lack of cultural innovations compared to people in Europe and Africa has been deemed a barrier to early settlement in the extensive arid zone. Here we present evidence from Warratyi rock shelter in the southern interior that shows that humans occupied arid Australia by around 49 ka, 10 thousand years (kyr) earlier than previously reported. The site preserves the only reliably dated, stratified evidence of extinct Australian megafauna, including the giant marsupial Diprotodon optatum, alongside artefacts more than 46 kyr old. We also report on the earliest-known use of ochre in Australia and Southeast Asia (at or before 49-46 ka), gypsum pigment (40-33 ka), bone tools (40-38 ka), hafted tools (38-35 ka), and backed artefacts (30-24 ka), each up to 10 kyr older than any other known occurrence. Thus, our evidence shows that people not only settled in the arid interior within a few millennia of entering the continent, but also developed key technologies much earlier than previously recorded for Australia and Southeast Asia.

  13. 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

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

    Directory of Open Access Journals (Sweden)

    Tancredo Augusto Feitosa de Souza

    2016-06-01

    Full Text Available Abstract 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.

  15. 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.

  16. 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.

  17. Does aridity influence the morphology, distribution and accumulation of calcium oxalate crystals in Acacia (Leguminosae: Mimosoideae)?

    Science.gov (United States)

    Brown, Sharon L; Warwick, Nigel W M; Prychid, Christina J

    2013-12-01

    Calcium oxalate (CaOx) crystals are a common natural feature of many plant families, including the Leguminosae. The functional role of crystals and the mechanisms that underlie their deposition remain largely unresolved. In several species, the seasonal deposition of crystals has been observed. To gain insight into the effects of rainfall on crystal formation, the morphology, distribution and accumulation of calcium oxalate crystals in phyllodes of the leguminous Acacia sect. Juliflorae (Benth.) C. Moore & Betche from four climate zones along an aridity gradient, was investigated. The shapes of crystals, which include rare Rosanoffian morphologies, were constant between species from different climate zones, implying that morphology was not affected by rainfall. The distribution and accumulation of CaOx crystals, however, did appear to be climate-related. Distribution was primarily governed by vein density, an architectural trait which has evolved in higher plants in response to increasing aridity. Furthermore, crystals were more abundant in acacias from low rainfall areas, and in phyllodes containing high concentrations of calcium, suggesting that both aridity and soil calcium levels play important roles in the precipitation of CaOx. As crystal formation appears to be calcium-induced, we propose that CaOx crystals in Acacia most likely function in bulk calcium regulation.

  18. 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.

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

    OpenAIRE

    Emmanuel Mavhura; Desmond Manatsa; Terence Mushore

    2015-01-01

    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 exami...

  20. 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

  1. 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

  2. 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.

  3. Analysis list: Arid1a [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Arid1a Adipocyte + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid1a....1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid1a.5.tsv http://dbarchive.biosciencedbc.jp/...kyushu-u/mm9/target/Arid1a.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Arid1a.Adipocyte.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Adipocyte.gml ...

  4. 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

  5. Rainfall Characterization In An Arid Area

    OpenAIRE

    Bazaraa, A. S.; Ahmed, Shamim

    1991-01-01

    The objective of this work is to characterize the rainfall in Doha which lies in an arid region. The rainfall data included daily rainfall depth since 1962 and the hyetographs of the individual storms since 1976. The rainfall is characterized by high variability and severe thunderstorms which are of limited geographical extent. Four probability distributions were used to fit the maximum rainfall in 24 hours and the annual rainfall depth. The extreme value distribution was found to have the be...

  6. Aridity increases below-ground niche breadth in grass communities

    Science.gov (United States)

    Butterfield, Bradley J.; Bradford, John B.; Munson, Seth M.; Gremer, Jennifer R.

    2017-01-01

    Aridity is an important environmental filter in the assembly of plant communities worldwide. The extent to which root traits mediate responses to aridity, and how they are coordinated with leaf traits, remains unclear. Here, we measured variation in root tissue density (RTD), specific root length (SRL), specific leaf area (SLA), and seed size within and among thirty perennial grass communities distributed along an aridity gradient spanning 190–540 mm of climatic water deficit (potential minus actual evapotranspiration). We tested the hypotheses that traits exhibited coordinated variation (1) among species, as well as (2) among communities varying in aridity, and (3) functional diversity within communities declines with increasing aridity, consistent with the “stress-dominance” hypothesis. Across communities, SLA and RTD exhibited a coordinated response to aridity, shifting toward more conservative (lower SLA, higher RTD) functional strategies with increasing aridity. The response of SRL to aridity was more idiosyncratic and was independent of variation in SLA and RTD. Contrary to the stress-dominance hypothesis, the diversity of SRL values within communities increased with aridity, while none of the other traits exhibited significant diversity responses. These results are consistent with other studies that have found SRL to be independent of an SLA–RTD axis of functional variation and suggest that the dynamic nature of soil moisture in arid environments may facilitate a wider array of resource capture strategies associated with variation in SRL.

  7. Arid sites stakeholder participation in evaluating innovative technologies: VOC-Arid Site Integrated Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, T.S.; McCabe, G.H.; Brockbank, B.R. [and others

    1995-05-01

    Developing and deploying innovative environmental cleanup technologies is an important goal for the U.S. Department of Energy (DOE), which faces challenging remediation problems at contaminated sites throughout the United States. Achieving meaningful, constructive stakeholder involvement in cleanup programs, with the aim of ultimate acceptance of remediation decisions, is critical to meeting those challenges. DOE`s Office of Technology Development sponsors research and demonstration of new technologies, including, in the past, the Volatile Organic Compounds Arid Site Integrated Demonstration (VOC-Arid ID), hosted at the Hanford Site in Washington State. The purpose of the VOC-Arid ID has been to develop and demonstrate new technologies for remediating carbon tetrachloride and other VOC contamination in soils and ground water. In October 1994 the VOC-Arid ID became a part of the Contaminant Plume Containment and Remediation Focus Area (Plume Focus Area). The VOC Arid ID`s purpose of involving stakeholders in evaluating innovative technologies will now be carried on in the Plume Focus Area in cooperation with Site Technology Coordination Groups and Site Specific Advisory Boards. DOE`s goal is to demonstrate promising technologies once and deploy those that are successful across the DOE complex. Achieving that goal requires that the technologies be acceptable to the groups and individuals with a stake in DOE facility cleanup. Such stakeholders include groups and individuals with an interest in cleanup, including regulatory agencies, Native American tribes, environmental and civic interest groups, public officials, environmental technology users, and private citizens. This report documents the results of the stakeholder involvement program, which is an integral part of the VOC-Arid ID.

  8. 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.

  9. 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/ARID3A.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.biosciencedbc.jp/kyushu-u/hg19/colo/ARID3A.Liver.tsv http://db...archive.biosciencedbc.jp/kyushu-u/hg19/colo/Blood.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Liver.gml ...

  10. 基于C5.0决策树算法的西北干旱区土地覆盖分类研究——以甘肃省武威市为例%The Study of the Northwest Arid Zone Land-Cover Classification Based on C5.0 Decision Tree Algorithm at Wuwei City,Gansu Province

    Institute of Scientific and Technical Information of China (English)

    齐红超; 祁元; 徐瑱

    2009-01-01

    西北干旱区面积广阔,由于土地利用类型多样,成因复杂,对环境变化敏感、变化过程快、幅度大、景观差异明显等特点,在影像上表现出的"同物异谱"现象明显;利用常规目视解译、监督非监督分类、人工参与的决策树分类等方法在效率或精度等方面各有其缺陷.采用机器学习C5.0决策树算法,综合利用地物波谱、NDVI、TC、纹理等信息,根据样本数据自动挖掘分类规则并对整个研究区进行地物分类.机器学习的决策树可以挖掘出更多的分类规则,C5.0算法对采样数据的分布没有要求,可以处理离散和连续数据,生成的规则易于理解,分类精度高,可以满足西北干旱区大面积的土地利用/覆被变化制图的需要.%In the broadly northwest arid regions,frequently,same object has different spectral characters because of the special characteristics of land cover change such as complex causes of formation,sensitivity to environment change,rapid and violent change and obvious differences in landscape. The conventional methods of classification including visual interpretation,supervised classification,unsupervised classification,and artificial decision tree classification have disadvantages in the efficiency or the accuracy. In this paper,machine learning algorithm based on C5. 0 decision tree was used to classify the entire study area automatically according to the sample data mining classification rules. Spectral features,NDVI,TC,texture and other informations were involved in the algorithm. More classification rules could be mined by machine learning decision tree. C5. 0 algorithm handling with both continuous and discrete data is independent of the distribution of sampling sites,The classification rules mined by this algorithm were interpretable. Other superiority of this algorithm included the fast speed of training and higher accuracy than many other classifiers. Thus,it is able to be used in the mapping of

  11. Analysis list: Arid3a [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Arid3a Pluripotent stem cell + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Ari...d3a.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid3a.5.tsv http://dbarchive.biosc...iencedbc.jp/kyushu-u/mm9/target/Arid3a.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Arid3a.Pluri...potent_stem_cell.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Pluripotent_stem_cell.gml ...

  12. 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.

  13. Soil moisture and vegetation memories in a cold, arid climate

    Science.gov (United States)

    Shinoda, Masato; Nandintsetseg, Banzragch

    2011-10-01

    Continental climate is established as a result of a complex interplay between the atmosphere and various land-surface systems such as the biosphere, soil, hydrosphere, and cryosphere. These systems function as climate memory, allowing the maintenance of interannual atmospheric anomalies. In this paper, we present new observational evidence of an interseasonal moisture memory mechanism mediated by the land surface that is manifested in the coupled cold and arid climate of Mongolia. Interannual anomalies of soil moisture and vegetation due to rainfall during a given summer are maintained through the freezing winter months to the spring, acting as an initial condition for subsequent summer land-surface and rainfall conditions. Both the soil moisture and vegetation memories were prominent over the eastern part of the Mongolian steppe zone (103-112°E and 46-50°N). That is, the cold-season climate with low evapotranspiration and strong soil freezing acts to prolong the decay time scale of autumn soil moisture anomalies to 8.2 months that is among the longest in the world. The vegetation also has a memory of the similar time scale, likely because the large rootstock of the perennial plants dominant in the Mongolian steppe may remain alive, retain belowground biomass anomalies during the winter, and have an impact on the initial vegetation growth during the spring.

  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. 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.

  16. 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.

  17. Systèmes de cultures améliorés à base de niébé (Vigna unguiculata (L. Walp pour une meilleure gestion de la sécurité alimentaire et des ressources naturelles en zone semi-aride du Burkina Faso

    Directory of Open Access Journals (Sweden)

    Zoundi, JS.

    2007-01-01

    Full Text Available Improved Cowpea Vigna unguiculata L. Walp Based Cropping Systems for Food Security and Natural Resource Management Enhancement in Semi-Arid Burkina Faso. Des plants au stade 4 feuilles de deux cultivars de fraisier, Darselect et Elsanta, ont été scindés en cinq lots et cultivées durant 10 semaines sous différents régimes thermique et photopériodique: [1] une température basse (3 °C associée à 8 h (4 semaines puis transférés à une température élevée (20 °C associée à 8 h ou 16 h (6 semaines ou bien [2] une température élevée (20 °C associée à 8 h et 16 h (10 semaines ou 8 h (4 semaines suivis de 16 h (6 semaines. Les résultats obtenus montrent que le pré-traitement thermique de 4 semaines détermine la croissance et l'état inflorescentiel des plants qui sera mesuré dès leur transfert à une température élevée (20 °C en présence des jours courts ou des jours longs durant 6 semaines. En effet, les températures élevées (20 °C augmentent le nombre de feuilles/plant, améliorent la surface foliaire totale et la longueur du pétiole, tandis que les basses températures (3 °C avancent le stade d'émergence du bourgeon terminal et accélèrent la croissance de son axe inflorescentiel. Dans ce cas, le transfert des plants de jours courts en jours longs favorise la croissance de l'axe inflorescentiel et la longueur du pétiole (Elsanta.

  18. 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.

  19. 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.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Roseboom, E.H. Jr.

    1983-12-31

    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 {sup 129}I and {sup 14}C to the atmosphere.

  2. 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)

  3. 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.

  4. 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).

  5. 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

  6. Organic textile waste as a resource for sustainable agriculture in arid and semi-arid areas.

    Science.gov (United States)

    Eriksson, Bo G

    2017-03-01

    New vegetation in barren areas offers possibilities for sequestering carbon in the soil. Arid and semi-arid areas (ASAs) are candidates for new vegetation. The possibility of agriculture in ASAs is reviewed, revealing the potential for cultivation by covering the surface with a layer of organic fibres. This layer collects more water from humidity in the air than does the uncovered mineral surface, and creates a humid environment that promotes microbial life. One possibility is to use large amounts of organic fibres for soil enhancement in ASAs. In the context of the European Commission Waste Framework Directive, the possibility of using textile waste from Sweden is explored. The costs for using Swedish textile waste are high, but possible gains are the sale of agricultural products and increased land prices as well as environmental mitigation. The findings suggest that field research on such agriculture in ASAs should start as soon as possible.

  7. 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.

  8. 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

  9. 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.

  10. Radioactive waste disposal in thick unsaturated zones.

    Science.gov (United States)

    Winogard, I J

    1981-06-26

    Portions of the Great Basin are undergoing crustal extension and have unsaturated zones as much as 600 meters thick. These areas contain multiple natural barriers capable of isolating solidified toxic wastes from the biosphere for tens of thousands to perhaps hundreds of thousands of years. An example of the potential utilization of such arid zone environments for toxic waste isolatic is the burial of transuranic radioactive wastes at relatively shallow depths (15 to 100 meters) in Sedan Crater, Yucca Flat, Nevada. The volume of this man-made crater is several times that of the projected volume of such wastes to the year 2000. Disposal in Sedan Crater could be accomplished at a savings on the order of $0.5 billion, in comparison with current schemes for burial of such wastes in mined repositories at depths of 600 to 900 meters, and with an apparently equal likelihood of waste isolation from the biosphere.

  11. 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.

  12. 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.

  13. The use of spatial empirical models to estimate soil erosion in arid ecosystems.

    Science.gov (United States)

    Abdullah, Meshal; Feagin, Rusty; Musawi, Layla

    2017-02-01

    The central objective of this project was to utilize geographical information systems and remote sensing to compare soil erosion models, including Modified Pacific South-west Inter Agency Committee (MPSIAC), Erosion Potential Method (EPM), and Revised Universal Soil Loss Equation (RUSLE), and to determine their applicability for arid regions such as Kuwait. The northern portion of Umm Nigga, containing both coastal and desert ecosystems, falls within the boundaries of the de-militarized zone (DMZ) adjacent to Iraq and has been fenced off to restrict public access since 1994. Results showed that the MPSIAC and EPM models were similar in spatial distribution of erosion, though the MPSIAC had a more realistic spatial distribution of erosion and presented finer level details. The RUSLE presented unrealistic results. We then predicted the amount of soil loss between coastal and desert areas and fenced and unfenced sites for each model. In the MPSIAC and EPM models, soil loss was different between fenced and unfenced sites at the desert areas, which was higher at the unfenced due to the low vegetation cover. The overall results implied that vegetation cover played an important role in reducing soil erosion and that fencing is much more important in the desert ecosystems to protect against human activities such as overgrazing. We conclude that the MPSIAC model is best for predicting soil erosion for arid regions such as Kuwait. We also recommend the integration of field-based experiments with lab-based spatial analysis and modeling in future research.

  14. 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.

  15. 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.

  16. Morphology and life cycle of a new species of Didymium (Myxomycetes) from arid areas of Mexico.

    Science.gov (United States)

    Wrigley de Basanta, D; Lado, C; Estrada-Torres, A

    2008-01-01

    A new species of myxomycete, Didymium umbilicatum, isolated from the bark of Agavaceae, is described from arid zones of Mexico. This species was obtained from moist chamber cultures of Yucca spp. bark, collected in four different years from two states (Puebla and Querétaro) in central Mexico and found in the field from Hidalgo, Oaxaca and Puebla on the dead remains of Agave sp. The new species has small, flat, white sporocarps or short plasmodiocarps, 0.2-1.3 mm diam, and 0.15-0.4 mm tall. They are sessile on a reduced base or have a short, calcareous pale stalk and warted spores, warts fused in an irregular subreticulum by SEM. It is the sixth species of Didymium recently described from arid areas. The stability of the taxonomic characters of the species was confirmed by spore-to-spore culture on agar. Life cycle events are described from germination to sporulation. The morphology of the myxomycete specimens was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included.

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. Tracer-based studies of soil water movement in semi-arid forests of New Mexico

    Science.gov (United States)

    Newman, Brent D.; Campbell, Andrew R.; Wilcox, Bradford P.

    1997-09-01

    The related issues of water movement and contaminant transport in arid and semi-arid environments have generated considerable interest and concern in the last few decades. Essential to understanding these issues is knowledge of how water moves through the soils that form the uppermost part of the vadose zone. The use of tracers, both natural and artificially introduced, is proving to be an effective method for gaining such knowledge in dry regions, where investigation by other means is difficult. In this study, natural stable-isotope and chloride tracers were used to investigate water movement in the soils of a piñon-juniper woodland and of a ponderosa pine forest on the Pajarito Plateau in northern New Mexico. The objectives were to (1) estimate and compare near-surface flux rates and evaluate the importance of evaporation in the two communities, and (2) determine to what extent differences in flux rates and evaporation are due to differences in plant cover and/or soil hydraulic properties. The results of this study will aid in evaluating the potential for contaminant mobility in semi-arid systems such as the Pajarito Plateau and, in addition, will increase understanding of nutrient distributions and plant water use in semi-arid environments. The stable-isotope data indicate a similarity between the piñon-juniper and ponderosa communities with respect to evaporation: in both, it is restricted mainly to the upper 10 cm of soil. Chloride profiles from the two communities, on the other hand, show a distinct difference with respect to downward fluxes: in the ponderosa pine forest, these fluxes (≈0.02 cm year -1) are an order of magnitude lower than those in the piñon-juniper woodland (≈0.2 cm year -1), even though total precipitation is about 4 cm year -1 higher in the ponderosa pine forest. This difference, however, appears to be related not to plant cover, but to differences in soil hydraulic properties. The soils of the ponderosa pine forest contain clay

  2. 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.

  3. Nebkha patterns in semi-arid environments

    Science.gov (United States)

    Nield, J. M.; Gillies, J. A.; Nickling, W. G.

    2014-12-01

    In semi-arid supply-limited, environments, nehbka dunes typically form through ecogeomorphic feedbacks. The size, shape and orientation of these dunes are controlled by the interactions between vegetation growth and aeolian sedimentations processes. Once established, these dune patterns modify sediment transport and often form streets of bare surfaces between dune corridors. We examine typical dune and vegetation patterns that form with varying amounts of sediment availability and nebkha maturity at Jornada in the Chihuahuan Desert, New Mexico, USA using terrestrial laser scanning (TLS) to separate the plant and sand elements. Manual and automated TLS shrub height extractions compare well at all sites (p = 0.48-0.94) enabling the quantification of both solid and plant roughness element components in three dimensions. We find that there is a switch in orientation of the dune elements with respect to dominant wind direction from perpendicular to parallel as the landscape develops from an incipient to mature configuration and mesquite-nebkha streets are enhanced. As the nebkha dunes develop the surface coverage of bare sand increases and dune surfaces exceed the size of their companion shrubs. Roughness density also increases at the mature dune site. Individual shrub orientations remain similar at each site, but nebkhas typically host multiple shrub crowns at the mature site. Over a two year period up to 20 cm of erosion was measured on the upwind faces of the mature nebkha dunes, in agreement with the dominant annual wind direction. However, deposition patterns were more diffuse and influenced by the vegetation patterns. This study highlights the importance of ecogeomorphic interactions in shaping nebkha landscape patterns.

  4. Changes of Sand Fly Populations and Leishmania infantum Infection Rates in an Irrigated Village Located in Arid Central Tunisia.

    Science.gov (United States)

    Barhoumi, Walid; Fares, Wasfi; Cherni, Saifedine; Derbali, Mohamed; Dachraoui, Khalil; Chelbi, Ifhem; Ramalho-Ortigao, Marcelo; Beier, John C; Zhioua, Elyes

    2016-03-16

    The current spread of zoonotic visceral leishmaniasis (ZVL) throughout arid areas of Central Tunisia is a major public health concern. The main objective of this study is to investigate whether the development of irrigation in arid bio-geographical areas in Central Tunisia have led to the establishment of a stable cycle involving sand flies of the subgenus Larroussius and Leishmania infantum, and subsequently to the emergence of ZVL. Sand flies were collected from the village of Saddaguia, a highly irrigated zone located within an arid bio-geographical area of Central Tunisia by using modified Centers for Diseases Control (CDC) light traps. Morphological keys were used to identify sand flies. Collected sand flies were pooled with up to 30 specimens per pool according to date and tested by nested Polymerase Chain Reaction (PCR) DNA sequencing from positive pools was used to identify Leishmania spp. A total of 4915 sand flies (2422 females and 2493 males) were collected from Saddaguia in September and in October 2014. Morphological identification confirmed sand flies of the subgenus Larroussius to be predominant. PCR analysis followed by DNA sequencing indicated that 15 pools were infected with L. infantum yielding an overall infection rate of 0.6%. The majority of the infected pools were of sand fly species belonging to subgenus Larroussius. Intense irrigation applied to the arid bio-geographical areas in Central Tunisia is at the origin of the development of an environment capable of sustaining important populations of sand flies of the subgenus Larroussius. This has led to the establishment of stable transmission cycles of L. infantum and subsequently to the emergence of ZVL.

  5. 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...

  6. 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.

  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. [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.

  9. Release of native and amended boron from arid zone soils after varying incubation times

    Science.gov (United States)

    In this study we evaluated the boron (B) release from soils containing elevated native B and examined the extent to which incubation time affected B release. Five soils varying in initial pH and clay content were selected for the study. The soils were spiked with five varying doses of B as H3BO3 (...

