Modeling the transport and fate of radioactive noble gases in very dry desert alluvium: Realistic scenarios

International Nuclear Information System (INIS)

Lindstrom, F.T.; Cawlfield, D.E.; Donahue, M.E.; Emer, D.F.; Shott, G.J.

1992-01-01

US DOE Order 5820.2A (1988) requires that a performance assessment of all new and existing low-level radioactive waste management sites be made. An integral part of every performance assessment is the mathematical modeling of the transport and fate of noble gas radionuclides in the gas phase. Current in depth site characterization of the high desert alluvium in Area 5 of the Nevada Test Site (NTS) is showing that the alluvium is very very dry all the way to the water table (240 meters below land surface). The potential for radioactive noble gas (e.g. Rn-220 and Rn-222) transport to the atmosphere from shallow land burial of Thorium and Uranium waste is very high. Objectives of this modeling effort include: Construct a physics based sits specific noble gas transport model; Include induced advection due to barometric pressure changes at the atmospheric boundary layer (thin) - dry desert alluvium interface; User selected option for use of NOAA barometric pressure or a ''home brewed'' barometric pressure wave made up of up to 15 sinusoids and cosinusoids; Use the model to help make engineering decisions on the design of the burial pits and associated closure caps

Simulation of fluid flow and energy transport processes associated with high-level radioactive waste disposal in unsaturated alluvium

Science.gov (United States)

Pollock, David W.

1986-01-01

Many parts of the Great Basin have thick zones of unsaturated alluvium which might be suitable for disposing of high-level radioactive wastes. A mathematical model accounting for the coupled transport of energy, water (vapor and liquid), and dry air was used to analyze one-dimensional, vertical transport above and below an areally extensive repository. Numerical simulations were conducted for a hypothetical repository containing spent nuclear fuel and located 100 m below land surface. Initial steady state downward water fluxes of zero (hydrostatic) and 0.0003 m yr−1were considered in an attempt to bracket the likely range in natural water flux. Predicted temperatures within the repository peaked after approximately 50 years and declined slowly thereafter in response to the decreasing intensity of the radioactive heat source. The alluvium near the repository experienced a cycle of drying and rewetting in both cases. The extent of the dry zone was strongly controlled by the mobility of liquid water near the repository under natural conditions. In the case of initial hydrostatic conditions, the dry zone extended approximately 10 m above and 15 m below the repository. For the case of a natural flux of 0.0003 m yr−1 the relative permeability of water near the repository was initially more than 30 times the value under hydrostatic conditions, consequently the dry zone extended only about 2 m above and 5 m below the repository. In both cases a significant perturbation in liquid saturation levels persisted for several hundred years. This analysis illustrates the extreme sensitivity of model predictions to initial conditions and parameters, such as relative permeability and moisture characteristic curves, that are often poorly known.

Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

Science.gov (United States)

de Boer, Hugo; Drake, Paul; Veneklaas, Erik

2017-04-01

The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on transpiration, 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. Critical is that leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈1. Although this theory is supported by observations on many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis we assembled leaf hydraulic, morphological and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent over-investment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf lifespan, high hydraulic and thermal capacitances, and high potential rates of leaf

ARID1B is a specific vulnerability in ARID1A-mutant cancers.

Science.gov (United States)

Helming, Katherine C; Wang, Xiaofeng; Wilson, Boris G; Vazquez, Francisca; Haswell, Jeffrey R; Manchester, Haley E; Kim, Youngha; Kryukov, Gregory V; Ghandi, Mahmoud; Aguirre, Andrew J; Jagani, Zainab; Wang, Zhong; Garraway, Levi A; Hahn, William C; Roberts, Charles W M