  10. The abiotic contribution to total CO2 flux for soils in arid zone

    Directory of Open Access Journals (Sweden)

    J. Ma

    2015-07-01

    Full Text Available As an important component of ecosystem carbon budgets, soil carbon dioxide (CO2 flux is determined by a combination of a series of biotic and abiotic processes. Although there is evidence that the abiotic component can be important in total soil CO2 flux, its relative importance has never been systematically assessed. In this study, the total soil CO2 flux (Rtotal was partitioned into biotic (Rbiotic and abiotic (Rabiotic components over eight typical landscapes in a desert–oasis ecotone, including cotton field, hops field, halophyte garden, reservoir edge, native saline desert, alkaline soil, dune crest and interdune lowland in the Gurbantunggut Desert, and the relative importance of these two components was analyzed. Results showed that Rabiotic always contributed to Rtotal for the eight landscapes, but the degree of contribution varied greatly. In the cotton and hops fields, the ratio of Rabiotic to Rtotal was extremely low (Rabiotic was dominant in the alkaline soil and dune crest. Statistically, Rabiotic/Rtotal decreased logarithmically with rising Rbiotic, suggesting that Rabiotic strongly affected Rtotal when Rbiotic was low. This pattern confirms that soil CO2 flux is predominantly biological in most ecosystems, but Rabiotic can dominate when biological processes are weak. On a diurnal basis, Rabiotic resulted in no net gain or loss of carbon but its effect on instantaneous CO2 flux was significant. Temperature dependence of Rtotal varied among the eight landscapes, determined by the predominant components of CO2 flux: with Rbiotic driven by soil temperature and Rabiotic regulated by the rate of change in temperature. Namely, declining temperature resulted in negative Rabiotic (CO2 went into soil, while rising temperature resulted in a positive Rabiotic (CO2 released from soil. Furthermore, without recognition of Rabiotic, Rbiotic would have been either overestimated (for daytime or underestimated (for nighttime. Thus, recognition that abiotic component in total soil CO2 flux is ubiquitous in soils has widespread consequences for the understanding of carbon cycling. While the abiotic flux will not change net daily soil CO2 exchange and not likely directly constitute a carbon sink, it can alter transient soil CO2 flux significantly, either in magnitude or in its temperature dependency.

  11. Thymus capitatus from Tunisian arid zone: chemical composition and in vitro anthelmintic effects on Haemonchus contortus.

    Science.gov (United States)

    Boubaker Elandalousi, Ramzi; Akkari, Hafidh; B'chir, Fatma; Gharbi, Mohamed; Mhadhbi, Moez; Awadi, Soufia; Darghouth, Mohamed Aziz

    2013-10-18

    The increasing prevalence of anthelmintic resistant strains of helminths, the drug residues in animal products and the high cost of conventional anthelmintics has created an interest in studying medicinal plants as an alternative source of anthelmintics. Thymus capitatus (Lamiales: Lamiaceae) is used traditionally by people as spices and reported to possess some biological effects. The objective of this study is to evaluate the anthelmintic efficacy of T. capitatus in comparison to albendazole against the gastrointestinal nematodes of sheep. To fulfil the objectives, in vitro anthelmintic activities of crude aqueous and crude ethanolic extracts of aerial parts of T. capitatus were investigated on the eggs and adults of the nematode parasite Haemonchus contortus. Both extract types of T. capitatus completely inhibited egg hatching at a concentration close to 2 mg/ml. LC₅₀ of ethanolic extract of T. capitatus was 0.368 mg/ml while that of aqueous extract was 6.344 mg/ml (p<0.05). The ethanolic extract showed higher in vitro activity against adult parasites than the aqueous one in terms of the paralysis and/or death of the worms at different hours post-treatment. Dose dependent effect was observed for both extracts. Chemical analyses revealed that the overall profile of both extracts was dominated by oxygenated constituents. In addition, ethanolic extract is mainly composed of phenols among which thymol (71.22%) and camphor (17.18%). As far as the literature could be ascertained, this is the first publication on anthelmintic activity of T. capitatus. The results of the present study suggest that T. capitatus extracts are a promising alternative to the commercially available anthelmintics like albendazole for the treatment of small ruminants' gastrointestinal nematodes.

  12. 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).

  13. 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.

  14. 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),

  15. 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.

  16. Effect of associated species on distribution of Commiphora wightii in Indian Arid Zone

    Directory of Open Access Journals (Sweden)

    Suresh KUMAR

    2017-01-01

    Full Text Available Commiphora wightii (Arn. Bhandari, a medicinal shrub of the family Burseraceae has been ruthlessly tapped for oleo-gum resin, thus killing its widespread populations in nature. Its regeneration being slow, the recruitment is also minimal. Consequently, existing sparse populations also face competition from its associates. Understanding vegetation composition and dynamics of associates of C. wightii are vital to arrive at clues for its ex-situ conservation and also for its in-situ populations build up. Present study carried out in 20 districts of Rajasthan at 604 sites revealed presence of C. wightii at 68 sites. Its associates were Acacia senegal, Euphorbia caducifolia, Grewia tenax, Prosopis juliflora, Acacia leucophloea and Boswellia serrata. In all the six districts, density of C. wightii varying from 1 to 20 per tenth hectare indicated its mutual co-existence with other species except P. juliflora. Regulating and controlling populations of P. juliflora emerged as a prime requirement to ensure success in both, in-situ and ex-situ conservation. Being ecologically co-dominant, it survives best in mixed plantation with suitable trees that serve as upper canopy in the plantation area. It also emerged that its optimum plantation density of 200 plants per hectare would most likely ensure its success in reintroduced paddocks.

  17. Development and application of water and energy saving irrigation systems in arid zones

    Energy Technology Data Exchange (ETDEWEB)

    Sourell, H.; Schoen, H.; Shani, U.

    1983-01-01

    This paper describes an irrigation system, which combines the flexibility and low labor intensity of the mobile irrigation equipment with the more accurate water distribution of the microirrigation equipment. The high volume sprinklers have been removed from the boom for this purpose and been replaced with nozzles or drip hoses, which apply the water more accurately and directly with low pressure in the vicinity of the plant. Experiments in the Negev desert performed in cooperation with the Institute of Agricultural Engineering, Volcani Center, Tel Aviv, revealed the following advantages: High efficiency of water application; water distribution independent of wind effects; low water distribution pressure and low energy requirements; high operational reliability; low investment costs; low leaf interception with possibility for use of saline water.

  18. 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

  19. Quantification of the Aridity Process in South-Western Romania

    Directory of Open Access Journals (Sweden)

    Daniel Peptenatu

    2013-05-01

    Full Text Available The report released by the Intergovernmental Committee for Climate Change indicates that Romania ranks among the top seven countries in Europe that would be strongly impacted by aridity in the next few years, with climate changes consisting in a rise of average annual temperatures by as much as 5°C. The research work was conducted in the South of the Oltenia South-Western Development Region, where more than 700,000 hectares of farmland is impacted by aridification, more than 100,000 hectares among them impacted by aridity. Research methodology encompassed the analysis of average annual temperatures over the time span data was available for, at three weather stations, an analysis of average annual precipitations, an analysis of the piezometric data, the evolution of land use as a result of the expansion of the aridity process. The assessment of the aridity process also involved taking into consideration the state of the vegetation by means of the normalized difference vegetation index (NDVI, used to assess the quality of the vegetal stratum, an important element in the complex analysis of the territory. The aridity process is an effect of global warming, and, based on the results of this study, the post-1990 escalation of its effects was brought about by socio-economic factors. The destruction of the irrigation systems and protective forest belts because of the uncertain situation of land ownership are the main factors that contributed to amplification of the effects of aridity on the efficiency of agricultural systems that nowadays are exposed to very high risks.

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

    Science.gov (United States)

    Scanlon, B.R.; Keese, K.E.; Flint, A.L.; Flint, L.E.; Gaye, C.B.; Edmunds, W.M.; Simmers, I.

    2006-01-01

    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 (40-374000 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 Nin??o Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Nin??os (1977-1998) relative to periods dominated by La Nin??as (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

  1. 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

  2. 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.

  3. Mediterranean semi-arid systems-sensitivity and adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Lavee, H.; Sarah, P.

    2009-07-01

    The semi-arid areas of the Mediterranean are sensitive to climate change as they are located. In many cases, between two different systems, the arid system and the Mediterranean sub-humid system. A number of quick response ecogeomorphological variables were monitored along a climatic transect in Israel, running from west to east, covering an annual rainfall range of 700-100mm. The relationships of climatic conditions-available water soil properties overland flow erosion, were investigates. Soil samples were taken from open areas between shrubs and overland flow was monitored in posts of 7, 14 and 21 m in length (3m width). (Author)

  4. 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.

  5. Effects of environmental conditions on soil salinity and arid region in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ahmed, C.; Ben Rouina, B.; Boukhris, M.

    2009-07-01

    The shortage of water resources of good water quality is becoming an issue in the arid and semi arid regions. for this reason, the use of water resources of marginal quality such as treated wastewater and saline groundwater has become and important consideration, particularly in arid region in Tunisia, where large quantities of saline water are used for irrigation. (Author)

  6. Reflexive Water Management in Arid Regions: The Case of Iran

    NARCIS (Netherlands)

    Balali, M.R.; Keulartz, F.W.J.; Korthals, M.

    2009-01-01

    To illuminate the problems and perspectives of water management in Iran and comparable (semi-) arid Middle East and North Africa (MENA) countries, three paradigms can be distinguished: the traditional, the industrial and the reflexive paradigm. Each paradigm is characterised by its key technical sys

  7. 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.

  8. 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.

  9. 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

  10. Interspecific facilitation and critical transitions in arid ecosystems

    NARCIS (Netherlands)

    Verwijmeren, Mart; Rietkerk, Max; Wassen, Martin J.; Smit, Christian

    2013-01-01

    Climate change and intensified land-use impose severe stress on arid ecosystems, resulting in relatively rapid degradation which is difficult to reverse. To prevent such critical transitions it is crucial to detect early warning signals. Increased patchiness' smaller and fewer vegetated patches is t

  11. 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.

  12. Local facilitation, bistability and transitions in arid ecosystems

    NARCIS (Netherlands)

    Kéfi, S.; Rietkerk, M.G.; Baalen, M. van; 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

  13. 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

  14. Improved climate risk simulations for rice in arid environments

    NARCIS (Netherlands)

    Oort, van P.A.J.; Vries, de M.; Yoshida, H.; Saito, K.

    2015-01-01

    We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potenti

  15. On dew and micrometeorology in an arid coastal ecosystem

    NARCIS (Netherlands)

    Heusinkveld, B.G.

    2008-01-01

    This study investigated intriguing aspects of dew within a sandy arid ecosystem situated in the NW Negev desert, Israel. The goal was to quantify dew formation and evaporation processes through sensor design, field measurements and modelling. To do this, two new sensors were developed. The first sen

  16. 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.

  17. 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.

  18. Determination of seasonal rainfall variability, onset and cessation in semi-arid Tharaka district, Kenya

    Science.gov (United States)

    Recha, C. W.; Makokha, G. L.; Traore, P. S.; Shisanya, C.; Lodoun, T.; Sako, A.

    2012-05-01

    The study quantified rainfall variability for March-May (MAM) and October-December (OND) seasons in Tharaka district, Kenya. The parameters analysed were inter-annual variability of seasonal rainfall, onset and cessation using daily rainfall data in three agro-ecological zones' stations. Percentage mean cumulative method was used to determine onset and cessation, and seasonal variability was estimated using rainfall variability indices. Although both seasons are highly variable, OND has been persistently below mean over time while MAM shows high within-season variability. Despite the near uniformity in the mean onset and cessation dates, the former is highly variable on an inter-annual scale. The two rainfall seasons are inherently dissimilar and therefore require specific cropping in agro-ecological zone LM4 and LM4-5. It is possible that farmers in IL5 are missing an opportunity by under-utilising MAM rainfall. The results should be incorporated in implications of climate variability and vulnerability assessment in semi-arid Tharaka district.

  19. Plant communities of the Soutpansberg Arid Northern Bushveld

    Directory of Open Access Journals (Sweden)

    Theo H.C. Mostert

    2009-01-01

    Full Text Available The Soutpansberg Arid Northern Bushveld is one of eight major vegetation types (MVT described for the Soutpansberg-Blouberg region. The plant communities of this MVT are described in detail. Main ecological drivers of the vegetation structure and species composition of these communities are discussed and some conservation recommendations are made. Phytosociological data from a subset of 72 Braun-Blanquet sample plots collected in the Soutpansberg Arid Northern Bushveld were classified using Two-way Indicator Species Analysis (TWINSPAN and ordinated using a Detrended Correspondence Analysis (DECORANA. The resulting classification was further refined with table-sorting procedures based on the Braun-Blanquet floristic-sociological approach to vegetation classification using the computer software MEGATAB and JUICE. Eight plant communities were identified and described as Commiphora tenuipetiolata-Adansonia digitata short open woodland, Ledebouria ovatifolia-Commiphora mollis short bushland, Phyllanthus reticulatus-Acacia nigrescens short bushland, Tinnea rhodesiana-Combretum apiculatum short bushland, Dichrostachys cinerea subsp. africana-Spirostachys africana low thickets, Themeda triandra-Pterocarpus rotundifolius short closed grassland on steep basaltic slopes, Cyperus albostriatus-Syzygium cordatum sandveld wetlands, and Sesamothamnus lugardii-Catophractes alexandri tall sparse shrubland. These plant communities are event-driven ecosystems, predominantly infl uenced by frequent droughts, exposure to desiccation and unpredictable rainfall events. The complex topography of the Soutpansberg further contributes to the aridity of these ecosystems. The classifi cation and ordination analyses show similar groupings in the vegetation of the Soutpansberg Arid Mountain Bushveld. This confi rms the usefulness of complimentary analysis, using both classifi cation and ordination methods on a single data set in order to examine patterns and to search for

  20. Causes of early Holocene desertification in arid central Asia

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Liya [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); University of Kiel, Institute of Geosciences, Kiel (Germany); Chen, Fahu [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); Morrill, Carrie [University of Colorado, Cooperative Institute for Research in Environmental Sciences, Boulder, CO (United States); NOAA' s National Climatic Data Center, Paleoclimatology Branch, Boulder, CO (United States); Otto-Bliesner, Bette L.; Rosenbloom, Nan [National Center for Atmospheric Research, Climate and Global Dynamics Division, Boulder, CO (United States)

    2012-04-15

    Paleoclimate records of effective moisture (precipitation minus evaporation, or P-E) show a dry (low effective moisture) period in mid-latitude arid/semi-arid central Asia during the early Holocene (11,000-8,000 years ago) relative to the middle and late Holocene, in contrast to evidence for greater-than-present precipitation at the same time in the south and east Asian monsoonal areas. To investigate the spatial differences in climate response over mid-latitude central Asia and monsoonal Asia we conducted a series of simulations with the Community Climate System Model version 3 coupled climate model for the early, middle and late Holocene. The simulations test the climatic impact of all important forcings for the early Holocene, including changes in orbital parameters, the presence of the remnant Laurentide ice sheet and deglacial freshening of the North Atlantic. Model results clearly show the early Holocene patterns indicated by proxy records, including both the decreased effective moisture in arid central Asia, which occurs in the model primarily during the winter months, and the increase in summer monsoon precipitation in south and east Asia. The model results suggest that dry conditions in the early Holocene in central Asia are closely related to decreased water vapor advection due to reduced westerly wind speed and less evaporation upstream from the Mediterranean, Black, and Caspian Seas in boreal winter. As an extra forcing to the early Holocene climate system, the Laurentide ice sheet and meltwater fluxes have a substantial cooling effect over high latitudes, especially just over and downstream of the ice sheets, but contribute only to a small degree to the early Holocene aridity in central Asia. Instead, most of the effective moisture signal can be explained by orbital forcing decreasing the early Holocene latitudinal temperature gradient and wintertime surface temperature. We find little evidence for regional subsidence related to a stronger summer Asian

  1. 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)

  2. 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.

  3. 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).

  4. Validation of humidex in evaluating heat stress in the outdoor jobs in arid and semi-arid climates of Iran

    Directory of Open Access Journals (Sweden)

    Hamid Reza Heidari

    2016-09-01

    Full Text Available Introduction: Regarding development of several thermal indices and limitations of each, in this research applicability and validity of temperature- humidity index (Humidex were examined against the standard heat index, Wet Bulb Globe Temperature -WBGT, as well as tympanic temperature of subjects. Material and Method:  This cross-sectional study was done on 163 subjects at spring and summer (2013 in outdoor jobs of arid and semi-arid climates of Iran. Environmental parameters as well as tympanic temperature of subjects were measured simultaneously and then heat indices were determined. Data were analyzed using linear correlation charts and Kappa coefficient of agreement by means of SPSS software version 20. Results: A strong correlation was obtained between WBGT and Humidex in both arid and semi-arid regions (r>0.98, while the correlation between Humidex and tympanic temperature was moderate (r=0.5-0.8. Based on the obtained Kappa value, the agreement coefficient between Humidex and WBGT was 0.878. This value was obtained equal to 0.226 for the Humidex and tympanic temperature. Conclusion: The results of this study showed that Humidex can be applied as an appropriate substitute for the WBGT index. However, if evaluation of environmental condition with low air temperature or very hot situation is considered, relying only on the Humidex results will not provide a realistic estimation of thermal strain imposed to individuals.

  5. 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.

  6. Spatiotemporal soil and saprolite moisture dynamics across a semi-arid woody plant gradient

    Science.gov (United States)

    Niemeyer, Ryan J.; Heinse, Robert; Link, Timothy E.; Seyfried, Mark S.; Klos, P. Zion; Williams, Christopher J.; Nielson, Travis

    2017-01-01

    Woody plant cover has increased 10-fold over the last 140+ years in many parts of the semi-arid western USA. Woody plant cover can alter the timing and amount of plant available moisture in the soil and saprolite. To assess spatiotemporal subsurface moisture dynamics over two water years in a snow-dominated western juniper stand we compared moisture dynamics horizontally across a discontinuous canopy, and vertically in soil and saprolite. We monitored soil moisture at 15 and 60 cm and conducted periodic electromagnetic induction and electrical resistivity tomography surveys aimed at sensing moisture changes within the root zone and saprolite. Timing of soil moisture dry down at 15 cm was very similar between canopy patches and interspace. Conversely, dry down at 60 cm occurred 22 days earlier in the interspace than under canopy patches. After rainfall, interspaces with more shrubs showed greater increases in soil moisture than interspaces with few shrubs. For the few rainfall events that were large enough to increase soil moisture at 60 cm, increases in moisture occurred almost exclusively below the canopy. Soil water holding capacity from 0 to 150 cm was a primary driver of areas that were associated with the greatest change in distributed electrical conductivity - an indicator of changes in soil moisture - across the growing season. Vegetation was also correlated with a greater seasonal change in electrical conductivity at these depths. The seasonal change in resistivity suggested moisture extraction by juniper well into the saprolite, as deep as 12 m below the surface. This change in deep subsurface resistivity primarily occurred below medium and large juniper trees. This study suggests how tree roots are both increasing infiltration below their canopy while also extracting moisture at depths of upwards of 12 m. Information from this study can help improve our understanding of juniper resilience to drought and the hydrologic impacts of semi-arid land cover

  7. Cutaneous and respiratory water loss in larks from arid and mesic environments.

    Science.gov (United States)

    Tieleman, B Irene; Williams, Joseph B

    2002-01-01

    Birds from deserts generally have lower total evaporative water loss (TEWL), the sum of cutaneous (CWL) and respiratory water loss (RWL), than species from mesic areas. We investigated the role of CWL and RWL as a function of air temperature (T(a)) in hoopoe larks (Alaemon alaudipes) and Dunn's larks (Eremalauda dunni) from the Arabian Desert and skylarks (Alauda arvensis) and woodlarks (Lullula arborea) from temperate mesic grasslands. The proportional contribution of CWL to TEWL in all larks at moderate T(a) ranged from 50% to 70%. At high T(a) (40 degrees -45 degrees C), larks enhanced CWL by only 45%-78% and relied on an increase in RWL by 676%-2,733% for evaporative cooling. Surface-specific CWL at 25 degrees C was 29% lower in the arid-zone species than in the mesic larks. When acclimated to constant T(a), 15 degrees C-acclimated hoopoe larks increased CWL by 22% compared with 35 degrees C-acclimated birds, but the other species did not change CWL. This study is consistent with the hypothesis that larks from deserts have a reduced CWL at moderate and low T(a) but provided no support for the hypothesis that at high T(a) larks from arid regions rely more on CWL than larks from mesic environments. Interspecific differences in CWL cannot be attributed to acclimation to environmental temperature and are possibly the result of genetic differences due to natural selection or of phenotypically plastic responses to divergent environments during ontogeny.

  8. 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 M.; Chorover, Jon

    2014-09-01

    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 in a semi-arid climate at an EPA Superfund Site in 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 samples with

  9. 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.

  10. Genomic and proteomic characterization of ARID1A chromatin remodeller in ampullary tumors

    Science.gov (United States)

    Nastase, Anca; Teo, Jin Yao; Heng, Hong Lee; Ng, Cedric Chuan Young; Myint, Swe Swe; Rajasegaran, Vikneswari; Loh, Jia Liang; Lee, Ser Yee; Ooi, London Lucien; Chung, Alexander Yaw Fui; Chow, Pierce Kah Hoe; Cheow, Peng Chung; Wan, Wei Keat; Azhar, Rafy; Khoo, Avery; Xiu, Sam Xin; Alkaff, Syed Muhammad Fahmy; Cutcutache, Ioana; Lim, Jing Quan; Ong, Choon Kiat; Herlea, Vlad; Dima, Simona; Duda, Dan G; Teh, Bin Tean; Popescu, Irinel; Lim, Tony Kiat Hon

    2017-01-01

    AT rich interactive domain 1A (ARID1A) is one of the most commonly mutated genes in a broad variety of tumors. The mechanisms that involve ARID1A in ampullary cancer progression remains elusive. Here, we evaluated the frequency of ARID1A and KRAS mutations in ampullary adenomas and adenocarcinomas and in duodenal adenocarcinomas from two cohorts of patients from Singapore and Romania, correlated with clinical and pathological tumor features, and assessed the functional role of ARID1A. In the ampullary adenocarcinomas, the frequency of KRAS and ARID1A mutations was 34.7% and 8.2% respectively, with a loss or reduction of ARID1A protein in 17.2% of the cases. ARID1A mutational status was significantly correlated with ARID1A protein expression level (P=0.023). There was a significant difference in frequency of ARID1A mutation between Romania and Singapore (2.7% versus 25%, P=0.04), suggestive of different etiologies. One somatic mutation was detected in the ampullary adenoma group. In vitro studies indicated the tumor suppressive role of ARID1A. Our results warrant further investigation of this chromatin remodeller as a potential early biomarker of the disease, as well as identification of therapeutic targets in ARID1A mutated ampullary cancers.

  11. 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.

  12. Climate Warming Threatens Semi-arid Forests in Inner Asia

    Science.gov (United States)

    WU, X.; Liu, H.; Qi, Z.; Li, X.

    2014-12-01

    A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes (such as fire and insect dynamics) in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected

  13. Climate warming threatens semi-arid forests in Inner Asia

    Science.gov (United States)

    WU, X.

    2015-12-01

    A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected. However, the functionally realistic

  14. Development and use of bioenergy feedstocks for semi-arid and arid lands.

    Science.gov (United States)

    Cushman, John C; Davis, Sarah C; Yang, Xiaohan; Borland, Anne M

    2015-07-01

    Global climate change is predicted to increase heat, drought, and soil-drying conditions, and thereby increase crop sensitivity to water vapour pressure deficit, resulting in productivity losses. Increasing competition between agricultural freshwater use and municipal or industrial uses suggest that crops with greater heat and drought durability and greater water-use efficiency will be crucial for sustainable biomass production systems in the future. Agave (Agavaceae) and Opuntia (Cactaceae) represent highly water-use efficient bioenergy crops that could diversify bioenergy feedstock supply yet preserve or expand feedstock production into semi-arid, abandoned, or degraded agricultural lands, and reclaim drylands. Agave and Opuntia are crassulacean acid metabolism species that can achieve high water-use efficiencies and grow in water-limited areas with insufficient precipitation to support traditional C3 or C4 bioenergy crops. Both Agave and Opuntia have the potential to produce above-ground biomass rivalling that of C3 and C4 crops under optimal growing conditions. The low lignin and high amorphous cellulose contents of Agave and Opuntia lignocellulosic biomass will be less recalcitrant to deconstruction than traditional feedstocks, as confirmed by pretreatments that improve saccharification of Agave. Refined environmental productivity indices and geographical information systems modelling have provided estimates of Agave and Opuntia biomass productivity and terrestrial sequestration of atmospheric CO2; however, the accuracy of such modelling efforts can be improved through the expansion of field trials in diverse geographical settings. Lastly, life cycle analysis indicates that Agave would have productivity, life cycle energy, and greenhouse gas balances comparable or superior to those of traditional bioenergy feedstocks, but would be far more water-use efficient.

  15. 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.

  16. 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.

  17. 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.

  18. Pollen transport in the Shiyang River drainage, arid China

    Institute of Scientific and Technical Information of China (English)

    ZHU Yan; XIE Yaowen; CHENG Bo; CHEN Fahu; ZHANG Jiawu

    2003-01-01

    In order to assess the contribution of the pollen transported by wind and fluvial flows to the pollen spectra in Shiyang River drainage, a typical small endorheic drainage in arid lands of northwest China, preliminary studies on modern pollen rain along two transects with 91 surface soil samples, 8 atmospheric samples, 30 modern fluvial flow samples and 50 riverbed mud samples, were carried out. Results show that dispersal agents (air, flowing water) have dissimilareffects on transport of pollen and the structure of pollen spectra. Fluvial flow has a stronger capacity than wind to transport large quantities of pollen overlong distances. Pollen transported by fluvial flow makes a large contribution to the pollen spectra of riverbed alluvial sediments. Paleoenvironmental reconstructions undertaken using pollen spectra from fluvial sediments in arid lands arestrongly influenced by pollen transport. Therefore, the sources, the transportation agents and the depositional condition of pollen should be systematically investigated before pollen assemblages are used to derive the environmental significance in such settings.

  19. 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).

  20. Spatial vegetation patterns and imminent desertification in Mediterranean arid ecosystems

    OpenAIRE

    2007-01-01

    Humans and climate affect ecosystems and their services, which may involve continuous and discontinuous transitions from one stable state to another. Discontinuous transitions are abrupt, irreversible and among the most catastrophic changes of ecosystems identified1. For terrestrial ecosystems, it has been hypothesized that vegetation patchiness could be used as a signature of imminent transitions. Here, we analyse how vegetation patchiness changes in arid ecosystems with different grazing pr...

  1. 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.

  2. 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

  3. Désertification des parcours arides au Maroc

    Directory of Open Access Journals (Sweden)

    Mahyou, H.

    2010-01-01

    Full Text Available Desertification of Arid Rangelands in Morocco. Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands. These areas represent livelihoods for thousands of people and protect the country from desertification. Despite the importance of the rangelands and the threat of desertification, it is surprising that up to date there is no comprehensive assessment of their condition and their evolution, hindering any plan for desertification alleviation. However, the available information on selected pilot areas shows that these rangelands are threatened by desertification. It's associated with biodiversity loss and contributes to climate change. The leading causes of land degradation are the human actions combined with climate. The establishment of a comprehensive surveillance system based on remote sensing, biophysics and socio-economic data must be envisaged to provide policymakers with an operational tool adapted to the spatio-temporal monitoring of desertification.

  4. 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.

  5. Changes of the transitional climate zone in East Asia: past and future

    Science.gov (United States)

    Wang, Lin; Chen, Wen; Huang, Gang; Zeng, Gang

    2016-10-01

    The transitional climate zone (TCZ) between humid and arid regions in East Asia is characterized by sharp climate and biome gradients, interaction between the East Asian summer monsoon and the mid-latitude westerly winds and mixed agriculture-pasture activities. Consequently, it is highly vulnerable to natural disturbances and particularly human-driven global change. This study aims to illuminate the spatial and temporal variation of TCZ across both the retrospective and the prospective periods. In the historical period, both the front and rear edges of TCZ exhibit wide year-to-year excursions and have experienced coastward migration with increasing aridity throughout TCZ. Furthermore, precipitation fluctuation mainly contributes to interannual variability of TCZ whereas potential evaporation behavior dominates the long-term trends of TCZ. Models are capable of largely reproducing the shape and orientation of TCZ, although northwestward bias is apparent. In global warming scenario period, there will be continuing southeastward displacement for the front edge but the opposite northwestward movement is projected for the rear one, as a consequence of significant drying trends in the humid zone together with regime shifts towards humid conditions in the arid zone. Despite expanded TCZ sector, however, the available water resources inside it suffer little magnitude changes without preferential tendency towards either drier or wetter conditions, implying neither deleterious nor beneficial effects on the TCZ environment. Moreover, interannual variability of TCZ is expected to become stronger, resulting in more frequent occurrences of extreme swings. Finally, it is noted that uncertainty arising from climate models dominates in the TCZ than dispersed emission scenarios, in contrast to the situation in humid and arid zones.

  6. 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)

    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.

  7. ANTIHELMINTIC TREATMENT OF GOATS ON AN ARID RANGE AND ITS EFFECT ON MILK PRODUCTION EARLY IN LACTATION

    Directory of Open Access Journals (Sweden)

    Raul Valdéz

    2006-10-01

    Full Text Available The effect of a single anthelmintic treatment at thebeginning of lactation on milk production and composition, live weight change and blood chemistry in mix-breeds goats was studied in an arid zone of northern Mexico. Ten adult goats were treated with Closantel ® subcutaneously at 8.0mg kg-1 BW. Eleven adult goats were used as untreated controls. The overall total trial reduction in fecal egg counts due to anthelmintic treatment was 96%, but this fecal egg counts reduction did not affect live weight change (-13 ±0.5 and -15 ± 0.3 g d-1 for treated and control does, milk yield(30.7 ± 0.4 and 33.6 ± 0.8 L in 73 days of lactation for treated and control does. No significant differences were seen in milk composition and blood profiles between treated and untreated goats. It was concluded that, in the present context of goat exploitation under traditional extensive village system in an arid environment, parasite burdens at the beginning of lactation were not sufficiently severe to affect milk production and weight change of goats. KEY WORDS: Anthelmintic treatment, blood chemistry, body weight, goats, milk production, gastrointestinal nematodes.

  8. 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.

  9. Genotypic and symbiotic diversity of Rhizobium populations associated with cultivated lentil and pea in sub-humid and semi-arid regions of Eastern Algeria

    OpenAIRE

    Riah, N.; Béna, Gilles; Djekoun, A.; Heulin, K.; De Lajudie, Philippe; Laguerre, G.

    2014-01-01

    The genetic structure of rhizobia nodulating pea and lentil in Algeria, Northern Africa was determined. A total of 237 isolates were obtained from root nodules collected on lentil (Lens culinaris), proteaginous and forage pea (Pisum sativum) growing in two eco-climatic zones, sub-humid and semi-arid, in Eastern Algeria. They were characterised by PCR-restriction fragment length polymorphism (RFLP) of the 16S-23S rRNA intergenic region (IGS), and the nodD-F symbiotic region. The combination of...

  10. 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

  11. 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.

  12. Modeling of Soil Water and Salt Dynamics and Its Effects on Root Water Uptake in Heihe Arid Wetland, Gansu, China

    Directory of Open Access Journals (Sweden)

    Huijie Li

    2015-05-01

    Full Text Available In the Heihe River basin, China, increased salinity and water shortages present serious threats to the sustainability of arid wetlands. It is critical to understand the interactions between soil water and salts (from saline shallow groundwater and the river and their effects on plant growth under the influence of shallow groundwater and irrigation. In this study, the Hydrus-1D model was used in an arid wetland of the Middle Heihe River to investigate the effects of the dynamics of soil water, soil salinization, and depth to water table (DWT as well as groundwater salinity on Chinese tamarisk root water uptake. The modeled soil water and electrical conductivity of soil solution (ECsw are in good agreement with the observations, as indicated by RMSE values (0.031 and 0.046 cm3·cm−3 for soil water content, 0.037 and 0.035 dS·m−1 for ECsw, during the model calibration and validation periods, respectively. The calibrated model was used in scenario analyses considering different DWTs, salinity levels and the introduction of preseason irrigation. The results showed that (I Chinese tamarisk root distribution was greatly affected by soil water and salt distribution in the soil profile, with about 73.8% of the roots being distributed in the 20–60 cm layer; (II root water uptake accounted for 91.0% of the potential maximal value when water stress was considered, and for 41.6% when both water and salt stress were considered; (III root water uptake was very sensitive to fluctuations of the water table, and was greatly reduced when the DWT was either dropped or raised 60% of the 2012 reference depth; (IV arid wetland vegetation exhibited a high level of groundwater dependence even though shallow groundwater resulted in increased soil salinization and (V preseason irrigation could effectively increase root water uptake by leaching salts from the root zone. We concluded that a suitable water table and groundwater salinity coupled with proper irrigation

  13. 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...

  14. 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.

  15. 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

    2016-11-01

    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.

  16. 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.

  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 different applications such as the estimation of climate changes and land cover features. It is known that thermal infrared (TIR) emissivity is affected by soil moisture, but there are very few works in literature on this issue. This study is aimed to analyze and find 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 fields 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 μm 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 different spectral channels, at 8.7 μm, 10.8 μm and 12 μm. A Kalman filter physical

  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.

    2016-09-01

    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.

  19. 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.

  20. Androgen Receptor Coactivator ARID4B Is Required for the Function of Sertoli Cells in Spermatogenesis.

    Science.gov (United States)

    Wu, Ray-Chang; Zeng, Yang; Pan, I-Wen; Wu, Mei-Yi

    2015-09-01

    Defects in spermatogenesis, a process that produces spermatozoa inside seminiferous tubules of the testis, result in male infertility. Spermatogenic progression is highly dependent on a microenvironment provided by Sertoli cells, the only somatic cells and epithelium of seminiferous tubules. However, genes that regulate such an important activity of Sertoli cells are poorly understood. Here, we found that AT-rich interactive domain 4B (ARID4B), is essential for the function of Sertoli cells to regulate spermatogenesis. Specifically, we generated Sertoli cell-specific Arid4b knockout (Arid4bSCKO) mice, and showed that the Arid4bSCKO male mice were completely infertile with impaired testis development and significantly reduced testis size. Importantly, severe structural defects accompanied by loss of germ cells and Sertoli cell-only phenotype were found in many seminiferous tubules of the Arid4bSCKO testes. In addition, maturation of Sertoli cells was significantly delayed in the Arid4bSCKO mice, associated with delayed onset of spermatogenesis. Spermatogenic progression was also defective, showing an arrest at the round spermatid stage in the Arid4bSCKO testes. Interestingly, we showed that ARID4B functions as a "coactivator" of androgen receptor and is required for optimal transcriptional activation of reproductive homeobox 5, an androgen receptor target gene specifically expressed in Sertoli cells and critical for spermatogenesis. Together, our study identified ARID4B to be a key regulator of Sertoli cell function important for male germ cell development.

  1. 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 33C. Seashore paspalum performed best followed by Tifway Bermuda grass and common Bermuda grass respectively.

  2. 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

  3. 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...... development of ZoneLib....

  4. 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.

  5. 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.

  6. Understanding Hydrologic Processes in Semi-Arid Cold Climates

    Science.gov (United States)

    Barber, M. E.; Beutel, M.; Lamb, B.; Watts, R.

    2004-12-01

    Water shortages destabilize economies and ecosystems. These shortages are caused by complex interactions between climate variability, ecosystem processes, and increased demand from human activities. In the semi-arid region of the northwestern U.S., water availability during drought periods has already reached crisis levels and the problems are expected to intensify as the effects of global climate change and population growth continue to alter the supply and demand patterns. Many of the problems are critical to this region because hydropower, agriculture, navigation, fish and wildlife survival, water supply, tourism, environmental protection, and water-based recreation are vital to state economies and our way of life. In order to assess the spatial and temporal nature of hydrologic responses, consistent and comprehensive long-term data sets are needed. In response to these needs, we would like to propose the Spokane River drainage basin as a long-term hydrologic observatory. The Spokane River basin is located in eastern Washington and northern Idaho and is a tributary of the Columbia River. The watershed consists of several major surface water tributaries as well as natural and man-made lakes and reservoirs. With headwaters beginning in the Rocky Mountains, the drainage area is approximately 6,640 mi2. In addition to providing an excellent study area for examining many conventional water resource problems, the Spokane River watershed also presents a unique opportunity for investigating many of the hydrologic processes found in semi-arid cold climates. Snowfall in the watershed varies spatially between 35 inches near the mouth of the basin to over 112 inches at the headwaters. These varied hydrologic uses provide a unique opportunity to address many common challenges faced by water resource professionals. This broad array of issues encompasses science, engineering, agriculture, social sciences, economics, fisheries, and a host of other disciplines. In addition

  7. Improved climate risk simulations for rice in arid environments.

    Science.gov (United States)

    van Oort, Pepijn A J; de Vries, Michiel E; Yoshida, Hiroe; Saito, Kazuki

    2015-01-01

    We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potential yields with yields simulated with default ORYZA2000, with modified subversions of ORYZA2000 and with ORYZA_S, a model developed for the region of interest in the 1990s. Rice variety 'IR64' was sown monthly 15-times in a row in two locations in Senegal. The Senegal River Valley is located in the Sahel, near the Sahara desert with extreme temperatures during day and night. The existing subroutines underestimated cold stress and overestimated heat stress. Forcing the model to use observed spikelet number and phenology and replacing the existing heat and cold subroutines improved accuracy of yield simulation from EF = -0.32 to EF =0.70 (EF is modelling efficiency). The main causes of improved accuracy were that the new model subversions take into account transpirational cooling (which is high in arid environments) and early morning flowering for heat sterility, and minimum rather than average temperature for cold sterility. Simulations were less accurate when also spikelet number and phenology were simulated. Model efficiency was 0.14 with new heat and cold routines and improved to 0.48 when using new cardinal temperatures for phenology and early leaf growth. The new adapted subversion of ORYZA2000 offers a powerful analytic tool for climate change impact assessment and cropping calendar optimisation in arid regions.

  8. Improved climate risk simulations for rice in arid environments.

    Directory of Open Access Journals (Sweden)

    Pepijn A J van Oort

    Full Text Available We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potential yields with yields simulated with default ORYZA2000, with modified subversions of ORYZA2000 and with ORYZA_S, a model developed for the region of interest in the 1990s. Rice variety 'IR64' was sown monthly 15-times in a row in two locations in Senegal. The Senegal River Valley is located in the Sahel, near the Sahara desert with extreme temperatures during day and night. The existing subroutines underestimated cold stress and overestimated heat stress. Forcing the model to use observed spikelet number and phenology and replacing the existing heat and cold subroutines improved accuracy of yield simulation from EF = -0.32 to EF =0.70 (EF is modelling efficiency. The main causes of improved accuracy were that the new model subversions take into account transpirational cooling (which is high in arid environments and early morning flowering for heat sterility, and minimum rather than average temperature for cold sterility. Simulations were less accurate when also spikelet number and phenology were simulated. Model efficiency was 0.14 with new heat and cold routines and improved to 0.48 when using new cardinal temperatures for phenology and early leaf growth. The new adapted subversion of ORYZA2000 offers a powerful analytic tool for climate change impact assessment and cropping calendar optimisation in arid regions.

  9. 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.

  10. Subduction of fracture zones

    Science.gov (United States)

    Constantin Manea, Vlad; Gerya, Taras; Manea, Marina; Zhu, Guizhi; Leeman, William

    2013-04-01

    Since Wilson proposed in 1965 the existence of a new class of faults on the ocean floor, namely transform faults, the geodynamic effects and importance of fracture zone subduction is still little studied. It is known that oceanic plates are characterized by numerous fracture zones, and some of them have the potential to transport into subduction zones large volumes of water-rich serpentinite, providing a fertile water source for magma generated in subduction-related arc volcanoes. In most previous geodynamic studies, subducting plates are considered to be homogeneous, and there is no clear indication how the subduction of a fracture zone influences the melting pattern in the mantle wedge and the slab-derived fluids distribution in the subarc mantle. Here we show that subduction of serpentinized fracture zones plays a significant role in distribution of melt and fluids in the mantle wedge above the slab. Using high-resolution tree-dimensional coupled petrological-termomechanical simulations of subduction, we show that fluids, including melts and water, vary dramatically in the region where a serpentinized fracture zone enters into subduction. Our models show that substantial hydration and partial melting tend to concentrate where fracture zones are being subducted, creating favorable conditions for partially molten hydrous plumes to develop. These results are consistent with the along-arc variability in magma source compositions and processes in several regions, as the Aleutian Arc, the Cascades, the Southern Mexican Volcanic Arc, and the Andean Southern Volcanic Zone.

  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. 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......) and 429–5,293 ng L-1 (average: 2,508 ng L-1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium...

  13. 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.

  14. Lipid accumulation in prokaryotic microorganisms from arid habitats.

    Science.gov (United States)

    Hauschild, Philippa; Röttig, Annika; Madkour, Mohamed H; Al-Ansari, Ahmed M; Almakishah, Naief H; Steinbüchel, Alexander

    2017-03-01

    This review shall provide support for the suitability of arid environments as preferred location to search for unknown lipid-accumulative bacteria. Bacterial lipids are attracting more and more attention as sustainable replacement for mineral oil in fuel and plastic production. The development of prokaryotic microorganisms in arid desert habitats is affected by its harsh living conditions. Drought, nutrient limitation, strong radiation, and extreme temperatures necessitate effective adaption mechanisms. Accumulation of storage lipids as energy reserve and source of metabolic water represents a common adaption in desert animals and presumably in desert bacteria and archaea as well. Comparison of corresponding literature resulted in several bacterial species from desert habitats, which had already been described as lipid-accumulative elsewhere. Based on the gathered information, literature on microbial communities in hot desert, cold desert, and humid soil were analyzed on its content of lipid-accumulative bacteria. With more than 50% of the total community size in single studies, hot deserts appear to be more favorable for lipid-accumulative species then humid soil (≤20%) and cold deserts (≤17%). Low bacterial lipid accumulation in cold deserts is assumed to result from the influence of low temperatures on fatty acids and the increased necessity of permanent adaption methods.

  15. 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.

  16. 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

  17. Resource flows, crops and soil fertility management in smallholder farming systems in semi-arid Zimbabwe

    NARCIS (Netherlands)

    Ncube, B.; Twomlow, S.J.; Dimes, J.P.; Wijk, van M.T.; Giller, K.E.

    2009-01-01

    Poor soil fertility and erratic rains are major constraints to crop production in semi-arid environments. In the smallholder farming systems of sub-Saharan Africa, these constraints are manifested in frequent crop failures and endemic food insecurity. We characterized a semi-arid smallholder farming

  18. 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.

  19. 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.

  20. 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

  1. Review and Synopsis of Natural and Human Controls on Fluvial Channel Processes in the Arid West

    Science.gov (United States)

    2007-09-01

    and other wet saline and alkaline soils: Problems identifying aquic conditions and hydric soils. In Aquic Conditions and Hydric Soils: The Problem...of-the-art of hydrology and hydrogeology in the arid and semi-arid areas of Africa. p. 255–266. Proceedings of the Sahel Forum 1989. Ouagadougou

  2. 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

  3. 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

  4. 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.

  5. 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)

  6. 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

  7. Risk of fire occurrence in arid and semi-arid ecosystems of Iran: an investigation using Bayesian belief networks.

    Science.gov (United States)

    Bashari, Hossein; Naghipour, Ali Asghar; Khajeddin, Seyed Jamaleddin; Sangoony, Hamed; Tahmasebi, Pejman

    2016-09-01

    Identifying areas that have a high risk of burning is a main component of fire management planning. Although the available tools can predict the fire risks, these are poor in accommodating uncertainties in their predictions. In this study, we accommodated uncertainty in wildfire prediction using Bayesian belief networks (BBNs). An influence diagram was developed to identify the factors influencing wildfire in arid and semi-arid areas of Iran, and it was populated with probabilities to produce a BBNs model. The behavior of the model was tested using scenario and sensitivity analysis. Land cover/use, mean annual rainfall, mean annual temperature, elevation, and livestock density were recognized as the main variables determining wildfire occurrence. The produced model had good accuracy as its ROC area under the curve was 0.986. The model could be applied in both predictive and diagnostic analysis for answering "what if" and "how" questions. The probabilistic relationships within the model can be updated over time using observation and monitoring data. The wildfire BBN model may be updated as new knowledge emerges; hence, it can be used to support the process of adaptive management.

  8. 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

  9. Soil microbial responses to nitrogen addition in arid ecosystems.

    Science.gov (United States)

    Sinsabaugh, Robert L; Belnap, Jayne; Rudgers, Jennifer; Kuske, Cheryl R; Martinez, Noelle; Sandquist, Darren

    2015-01-01

    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 N ha(-1) y(-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 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 amendment that included data from 14 other studies. Effect sizes were calculated for biomass and metabolic responses. Regressions of effect sizes, calculated for biomass, and metabolic responses, showed similar trends in relation to N application rate and N load (rate × duration). The critical points separating positive from negative treatment effects were 88 kg ha(-1) y(-1) and 159 kg ha(-1), respectively, for biomass, and 70 kg ha(-1) y(-1) and 114 kg ha(-1), respectively, for metabolism. These critical values are comparable to those for microbial biomass, decomposition rates and respiration reported in broader meta-analyses of N amendment effects in mesic ecosystems. However, large effect sizes at low N

  10. 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.

  11. Microgravity silicon zoning investigation

    Science.gov (United States)

    Kern, E. L.; Gill, G. L., Jr.