2014-03-01

Recent studies have revealed that ARID1A, encoding AT-rich interactive domain 1A (SWI-like), is frequently mutated across a variety of human cancers and also has bona fide tumor suppressor properties. Consequently, identification of vulnerabilities conferred by ARID1A mutation would have major relevance for human cancer. Here, using a broad screening approach, we identify ARID1B, an ARID1A homolog whose gene product is mutually exclusive with ARID1A in SWI/SNF complexes, as the number 1 gene preferentially required for the survival of ARID1A-mutant cancer cell lines. We show that loss of ARID1B in ARID1A-deficient backgrounds destabilizes SWI/SNF and impairs proliferation in both cancer cells and primary cells. We also find that ARID1A and ARID1B are frequently co-mutated in cancer but that ARID1A-deficient cancers retain at least one functional ARID1B allele. These results suggest that loss of ARID1A and ARID1B alleles cooperatively promotes cancer formation but also results in a unique functional dependence. The results further identify ARID1B as a potential therapeutic target for ARID1A-mutant cancers.

Characterization of hydraulic conductivity of the alluvium and basin fill, Pinal Creek Basin near Globe, Arizona

Science.gov (United States)

Angeroth, Cory E.

2002-01-01

Acidic waters containing elevated concentrations of dissolved metals have contaminated the regional aquifer in the Pinal Creek Basin, which is in Gila County, Arizona, about 100 kilometers east of Phoenix. The aquifer is made up of two geologic units: unconsolidated stream alluvium and consolidated basin fill. To better understand how contaminants are transported through these units, a better understanding of the distribution of hydraulic conductivity and processes that affect it within the aquifer is needed. Slug tests were done in September 1997 and October 1998 on 9 wells finished in the basin fill and 14 wells finished in the stream alluvium. Data from the tests were analyzed by using either the Bouwer and Rice (1976) method, or by using an extension to the method developed by Springer and Gellhar (1991). Both methods are applicable for unconfined aquifers and partially penetrating wells. The results of the analyses show wide variability within and between the two geologic units. Hydraulic conductivity estimates ranged from 0.5 to 250 meters per day for the basin fill and from 3 to 200 meters per day for the stream alluvium. Results of the slug tests also show a correlation coefficient of 0.83 between the hydraulic conductivity and the pH of the ground water. The areas of highest hydraulic conductivity coincide with the areas of lowest pH, and the areas of lowest hydraulic conductivity coincide with the areas of highest pH, suggesting that the acidic water is increasing the hydraulic conductivity of the aquifer by dissolution of carbonate minerals.

Role of Aeolian Dust in Shaping Landscapes and Soils of Arid and Semi-Arid South Africa

Directory of Open Access Journals (Sweden)

Joseph R. McAuliffe

2018-05-01

Full Text Available The deposition of fine aeolian sediment profoundly influences the morphology of several different landscapes of the arid and semi-arid western portion of South Africa. Such landscapes and features include: (1 regularly-spaced mounds known as heuweltjies of the succulent Karoo region, (2 barren stone pavements in the more arid regions, and (3 hillslopes with smooth, curvilinear slope profiles that are mantled with coarse, stony colluvium. Investigations of each of these are presented, together with comparisons of similar features found within arid and semi-arid portions of Western North America. Recent findings suggest that the formation of the distinct, regularly-spaced heuweltjies involves a linked set of biological and physical processes. These include nutrient accumulation by termites and the production of dense vegetation patches, which, in turn, serve as a trap for aeolian sediments. Dust deposition is also responsible for the formation of stone pavements as demonstrated by research conducted principally in the Mojave Desert region of the United States. Mineralogical and geochronological studies have demonstrated that the stone clasts remain on the surface as fine aeolian sediments are translocated downward beneath the clasts resulting in a silt-rich soil horizon directly beneath the clasts. Pavements examined in South Africa have the same morphological features that can only be explained by the same process. The formation of soils on hillslopes mantled with stony colluvium are commonly viewed as having formed through the in-situ weathering of the stony colluvium. However, like pavements, mantles of coarse, stony colluvium are effective dust traps that provide the long-term stability required for advanced development of thick, fine-grained soils. This process contributes to the evolution of smooth, vegetated, curvilinear slope profiles. In each of these examples, the accumulation of dust has a profound influence, not only in soil formation

Bacterial community in ancient permafrost alluvium at the Mammoth Mountain (Eastern Siberia).