    1985-01-01

    The flow instabilities in floating zones of silicon were investigated and methods for investigation of these instabilities in microgravity were defined. Three principal tasks were involved: (1) characterization of the float zone in small diameter rods; (2) investigation of melt flow instabilities in circular melts in silicon disks; and (3) the development of a prototype of an apparatus that could be used in near term space experiments to investigate flow instabilities in a molten zone. It is shown that in a resistance heated zoner with 4 to 7 mm diameter silicon rods that the critical Marangoni number is about 1480 compared to a predicted value of 14 indicative that viable space experiments might be performed. The prototype float zone apparatus is built and specifications are prepared for a flight zoner should a decision be reached to proceed with a space flight experimental investigation.

  12. The gray zone.

    Science.gov (United States)

    Kisner, H J

    1998-01-01

    Think for a minute about the terms equivocal and indeterminate. Equivocal is defined as "of uncertain significance", and indeterminate is defined as "indefinite, uncertain". Now think of the context in which laboratory results are reported: either by using the exact words equivocal or indeterminate or cloaked in technical jargon (e.g., cytologic diagnoses "ASCUS" or "AGUS"). Clinicians expect (or at least want) laboratory results to be black or white (i.e., bimodally distributed), whereas laboratorians strive for the perfect shade of gray because of data that often are bimodal but overlapping. A consequence of this color war is "the gray zone" (often confused with the "twilight zone"), a noncommittal zone that leaves laboratorians and clinicians alike plenty of wiggle room, allowing us to interpret results on either side of the fence. This article examines the root causes of the gray zone, with several clinical examples of how it permeates laboratory interpretation.

  13. Promise Zones for Applicants

    Data.gov (United States)

    Department of Housing and Urban Development — This tool assists applicants to HUD's Promise Zone initiative prepare data to submit with their application by allowing applicants to draw the exact location of the...

  14. 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...

  15. Simulated floating zone method

    OpenAIRE

    Ozawa, Ryo; Kato, Yasuyuki; Motome, Yukitoshi

    2016-01-01

    This paper provides the simulated floating zone (SFZ) method that is an efficient simulation technique to obtain thermal equilibrium states, especially useful when domain formation prevents the system from reaching a spatially-uniform stable state. In the SFZ method, the system is heated up locally, and the heated region is steadily shifted, similar to the floating zone method for growing a single crystal with less lattice defect and impurity in experiments. We demonstrate that the SFZ method...

  16. Dung of Mammuthus in the arid Southwest, North America

    Science.gov (United States)

    mead, Jim I.; Agenbroad, Larry D.; Davis, Owen K.; Martin, Paul S.

    1986-01-01

    The discovery of a unique organic deposit in a dry cave on the Colorado Plateau, southern Utah, permits the first comparison of the physical characteristics and the diet of the dung of the extinct mammoths from the arid Southwest, North America, with that of mammoths from Siberia and northern China, the only other known locations of such remains. The deposit buried beneath sand and rockfall is composed primarily of mammoth dung, estimated at over 300 m 3. Radiocarbon dates on dung boluses indicate that the mammoths frequented the cave between approximately 14,700 and 11,000 yr B.P. (the range of ages at 2σ). The desiccated boluses, measuring approximately 230 × 170 × 85 mm, are nearly identical in size to dung from extant elephants. The largest contents in the dung are stalks measuring 60 × 4.5 mm. Grasses and sedges dominated the diet, although woody species were commonly eaten.

  17. Passive options for solar cooling of buildings in arid areas

    Energy Technology Data Exchange (ETDEWEB)

    Amer, Emad H. [Department of Mechanical Power Engineering, Faculty of Engineering, Menofiya University, Gamal Abdul Nasser St., Shebin El-kom, Menofiya (Egypt)

    2006-07-15

    The major heat load of buildings and workshops, made of metal structures, is the solar energy supplied through the roof. Several passive modifications have been introduced to the roof in order to reduce the temperature of indoor air in arid areas. An experimental investigation, employing passive modifications, has been carried out to study the reduction in air temperature. The results show that the inside air temperature falls to within 6 and 3{sup o}C, respectively, from the ambient temperature when the ceiling is painted white, or provided with a layer of thermal insulation. Using evaporative cooling or a solar chimney leads to an inside temperature within 1{sup o}C of the ambient temperature. (author)

  18. 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.

  19. 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.

  20. Remote sensing of threshold conditions in an arid ecosystem

    Science.gov (United States)

    Steele, C. M.; Bestelmeyer, B. T.; Rango, A.; Smith, P. L.; Laliberte, A. S.

    2007-12-01

    Land management in the arid southwestern USA increasingly addresses thresholds in response to recent concepts adopted by private and public lands agencies and conservation organizations. Vegetation in arid rangelands typically presents as distinctive mosaics of vegetation patches, which persist in dynamic equilibrium with the abiotic environment and facilitative-competitive interactions between organisms. Theory and observation suggest that as an area approaches a threshold in response to disturbance, there is a concomitant change in the spatial arrangement of vegetation patches. This change is readily identifiable on fine spatial resolution aerial photography or satellite sensor imagery. We propose a classification method for identifying threshold-inducing change in vegetation pattern. To illustrate this method, we have applied an object-oriented, supervised classification to subsets of Quickbird imagery (70 cm ground resolution) over the Jornada basin in southern New Mexico. The imagery covers several land management regimes (private, public, federal) and provides spatial variation in ecosystem conditions. Imagery was first segmented to create fine and coarse resolution image objects. Fine resolution image objects are defined as having within-object spectral homogeneity at the scale of the shrub or single patch of grass or soil. Coarse resolution image objects are defined as containing spectral homogeneity at the scale of the vegetation stand. A classification tree was used to classify coarse resolution image objects to high risk of a threshold, low risk of a threshold, or post-threshold according to the content and spatial arrangement of shrub, grass and soil patches within them. Ground-based monitoring to detect localized threshold conditions across broad management areas is intractable so the use of remote sensing is essential to successful prevention of threshold development.

  1. 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.

  2. 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.

  3. 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.

  4. Arid3b is essential for second heart field cell deployment and heart patterning.

    Science.gov (United States)

    Uribe, Verónica; Badía-Careaga, Claudio; Casanova, Jesús C; Domínguez, Jorge N; de la Pompa, José Luis; Sanz-Ezquerro, Juan José

    2014-11-01

    Arid3b, a member of the conserved ARID family of transcription factors, is essential for mouse embryonic development but its precise roles are poorly understood. Here, we show that Arid3b is expressed in the myocardium of the tubular heart and in second heart field progenitors. Arid3b-deficient embryos show cardiac abnormalities, including a notable shortening of the poles, absence of myocardial differentiation and altered patterning of the atrioventricular canal, which also lacks epithelial-to-mesenchymal transition. Proliferation and death of progenitors as well as early patterning of the heart appear normal. However, DiI labelling of second heart field progenitors revealed a defect in the addition of cells to the heart. RNA microarray analysis uncovered a set of differentially expressed genes in Arid3b-deficient tissues, including Bhlhb2, a regulator of cardiomyocyte differentiation, and Lims2, a gene involved in cell migration. Arid3b is thus required for heart development by regulating the motility and differentiation of heart progenitors. These findings identify Arid3b as a candidate gene involved in the aetiology of human congenital malformations.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. Co-evolution of Vegetation, Sediment Transport and Infiltration on semi-arid hillslopes

    Science.gov (United States)

    Harman, C. J.; Troch, P. A.; Lohse, K. A.; Sivapalan, M.

    2011-12-01

    Soils in semi-arid landscapes can vary over very small distances, with a great deal of variation associated with 'resource islands' created and maintained by woody vegetation. The distinct physical and hydraulic properties that arise in these islands can lead to spatial patterns of infiltration that have been implicated in the maintenance of the vegetation populating the island. Less well understood are the roles that the small-scale variability in soils plays in determining the transport of sediments, water and sediment-bound carbon and nitrogen across hillslopes. Here we explore these relationships using a coupled field and modeling approach. Detailed field data from hillslopes underlain by both granite and schist parent materials in the Santa Catalina mountains (part of the JSC Critical Zone Observatory) suggest that soils under individual velvet mesquite (latin name) contain higher concentration of soil organic matter and have higher hydraulic conductivity and water holding capacity. Greater infiltration and increased roughness under the canopy appears to lead to the formation of mounds that alter overland flow lines around the area under the canopy, particularly in the finer schist soils. This diversion leads to a complex distribution of shear stresses across the hillslope, creating systematic patterns in the transport of carbon and nitrogen rich soils under the canopies. The relationship between the small scale mechanism and the emergent pattern dynamics in the temporal variability of materials delivered to the stream from the hillslope are also examined, and the implications of these results for the modeling of water, sediment and nutrient fluxes at hillslope scales will be discussed.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Zones of emotional labour

    DEFF Research Database (Denmark)

    Strøbæk, Pernille Solveig

    2011-01-01

    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......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...

  18. 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...

  19. 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 \

  20. 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)

  1. Evaluation of mulched drip irrigation for cotton in arid Northwest China

    NARCIS (Netherlands)

    Wang, Z.; Jin, M.; Simunek, J.; van Genuchten, M.T.

    2014-01-01

    Field experiments were conducted in arid Southern Xinjiang, Northwest China, for 3 years to evaluate sustainable irrigation regimes for cotton. The experiments involved mulched drip irrigation during the growing season and flood irrigation afterward. The drip irrigation experiments included control

  2. 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.

  3. 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

  4. 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...

  5. Lake Evaporation in a Hyper-Arid Environment, Northwest of China—Measurement and Estimation

    OpenAIRE

    Xiao Liu; Jingjie Yu; Ping Wang; Yichi Zhang; Chaoyang Du

    2016-01-01

    Lake evaporation is a critical component of the hydrological cycle. Quantifying lake evaporation in hyper-arid regions by measurement and estimation can both provide reliable potential evaporation (ET0) reference and promote a deeper understanding of the regional hydrological process and its response towards changing climate. We placed a floating E601 evaporation pan on East Juyan Lake, which is representative of arid regions’ terminal lakes, to measure daily evaporation and conducted simulta...

  6. Review of Ordinary High Water Mark Indicators for Delineating Arid Streams in the Southwestern United States

    Science.gov (United States)

    2004-01-01

    Hydrogeology in the Arid and Semi-arid Areas of Africa, Proceedings of the Sahel Forum, Ouagadougou, 1989, p. 255–266. Nouh, M. (1990) Flood hydrograph... salinity levels may compound the effects of drought stress, leading to mortality in salt-intolerant species (Vandersande et al. 2001). At elevated... salinity levels in greenhouse experiments, rooted cuttings of T. ramosissima and P. sericea had higher water use efficiency than did P. fremontii, S

  7. Aridity influences the recovery of vegetation and shrubland birds after wildfire.

    Science.gov (United States)

    Puig-Gironès, Roger; Brotons, Lluís; Pons, Pere

    2017-01-01

    Wildfires play a determining role in the composition and structure of many plant and animal communities. On the other hand, climate change is considered to be a major driver of current and future fire regime changes. Despite increases in drought in many areas of the world, the effects of aridity on post-fire colonization by animals have been rarely addressed. This study aims to analyse how a regional aridity gradient affects post-fire recovery of vegetation, bird species richness and the numbers of four early to middle-successional warbler species associated with the shrub cover. The database contains bird relative abundance and environmental variables from 3072 censuses in 695 transects located in 70 recently burnt areas (1 to 11 years after wildfire) in Catalonia (Spain), which were sampled between 2006 and 2013. Generalized linear mixed models (GLMMs) showed that plant cover was affected by time since fire, aridity and forest management. However, only the highest vegetation height layer (>100 cm) recovered slower in arid areas after fire. Time since fire positively influenced bird species richness and the relative abundance of the four focal species. The post-fire recovery of Melodious (Hippolais polyglotta) and Subalpine warblers (Sylvia cantillans) was hampered by aridity. Although this was not demonstrated for Dartford (S. undata) and Sardinian warblers (S. melanocephala), their occurrence was low in the driest areas during the first three years after fire. Overall, this study suggests that future increases in aridity can affect plant regeneration after fire and slow down the recovery of animal populations that depend on understorey and shrublands. Given the recently highlighted increases in aridity and fire frequency in Mediterranean-climate regions, improved knowledge on how aridity affects ecological succession is especially necessary.

  8. Flexible 'zoning' aids adaptability.

    Science.gov (United States)

    Corben, Simon

    2013-09-01

    Simon Corben, business development director at Capita Symonds' Health team, examines how 'clever use of zoning' when planning new healthcare facilities could improve hospital design, increase inherent flexibility, and reduce lifetime costs, and argues that a 'loose-fit, non-bespoke approach' to space planning will lead to 'more flexible buildings that are suitable for conversion to alternative uses'.

  9. 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

  10. Changes in precipitation recycling over arid regions in the Northern Hemisphere

    Science.gov (United States)

    Li, Ruolin; Wang, Chenghai; Wu, Di

    2016-11-01

    Changes of precipitation recycling (PR) in Northern Hemisphere from 1981 to 2010 are investigated using a water recycling model. The temporal and spatial characteristics of recycling in arid regions are analyzed. The results show that the regional precipitation recycling ratio (PRR) in arid regions is larger than in wet regions. PRR in arid regions has obvious seasonal variation, ranging from more than 25 % to less than 1 %. Furthermore, in arid regions, PRR is significantly negatively correlated with precipitation (correlation coefficient r = -0.5, exceeding the 99 % significance level). Moreover, the trend of PRR is related to changes in precipitation in two ways. PRR decreases with increasing precipitation in North Africa, which implies that less locally evaporated vapor converts into actual precipitation. However, in Asian arid regions, the PRR increases as precipitation reduces, which implies that more locally evaporated vapor converts into rainfall. Further, as PRR mainly depends on evapotranspiration, the PRR trend in Asian arid regions develops as temperature increases and more evaporated vapor enters the atmosphere to offset the reduced rainfall.

  11. Genomic dissection of genotype x environment interactions conferring adaptation of cotton to arid conditions.

    Science.gov (United States)

    Saranga, Y; Menz, M; Jiang, C X; Wright, R J; Yakir, D; Paterson, A H

    2001-12-01

    The interaction of genotype with environment is of primary importance in many aspects of genomic research and is a special priority in the study of major crops grown in a wide range of environments. Water deficit, the major factor limiting plant growth and crop productivity worldwide, is expected to increase with the spread of arid lands. In genetically equivalent cotton populations grown under well-watered and water-limited conditions (the latter is responsible for yield reduction of approximately 50% relative to well-watered conditions), productivity and quality were shown to be partly accounted for by different quantitative trait loci (QTLs), indicating that adaptation to both arid and favorable conditions can be combined in the same genotype. QTL mapping was also used to test the association between productivity and quality under water deficit with a suite of traits often found to differ between genotypes adapted to arid versus well-watered conditions. In this study, only reduced plant osmotic potential was clearly implicated in improved cotton productivity under arid conditions. Genomic tools and approaches may expedite breeding of genotypes that respond favorably to specific environments, help test roles of additional physiological factors, and guide the isolation of genes that protect crop performance under arid conditions toward improved adaptation of crops to arid cultivation.

  12. 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.

  13. 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.

  14. 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

  15. Sources and transport of nitrogen in arid urban watersheds.

    Science.gov (United States)

    Hale, Rebecca L; Turnbull, Laura; Earl, Stevan; Grimm, Nancy; Riha, Krystin; Michalski, Greg; Lohse, Kathleen A; Childers, Daniel

    2014-06-03

    Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3-) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3- (δ15N, δ18O, and Δ17O) to identify sources and transformations of NO3- during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover--retention basins, pipes, and grass cover--dictated the sourcing of NO3- in runoff. Urban watersheds were strong sinks or sources of N to stormwater depending on runoff, which in turn was inversely related to retention basin density and positively related to imperviousness and precipitation. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the time scale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms.

  16. 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.

  17. 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.

  18. 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.

  19. Reintroduction of locally extinct vertebrates impacts arid soil fungal communities.

    Science.gov (United States)

    Clarke, Laurence J; Weyrich, Laura S; Cooper, Alan

    2015-06-01

    Introduced species have contributed to extinction of native vertebrates in many parts of the world. Changes to vertebrate assemblages are also likely to alter microbial communities through coextinction of some taxa and the introduction of others. Many attempts to restore degraded habitats involve removal of exotic vertebrates (livestock and feral animals) and reintroduction of locally extinct species, but the impact of such reintroductions on microbial communities is largely unknown. We used high-throughput DNA sequencing of the fungal internal transcribed spacer I (ITS1) region to examine whether replacing exotic vertebrates with reintroduced native vertebrates led to changes in soil fungal communities at a reserve in arid central Australia. Soil fungal diversity was significantly different between dune and swale (interdune) habitats. Fungal communities also differed significantly between sites with exotic or reintroduced native vertebrates after controlling for the effect of habitat. Several fungal operational taxonomic units (OTUs) found exclusively inside the reserve were present in scats from reintroduced native vertebrates, providing a direct link between the vertebrate assemblage and soil microbial communities. Our results show that changes to vertebrate assemblages through local extinctions and the invasion of exotic species can alter soil fungal communities. If local extinction of one or several species results in the coextinction of microbial taxa, the full complement of ecological interactions may never be restored.

  20. 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.

  1. 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.

  2. Sources and transport of nitrogen in arid urban watersheds

    Energy Technology Data Exchange (ETDEWEB)

    Hale, Rebecca L.; Turnbull, Laura; Earl, Stevan; Grimm, Nancy B.; Riha, Krystin M.; Michalski, Greg; Lohse, Kathleen; Childers, Daniel L.

    2014-06-03

    Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3–) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3– (δ15N, δ18O, and Δ17O) to identify sources and transformations of NO3– during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover—retention basins, pipes, and grass cover—dictated the sourcing of NO3– in runoff. Urban watersheds can be strong sinks or sources of N to stormwater depending on the proportion of rainfall that leaves the watershed as runoff, but we found no evidence that denitrification occurred during storms. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the timescale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms.

  3. 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.

  4. Nutraceutical potential, antioxidant and antibacterial activities of Terfezia boudieri Chatin, a wild edible desert truffle from Tunisia arid zone

    Directory of Open Access Journals (Sweden)

    Amina Hamza

    2016-05-01

    Full Text Available Nutritional composition, antioxidant and antibacterial properties of Terfezia boudieri Chatin, a desert truffle largely distributed in Southern Tunisia were evaluated. Carbohydrates were the most abundant macronutrients (62.03 g/100 g followed by proteins (26.12 g/100 g in T. boudieri truffle (dry mass. The ash content was 4.49 g/100 g dry mass and potassium, phosphorus, iron, and calcium were found to be particularly abundant in T. boudieri. The fat content of the truffle was 8 g/100 g dry mass, characterized by its higher content of the essential linoleic acid (n-6 (54.18%. Eight volatile compounds were identified by GC and GC/MS and they were dominated by fatty acids. The results of ascorbic acid, total carotenoids and total anthocyanins expressed on a truffle dry mass were 12.20 mg/100 g, 1.43 mg/100 g and 35.40 mg/100 g, respectively. The methanolic extract, containing the highest amounts of phenolics and flavonoids, displayed the highest DPPH radical-scavenging activity (IC50 = 0.20 mg/ml and the lipid peroxidation inhibitory activity (IC50 = 0.36 mg/ml. Furthermore, the truffle extracts were tested for their antibacterial activity against seven species of bacteria. The methanolic extract also exhibited remarkable inhibitory activity on the tested strains, which minimum inhibitory concentration values ranged from 0.25 to 1.3 mg/ml.

  5. Vegetation Responses to Climate Variability in the Northern Arid to Sub-Humid Zones of Sub-Saharan Africa

    Directory of Open Access Journals (Sweden)

    Khaldoun Rishmawi

    2016-11-01

    Full Text Available In water limited environments precipitation is often considered the key factor influencing vegetation growth and rates of development. However; other climate variables including temperature; humidity; the frequency and intensity of precipitation events are also known to affect productivity; either directly by changing photosynthesis and transpiration rates or indirectly by influencing water availability and plant physiology. The aim here is to quantify the spatiotemporal patterns of vegetation responses to precipitation and to additional; relevant; meteorological variables. First; an empirical; statistical analysis of the relationship between precipitation and the additional meteorological variables and a proxy of vegetation productivity (the Normalized Difference Vegetation Index; NDVI is reported and; second; a process-oriented modeling approach to explore the hydrologic and biophysical mechanisms to which the significant empirical relationships might be attributed. The analysis was conducted in Sub-Saharan Africa; between 5 and 18°N; for a 25-year period 1982–2006; and used a new quasi-daily Advanced Very High Resolution Radiometer (AVHRR dataset. The results suggest that vegetation; particularly in the wetter areas; does not always respond directly and proportionately to precipitation variation; either because of the non-linearity of soil moisture recharge in response to increases in precipitation; or because variations in temperature and humidity attenuate the vegetation responses to changes in water availability. We also find that productivity; independent of changes in total precipitation; is responsive to intra-annual precipitation variation. A significant consequence is that the degree of correlation of all the meteorological variables with productivity varies geographically; so no one formulation is adequate for the entire region. Put together; these results demonstrate that vegetation responses to meteorological variation are more complex than an equilibrium relationship between precipitation and productivity. In addition to their intrinsic interest; the findings have important implications for detection of anthropogenic dryland degradation (desertification; for which the effects of natural fluctuations in meteorological variables must be controlled in order to reveal non-meteorological; including anthropogenic; degradation.

  6. 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%.

  7. 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.

  8. Impending sources of energy to replace fire wood in semi arid climatic zones: A case study in Ethiopia

    Directory of Open Access Journals (Sweden)

    Mihret Dananto Ulsido

    2013-06-01

    Full Text Available The present study paper shows an alternative source of energy that can decrease the extensive use of fire wood in Ethiopia. The country’s entire rural area and significant part of urban population is completely dependent on fire wood as a source of energy. This practice takes its own toll, the forest is on the verge of being wiped out and as a result a clear change of climate and loss of natural biodiversity resources is visible. Fire wood is not the only source of energy available in the country. In this paper, based on their low cost, construction material availability and the required unskilled labor it is shown that biogas and solar energy are potentially feasible source of energy to replace firewood for cooking.

  9. 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.

  10. The influence of tillage on field scale water fluxes and maize yields in semi-arid environments: A case study of Potshini catchment, South Africa

    Science.gov (United States)

    Kosgei, J. R.; Jewitt, G. P. W.; Kongo, V. M.; Lorentz, S. A.

    Water is a limiting resource to crop production in arid and semi-arid lands (ASALs) and is responsible for substantial yield losses annually. These lands are often occupied by resource poor smallholder rainfed farmers who have little capacity to establish conventional irrigation infrastructure to mitigate recurrent droughts and dry spells. In situ water harvesting techniques in the form of conservation agriculture practices have been identified and promoted as measures that can improve soil water availability and thus enhance crop yields. Land use practices e.g. tillage influences mechanisms of lateral flow, infiltration, storage, redistribution and residence times of water at field scale. Such alterations in flow paths have not been adequately studied in ASALs where small perturbations at field scale upstream of a catchment may have significant effects downstream. Quantifying these fluxes enables better understanding of productive and non-productive water transition processes and thus to evaluate cropping and management systems. On this study the effects of tillage on water fluxes, soil physical properties and maize ( Zea mays L.) yields were examined at three sites in the Potshini catchment, South Africa. Measurements were made on plots under no-till ( NT) and conventional till ( CT) practices. Seasonal analysis indicated that nearly twice as much runoff was generated from CT treatments when compared to NT plots. However, this was not the case at the beginning of the season. The moisture content in the root zone was significantly higher in NT treatments. Maize yield was also higher in NT compared to CT plots.