Science.gov (United States)

Brouchkov, Anatoli; Kabilov, Marsel; Filippova, Svetlana; Baturina, Olga; Rogov, Victor; Galchenko, Valery; Mulyukin, Andrey; Fursova, Oksana; Pogorelko, Gennady

2017-12-15

Permanently frozen (approx. 3.5Ma) alluvial Neogene sediments exposed in the Aldan river valley at the Mammoth Mountain (Eastern Siberia) are unique, ancient, and poorly studied permafrost environments. So far, the structure of the indigenous bacterial community has remained unknown. Use of 16S metagenomic analysis with total DNA isolation using DNA Spin Kit for Soil (MO-Bio) and QIAamp DNA Stool Mini Kit (Qiagen) has revealed the major and minor bacterial lineages in the permafrost alluvium sediments. In sum, 61 Operational Taxonomic Units (OTUs) with 31,239 reads (Qiagen kit) and 15,404 reads (Mo-Bio kit) could be assigned to the known taxa. Only three phyla, Bacteroidetes, Proteobacteria and Firmicutes, comprised >5% of the OTUs abundance and accounted for 99% of the total reads. OTUs pertaining to the top families (Chitinophagaceae, Caulobacteraceae, Sphingomonadaceae, Bradyrhizobiaceae, Halomonadaceae) held >90% of reads. The abundance of Actinobacteria was less (0.7%), whereas members of other phyla (Deinococcus-Thermus, Cyanobacteria/Chloroplast, Fusobacteria, and Acidobacteria) constituted a minor fraction of reads. The bacterial community in the studied ancient alluvium differs from other permafrost sediments, mainly by predominance of Bacteroidetes (>52%). The diversity of this preserved bacterial community has the potential to cause effects unknown if prompted to thaw and spread with changing climate. Therefore, this study elicits further reason to study how reintroduction of these ancient bacteria could affect the surrounding ecosystem, including current bacterial species. Copyright © 2017 Elsevier B.V. All rights reserved.

Arid Zone Hydrology

Science.gov (United States)

Arid zone hydrology encompasses a wide range of topics and hydro-meteorological and ecological characteristics. Although arid and semi-arid watersheds perform the same functions as those in humid environments, their hydrology and sediment transport characteristics cannot be readily predicted by inf...

Rainwater harvesting in arid and semi-arid zones

NARCIS (Netherlands)

Boers, T.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

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats1[OPEN

Science.gov (United States)

de Boer, Hugo J.; Drake, Paul L.; Wendt, Erin; Price, Charles A.; Schulze, Ernst-Detlef; Turner, Neil C.; Nicolle, Dean

2016-01-01

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. PMID:27784769

Evidence of young, proximal and primary (YPP diamond source occurring in alluviums in the Santo Antônio do Bonito, Santo Inácio and Douradinho rivers in Coromandel region, Minas Gerais

Directory of Open Access Journals (Sweden)

Rogério Silvestre Pereira

Full Text Available ABSTRACT: Magmatism associated with the Alto Paranaíba structural high comprises kimberlites, kamafugites, and alkaline complexes, forming an approximately 400 x 150 km NW-SE belt in the southern São Francisco Craton. Dating of some intrusions reveals ages between 120 and 75 Ma. Chemical analyses of garnet recovered in alluvium from traditional diamond digging areas indicate peridotitic garnet windows in Três Ranchos and Coromandel. Six hundred and eighty (680 diamonds acquired or recovered during mineral exploration in the digging areas of Romaria, Estrela do Sul, Três Ranchos and Coromandel show unique characteristics, certain populations indicating young, proximal and primary sources (YPP. Analyses of 201 stones from Santo Antônio do Bonito, Santo Inácio and Douradinho rivers alluvium, Coromandel, present no evidence of transport, characterizing a proximal source. Within these river basins, exposures of the Late Cretaceous Capacete Formation basal conglomerate contain mainly small rounded and/or angular quartzite pebbles and of basic and ultrabasic rocks, as well as kimberlite minerals (garnet, ilmenite, spinel, sometimes diamond. A magnetotelluric profile between the Paraná and Sanfranciscana basins shows that the thick underlying lithosphere in the Coromandel region coincides with the peridotitic garnet window and with a diamond population displaying proximal source characteristics. Diamond-bearing kimberlite intrusions occur in different areas of Alto Paranaíba.

Is annual recharge coefficient a valid concept in arid and semi-arid regions?

Directory of Open Access Journals (Sweden)

Y. Cheng

2017-10-01

Full Text Available Deep soil recharge (DSR (at depth greater than 200 cm is an important part of water circulation in arid and semi-arid regions. Quantitative monitoring of DSR is of great importance to assess water resources and to study water balance in arid and semi-arid regions. This study used a typical bare land on the eastern margin of Mu Us Sandy Land in the Ordos Basin of China as an example to illustrate a new lysimeter method of measuring DSR to examine if the annual recharge coefficient is valid or not in the study site, where the annual recharge efficient is the ratio of annual DSR over annual total precipitation. Positioning monitoring was done on precipitation and DSR measurements underneath mobile sand dunes from 2013 to 2015 in the study area. Results showed that use of an annual recharge coefficient for estimating DSR in bare sand land in arid and semi-arid regions is questionable and could lead to considerable errors. It appeared that DSR in those regions was influenced by precipitation pattern and was closely correlated with spontaneous strong precipitation events (with precipitation greater than 10 mm other than the total precipitation. This study showed that as much as 42 % of precipitation in a single strong precipitation event can be transformed into DSR. During the observation period, the maximum annual DSR could make up 24.33 % of the annual precipitation. This study provided a reliable method of estimating DSR in sandy areas of arid and semi-arid regions, which is valuable for managing groundwater resources and ecological restoration in those regions. It also provided strong evidence that the annual recharge coefficient was invalid for calculating DSR in arid and semi-arid regions. This study shows that DSR is closely related to the strong precipitation events, rather than to the average annual precipitation, as well as the precipitation patterns.

Evaluating rainwater harvesting systems in arid and semi-arid regions

NARCIS (Netherlands)

Ammar, Adham Ali

2017-01-01

Rainwater harvesting (RWH) is an ancient traditional technology practised in many parts of the world, especially in arid and semi-arid regions (ASARs). ASARs represent 40% of the earth’s land surface and are characterised by low average annual rainfall and uneven temporal and spatial

Distribution of moisture, tritium, and plutonium in the alluvium, aquifer, and underlying tuff in Mortandad Canyon

International Nuclear Information System (INIS)

Purtymun, W.D.; Maes, M.N.; Peters, R.

1985-01-01

A study of the distribution of moisture, tritium, and plutonium in the Mortandad Canyon aquifer indicates some infiltration of water into the underlying tuff. This infiltration was accompanied by similar movement of tritium. The concentrations of plutonium on the sediments in the aquifer were low when compared with the high concentrations in solution in an ionic complex that does not readily exchange or is adsorbed by clay minerals in the alluvium. 2 references, 4 figures, 2 tables

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

International Nuclear Information System (INIS)

2001-03-01

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

A field- and laboratory-based quantitative analysis of alluvium: Relating analytical results to TIMS data

Science.gov (United States)

Wenrich, Melissa L.; Hamilton, Victoria E.; Christensen, Philip R.