  11. Mapping Prosopis spp. with Landsat 8 data in arid environments: Evaluating effectiveness of different methods and temporal imagery selection for Hargeisa, Somaliland

    Science.gov (United States)

    Ng, Wai-Tim; Meroni, Michele; Immitzer, Markus; Böck, Sebastian; Leonardi, Ugo; Rembold, Felix; Gadain, Hussein; Atzberger, Clement

    2016-12-01

    Prosopis spp. is a fast and aggressive invader threatening many arid and semi-arid areas globally. The species is native to the American dry zones and was introduced in Somaliland for dune stabilization and fuel wood production in the 1970⿿s and 1980⿿s. Its deep rooting system is capable of tapping into the groundwater table thereby reducing its reliance on infrequent rainfalls and near-surface water. The competitive advantage of Prosopis is further fuelled by the hybridization of the many introduced subspecies that made the plant capable of adapting to the new environment and replacing endemic species. This study aimed to test the mapping accuracy achievable with Landsat 8 data acquired during the wet and the dry seasons within a Random Forest (RF) classifier, using both pixel- and object-based approaches. Maps are produced for the Hargeisa area (Somaliland), where reference data was collected during the dry season of 2015. Results were assessed through a 10-fold cross-validation procedure. In our study, the highest overall accuracy (74%) was achieved when applying a pixel-based classification using a combination of the wet and dry season Earth observation data. Object-based mapping were less reliable due to the limitations in spatial resolution of the Landsat data (15⿿30 m) and problems in finding an appropriate segmentation scale.

  12. 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...

  13. 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.

  14. 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

  15. The Habitable Zone Gallery

    CERN Document Server

    Kane, Stephen R

    2012-01-01

    The Habitable Zone Gallery (www.hzgallery.org) is a new service to the exoplanet community which provides Habitable Zone (HZ) information for each of the exoplanetary systems with known planetary orbital parameters. The service includes a sortable table with information on the percentage of orbital phase spent within the HZ, planetary effective temperatures, and other basic planetary properties. In addition to the table, we also plot the period and eccentricity of the planets with respect to their time spent in the HZ. The service includes a gallery of known systems which plot the orbits and the location of the HZ with respect to those orbits. Also provided are animations which aid in orbit visualization and provide the changing effective temperature for those planets in eccentric orbits. Here we describe the science motivation, the under-lying calculations, and the structure of the web site.

  16. Book title: Exotic brome grasses in arid and semi-arid ecosystems of the western US: causes, consequences, and management implications

    Science.gov (United States)

    Exotic invasive annual grass research and management in arid and semiarid ecosystems of the western US have historically focused on the outcome of efforts to reduce weed abundance. Given the current impact of invasive annual grasses and their continued spread in this region, we assessed components ...

  17. 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.

  18. 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

    or nonsense mutations in all of them. Conclusions: This study broadens the spectrum of ARID1B associated phenotypes by describing a distinctive phenotype including plantar fat pads but lacking the hypertrichosis or fifth nail hypoplasia associated with Coffin-Siris syndrome. We present the first direct...

  19. 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

  20. 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-

  1. Ecological zones of California deserts

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The dataset delineates ecological zones within California deserts. We derived ecological zones by reclassifying LANDFIRE vegetation biophysical setting types, plus...

  2. Radiant zone heated particulate filter

    Science.gov (United States)

    Gonze, Eugene V [Pinckney, MI

    2011-12-27

    A system includes a particulate matter (PM) filter including an upstream end for receiving exhaust gas and a downstream end. A radiant zoned heater includes N zones, where N is an integer greater than one, wherein each of the N zones includes M sub-zones, where M is an integer greater than or equal to one. A control module selectively activates at least a selected one of the N zones to initiate regeneration in downstream portions of the PM filter from the one of the N zones, restricts exhaust gas flow in a portion of the PM filter that corresponds to the selected one of the N zones, and deactivates non-selected ones of the N zones.

  3. Scarce data in hydrology and hydrogeology: Estimation and modelling of groundwater recharge for a numerical groundwater flow model in a semi-arid to arid catchment

    Science.gov (United States)

    Gräbe, Agnes; Schulz, Stephan; Rödiger, Tino; Kolditz, Olaf

    2013-04-01

    Water resources are strongly limited in semi-arid to arid regions and groundwater constitutes often the only possibility for fresh water for the population and industry. An understanding of the hydrological processes and the estimation of magnitude of water balance parameters also includes the knowledge of processes of groundwater recharge. For the sustainable management of water resources, it is essential to estimate the potential groundwater recharge under the given climatic conditions. We would like to present the results of a hydrological model, which is based on the HRU- concept and intersected the parameters of climatic conditions, topography, geology, soil, vegetation and land use to calculate the groundwater recharge. This model was primarily developed for humid area applications and has now been adapted to the regional conditions in the semi-arid to arid region. It was quite a challenge to understand the hydrological processes in the semi-arid to arid study area and to implement those findings (e.g. routing [Schulz (in prep.)]) into the model structure. Thus we compared the existing approaches for groundwater recharge estimations (chloride mass balance [Marei et. al 2000], empirical relations such as rainfall and base flow-relation [Goldschmidt 1960; Guttman 2000; Hughes 2008; Issar 1993; Lerner 1990; De Vries et. al 2002]) with the results of our numerical model. References: De Vries, J. J., I. Simmers (2002): Groundwater recharge: an overview of processes and challenges. Hydrogeology Journal (2002) 10: 5-17. DOI 10.1007/s10040-001-0171-7. Guttman, J., 2000. Multi-Lateral Project B: Hydrogeology of the Eastern Aquifer in the Judea Hills and Jordan Valley. Mekorot Water Company, Report 468, p. 36. Hughes, A. G., M. M. Mansour, N. S. Robins (2008): Evaluation of distributed recharge in an upland semi-arid karst system: the West Bank Mountain Aquifer, Middle East. Hydrogeology Journal (2008) 16: 845-854. DOI 10.1007/s10040-008-0273-6 Issar, A. S. (1993

  4. 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.

  5. Comparaison instrumentale de la mesure des précipitations en climat méditerranéen semi-aride

    OpenAIRE

    Brunel, Jean-Pierre

    1986-01-01

    La pluie est un élément important du cycle de l'eau mesuré à l'aide d'appareils très divers. A partir des données d'une station agrométéorologique du Nord de la Tunisie (zone semi-aride), il est montré dans quelles proportions peuvent varier les précipitations mesurées par différents capteurs. L'influence du vent est mise en évidence dans l'écart observé entre pluie mesurée au sol et pluie mesurée au-dessus du sol. (Résumé d'auteur)

  6. Immunohistochemical expression of ARID1A in penile squamous cell carcinomas: a tissue microarray study of 112 cases.

    Science.gov (United States)

    Faraj, Sheila F; Chaux, Alcides; Gonzalez-Roibon, Nilda; Munari, Enrico; Cubilla, Antonio L; Shih, Ie-Ming; Netto, George J

    2015-05-01

    ARID1A, a member of the chromatin remodeling genes family, has been suggested as a novel tumor suppressor gene in gynecologic malignancies. However, its role in penile cancer has yet to be determined. This study assesses the immunohistochemical expression of ARID1A in penile squamous cell carcinoma (SCC) and its association with pathologic features, human papillomavirus (HPV) status, and previously reported mammalian target of rapamycin pathway markers in the same cohort. Four tissue microarrays were constructed from 112 cases of formalin-fixed, paraffin-embedded penile SCC from Paraguay. Each tumor was sampled 3 to 12 times. ARID1A expression was evaluated by immunohistochemistry using a polyclonal rabbit anti-ARID1A (BAF250A) antibody. An H score was calculated in each spot as the sum of expression intensity (0-3+) by extent (0%-100%). Median H score per case was used for statistical analysis. ARID1A expression was observed in all cases, ranging from 3% to 100% of tumor cells (median, 95%). In 96 cases (86%), ARID1A expression was observed in 90% or more tumor cells. HPV DNA was detected in 20 (38%) of 52 analyzed samples. There was a significant trend of association between ARID1A and histologic grade. ARID1A expression was not associated with histologic subtype (P = .61) or HPV status (P = .18). ARID1A expression decreased with decreasing levels of PTEN expression (P = .01). ARID1A was expressed in penile SCC, in most cases at high levels. A significant trend of association was found between histologic grade and ARID1A expression, with lower ARID1A expression, lower histologic grades, and decreased PTEN expression.

  7. Immunohistochemical expression of ARID1A in penile squamous cell carcinomas: a tissue microarray study of 112 cases☆

    Science.gov (United States)

    Faraj, Sheila F.; Chaux, Alcides; Gonzalez-Roibon, Nilda; Munari, Enrico; Cubilla, Antonio L.; Shih, Ie-Ming; Netto, George J.

    2015-01-01

    Summary ARID1A, a member of the chromatin remodeling genes family, has been suggested as a novel tumor suppressor gene in gynecologic malignancies. However, its role in penile cancer has yet to be determined. This study assesses the immunohistochemical expression of ARID1A in penile squamous cell carcinoma (SCC) and its association with pathologic features, human papillomavirus (HPV) status, and previously reported mammalian target of rapamycin pathway markers in the same cohort. Four tissue microarrays were constructed from 112 cases of formalin-fixed, paraffin-embedded penile SCC from Paraguay. Each tumor was sampled 3 to 12 times. ARID1A expression was evaluated by immunohistochemistry using a polyclonal rabbit anti-ARID1A (BAF250A) antibody. An H score was calculated in each spot as the sum of expression intensity (0-3+) by extent (0%-100%). Median H score per case was used for statistical analysis. ARID1A expression was observed in all cases, ranging from 3% to 100% of tumor cells (median, 95%). In 96 cases (86%), ARID1A expression was observed in 90% or more tumor cells. HPV DNA was detected in 20 (38%) of 52 analyzed samples. There was a significant trend of association between ARID1A and histologic grade. ARID1A expression was not associated with histologic subtype (P = .61) or HPV status (P = .18). ARID1A expression decreased with decreasing levels of PTEN expression (P = .01). ARID1A was expressed in penile SCC, in most cases at high levels. A significant trend of association was found between histologic grade and ARID1A expression, with lower ARID1A expression, lower histologic grades, and decreased PTEN expression. PMID:25776029

  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. Spatial differences of aeolian desertification responses to climate in arid Asia

    Science.gov (United States)

    Wang, Xunming; Hua, Ting; Lang, Lili; Ma, Wenyong

    2017-01-01

    Most areas of arid Asia are covered by aeolian dunes, sand sheets, gravels, and desert steppes, and may jeopardize nearly 350 million people if climate change increases aeolian desertification. Although the aeolian desertification is mainly triggered by climate changes are extensively acknowledged, the responses of aeolian desertification to various climate scenarios are poorly understood. Based on the tight combinations of dune activity index (DAI) trends and of aeolian desertification, here the spatial differences of aeolian desertification responses on various climate scenarios were reported. The analyzed results show that the variations in temperature, precipitation and wind regime have no significant contributions on aeolian desertification in the extremely arid Asia. From the early to blooming periods of vegetation growth, although temperature rise may benefit vegetation growths in some high latitudes and altitudes, the temperature rise may increase aeolian desertification in most arid Asia regions such as Mongolia, West and Central Asia. In arid Asia, although precipitation increases may benefit the rehabilitation, decreases in precipitation is not the key role on aeolian desertification occurrences in extremely arid regions. From the early to blooming periods of vegetation growths, spatial trends of the sensitivity of aeolian desertification to wind regime varied. Generally, at the regional scales there are relative high sensitivities for aeolian desertification to climate changes in the eastern and western regions of arid Asia, and the climate changes may not play important roles on aeolian desertification occurrence in the central regions. The spatial differences of aeolian desertification responses to climate changes indicate various strategies for aeolian desertification combating are needed in different regions of arid Asia.

  10. 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.

  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. 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.

  13. 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

    2016-11-01

    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.

  14. 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.

  15. Integrated approach to ecohydrology of semi-arid sites in areas of complex topography and biome transitions

    Science.gov (United States)

    Gutierrez, H. A.; Ivanov, V. Y.; Vivoni, E. R.; Bras, R. L.

    2005-05-01

    Vegetation constitutes an essential link in the hydrologic cycle at the land surface - atmosphere interface. Vegetation exerts a predominant control over the partition of rainfall into soil infiltration and evapotranspiration and determines to a great extent the water budget of entire regions. Conversely, water availability has a strong influence on the vegetation dynamics, including growth rates and overall health. In semiarid areas, changes in vegetation composition can follow slight variations in climate-derived moisture availability that, in turn, have a feedback effect on the surface water and energy balance. In this study, we present an integrated approach for studying the ecohydrology of semiarid regions characterized by complex topography and transitions between different vegetation life forms (grasses, shrubs, trees). We first present a set of hypotheses on the interaction between vegetation, landscape conditions, and climate variability in biome transitions zones. These hypotheses will be tested via the combination of numerical modeling and field data collection in the Sevilleta National Wildlife Refuge, central New Mexico. The field site is a first-order drainage basin consisting of two opposing hillslopes that differentially support a shrub-grass ecosystem and a conifer-grass community. Our modeling approaches consist of an ecohydrological module coupled to a 1-D vadose zone model as well as a more complex 3-D ecohydrological framework capable of simulating full vegetation dynamics at the watershed scale. The field instrumentation and model development efforts will be used synergistically to improve our understanding of the ecohydrology of semiarid complex watersheds. We then present an analysis of the ecohydrological model simulations driven by short- term meteorological data (~10 years) as well as by longer term, synthetically-generated climate scenarios. In particular, we will focus on the response of different vegetation communities to the

  16. 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

  17. Developing an Agro-Ecological Zoning Model for Tumbleweed (Salsola kali), as Energy Crop in Drylands of Argentina

    Science.gov (United States)

    Falasca, Silvia; Pitta-Alvarez, Sandra; Ulberich, Ana

    2016-12-01

    Salsola kali is considered extremely valuable as an energy crop worldwide because it adapts easily to environments with strong abiotic stresses (hydric, saline and alkaline) and produces large amounts of biomass in drylands. This species is categorized as an important weed in Argentina. The aim of this work was to design an agro-ecological zoning model for tumbleweed in Argentina, employing a Geography Information System. Based on the bioclimatic requirements for the species and the climatic data for Argentina (1981-2010 period), an agro-climatic suitability map was drawn. This map was superimposed on the saline and alkaline soil maps delineated by the Food and Agriculture Organization for dry climates, generating the agro-ecological zoning on a scale of 1 : 500 000. This zoning revealed very suitable and suitable cultivation areas on halomorphic soils. The potential growing areas extend from N of the Salta province (approximately 22° S) to the Santa Cruz province (50° S). The use of tumbleweed on halomorphic soils under semi-arid to arid conditions, for the dual purpose of forage use and source of lignocellulosic material for bioenergy, could improve agricultural productivity in these lands. Furthermore, it could also contribute to their environmental sustainability, since the species can be used to reclaim saline soils over the years. Based on international bibliography, the authors outlined an agro-ecological zoning model. This model may be applied to any part of the world, using the agro-ecological limits presented here.

  18. 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.

  19. 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.

  20. Evaluating the generalizability of GEP models for estimating reference evapotranspiration in distant humid and arid locations

    Science.gov (United States)

    Kiafar, Hamed; Babazadeh, Hosssien; Marti, Pau; Kisi, Ozgur; Landeras, Gorka; Karimi, Sepideh; Shiri, Jalal

    2016-08-01

    Evapotranspiration estimation is of crucial importance in arid and hyper-arid regions, which suffer from water shortage, increasing dryness and heat. A modeling study is reported here to cross-station assessment between hyper-arid and humid conditions. The derived equations estimate ET0 values based on temperature-, radiation-, and mass transfer-based configurations. Using data from two meteorological stations in a hyper-arid region of Iran and two meteorological stations in a humid region of Spain, different local and cross-station approaches are applied for developing and validating the derived equations. The comparison of the gene expression programming (GEP)-based-derived equations with corresponding empirical-semi empirical ET0 estimation equations reveals the superiority of new formulas in comparison with the corresponding empirical equations. Therefore, the derived models can be successfully applied in these hyper-arid and humid regions as well as similar climatic contexts especially in data-lack situations. The results also show that when relying on proper input configurations, cross-station might be a promising alternative for locally trained models for the stations with data scarcity.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Global and continental changes of arid areas using the FAO Aridity Index over the periods 1951-1980 and 1981-2010

    Science.gov (United States)

    Spinoni, Jonathan; Micale, Fabio; Carrao, Hugo; Naumann, Gustavo; Barbosa, Paulo; Vogt, Jürgen

    2013-04-01

    An increase in arid areas and progressing land degradation are two of the main consequences of global climate change. In the 2nd edition of the World Atlas of Desertification (WAD), published by the United Nation Environment Program (UNEP) in 1997, a global aridity map was presented. This map was based on the Food and Agriculture Organization (FAO) Aridity Index (AI) that takes into account the annual ratio between precipitation (RR) and Potential Evapo-Transpiration (PET). According to the long-term mean value of this ratio, climate is therefore classified in hyper-arid (0.65); a special case are cold climates, which occur if the mean annual PET is below 400 mm. In the framework of the 3rd edition of the WAD, we computed new global aridity maps to improve and update the old version that was based on a single dataset (CRU dataset, Climate Research Unit of University of East Anglia) related to the 1951-80 period only. We computed the AI on two different time intervals (1951-80 and 1981-2010) in order to account for shifts in classes between the two periods and we used two different datasets: PET from CRU (version 3.2), and precipitation from the global 0.5˚x0.5˚ gridded monthly precipitation of the Global Precipitation Climatology Center (GPCC) of the Deutscher Wetterdienst (DWD). We used the GPCC Full Data Reanalysis Version 6.0, which showed a high reliability during many quality checks and is based on more stations than the CRU's precipitation counterpart. The results show that the "arid areas" (i.e. AI Spain, the Southern Sahara and North-Eastern Kalahari deserts, Rajasthan and Madhya Pradesh (India), Mongolia, the Yang-Tze Basin (China), and the North-Eastern and South-Western Australian coasts. On the other hand, Central U.S., Paraguay and Northern Argentina, Scandinavia, Northern Australia, and Western China moved to a wetter climate in the last period. Due to the low data availability, we assumed that no changes took place in Antarctica, which is meant to

  7. 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

  8. Nitrogen Uptake Preferences by Plants in Arid and Semiarid Ecosystems

    Science.gov (United States)

    Macko, S.; Wang, L.; D'Odorico, P.

    2005-12-01

    In arid and semiarid ecosystems like African savannas, nutrient availability varies spatially and temporally and nutrients are considered to be a major limiting factor for growth in addition to water availability. Preference for different nitrogen forms presumably enhances the survivorship and fitness of plants since the relative abundances of nitrate and ammonium varies between drier and wetter areas. To test the hypothesis that species developing in dry areas will prefer nitrate whereas species growing in wet areas will prefer ammonium, a controlled experiment using a greenhouse was undertaken. Six native African grass species from different precipitation regimes were used in this study. Two species were from relatively wet areas (Pandamatenga, Botswana, precipitation = 698 mm/year), two were from relatively dry areas (Tshane, Botswana, precipitation = 232 mm/year) and other two were from intermediate environments (Ghanzi, Botswana, precipitation = 400 mm/year). The grass seeds were collected in the field during the dry season of 2004 and using germination pans, were grown in a greenhouse. When individuals were mature, they were transferred into plastic pots (one individual per pot) containing commercial sand. After one week period of adjustment, a 15N labeled fertilizer (NH4NO3) was applied. The total N applied as fertilizer was comparable to the mineralized field N based on a calculated rate for the top 15 cm of soil. A pair of individual plants was treated as an experimental unit. Each plant received the same amount of total N fertilizer, but one was 15NO3 labeled and another was 15NH4 labeled. Nutrient uptake preference was determined by the 15N difference between pairs. The preliminary results with three species shows that, the individuals from dry area ( Enneapogon cenchroides from Tshane) has significantly higher foliar 15N signatures in the 15NO3 labeling treatment (p = 0.0103) and no difference in root 15N signatures. Whereas individuals from the wet

  9. 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

  10. Seal formation in arid soil under natural and laboratory conditions

    Science.gov (United States)

    Sarah, Pariente; Sachs, Eyal

    2013-04-01

    Runoff is of considerable importance in the functioning of a desert ecosystem. The hydrological characteristics of runoff developing on arid soil under natural field conditions and those of runoff occurring in laboratory-controlled rain simulation experiments using the same type of soil were investigated. Runoff and erosion measurements were carried out in small plots (0.2-0.8 m2) on a south-facing hillslope in the northern Negev, Israel (90 mm ave. annual rainfall). Soil from the area near to the runoff plots was collected for the rain simulation experiments conducted in the laboratory. The soil was collected from 0-1 cm and 1-5 cm depths, and then placed within boxes (1.16 m long and 0.55 m wide) in the laboratory in the same order as they had been in the field. Representative surface stones were collected in the field and scattered randomly on the soil surface in the laboratory boxes. In some of the laboratory experiments soil, 5 cm in depth, was placed on a geotechnical sheet on a metal screen, while in other experiments, soil of 5 cm depth was placed on a Terzaghi filter. Rain simulator used had a rotating disk with a tilted nozzle to simulate raindrop size dispersion and kinetic energy of natural rain. The sprinkling intensity was set at a rate of 18 mm/hour. Soil crusts in the field were more stable than those created in the lab for two standard tests: Emerson - immersion test, and the 'single water drop' test. Whereas weak activity of microphytes was found in the field there was no such activity in the lab. The rain depth until runoff in the field was less than under laboratory conditions, while the sediment yield was greater in the field than in the laboratory (8.64 g/m2 versus 0.58 g/m2). The rain simulator experiments that had included a Terzaghi filter showed significantly higher final infiltration rate (7.5 mm/h versus 4.2 mm/h), shorter accumulated watering depth until stabilization of soil seal formation (100-200 mm versus 50 mm), and smaller

  11. 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.

  12. 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.)