1995-01-01

Thermal Infrared Multispectral Scanner (TIMS) data were acquired over the McDowell Mountains northeast of Scottsdale, Arizona during August 1994. The raw data were processed to emphasize lithologic differences using a decorrelation stretch and assigning bands 5, 3, and 1 to red, green, and blue, respectively. Processed data of alluvium flanking the mountains exhibit moderate color variation. The objective of this study was to determine, using a quantitative approach, what environmental variable(s), in the absence of bedrock, is/are responsible for influencing the spectral properties of the desert alluvial surface.

Development of hardy sorghum cultivars for the arid and semi arid ...

African Journals Online (AJOL)

Development of hardy sorghum cultivars for the arid and semi arid regions. MN Makobe, EM Kahangi, AK Misra, MO Imbuga. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

Radioactive waste isolation in arid zones

International Nuclear Information System (INIS)

Nativ, R.

1991-01-01

Arid zones are currently considered ideal sites for the isolation of radioactive and other hazardous wastes. Because arid zones have low precipitation, other hydrological features such as minimal surface water, low recharge rates, small hydraulic gradients, deep water table and lower water quality are also inferred. These premises have proved to be misleading in many circumstances, resulting in groundwater contamination by radionuclides. Case studies indicating surface water damages, occurrence of active recharge, groundwater flow and considerable discharge of potable water in arid and hyper-arid terrains, as well as the possibility of future climatic changes, require careful hydrological assessment of proposed sites in arid areas. (author)

Surface motion near underground nuclear explosions in desert alluvium Operation Nougat I, Area 3, Nevada Test Site

International Nuclear Information System (INIS)

Perret, W.R.

1978-05-01

During Operation Nougat I, which was conducted in late 1961 and the first half of 1962, Sandia Laboratories measured surface motion in the vicinity of all contained underground nuclear explosions conducted by the Los Alamos Scientific Laboratory in Area 3 of the Nevada Test Site. This report presents and analyses most of the data derived from that study. Propagation velocities in the desert alluvium, 4440 ft/sec, and underlying tuff, 6020 ft/sec, are typical of those derived from later measurements. Motion attenuation data exhibit considerable scatter, in part because of early measurement and data reduction techniques but primarily because of differences in the characteristics of the geologic media which had not then been recognized. However, regression fits to the scaled data show attenuation of scaled acceleration at a rate 35% greater than that observed for Merlin event data (Merlin was conducted later in Area 3). The attenuation rate for particle velocity data from Nougat I events was 47% less than that for Merlin data, and the Nougat I scaled displacement data attenuation rate was 87% less than that for Merlin data. Analysis of data from a vertical string of gages extending to the surface above the Mink explosion has established a significant difference between normal spallation above contained explosions in competent rock and the reaction of uncemented alluvium to similar explosive loading

Contaminant migration at two low-level radioactive waste sites in arid western United States - a review

International Nuclear Information System (INIS)

Wilshire, H.G.; Friedman, I.

1999-01-01

Contamination of the unsaturated zone and ground water at the Beatty, Nevada and Richland, Washington low-level radioactive waste sites shows that pathways exist for rapid lateral and vertical migration of contaminants through unconsolidated clastic sediments that comprise the 100 m-thick unsaturated zones of those arid disposal sites. Disposal of liquid wastes at the Beatty site until 1975 may have contributed to rapid migration of contaminants, but negligible amounts of liquid wastes reportedly were disposed at the Richland LLRW site and similar problems of contaminant migration exist. Pathways for vertical migration in the unsaturated zone include fractures and, at Richland, clastic dikes; lateral migration pathways likely are facies-controlled. Disturbance of the disposal sites contributed to increased infiltration of the unlined waste trenches after closure; simulations that used Beatty sample data show dramatic increases in recharge with disturbances necessary to develop the site. Because neither and arid climate nor presence of a thick unsaturated zone offer effective barriers to ground-water contamination, reliance on those factors at proposed sites such as Ward Valley, California and elsewhere is unwarranted. (orig.)

A threshold in soil formation at Earth’s arid hyperarid transition

Science.gov (United States)

Ewing, Stephanie A.; Sutter, Brad; Owen, Justine; Nishiizumi, Kunihiko; Sharp, Warren; Cliff, Steven S.; Perry, Kevin; Dietrich, William; McKay, Christopher P.; Amundson, Ronald

2006-11-01

The soils of the Atacama Desert in northern Chile have long been known to contain large quantities of unusual salts, yet the processes that form these soils are not yet fully understood. We examined the morphology and geochemistry of soils on post-Miocene fans and stream terraces along a south-to-north (27° to 24° S) rainfall transect that spans the arid to hyperarid transition (21 to ˜2 mm rain y -1). Landform ages are ⩾ 2 My based on cosmogenic radionuclide concentrations in surface boulders, and Ar isotopes in interbedded volcanic ash deposits near the driest site indicate a maximum age of 2.1 My. A chemical mass balance analysis that explicitly accounts for atmospheric additions was used to quantify net changes in mass and volume as a function of rainfall. In the arid (21 mm rain y -1) soil, total mass loss to weathering of silicate alluvium and dust (-1030 kg m -2) is offset by net addition of salts (+170 kg m -2). The most hyperarid soil has accumulated 830 kg m -2 of atmospheric salts (including 260 kg sulfate m -2 and 90 kg chloride m -2), resulting in unusually high volumetric expansion (120%) for a soil of this age. The composition of both airborne particles and atmospheric deposition in passive traps indicates that the geochemistry of the driest soil reflects accumulated atmospheric influxes coupled with limited in-soil chemical transformation and loss. Long-term rates of atmospheric solute addition were derived from the ion inventories in the driest soil, divided by the landform age, and compared to measured contemporary rates. With decreasing rainfall, the soil salt inventories increase, and the retained salts are both more soluble and present at shallower depths. All soils generally exhibit vertical variation in their chemistry, suggesting slow and stochastic downward water movement, and greater climate variability over the past 2 My than is reflected in recent (˜100 y) rainfall averages. The geochemistry of these soils shows that the transition

Use of the method of neutrons moderation to the adjustment of the concrete dosage through the total humidity of the arid s

International Nuclear Information System (INIS)

Howland, J.; Morejon, D.; Simeon, G.; Gracia, R.; Desdin, L.; O'Reilly, V.

1997-01-01

The method of neutrons moderation to the fast determination was applied of the content of humidity in the fine and thick arid s. The measure values of humidity were employed in the adjustment of the Dosification of concrete by the total humidity of the arid. The obtained results indicate that the employment of this fitting method allows to get higher values of resistance to the compression and also reduces the dispersions in the concretes production. This method would permit a considerable saving of cement in comparison with the traditional method. (author) [es

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 ...

Groundwater Modeling and Sustainability of a Transboundary Hardrock–Alluvium Aquifer in North Oman Mountains

Directory of Open Access Journals (Sweden)

Azizallah Izady

2017-02-01

Full Text Available This study aims at modeling groundwater flow using MODFLOW in a transboundary hardrock–alluvium aquifer, located in northwestern Oman. A three-dimensional stratigraphic model of the study area representing the vertical and spatial extent of four principal hydro-geologic units (specifically, the Hawasina, ophiolite, Tertiary and alluvium was generated using data collected from hundreds drilled borehole logs. Layer elevations and materials for four layers grid cells were taken from the generated stratigraphic model in which the materials and elevations were inherited from the stratigraphic model that encompasses the cell. This process led to accurate grid so that the developed groundwater conceptual model was mapped to simulate the groundwater flow and to estimate groundwater balance components and sustainable groundwater extraction for the October 1996 to September 2013 period. Results show that the long-term lateral groundwater flux ranging from 4.23 to 11.69 Mm3/year, with an average of 5.67 Mm3/year, drains from the fractured eastern ophiolite mountains into the alluvial zone. Moreover, the long-term regional groundwater sustainable groundwater extraction is 18.09 Mm3/year for 17 years, while it is, respectively, estimated as 14.51, 16.31, and 36.00 Mm3/year for dry, normal, and wet climate periods based on standardized precipitation index (SPI climate condition. Considering a total difference in groundwater levels between eastern and western points of the study area on the order of 228 m and a 12-year monthly calibration period (October 1996 to September 2008, a root mean squared error (RMSE in predicted groundwater elevation of 2.71 m is considered reasonable for the study area characterized by remarkable geological and hydrogeological diversity. A quantitative assessment of the groundwater balance components and particularly sustainable groundwater extraction for the different hydrological period would help decision makers to better