  13. Hydrological modeling of the semi-arid Andarax river basin in southern Spain

    DEFF Research Database (Denmark)

    Andersen, Flemming Hauge; Jensen, Karsten Høgh; Sandholt, Inge

      The 2,265 km2 Andarax river basin located in Southern Spain is one of the most arid regions in Europe with a mean annual precipitation of 250-350 mm, which mainly falls (70%) in autumn and winter. The terrain changes from sea level at the coast to more than 2,500 m in the Sierra Nevada Mountains....... Most of the precipitation falling in the mountainous areas, where the unit Triassic schists dominates, is converted into overland flow, which runs directly to the rivers. In areas with limestone most of the precipitation infiltrates and is subsequently routed through fractures before discharging...... availability in the delta region. Due to the high evapotranspiration in semi-arid or arid regions groundwater recharge can be as low as 1 % of the precipitation. Thus it is essential to accurately predict the seasonal and regional distribution of actual evapotranspiration (ET) within the river catchment...

  14. 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.

  15. A multiscale, hierarchical model of pulse dynamics in arid-land ecosystems

    Science.gov (United States)

    Collins, Scott L.; Belnap, Jayne; Grimm, N. B.; Rudgers, J. A.; Dahm, Clifford N.; D'Odorico, P.; Litvak, M.; Natvig, D. O.; Peters, Douglas C.; Pockman, W. T.; Sinsabaugh, R. L.; Wolf, B. O.

    2014-01-01

    Ecological processes in arid lands are often described by the pulse-reserve paradigm, in which rain events drive biological activity until moisture is depleted, leaving a reserve. This paradigm is frequently applied to processes stimulated by one or a few precipitation events within a growing season. Here we expand the original framework in time and space and include other pulses that interact with rainfall. This new hierarchical pulse-dynamics framework integrates space and time through pulse-driven exchanges, interactions, transitions, and transfers that occur across individual to multiple pulses extending from micro to watershed scales. Climate change will likely alter the size, frequency, and intensity of precipitation pulses in the future, and arid-land ecosystems are known to be highly sensitive to climate variability. Thus, a more comprehensive understanding of arid-land pulse dynamics is needed to determine how these ecosystems will respond to, and be shaped by, increased climate variability.

  16. Soil fertility, salinity and nematode diversity influenced by Tamarix ramosissima in different habitats in an arid desert oasis.

    Science.gov (United States)

    Yong-zhong, Su; Xue-fen, Wang; Rong, Yang; Xiao, Yang; Wen-jie, Liu

    2012-08-01

    The aim of this paper was to assess the influence of tamarisk shrubs on soil fertility, salinity and nematode communities in various habitats located in an arid desert-oasis region in northwest China. Three habitats were studied: sand dune, riparian zone and saline meadow, where tamarisk shrubs have been established in recent decades in order to vegetation restoration used as desertification control and saline land rehabilitation projects and become the dominant plant community. The parameters measured include soil organic carbon (SOC), total nitrogen, available phosphorus (P) and potassium (K), pH, salt component, and nematode community characteristics. Enrichment ratios (a comparison of the soil measurements between soils under canopy and in the open interspaces) for soil nutrients and salinity were used to evaluate fertility and salinity islands underneath the tamarisk shrubs. The soil nematode community was used as a biological indicator of soil condition. SOC and available P and K were higher beneath the plant canopy than in the open interspaces outside that canopy. The enrichment ratios for SOC and nutrients were highest for the sand dune habitat and tamarisk shrubs clearly created islands of greater salinity under the canopies. Nematode abundance per 100 g dry soil varied considerably between the locations and habitats, with the highest abundance found in sand dune and the lowest in saline meadow. A significantly higher nematode abundance and a lower trophic diversity were found in soils under the canopy compared to the soils in the open interspaces. With the exception of saline meadow, the abundance of bacterivores increased and fungivores decreased under the canopy relative to the open interspaces, and bacterivores dominated under the canopies in the sand dune and riparian habitats. The enrichment ratios for salinity were higher than for fertility, suggesting that improved soil fertility can not limit the impact of salinization beneath tamarisk shrubs. The

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Impacts of Future Climate Changes on Shifting Patterns of the Agro-Ecological Zones in China

    Directory of Open Access Journals (Sweden)

    Yingzhi Lin

    2013-01-01

    Full Text Available An agroecological zone (AEZ is a land resource mapping unit, defined in terms of climate, landform, and soils, and has a specific range of potentials and constraints for cropping (FAO, 1996. The shifting patterns of AEZs in China driven by future climatic changes were assessed by applying the agroecological zoning methodology proposed by International Institute for Applied Systems Analysis (IIASA and Food and Agriculture Organization of the United Nations (FAO in this study. A data processing scheme was proposed in this study to reduce systematic errors in projected climate data using observed data from meteorological stations. AEZs in China of each of the four periods: 2011–2020, 2021–2030, 2031–2040, and 2041–2050 were drawn. It is found that the future climate change will lead to significant local changes of AEZs in China and the overall pattern of AEZs in China is stable. The shifting patterns of AEZs will be characterized by northward expansion of humid AEZs to subhumid AEZs in south China, eastward expansion of arid AEZs to dry and moist semiarid AEZs in north China, and southward expansion of dry semiarid AEZs to arid AEZs in southwest China.

  3. 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...

  4. 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

  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. Dynamics in carbon exchange fluxes for a grazed semi-arid savanna ecosystem in West Africa

    DEFF Research Database (Denmark)

    Tagesson, Torbern; Fensholt, Rasmus; Cropley, Ford;

    2015-01-01

    The main aim of this paper is to study land-atmosphere exchange of carbon dioxide (CO2) for semi-arid savanna ecosystems of the Sahel region and its response to climatic and environmental change. A subsidiary aim is to study and quantify the seasonal dynamics in light use efficiency (ε) being a key...... variable in scaling carbon fluxes from ground observations using earth observation data. The net ecosystem exchange of carbon dioxide (NEE) 2010-2013 was measured using the eddy covariance technique at a grazed semi-arid savanna site in Senegal, West Africa. Night-time NEE was not related to temperature...

  7. 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.

  8. Can biochar be used as a seed coating to improve native plant germination and growth in arid conditions?

    Science.gov (United States)

    Millions of hectares of arid and semi-arid rangelands throughout the world have been disturbed by fire and invasive weeds and are relatively difficult to restore using traditional seeding approaches. Biochar is an organic charcoal product that has been used extensively as a soil amendment to improv...

  9. Morphological Characteristics and Water-Use Efficiency of Siberian Elm Trees (Ulmus pumila L. within Arid Regions of Northeast Asia

    Directory of Open Access Journals (Sweden)

    Go Eun Park

    2016-11-01

    Full Text Available The Siberian elm (Ulmus pumila L. is one of the most commonly found tree species in arid areas of northeast Asia. To understand the morphological and physiological characteristics of Siberian elms in arid regions, we analyzed leaves from seven study sites (five arid or semi-arid and two mesic in China, Mongolia and the Republic of Korea, which covered a wide range of average annual precipitation (232 mm·year−1 to 1304 mm·year−1 under various aridity indexes (AI and four different microenvironments: sand dune, steppe, riverside and forest. The traits of Siberian elms varied widely along different annual precipitation (P and AI gradients. Tree height (H, leaf size (LS and stomatal area per unit leaf area (AS/AL decreased with increasing AI, whereas leaf mass per unit leaf area (LMA and water-use efficiency (WUE increased significantly. In addition, trees at the five arid sites showed significant differences in LS, LMA and AS/AL but not in H and WUE. Thus, our study indicated that indigenous Siberian elm trees in arid areas have substantially altered their morphological and physiological characteristics to avoid heat stress and increase water conservation in comparison to mesic areas. However, their changes differed depending on the surrounding microenvironment even in arid areas. Trees in sand dunes had a smaller LS, higher LMA, thicker leaf cuticle layer and higher stomatal density and AS than those in steppes and near a riverside.

  10. Initial generation of sand across climate zones of the Mojave, Sierra Nevada, and Klamath Batholiths in California, U.S.A.

    Science.gov (United States)

    Hessler, Angela M.; Lowe, Donald R.

    2017-03-01

    The generation of modern, plutoniclastic sediment across California varies with climate, resulting in significant mineralogical and geochemical differences between parent rock, weathering profile material, and low-order stream sand. With average precipitation of 15 cm/yr in the arid zones and 120 cm/yr in the temperate zones, feldspar is relatively decreased in stream sand (compared to parent rock) by paleoclimate studies, where a moderate precipitation shift is capable of producing a significant loss of feldspar. The differential response of common minerals to chemical weathering should be considered for studies and modeling related to bedrock erodibility, sediment supply, and landscape evolution.

  11. 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.

  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. 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

  14. The sensitivity of water availability to aridity changes and other factors - a probabilistic analysis in the Budyko-space

    Science.gov (United States)

    Gudmundsson, Lukas; Greve, Peter

    2016-04-01

    One of the pending questions in the context of global change is (i) whether climatic drivers or (ii) other factors have a stronger influence on water availability. Here we present an idealised approach that allows to estimate the probability that changes in climatological aridity have a larger effect on water availability than other factors. The analysis builds upon a probabilistic extension of the Budyko framework, which is subject to an analytical sensitivity assessment. The results show that changes in water availability are dominated by changes in the aridity index in humid climates. In arid climates other factors are dominating. A global application predicts only little influence of aridity changes on water availability in drylands. This implies that the projected intensification of aridity in dry regions may have less influence on water availability than commonly assumed. Instead other factors, including e.g. land use change, are likely dominating.

  15. 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

    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......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...... 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...

  16. 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...

  17. Impact of soil salinity on arbuscular mycorrhizal fungi biodiversity and microflora biomass associated with Tamarix articulata Vahll rhizosphere in arid and semi-arid Algerian areas.

    Science.gov (United States)

    Bencherif, Karima; Boutekrabt, Ammar; Fontaine, Joël; Laruelle, Fréderic; Dalpè, Yolande; Sahraoui, Anissa Lounès-Hadj

    2015-11-15

    Soil salinization is an increasingly important problem in many parts of the world, particularly under arid and semi-arid areas. Unfortunately, the knowledge about restoration of salt affected ecosystems using mycorrhizae is limited. The current study aims to investigate the impact of salinity on the microbial richness of the halophytic plant Tamarix articulata rhizosphere. Soil samples were collected from natural sites with increasing salinity (1.82-4.95 ds.m(-1)). Six arbuscular mycorrhizal fungi (AMF) species were isolated from the different saline soils and identified as Septoglomus constrictum, Funneliformis mosseae, Funneliformis geosporum, Funneliformis coronatum, Rhizophagus fasciculatus, and Gigaspora gigantea. The number of AMF spores increased with soil salinity. Total root colonization rate decreased from 65 to 16% but remained possible with soil salinity. Microbial biomass in T. articulata rhizosphere was affected by salinity. The phospholipid fatty acids (PLFA) C16:1ω5 as well as i15:0, a15:0, i16:0, i17:0, a17:0, cy17:0, C18:1ω7 and cy19:0 increased in high saline soils suggesting that AMF and bacterial biomasses increased with salinity. In contrast, ergosterol amount was negatively correlated with soil salinity indicating that ectomycorrhizal and saprotrophic fungal biomasses were reduced with salinity. Our findings highlight the adaptation of arbuscular and bacterial communities to natural soil salinity and thus the potential use of mycorrhizal T. articulata trees as an approach to restore moderately saline disturbed arid lands.

  18. Zoning should promote public health.

    Science.gov (United States)

    Hirschhorn, Joel S

    2004-01-01

    Legally, governments use their police powers to protect public health, safety, and welfare through zoning. This paper presents a case for revisiting zoning on the basis of increasing evidence that certain types of community design promote public health, as opposed to the dominant pattern of sprawl development, which does not. Zoning, and the land use planning linked to it, that prohibits or disfavors health-promoting community designs contradicts the inherent public policy goal on which it is based. If there is a paradigm shift underway, from traditional sprawl to health-promoting community designs, then health professionals and others should understand why zoning must be reassessed.

  19. Work Zone Data Collection Trailer

    Data.gov (United States)

    Federal Laboratory Consortium — The Work Zone Data Collection Trailer was designed and constructed to enhance data collection and analysis capabilities for the "Evaluating Roadway Construction Work...

  20. 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

  1. 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

  2. The first Editorial Board meeting of Journal of Arid Land in 2010 was held in Urumqi

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    On Sep. 5, 2010, the first Editorial Board meeting of Journal of Arid Land (JAL) was held in Urumqi. The director of Xinjiang Institute of Ecology and Geography (XIEG), Chinese Academy of Sciences (CAS) and the editor-in-chief of JAL, Professor Chen Xi, another editor-in-chief, Professor Li Bailian, University of California,

  3. 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.

  4. Using hydrogel filled, embedded tubes to sustain grass transplants for arid land restoration

    Science.gov (United States)

    Grass restoration on remote arid rangelands may require irrigation to stimulate seedling establishment. However, irrigation on undeveloped sites is costly. In this study, the survival, growth, and development of Bouteloua eriopoda seedlings irrigated with either starch- or acrylic-based hydrogels c...

  5. Economic analysis of a simulated alley cropping system for semi-arid conditions, using micro computers

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, D.A.

    1983-01-01

    Returns were simulated for the semi-arid areas in Mackakos District, Kenya (bimodal rainfall distribution, 600 mm/yr) comparing the present system (maize and beans intercropped twice a year) with a Leucaena leucocephala hedgerow system. Although some of the assumptions contain a large element of uncertainty, the results were promising enough for the system to be considered further. 4 references.

  6. Complexity and coexistence in a simple spatial model for arid savanna ecosystems

    NARCIS (Netherlands)

    Baudena, M.; Rietkerk, M.

    2012-01-01

    Tree–grass coexistence is broadly observed in tropical savannas. Recent studies indicate that, in arid savannas, such coexistence is stable and related to water availability. The role of different factors (from niche separation to demographic structure) has been explored. Nevertheless, spatial mecha

  7. Preface paper to the Semi-Arid Land-Surface-Atmosphere (SALSA) Program special issue

    Science.gov (United States)

    Goodrich, D.C.; Chehbouni, A.; Goff, B.; MacNish, B.; Maddock, T.; Moran, S.; Shuttleworth, W.J.; Williams, D.G.; Watts, C.; Hipps, L.H.; Cooper, D.I.; Schieldge, J.; Kerr, Y.H.; Arias, H.; Kirkland, M.; Carlos, R.; Cayrol, P.; Kepner, W.; Jones, B.; Avissar, R.; Begue, A.; Bonnefond, J.-M.; Boulet, G.; Branan, B.; Brunel, J.P.; Chen, L.C.; Clarke, T.; Davis, M.R.; DeBruin, H.; Dedieu, G.; Elguero, E.; Eichinger, W.E.; Everitt, J.; Garatuza-Payan, J.; Gempko, V.L.; Gupta, H.; Harlow, C.; Hartogensis, O.; Helfert, M.; Holifield, C.; Hymer, D.; Kahle, A.; Keefer, T.; Krishnamoorthy, S.; Lhomme, J.-P.; Lagouarde, J.-P.; Lo, Seen D.; Luquet, D.; Marsett, R.; Monteny, B.; Ni, W.; Nouvellon, Y.; Pinker, R.; Peters, C.; Pool, D.; Qi, J.; Rambal, S.; Rodriguez, J.; Santiago, F.; Sano, E.; Schaeffer, S.M.; Schulte, M.; Scott, R.; Shao, X.; Snyder, K.A.; Sorooshian, S.; Unkrich, C.L.; Whitaker, M.; Yucel, I.

    2000-01-01

    The Semi-Arid Land-Surface-Atmosphere Program (SALSA) is a multi-agency, multi-national research effort that seeks to evaluate the consequences of natural and human-induced environmental change in semi-arid regions. The ultimate goal of SALSA is to advance scientific understanding of the semi-arid portion of the hydrosphere-biosphere interface in order to provide reliable information for environmental decision making. SALSA approaches this goal through a program of long-term, integrated observations, process research, modeling, assessment, and information management that is sustained by cooperation among scientists and information users. In this preface to the SALSA special issue, general program background information and the critical nature of semi-arid regions is presented. A brief description of the Upper San Pedro River Basin, the initial location for focused SALSA research follows. Several overarching research objectives under which much of the interdisciplinary research contained in the special issue was undertaken are discussed. Principal methods, primary research sites and data collection used by numerous investigators during 1997-1999 are then presented. Scientists from about 20 US, five European (four French and one Dutch), and three Mexican agencies and institutions have collaborated closely to make the research leading to this special issue a reality. The SALSA Program has served as a model of interagency cooperation by breaking new ground in the approach to large scale interdisciplinary science with relatively limited resources.

  8. Determining soil erosion rates on semi-arid watersheds using radioisotope-derived sedimentation chronology 2327

    Science.gov (United States)

    This study investigates erosion dynamics of the past 90 years on three small semi-arid watersheds with histories of grazing and vegetation change. Activity of 137Cs and excess 210Pb from 18 cores collected from sedimentation ponds were measured using a gamma spectrometer. The sediment was dated usi...

  9. Evaluation of six potential evapotranspiration models for estimating crop potential and actual evapotranspiration in arid regions

    Science.gov (United States)

    Li, Sien; Kang, Shaozhong; Zhang, Lu; Zhang, Jianhua; Du, Taisheng; Tong, Ling; Ding, Risheng

    2016-12-01

    Using potential evapotranspiration (PET) to estimate crop actual evapotranspiration (AET) is a critical approach in hydrological models. However, which PET model performs best and can be used to predict crop AET over the entire growth season in arid regions still remains unclear. The six frequently-used PET models, i.e. Blaney-Criddle (BC), Hargreaves (HA), Priestley-Taylor (PT), Dalton (DA), Penman (PE) and Shuttleworth (SW) models were considered and evaluated in the study. Five-year eddy covariance data over the maize field and vineyard in arid northwest China were used to examine the accuracy of PET models in estimating daily crop AET. Results indicate that the PE, SW and PT models underestimated daily ET by less than 6% with RMSE lower than 35 W m-2 during the four years, while the BC, HA and DA models under-predicted daily ET approximately by 10% with RMSE higher than 40 W m-2. Compared to BC, HA and DA models, PE, SW and PT models were more reliable and accurate for estimating crop PET and AET in arid regions. Thus the PE, SW and PT models were recommended for predicting crop evapotranspiration in hydrological models in arid regions.

  10. Conservation tillage systems and water productivity implications for smallholder farmers in semi-arid Ethiopia

    NARCIS (Netherlands)

    Temesgen, M.L.

    2007-01-01

    Conservation tillage systems have been adopted by farmers in many countries to solve the problem of land degradation and declining water productivity. However, direct application of such tillage systems was not possible among resource poor smallholder farmers in semi arid areas of Ethiopia. Problems

  11. 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.

  12. 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...

  13. Acclimation of Pistacia integerrima trees to frost in semi-arid environments depends on autumn's drought.

    Science.gov (United States)

    Sperling, Or; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

    2017-03-01

    Main conclusion Cold acclimation is revealed through induced stem respiration during pre-winter frost of native Pistacia integerrima trees in continental semi-arid environments. Semi-arid environments challenge vegetation by simultaneous abiotic stresses. In this study, we examine the combined effects of water stress and frost on the physiology of Pistacia integerrima stems. This species is native to semi-arid environments where drought and frost frequently co-occur. We quantified carbohydrates and proline in P. integerrima stems responding to frost and experiencing water potentials between -0.2 and -1.8 MPa. We report that dehydrated trees (i.e., Ψstem <=-1 MPa) had more soluble sugars and proline than the well-watered trees (-0.2 MPa). The dehydrated trees also froze at lower temperatures and were less damaged by freezing. Interestingly, we observed a significant increase in stem CO2 efflux at near-freezing temperatures that could be linked to frost protection. This novel finding challenges current paradigm of plant respiration-kinetics which predicts, according to Arrhenius equation, lower respiration rates during frost. Our results support the notion that drought and frost are analogous stresses that can independently activate corresponding physiological processes in trees and amplify protection. This inevitable stress response 'collaboration' may be the key to understanding how non-dormant perennial plants survive the highly variable weather patterns of early winters in semi-arid environments.

  14. 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

  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. Spatial, ontogenetic and sexual effects on the diet of a Teiid lizard in arid South America

    NARCIS (Netherlands)

    Leeuwen, van J.P.; Catenazzi, A.; Holmgren, M.

    2011-01-01

    Most lizard species feed on small arthropods, and although some are omnivorous, only a few species are strict herbivores. We studied the diet of Dicrodon guttulatum, a teiid lizard endemic to the arid coastal deserts and dry forests of northern Peru. Herbivory by this lizard has been identified as a

  17. 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.

  18. The challenges of rehabilitating denuded patches of a semi-arid environment in Kenya

    NARCIS (Netherlands)

    Mganga, K.Z.; Nyangito, M.M.; Musimba, N.K.R.; Nyariki, D.M.; Mwangombe, A.W.; Ekaya, W.N.; Muiri, W.M.; Clavel, D.; Francis, J.; Kaufmann, Von R.; Verhagen, J.

    2010-01-01

    Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the habited semiarid lands. In Kenya, grass reseeding technology has been used to combat land degradation. However,

  19. Energetics of the green iguana (Iguana iguana) in a semi-arid environment

    NARCIS (Netherlands)

    van Marken Lichtenbelt, Wouter David

    1991-01-01

    Energy budgets in the herbivorous green iguana (Iguana Iguana) were studied from April 1985-October 1988 in a strongly seasonal environment on the semi-arid island Curacao (Netherlands Antilles) under the auspices of the CARMABI Foundation in cooperation with the State University of Groningen (The N

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. Polyacrylamide molecular weight and phosphogypsum effects on infiltration and erosion in semi-arid soils

    Science.gov (United States)

    Seal formation at the surface of semi-arid soils during rainstorms reduces soil infiltration rate (IR) and causes runoff and erosion. Surface application of dry anionic polyacrylamide (PAM) with high molecular weight (MW) has been found to be effective in stabilizing soil aggregates, and decreasing ...

  8. Effects of irrigation and plastic mulch on soil properties on semi-arid abandoned fields

    NARCIS (Netherlands)

    van der Meulen, E.S.; Nol, L.; Cammeraat, L.H.