Attribute Analysis of Aridity Variability in North Xinjiang, China

Directory of Open Access Journals (Sweden)

Yanfeng Wu

2016-01-01

Full Text Available Identifying the dominant meteorological factors affecting aridity variability can improve our understanding of climate change and its future trend in arid and semiarid regions. This study investigated the spatiotemporal aridity variability in North Xinjiang, China, from 1961 to 2013, based on the UNESCO aridity index (precipitation/potential evapotranspiration, and analyzed its association with meteorological factors. The results suggest that North Xinjiang is becoming more humid with an increasing trend in aridity index. Precipitation, temperature, and relative humidity have positive correlation with aridity, and evapotranspiration, sunshine hours, and wind speed have negative correlation with aridity. Wind speed and sunshine hours have a higher sensitivity and more contribution to aridity. This study provides an understanding of the effect of recent climate change on drought in northwest China.

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

Arid and semiarid land stewardship: A 10-year review of accomplishments and contributions of the lnternational Arid Lands Consortium

Science.gov (United States)

Peter F. Ffolliott; Jeffrey O. Dawson; James T. Fisher; Itshack Moshe; Darrell W. DeBoers; Timothy. E. Fulbright; John Tracy; Abdullah Al Musa; Carter Johnson; Jim P. M. Chamie

2001-01-01

The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training activities related to the development, management, and restoration or reclamation of arid and semiarid lands worldwide. The IALC, a leading international organization, supports ecological sustainability and development of arid and semiarid lands. Building...

Future aridity under conditions of global climate change

Science.gov (United States)

Asadi Zarch, Mohammad Amin; Sivakumar, Bellie; Malekinezhad, Hossein; Sharma, Ashish

2017-11-01

Global climate change is anticipated to cause some major changes in hydroclimatic conditions around the world. As aridity is a reliable indicator of potential available water, assessment of its changes under future climatic conditions is important for proper management of water. This study employs the UNESCO aridity/humidity index, which is a derivative of precipitation (P) and potential evapotranspiration (PET), for assessment of aridity. Historical (1901-2005) simulations and future (2006-2100) projections of 22 global climate models (GCMs) from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) are studied. The Nested Bias Correction (NBC) approach is used to correct possible biases of precipitation (simulated directly by the GCMs) and PET (estimated by applying FAO56-Penman-Monteith model on simulated parameters of the GCMs). To detect future aridity changes, the areal extents of the aridity zones in the past and future periods as well as through four sub-periods (2006-2025, 2026-2050, 2051-2075, and 2076-2100) of the future are compared. The results indicate that changes in climate will alter the areal extents of aridity zones in the future. In general, from the first sub-period towards the last one, the area covered by hyper-arid, arid, semi-arid, and sub-humid zones will increase (by 7.46%, 7.01%, 5.80%, and 2.78%, respectively), while the area of the humid regions will decrease (by 4.76%), suggesting that there will be less water over the global land area in the future. To understand the cause of these changes, precipitation and PET are also separately assumed to be stationary throughout the four future sub-periods and the resulting aridity changes are then analyzed. The results reveal that the aridity changes are mostly caused by the positive PET trends, even though the slight precipitation increase lessens the magnitude of the changes.

Arid Green Infrastructure for Water Control and Conservation ...