    2006-01-01

    The Guadalentín Basin in Spain is one of the driest areas of Europe and has problems with high evaporation rates, and high risks of desertification exist including soil quality loss and soil erosion. Farmers in this semi-arid region use polyethylene covers on their irrigated croplands to reduce evap

  9. Downregulation of ARID1A, a component of the SWI/SNF chromatin remodeling complex, in breast cancer

    Science.gov (United States)

    Takao, Chika; Morikawa, Akemi; Ohkubo, Hiroshi; Kito, Yusuke; Saigo, Chiemi; Sakuratani, Takuji; Futamura, Manabu; Takeuchi, Tamotsu; Yoshida, Kazuhiro

    2017-01-01

    Recent studies unraveled that AT-rich interactive domain-containing protein 1A (ARID1A), a subunit of the mammary SWI/SNF chromatin remodeling complex, acts as a tumor suppressor in various cancers. In this study, we first evaluated ARID1A expression by immunohistochemistry in invasive breast cancer tissue specimens and assessed the correlation with the prognosis of patients with breast cancer. Non-tumorous mammary duct epithelial cells exhibited strong nuclear ARID1A staining, whereas different degrees of loss in ARID1A immunoreactivity were observed in many invasive breast cancer cells. We scored ARID1A immunoreactivity based on the sum of the percentage score in invasive cancer cells (on a scale of 0 to 5) and the intensity score (on a scale of 0 to 3), for a possible total score of 0 to 8. Interestingly, partial loss of ARID1A expression, score 2 to 3, was significantly correlated with poor disease free survival of the patients. Subsequently, we performed siRNA-mediated ARID1A knockdown in cultured breast cancer cells followed by comprehensive gene profiling and quantitative RT-PCR. Interestingly, many genes were downregulated by partial loss of ARID1A, whereas RAB11FIP1 gene expression was significantly upregulated by partial loss of ARID1A expression in breast cancer cells. In contrast, a more than 50% reduction in ARID1A mRNA decreased RAB11FIP1gene expression. Immunoblotting also demonstrated that partial downregulation of ARID1A mRNA at approximately 20% reduction significantly increased the expression of RAB11FIP1 protein in MCF-7 cells, whereas, over 50% reduction of ARID1A mRNA resulted in reduction of RAB11FIP1 protein in cultured breast cancer cells. Recent studies reveal that RAB11FIP1 overexpression leads to breast cancer progression. Altogether, the present findings indicated that partial loss of ARID1A expression is linked to unfavorable outcome for patients with breast cancer, possibly due to increased RAB11FIP1 expression.

  10. Excavation damaged zone

    Energy Technology Data Exchange (ETDEWEB)

    Poulain, S.; Sergeant, C.; Vesvres, M.H.; Simonoff, M.; Lavielle, B.; Thomas, B.; Gilabert, E. [Bordeaux-1 Univ., I and 2/CNRS and GdR FORPRO 0788, Nuclear Analytical and Bioenvironmental Chemistry 33 - Gradignan (France); Poulain, S.; Altmann, S.; Lenoir, N.; Barnichon, J.D.; Wileveau, Y.; Lebon, P. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Le Marrec, C. [Bordeaux-1 Univ., ISTAB, INRA, UMR Oenologie - ISVV, 33 - Talence (France); Vinsot, A.; Dewonck, S.; Wileveau, Y.; Armand, G.; Cruchaudet, P.; Rebours, H.; Morel, J. [Agence Nationale pour la Gestion des Dechets Radioactifs, Lab. de Souterrain de Meuse/Haute-Marne, 55 - Bure (France); Lanyon, G.W. [Fracture Systems Ltd, Tregurrian, Ayr, St Ives, Cornwall (United Kingdom); Marschall, P.; Vietor, T. [NAGRA - National Cooperative for the Disposal of Radioactive Waste, Wettingen (Switzerland); Bourdeau, C.; Dedecker, F.; Billaux, D. [ITASCA Consultants, S.A.S., 69 - Ecully (France); Lenoir, N.; Desrues, J.; Viggiani, G.; Besuelle, P. [Laboratoire 3S-R - Sols Solides Structures-Risques, 38 - Grenoble (France); Bornert, M. [Ecole Polytechnique, LMS - Lab. de Mecanique des Solides, 91 - Palaiseau (France); Arson, C.; Gatmiri, B. [CERMES, Ecole Nationale des Ponts et Chaussees, 77 - Marne-la-Vallee (France); Gatmiri, B. [University of Tehran (Iran, Islamic Republic of); Bernier, F. [ESV EURIDICE GIE - European Underground Research Infrastructure for Disposal of Nuclear Waste in Clay Environment (Belgium); Nussbaum, C.; Mori, O. [Geotechnical Institute Ltd., Fabrique de Chaux, St-Ursanne (Switzerland); Bossart, P. [Swisstopo - Federal Office of Topography, Wabern (Switzerland); Schuster, K.; Alheid, H.J. [BGR - Bundesanstalt fur Geowissenschaften und Rohstoffe, Hannover (Germany); Lavanchy, J.M.; Croise, J.; Schwarz, R. [Colenco Power Engineering AG, Groundwater Protection and Waste Disposal, Baden (Switzerland)] [and others

    2007-07-01

    This session gathers 13 articles dealing with: autochthonous and colonizing microorganisms in argillaceous underground environments (S. Poulain, C. Sergeant, C. Le Marrec, M.H. Vesvres, A. Vinsot, S. Dewonck, M. Simonoff, S. Altmann); the discrete fracture network modelling of the Hg-a experiment at the Mont Terri rock Laboratory (G.W. Lanyon, P. Marschall, T. Vietor); the discrete modelling of drift behaviour in the Meuse/Haute-Marne URL, France (C. Bourdeau, F. Dedecker, D. Billaux); the fracturing in Callovo-Oxfordian argillite under triaxial compression studied by X-ray microtomography (N. Lenoir, J. Desrues, G. Viggiani, P. Besuelle, M. Bornert, J.D. Barnichon); a general review of the damage models for the EDZ creation (C. Arson, B. Gatmiri); similarities in the Hydro-Mechanical response of Callovo-Oxfordian clay and Boom clay during gallery excavation (Y. Wileveau, F. Bernier); the different geometries of the EDZ fracture networks in the Mont Terri and Meuse/Haute-Marne rock laboratories: Structural approach (C. Nussbaum, Y. Wileveau, P. Bossart, A. Moeri, G. Armand); the characterisation of the Excavation-Damaged Zone in the Meuse/Haute-Marne Underground Research Laboratory (G. Armand, P. Lebon, M. Cruchaudet, H. Rebours, J. Morel, Y. Wileveau); the EDZ characterisation with ultrasonic interval velocity measurements in the Meuse/Haute-Marne URL, performed between depth of 85 m and 504 m (K. Schuster, H.J. Alheid); the clay formation at the Meuse Haute Marne URL: evaluation of the impact of resin filled slots on flow paths characteristics within the EDZ (J.M. Lavanchy, J. Croise, R. Schwarz, G. Armand, M. Cruchaudet); the characterisation and evolution of EDZ by extraction and analyse of noble gases in pore waters in the Meuse/Haute Marne URL site (B. Lavielle, B. Thomas, E. Gilabert); in-situ gas test for the characterisation of Excavation Disturbed Zone at the Meuse/Haute Marne URL (H. Shao, K. Schuster, J. Soennke, V. Braeuer); and the flow and reactive

  11. Distribution of stable isotopes in arid storms . II. A double-component model of kinematic wave flow and transport

    Science.gov (United States)

    Yakirevich, Alexander; Dody, Avraham; Adar, Eilon M.; Borisov, Viacheslav; Geyh, Mebus

    A new mathematical method based on a double-component model of kinematic wave flow and approach assesses the dynamic isotopic distribution in arid rain storms and runoff. This model describes the transport and δ18O evolution of rainfall to overland flow and runoff in an arid rocky watershed with uniformly distributed shallow depression storage. The problem was solved numerically. The model was calibrated using a set of temporal discharge and δ18O distribution data for rainfall and runoff collected on a small rocky watershed at the Sede Boker Experimental Site, Israel. Simulation of a reliable result with respect to observation was obtained after parameter adjustment by trial and error. Sensitivity analysis and model application were performed. The model is sensitive to changes in parameters characterizing the depression storage zones. The model reflects the effect of the isotopic memory in the water within the depression storage between sequential rain spells. The use of the double-component model of kinematic wave flow and transport provides an appropriate qualitative and quantitative fitting between computed and observed δ18O distribution in runoff. RésuméUne nouvelle méthode mathématique basée sur un modèle à double composante d'écoulement et de transport par une onde cinématique a été développée pour évaluer la distribution dynamique en isotopes dans les précipitations et dans l'écoulement en région aride. Ce modèle décrit le transport et les variations des δ18O de la pluie vers le ruissellement et l'écoulement de surface dans un bassin aride rocheux où le stockage se fait dans des dépressions peu profondes uniformément réparties. Le problème a été résolu numériquement. Le modèle a été calibré au moyen d'une chronique de débits et d'une distribution des δ18O dans la pluie et dans l'écoulement de surface sur un petit bassin versant rocheux du site expérimental de Sede Boker (Israël). La simulation d'un résultat cr

  12. Effect of Different Mulches under Rainfall Concentration System on Corn Production in the Semi-arid Areas of the Loess Plateau

    Science.gov (United States)

    Ren, Xiaolong; Zhang, Peng; Chen, Xiaoli; Guo, Jingjing; Jia, Zhikuan

    2016-01-01

    The ridge and furrow farming system for rainfall concentration (RC) has gradually been popularized to improve the water availability for crops and to increase the water use efficiency (WUE), thereby stabilizing high yields. In the RC system, plastic-covered ridges are rainfall harvesting zones and furrows are planting zones. In this study, we optimized the mulching patterns for RC planting to mitigate the risks of drought during crop production in semi-arid agricultural areas. We conducted a four-year field study to determine the effects on corn production of mulching with 0.08-mm plastic film, maize straw, 8% biodegradable film, liquid film, bare furrow, and conventional flat (CF) farming. We found that RC significantly increased (P > 0.05) the soil moisture storage in the top 0–100 cm layer and the topsoil temperature (0–10 cm) during the corn-growing season. Combining RC with mulching further improved the rain-harvesting, moisture-retaining, and yield-increasing effects in furrows. Compared with CF, the four-year average yield increased by 1497.1 kg ha–1 to 2937.3 kg ha–1 using RC with mulch treatments and the WUE increased by 2.3 kg ha–1 mm–1 to 5.1 kg ha–1 mm–1.

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

    Directory of Open Access Journals (Sweden)

    Jonathan Deborde

    2015-02-01

    Full Text Available 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/ increase in: (i water content; (ii TOC; (iii mangrove-derived OM; II/ and decrease in: (i salinity; (ii redox; (iii pH; (iv solid Fe and solid P. Beneath Avicennia and Rhizophora, TS accumulated at depth, probably as a result of reduction of iron oxides and sulfate. The loss of total Fe observed towards the sea-side may be related to sulfur oxidation and to more intense tidal flushing of dissolved components. Except the organic forms, dissolved N and P concentrations were very low beneath Avicennia and Rhizophora stands, probably as a result of their uptake by the root systems. However, in the unvegetated salt-flat, NH4+ can accumulate in organic rich and anoxic layers. This study shows: (i the evolution of mangrove sediment biogeochemistry along the intertidal zone as a result of the different duration of tidal inundation and organic enrichment; and (ii the strong links between the distribution and speciation of the different elements.

  14. Genotypic and symbiotic diversity of Rhizobium populations associated with cultivated lentil and pea in sub-humid and semi-arid regions of Eastern Algeria.

    Science.gov (United States)

    Riah, Nassira; Béna, Gilles; Djekoun, Abdelhamid; Heulin, Karine; de Lajudie, Philippe; Laguerre, Gisèle

    2014-07-01

    The genetic structure of rhizobia nodulating pea and lentil in Algeria, Northern Africa was determined. A total of 237 isolates were obtained from root nodules collected on lentil (Lens culinaris), proteaginous and forage pea (Pisum sativum) growing in two eco-climatic zones, sub-humid and semi-arid, in Eastern Algeria. They were characterised by PCR-restriction fragment length polymorphism (RFLP) of the 16S-23S rRNA intergenic region (IGS), and the nodD-F symbiotic region. The combination of these haplotypes allowed the isolates to be clustered into 26 distinct genotypes, and all isolates were classified as Rhizobium leguminosarum. Symbiotic marker variation (nodD-F) was low but with the predominance of one nod haplotype (g), which had been recovered previously at a high frequency in Europe. Sequence analysis of the IGS further confirmed its high variability in the studied strains. An AMOVA analysis showed highly significant differentiation in the IGS haplotype distribution between populations from both eco-climatic zones. This differentiation was reflected by differences in dominant genotype frequencies. Conversely, no host plant effect was detected. The nodD gene sequence-based phylogeny suggested that symbiotic gene diversity in pea and lentil nodulating rhizobial populations in Algeria was low compared to that reported elsewhere in the world.

  15. 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...

  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. Zone refining of plutonium metal

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Michael S. [Univ. of Idaho, Moscow, ID (United States)

    1994-08-01

    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, {delta}-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.

  18. 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.

  19. Increasing aridity reduces soil microbial diversity and abundance in global drylands.

    Science.gov (United States)

    Maestre, Fernando T; Delgado-Baquerizo, Manuel; Jeffries, Thomas C; Eldridge, David J; Ochoa, Victoria; Gozalo, Beatriz; Quero, José Luis; García-Gómez, Miguel; Gallardo, Antonio; Ulrich, Werner; Bowker, Matthew A; Arredondo, Tulio; Barraza-Zepeda, Claudia; Bran, Donaldo; Florentino, Adriana; Gaitán, Juan; Gutiérrez, Julio R; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Mau, Rebecca L; Miriti, Maria; Naseri, Kamal; Ospina, Abelardo; Stavi, Ilan; Wang, Deli; Woods, Natasha N; Yuan, Xia; Zaady, Eli; Singh, Brajesh K

    2015-12-22

    Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands.

  20. Land cover change drives climate extremes and aridity in non-Amazonian South America

    Science.gov (United States)

    Larsen, J.; Salazar, A.; Mcalpine, C. A.; Syktus, J.; Katzfey, J.

    2015-12-01

    Increasing evidence is showing the relevance of land cover change on the regional mean climate. However, the mechanisms that explain these interactions remain a challenge in land - atmosphere interactions science. This challenge is particularly significant in understanding the role of vegetation change on climate extremes and aridity, which has been barely addressed by the literature. In this paper we focus on this gap by investigating the effects of land use and land cover change on selected climate extremes indices and aridity in non-Amazonian South America over an area of about 3 million km2. We run a 3 ensemble climate model nudged with the ERA-Interim reanalysis and stretched to 25 km resolution for present (year 2005) land cover relative to realistic historic vegetation distribution. The most important results of this experiment are that the degree of change in vegetation structure determines whether extreme daytime temperatures will increase or decrease, particularly during the dry season. This is because a large change in surface roughness promotes increased wind speeds and heat advection, whereas a small change in surface roughness does not increase wind and can increase heat build-up in the atmosphere since the sensible heat flux also increases. We also put these results in a wider context of land surface - atmospheric feedbacks by looking at the corresponding change in aridity (precipitation / potential evapotranspiration). This shows the processes that drive the changes in temperature extremes also determine whether significant changes in aridity occur, since all the change in aridity can be prescribed to changes in potential evaporation, or atmospheric water demand. We propose a conceptual model of the mechanisms that explain these alterations which is an advance in understanding land-atmosphere interactions and provides evidence of the main mechanisms responsible of changes in the feedbacks because of changes in natural vegetation.

  1. Tackling the salinity-pollution nexus in coastal aquifers from arid regions using nitrate and boron isotopes.

    Science.gov (United States)

    Re, V; Sacchi, E

    2017-01-22

    Salinization and nitrate pollution are generally ascertained as the main issues affecting coastal aquifers worldwide. In arid zones, where agricultural activities also result in soil salinization, both phenomena tend to co-exist and synergically contribute to alter groundwater quality, with severe negative impacts on human populations and natural ecosystems' wellbeing. It becomes therefore necessary to understand if and to what extent integrated hydrogeochemical tools can help in distinguishing among possible different salinization and nitrate contamination origins, in order to provide adequate science-based support to local development and environmental protection. The alluvial plain of Bou-Areg (North Morocco) extends over about 190 km(2) and is separated from the Mediterranean Sea by the coastal Lagoon of Nador. Its surface is covered for more than 60% by agricultural activities, although the region has been recently concerned by urban population increase and tourism expansion. All these activities mainly rely on groundwater exploitation and at the same time are the main causes of both aquifer and lagoon water quality degradation. For this reason, it was chosen as a case study representative of the typical situation of coastal aquifers in arid zones worldwide, where a clear identification of salinization and pollution sources is fundamental for the implementation of locally oriented remedies and long-term management strategies. Results of a hydrogeochemical investigation performed between 2009 and 2011 show that the Bou-Areg aquifer presents high salinity (often exceeding 100 mg/L in TDS) due to both natural and anthropogenic processes. The area is also impacted by nitrate contamination, with concentrations generally exceeding the WHO statutory limits for drinking water (50 mg/L) and reaching up to about 300 mg/L, in both the rural and urban/peri-urban areas. The isotopic composition of dissolved nitrates (δ(15)NNO3 and δ(18)ONO) was used to constrain

  2. Seedling survival of Handroanthus impetiginosus (Mart ex DC Mattos in a semi-arid environment through modified germination speed and post-germination desiccation tolerance

    Directory of Open Access Journals (Sweden)

    J. R. Martins

    Full Text Available Abstract Uniform rapid seed germination generally forms a great risk for the plant population if subsequent intermittent precipitation causes desiccation and seedling death. Handroanthus impetiginosus can be found commonly in a wide range of biomes within Brazil including those that are semi-arid. Germination and early growth was studied to understand how germinated seeds survive under these stringent conditions. Accessions were sampled from four seasonally dry biomes in Brazil. Precipitation at the start of the rainy season in the Caatinga, a semi-arid biome, is less predictable and the number of successive dry days per dry interval in the first four months of the rainy season was higher than in the other studied biomes. Plants from the Caatinga produced thicker seeds and this trait concurred with slow germination and stronger osmotic inhibition of germination across the accessions, forming a stress avoidance mechanism in the Caatinga. Post-germination desiccation tolerance was high in the Caatinga accession, could be re-induced in accessions from biomes with more regular precipitation (Cerrado and transition zone, but remained poor in the Cerradão accession; thus forming a stress tolerance mechanism. Production of adventitious roots ascertained survival of all tested individuals from all four locations, even if protruded radicles did not survive desiccation, forming an additional stress tolerance mechanism. A sequence of stress avoidance and stress tolerance mechanisms in seeds and germinated seeds was associated with precipitation patterns in different biomes. These mechanisms purportedly allow rapid seedling establishment when conditions are suitable and enable survival of the young seedling when conditions are adverse.

  3. Modeling the distributed effects of forest thinning on the long-term water balance and streamflow extremes for a semi-arid basin in the southwestern US

    Science.gov (United States)

    Moreno, Hernan A.; Gupta, Hoshin V.; White, Dave D.; Sampson, David A.

    2016-03-01

    To achieve water resource sustainability in the water-limited southwestern US, it is critical to understand the potential effects of proposed forest thinning on the hydrology of semi-arid basins, where disturbances to headwater catchments can cause significant changes in the local water balance components and basinwise streamflows. In Arizona, the Four Forest Restoration Initiative (4FRI) is being developed with the goal of restoring 2.4 million acres of ponderosa pine along the Mogollon Rim. Using the physically based, spatially distributed triangulated irregular network (TIN)-based Real-time Integrated Basin Simulator (tRIBS) model, we examine the potential impacts of the 4FRI on the hydrology of Tonto Creek, a basin in the Verde-Tonto-Salt (VTS) system, which provides much of the water supply for the Phoenix metropolitan area. Long-term (20-year) simulations indicate that forest removal can trigger significant shifts in the spatiotemporal patterns of various hydrological components, causing increases in net radiation, surface temperature, wind speed, soil evaporation, groundwater recharge and runoff, at the expense of reductions in interception and shading, transpiration, vadose zone moisture and snow water equivalent, with south-facing slopes being more susceptible to enhanced atmospheric losses. The net effect will likely be increases in mean and maximum streamflow, particularly during El Niño events and the winter months, and chiefly for those scenarios in which soil hydraulic conductivity has been significantly reduced due to thinning operations. In this particular climate, forest thinning can lead to net loss of surface water storage by vegetation and snowpack, increasing the vulnerability of ecosystems and populations to larger and more frequent hydrologic extreme conditions on these semi-arid systems.

  4. Modeling the distributed effects of forest thinning on the long-term water balance and stream flow extremes for a semi-arid basin in the southwestern US

    Directory of Open Access Journals (Sweden)

    H. A. Moreno

    2015-10-01

    Full Text Available To achieve water resources sustainability in the water-limited Southwestern US, it is critical to understand the potential effects of proposed forest thinning on the hydrology of semi-arid basins, where disturbances to headwater catchments can cause significant changes in the local water balance components and basin-wise stream flows. In Arizona, the Four Forest Restoration Initiative (4FRI is being developed with the goal of restoring 2.4 million acres of ponderosa pine along the Mogollon Rim. Using the physically based, spatially distributed tRIBS model, we examine the potential impacts of the 4FRI on the hydrology of Tonto Creek, a basin in the Verde–Tonto–Salt (VTS system, which provides much of the water supply for the Phoenix Metropolitan Area. Long-term (20 year simulations indicate that forest removal can trigger significant shifts in the spatio-temporal patterns of various hydrological components, causing increases in net radiation, surface temperature, wind speed, soil evaporation, groundwater recharge, and runoff, at the expense of reductions in interception and shading, transpiration, vadose zone moisture and snow water equivalent, with south facing slopes being more susceptible to enhanced atmospheric losses. The net effect will likely be increases in mean and maximum stream flow, particularly during El Niño events and the winter months, and chiefly for those scenarios in which soil hydraulic conductivity has been significantly reduced due to thinning operations. In this particular climate, forest thinning can lead to net loss of surface water storage by vegetation and snow pack, increasing the vulnerability of ecosystems and populations to larger and more frequent hydrologic extreme conditions on these semi-arid systems.

  5. Relationships between physical and chemical factors and aquatic macroinvertebrates in perennial streams in the arid northern mountain basin El Batinah, Oman

    Directory of Open Access Journals (Sweden)

    S. Boulaaba

    2014-08-01

    Full Text Available The relationships between physical properties, water chemistry and aquatic macroinvertebrates were investigated in riffles of four perennial streams in the arid northern Oman. Samples were collected monthly in autumn, winter and spring with a Surber net. Thirty two invertebrate taxa were recorded, most species are widely distributed, but few species with very restricted distribution were also captured. Diptera followed by Pulmonata, Coleoptera and Odonata were the most represented taxa, Trichoptera and Heteroptera were a significant component only in one station (the Fezeh, where the lowest mean water temperature (23°C was recorded. In the dry months from May to October, aquatic macroinvertebrates were completely absent. In order to summarise the community response some biotic indices were calculated. The highest diversity was observed in the Fezeh station. A seasonal gradient was also observed, with the highest diversity values in January, April, and December. The low faunal diversity was attributed to the high air and water temperature and the hydrological regime instability. A between station and a between month coinertia analysis was carried out, to analyse the response to spatial and seasonal factors. The first coinertia axis was correlated with altitude and substrate composition, while the second axis was correlated with air and water temperature. The present research emphasizes the urgency for preserving the less disturbed wadis in arid zones, because, despite their species poorness, their uniqueness in faunal composition requires special attention. The presence of few endemic species with very restricted distribution highlights the topicality and the value in investigating these areas, allowing the increase of our knowledge on biodiversity, ecology and biogeography about the benthic macroinvertebrates living in these extreme habitats.

  6. miR-208-3p promotes hepatocellular carcinoma cell proliferation and invasion through regulating ARID2 expression

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Peng; Wu, Dingguo; You, Yu; Sun, Jing; Lu, Lele; Tan, Jiaxing; Bie, Ping, E-mail: bieping2010@163.com

    2015-08-15

    MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression at post-transcriptional level. miRNA dysregulation plays a causal role in cancer progression. In this study, miR-208-3p was highly expressed and directly repressed ARID2 expression. As a result, ARID2 expression in hepatocellular carcinoma (HCC) was decreased. In vitro, miR-208-3p down-regulation and ARID2 over-expression elicited similar inhibitory effects on HCC cell proliferation and invasion. In vivo test results revealed that miR-208-3p down-regulation inhibited HCC tumorigenesis in Hep3B cells. Moreover, ARID2 was possibly a downstream element of transforming growth factor beta1 (TGFβ1)/miR-208-3p/ARID2 regulatory pathway. These findings suggested that miR-208-3p up-regulation is associated with HCC cell progression and may provide a new target for liver cancer treatment. - Highlights: • miR-208-3p was highly expressed and directly repressed the expression of ARID2 in HCC. • miR-208-3p contributed to HCC cell progression both in vitro and in vivo. • Over-expression of ARID2 inhibited the HCC cell proliferation and invasion. • Restoration of ARID2 partly reversed the the effect of miR-208-3p down-regulation on HCC cells. • Newly regulatory pathway: miR-208-3p mediated the repression of ARID2 by TGFβ1 in HCC cells.

  7. 49 CFR 71.8 - Mountain zone.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Mountain zone. 71.8 Section 71.8 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE BOUNDARIES § 71.8 Mountain zone. The fourth zone, the mountain standard time zone, includes that part of the United States that is west of...

  8. Spectral mixture analysis (SMA and change vector analysis (CVA methods for monitoring and mapping land degradation/desertification in arid and semiarid areas (Sudan, using Landsat imagery

    Directory of Open Access Journals (Sweden)

    Abdelrahim A.M. Salih

    2017-04-01

    Full Text Available The severe Sahel catastrophe in 1968–1974 as well as repeated famines and food shortage that have hit many African countries during the 1970s have highlighted the need for further research concerning land degradation and environmental monitoring in arid and semi-arid areas. Land degradation, and desertification processes in arid and semi-arid environment were increased in the last four decades, especially in the developing countries like Sudan. To test to what extent remote sensing and geographical information science (GIS methodologies and techniques could be used for monitoring changes in arid and semi-arid regions and environment, these methodologies have long been suggested as a time and cost-efficient method. In this frame, spectral Mixture Analysis (SMA, Object-based oriented classification (Segmentation, and Change Vector Analysis are recently much recommended as a most suitable method for monitoring and mapping land cover changes in arid and semi-arid environment. Therefor the aim of this study is to use these methods and techniques for environmental monitoring with emphasis on desertification and to find model that can describe and map the status and rate of desertification processes and land cover changes in semi-arid areas in White Nile State (Sudan by using multi-temporal imagery of the Landsat satellite TM (1987, TM (2000, and ETM+ (2014 respectively. The paper also discusses and evaluates the efficiency of the adapted methodologies in monitoring the land degradation processes and changes in the arid and semi-arid regions.

  9. Comparative characteristics of anatomical and morphological adaptations of plants of two subgenera Haworthia Duval to arid environmental conditions

    Directory of Open Access Journals (Sweden)

    Nataliya Volodymyrivna Nuzhyna

    2015-03-01

    Full Text Available This paper presents the comparative anatomical and morphological characteristics of plants of two subgenera: Haworthia and Hexangularis. The study revealed two different strategies of adaptation to arid conditions of the growth of different subgenera of the genus Haworthia. Plants of the subgenus Haworthia adapted to arid conditions by increasing the accumulation of water, the presence of “windows”, a smaller stoma size, and a thinner outer wall of the epidermis cells. On the other hand, plants of the subgenus Hexangularis adapted to arid conditions by reducing overheating and transpiration as well as by the presence of papillae and a thickened outer wall of the epidermis cells.

  10. Formalized morphostructural zoning of the mountain zone of the Andes

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielov, A.M.; Gvishiani, A.D.; Zhidkov, M.P.

    1982-01-01

    A plan is presented for morphostructural zoning of the Andes compiled according to formalized signs for purposes of seismic forecasting. Characteristics are presented for the basic morphostructural subdivisions of the Andes.

  11. Decoupling of above and belowground C and N pools within predominant plant species Stipa grandis along a precipitation gradient in Chinese steppe zone

    Directory of Open Access Journals (Sweden)

    X. H. Ye

    2013-03-01

    Full Text Available The coupling of the carbon and nutrient cycles drives the food web structure and biogeochemistry of ecosystems. However, across precipitation gradients, there may be a shift in C and N pools from above- to belowground because of shifting plant stoichiometry and allocation. Here, we present a study which is the first to explicitly compare above- and belowground pool sizes of N and C within predominant plant species along precipitation gradient. We dissected these pools into biomass allocation and nutrient concentrations. Based on previous evidence, biomass allocation to roots should increase with aridity, while leaf [N] should increase. If their effect sizes are equal, they should cancel each other out, and the above- and belowground proportions of the N would remain constant. Along a precipitation gradient in Chinese steppe zone, the effect sizes of the biomass shifts were remarkably consistent among the predominant species, Stipa grandis. The effect sizes of biomass allocation and [N] were equal and the proportion of N of above- and belowground did not change with aridity, but the shift in leaf [C] with aridity was much weaker than the biomass shift, leading to a decrease in the proportion of C belowground at dry sites. Precipitation gradients do decouple the C and N pool of S. grandis along a precipitation gradient in Chinese steppe zone.

  12. Mapping Soil hydrologic features in a semi-arid irrigated area in Spain

    Science.gov (United States)

    Jiménez-Aguirre, M.° Teresa; Isidoro, Daniel; Usón, Asunción

    2016-04-01

    The lack of soil information is a managerial problem in irrigated areas in Spain. The Violada Irrigation District (VID; 5234 ha) is a gypsic, semi-arid region in the Middle Ebro River Basin, northeast Spain. VID is under irrigation since the 1940's. The implementation of the flood irrigation system gave rise to waterlogging problems, solved along the years with the installation of an artificial drainage network. Aggregated water balances have been performed in VID since the early 1980's considering average soil properties and aggregated irrigation data for the calculations (crop evapotranspiration, canal seepage, and soil drainage). In 2008-2009, 91% of the VID was modernized to sprinkler irrigation. This new system provides detailed irrigation management information that together with detailed soil information would allow for disaggregated water balances for a better understanding of the system. Our goal was to draw a semi-detailed soil map of VID presenting the main soil characteristics related to irrigation management. A second step of the work was to set up pedotransfer functions (PTF) to estimate the water content and saturated hydraulic conductivity (Ks) from easily measurable parameters. Thirty four pits were opened, described and sampled for chemical and physical properties. Thirty three additional auger holes were sampled for water holding capacity (WHC; down to 60 cm), helping to draw the soil units boundaries. And 15 Ks tests (inverse auger hole method) were made. The WHC was determined as the difference between the field capacity (FC) and wilting point (WP) measured in samples dried at 40°C during 5 days. The comparison with old values dried at 105°C for 2 days highlighted the importance of the method when gypsum is present in order to avoid water removal from gypsum molecules. The soil map was drawn down to family level. Thirteen soil units were defined by the combination of five subgroups [Typic Calcixerept (A), Petrocalcic Calcixerept (B), Gypsic

  13. Importance of Biological Loess Crusts for Loess Formation in Semi-Arid Environments

    Science.gov (United States)

    Svirčev, Z.; Marković, S. B.; Stevens, T.; Smalley, I. J.; Hambach, U.; Obreht, I.; Lukić, T.; Vasiljević, Dj. A.

    2012-04-01

    The essential components for loess deposition are: material, atmospheric circulation and appropriate surface conditions for the trapping of aeolian material as well as the subsequent development of typical loess sedimentary structures. In spite of the world-wide distribution of loess deposits, knowledge of the processes of transformation from accumulated dust to mature loess sediment is still inadequate. Some recent studies highlight the potential importance of biologically crusted surfaces (BCS) in loess formation. BCS are highly specialized extremophile communities and generally play an important role in atmospheric dust trapping and erosion prevention. Our initial results indicate that cyanobacterial strains isolated from loess exhibit some specific morphological and ecophysiological characteristics that play a key role in loess formation, warranting adoption of the new term biological loess crusts (BLC). We suggest that loessification is heavily influenced by the metabolic activity of BLC microorganisms mainly through polysaccharides. The sticky polysaccharide glue on the topographic surface, exuded mostly by cyanobacteria, can trap silty particles suspended in a dusty atmosphere. This collection of airborne loess forming particles is part of the life strategy of crust organisms in so far as they provide the necessary minerals for further growth of the BLC, which in turn provides protection from desiccation during dry periods. Simultaneously, polysaccharides secreted by crust organisms bind particles inside the BLC zone, forming a cohesive crust that resists both wind and water erosion during dry periods. Metabolized particles, exuded metabolites and unused airborne particles become the uppermost loess sediment covered with BLC. During moist periods, accumulation of dust and loess forming particles is very active. During the dry phases, the BLC becomes very stable and develops a resistant surface preventing wind and water erosion. The drying period induces

  14. Chaotic zones around gravitating binaries

    CERN Document Server

    Shevchenko, Ivan I

    2014-01-01

    The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound bodies (a double star, a double black hole, a binary asteroid, etc.) is estimated analytically, in function of the tertiary's orbital eccentricity. The separatrix map theory is used to demonstrate that the central continuous chaos zone emerges due to overlapping of the orbital resonances corresponding to the integer ratios p:1 between the tertiary and the binary periods. The binary's mass ratio, above which such a chaotic zone is universally present, is also estimated.

  15. Transfer of {sup 137}Cs in Zea mays and Phaseolus vulgaris in a semi-arid ecosystem; Transferencia de {sup 137}Cs en Zea mays y Phaseolus vulgaris en un ecosistema semiarido

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, M.L.; Segovia, N.; Gaso P, M.I.; Palacios, J.C. [Instituto Nacional de Investigaciones Nucleares, Laboratorio de Vigilancia Radiologica Ambiental, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    With the objective to analyse the transference of {sup 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 {sup 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 {sup 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)

  16. Facies-architecture of fossil arid siliciclastic depositional systems as outcrop analogue for Rotliegend reservoirs. Literature study; Faziesarchitektur fossiler arid-klastischer Ablagerungsraeume als Rotliegend-Reservoiranalog. Literaturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Irmen, A.

    1999-08-01

    In this project a literature-based study was carried out in order to document the facies-architecture of siliciclastic sediments from arid environments and to investigate their suitability as outcrop-analogues for the strata of the Southern Permian Basin. The report resulting from this investigation presents possible analogues and case-studies. Three Formations (Flechtingen Sandstone, Corrie Sandstone and Cedar Mesa Sandstone of the Cutler Group) are especially well suited to serve as outcrop analogue for the 'Rotliegend' Sediments of the Southern Permian Basin. Possible analogues are documented at various scales, ranging from bed-scale to formation scale. Also, special attention was paid to general trends and what factors control them. To make a comparison of Formations from different settings possible, criteria were elaborated to qualify the relevant controlling factors. The catalog itself is preceded by a comprehensive preface, that introduces to the subject and points out the connection between the primary sediment fabric and its petrophysical properties. (orig.) [German] Im Rahmen dieses DGMK Forschungsvorhabens wurde eine Literaturstudie durchgefuehrt, welche die Faziesarchitektur fossiler arid-klastischer Sedimente darstellt und auf ihre Eignung als Rotliegend-Reservoiranalog untersucht. Die vorliegende Dokumentation stellt verschiedene moegliche Analoge und Fallbeispiele dar, wobei drei Abfolgen als besonders geeignet erscheinen. Es wurden Kriterien erarbeitet, die relevante Kontrollfaktoren qualifizieren, um einen Vergleich verschiedener arid-klastischer Sedimentationsraeume zu ermoeglichen. Die Bandbreite der Darstellung moeglicher Analoge umfasst das gesamte Spektrum vom Gefuegemassstab bis hin zu genetischen Einheiten und beleuchtet die jeweiligen Steuerungsfaktoren der Ablagerung. Der eigentlichen Dokumentation wurde eine umfassende Einleitung vorangestellt, welche in die Thematik einfuehrt und Zusammenhaenge zwischen primaerem

  17. Vegetation Change and Soil Nutrient Distribution along an Oasis-Desert Transitional Zone in Northwestern China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Many studies have focused on soil nutrient heterogeneity and islands of fertility in arid ecosystems.However,few have been conducted on an oasis-desert transitional zone where there is a vegetation pattern changing from shrubs to annual herbs.The goal of the present study was to understand vegetation and soil nutrient heterogenity along an oasis-desert transitional zone in northwestern China.Three replicated sampling belts were selected at 200 m Intervals along the transitional zone.Twenty-one quadrats(10 × 10m) at 50 m intervals were located along each sampling belt.The vegetation cover was estimated through the quadrats,where both the soil under the canopy and the open soil were sampled simultaneously.The dominated shrub was Haloxylon ammodendron in the areas close to the oasis and Nitraria tangutorum dominated the areas close to the desert.In general,along the transitional zone the vegetation cover decreased within 660 m,increased above 660 m and decreased again above 1020 m(close to the desert).The soil nutrients(organic matter,total N,NO3- and NH4+)showed significant differences along the zone.The soil nutrients except the soil NH4+ under the canopy were higher than those in open soil,confirming "Islands of fertility" or nutrient enrichment.Only a slight downward trend of the level of "islands of fertility" for soil organic matter appeared in the area within 900 m.Soil organic matter both under canopy and in interspace showed a positive correlation with the total vegetation cover,however,there was no significant correlation between the other soil nutrients and the total vegetation cover.We also analyzed the relationship between the shrubs and annuals and the soil nutrients along the zone.Similarly,there was no significant correlation between them,except soil organic matter with the annuals.The results implied that annual plants played an important role in soil nutrient enrichment in arid ecosystem.

  18. Edge effect of the ecotone of wetland and arid grassland in a semi-arid region of China

    Institute of Scientific and Technical Information of China (English)

    Ruiping HOU; Rui LI; Kebin ZHANG; Yunfang LIU

    2008-01-01

    The edge effect of plant communities was investigated in a wetland-dry grassland ecosystem at the Siertan Wetland in Yanchi County, Ningxia Hui Autonomous Region, China. Four transects lines, with each about 1 km long, were established for a vegetation survey in July 2005, along biotope gradients in four direc-tions: east, northeast, west and northwest. The data was analyzed using TWINSPAN classification method. The vegetation in this wetland was classified into three vegeta-tion types: halophytic marsh vegetation, meadow vegeta-tion and grassland vegetation. Based on the calculation of the community structure indices, the edge effect was studied which revealed distinct differences among those three vegetation zones along each transect line. The eco-tone had high richness indices (R), a high diversity index (SW) and ecological dominance (SP). Evenness, as mea-sured by the index (E), was less apparent. From the four transect lines, it appears that the ecotone in the northeast-erly direction scored higher in each community structure indicator than any of the other directions and those towards the northwest were least. The variation in the edge effect between the different transect lines is caused by human disturbances and topographic uplift.

  19. Impact of hydrological alterations on river-groundwater exchange and water quality in a semi-arid area: Nueces River, Texas.

    Science.gov (United States)

    Murgulet, Dorina; Murgulet, Valeriu; Spalt, Nicholas; Douglas, Audrey; Hay, Richard G

    2016-12-01

    There is a lack of understanding and methods for assessing the effects of anthropogenic disruptions, (i.e. river fragmentation due to dam construction) on the extent and degree of groundwater-surface water interaction and geochemical processes affecting the quality of water in semi-arid, coastal catchments. This study applied a novel combination of electrical resistivity tomography (ERT) and elemental and isotope geochemistry in a coastal river disturbed by extended drought and periodic flooding due to the operation of multiple dams. Geochemical analyses show that the saltwater barrier causes an increase in salinity in surface water in the downstream river as a result of limited freshwater inflows, strong evaporation effects on shallow groundwater and mostly stagnant river water, and is not due to saltwater intrusion by tidal flooding. Discharge from bank storage is dominant (~84%) in the downstream fragment and its contribution could increase salinity levels within the hyporheic zone and surface water. When surface water levels go up due to upstream freshwater releases the river temporarily displaces high salinity water trapped in the hyporheic zone to the underlying aquifer. Geochemical modeling shows a higher contribution of distant and deeper groundwater (~40%) in the upstream river and lower discharge from bank storage (~13%) through the hyporheic zone. Recharge from bank storage is a source of high salt to both upstream and downstream portions of the river but its contribution is higher below the dam. Continuous ERT imaging of the river bed complements geochemistry findings and indicate that while lithologically similar, downstream of the dam, the shallow aquifer is affected by salinization while fresher water saturates the aquifer in the upstream fragment. The relative contribution of flows (i.e. surface water releases or groundwater discharge) as related to the river fragmentation control changes of streamwater chemistry and likely impact the interpretation

  20. Aridity induces super-optimal investment in leaf venation by Eucalyptus and Corymbia

    Science.gov (United States)

    Drake, Paul L.; de Boer, Hugo J.; Price, Charles A.; Veneklaas, Erik J.

    2016-04-01

    The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on carbon uptake, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Zwieniecki and Boyce (2014) proposed a generic framework on the hydraulic architecture of leaves based on the argument that water is optimally distributed when the lateral distance between neighboring water transport veins (dx) is approximately equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈1. Many derived angiosperms realize this optimal hydraulic architecture by closely coordinating leaf vein density with leaf thickness and the lateral position of veins inside the leaf. Zwieniecki and Boyce (2014) further suggested that over-investment in veins (dx:dy photosynthetic traits of 65 species (401 individuals) within the widely distributed and closely related genera Eucalyptus and Corymbia along a 2000-km-long aridity gradient in Western Australia (see Schulze et al., 2006). We inferred the potential functional benefit of reducing dx beyond dy using a semi-empirical model that links leaf morphology and hydraulics to photosynthesis. Our results reveal that Eucalyptus and Corymbia evolved extremely high vein densities in addition to thick amphistomatous leaf morphologies along the natural aridity gradient resulting in dx:dy ratios ranging between 0.8 and 0.08. We propose that as the thickness of amphistomatous leaves increases, the effect of reducing dx beyond dy is to offset the reduction in photosynthesis that would result from the theoretical optimal architecture of dx:dy ≈1. Our model quantified the resulting relative gain in photosynthesis at 10% to 15%, which could provide a crucial gas exchange advantage. We conclude that aridity

  1. Hydrologic feasibility of artificial forestation in the semi-arid Loess Plateau of China

    Directory of Open Access Journals (Sweden)

    T. T. Jin

    2011-08-01

    Full Text Available Hydrologic viability, in terms of moisture availability, is fundamental to ecosystem sustainability in arid and semi-arid regions. In this study, we examine the spatial distribution and after-planting variations of soil moisture content (SMC in black locust tree (Robinia pseudoacacia L. plantings in the Loess Plateau of China at a regional scale. Thirty sites (5 to 45 yr old were selected, spanning an area of 300 km by 190 km in the northern region of the Shaanxi Province. The SMC was measured to a depth of 100 cm at intervals of 10 cm. Geographical, topographic and vegetation information was recorded, and soil organic matter was evaluated. The results show that, at the regional scale, SMC spatial variability was most highly correlated with rainfall. The negative relationship between the SMC at a depth of 20–50 cm and the stand age was stronger than at other depths, although this relationship was not significant at a 5 % level. Watershed analysis shows that the after-planting SMC variation differed depending upon precipitation. The SMC of plantings in areas receiving sufficient precipitation (e.g., mean annual precipitation (MAP of 617 mm may increase with stand age due to improvements in soil water-holding capacity and water-retention abilities after planting. For areas experiencing water shortages (e.g., MAP = 509 mm, evapotranspiration may cause planting soils to dry within the first 20 yr of growth. It is expected that, as arid and semi-arid plantings age, evapotranspiration will decrease, and the soil profile may gradually recover. In extremely dry areas (e.g., MAP = 352 mm, the variation in after-planting SMC with stand age was found to be negligible. The MAP can be used as an index to divide the study area into different ecological regions. Afforestation may sequentially exert positive, negative and negligible effects on SMCs with a decrease in the MAP. Therefore, future restoration measures should correspond to the local climate

  2. Ecological adaptation of Reaumuria soongorica root system architecture to arid environments

    Institute of Scientific and Technical Information of China (English)

    LiShan Shan; Yi Li; DongMei Geng; QiuLian Dong

    2014-01-01

    The architectural parameters of Reaumuria soongorica root system in different habitats of Gansu Province, China were analyzed to examine its ecological adaptability to arid environments. Results show that:(1) Topological indices of R. Soongorica root sys-tem are small in all habitats, and root branching pattern tends to be dichotomous. Also, the indices gradually increase in the Min-qin windblown sand region and the Zhangye Gobi region in Hexi Corridor, which indicates that drought tends to produce her-ringbone-like root branching patterns. (2) Fractal dimension values of R. Soongorica root system are small and not obvious in the Minqin windblown sand region and the Zhangye Gobi region in Hexi Corridor, with values of 1.1778 and 1.1169, respectively. Fractal dimension values are relatively large in Jiuzhoutai semi-arid hilly and gully region of the Loess Plateau, which indicates that the R. Soongorica root system has better fractal characteristics in this region than in the other regions. (3) Total branching ra-tios of the R. Soongorica root system in arid regions of Hexi Corridor are smaller than that in the Jiuzhoutai semi-arid hilly and gully region of the Loess Plateau. This shows that root branching ability in the semi-arid region is stronger, and it decreases to some degree with increased drought. (4) The root connection lengths of R. soongorica root system are long in all habitats, but there are significant length differences between the different habitats. The root connection length at the Minqin windblown sand region is the longest. It is concluded that R. soongorica adapts to arid environments by decreasing root branching, decreasing root overlap and increasing root connection length, which makes its root branching pattern tend to be herringbone-like to reduce com-petition in root internal environment for nutrients and to enhance root absorption rate of nutrients, and ensure effective nutrition space. Thus the roots can absorb enough water and nutrients

  3. ShoreZone Survey Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is a point file showing GPS trackline data collected during a ShoreZone aerial imaging survey. This flight trackline is recorded at 1-second intervals...

  4. In situ vadose zone bioremediation.