Science.gov (United States)

Green infrastructure is an approach to managing wet weather flows using systems and practices that mimic natural processes. It is designed to manage stormwater as close to its source as possible and protect the quality of receiving waters. Although most green infrastructure practices were first developed in temperate climates, green infrastructure also can be a cost-effective approach to stormwater management and water conservation in arid and semi-arid regions, such as those found in the western and southwestern United States. Green infrastructure practices can be applied at the site, neighborhood and watershed scales. In addition to water management and conservation, implementing green infrastructure confers many social and economic benefits and can address issues of environmental justice. The U.S. Environmental Protection Agency (EPA) commissioned a literature review to identify the state-of-the science practices dealing with water control and conservation in arid and semi-arid regions, with emphasis on these regions in the United States. The search focused on stormwater control measures or practices that slow, capture, treat, infiltrate and/or store runoff at its source (i.e., green infrastructure). The material in Chapters 1 through 3 provides background to EPA’s current activities related to the application of green infrastructure practices in arid and semi-arid regions. An introduction to the topic of green infrastructure in arid and semi-arid regions i

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.

Use of environmental isotopes in arid zone hydrology

International Nuclear Information System (INIS)

Dincer, T.

1980-01-01

After aridity is defined some physical and hydrologic features common in arid lands are described. An attempt has been made to identify various groundwater recharge mechanisms in arid countries and to assess their relative importance. The influence of the arid climates on the isotopic composition of the precipitation is discussed. The use of environmental isotopes in run-off and precipitation infiltration and recharge is evaluated, and the importance of isotopic studies in investigating interrelations between aquifers is stressed. Finally, some examples of isotope applications in surface water and its relation to groundwater are given. (author)

Soil water movement in the unsaturated zone of an inland arid region: Mulched drip irrigation experiment

Science.gov (United States)

Han, Dongmei; Zhou, Tiantian

2018-04-01

Agricultural irrigation with trans-basin water diversion can effectively relieve the water paucity in arid and semi-arid regions, however, this may be accompanied by eco-environmental problems (e.g., saline soils, rising groundwater levels, water quality problems). The mechanism of soil water movement under irrigation in the unsaturated zone of arid regions is a key scientific problem that should be solved in order to evaluate agricultural water management and further improve current irrigation practices. This study investigated the impact of drip irrigation on soil water movement in the unsaturated zone of a cotton field in an inland arid region (the Karamay Agricultural Development Area), northwest China. Combining in situ observational physical data with temporal variation in stable isotopic compositions of soil water, we described the soil water flow system and mechanism in severe (Plot 1) and mild (Plot 2) saline-alkali cotton fields. The infiltration depths are 0-150 cm for both plots. Drip irrigation scheduling makes no significant contribution to local groundwater recharge, however, groundwater can move into the unsaturated zone through capillary rise during cotton flowering and boll periods. Plot 2 is less prone to having secondary soil salinization than Plot 1 due to the existence of a middle layer (approximately 100 cm thick), which elongated the distance between the root zone and aquifer. Rise in the water table (approximately 60 cm for Plot 1 and 50 cm for Plot 2) could be caused by lateral groundwater flow instead of vertical infiltration. We estimated the soil water storage changes in the unsaturated zone and proposed a conceptual model for deciphering the movement process of soil water. This study provides a scientific basis for determining the rise of groundwater levels and potential development of saline soils and improving agricultural water management in arid regions.

Influence of geochemical processes on hydrochemistry and irrigation suitability of groundwater in part of semi-arid Deccan Plateau, India

Science.gov (United States)

Vasu, Duraisamy; Singh, Surendra Kumar; Tiwary, Pramod; Sahu, Nisha; Ray, Sanjay Kumar; Butte, Pravin; Duraisami, Veppangadu Perumal

2017-11-01

Major ion geochemistry was used to characterise the chemical composition of groundwater in part of semi-arid Deccan plateau region to understand the geochemical evolution and to evaluate the groundwater quality for irrigation. The study area comprises peninsular gneissic complex of Archean age, younger granites and basaltic alluvium. Forty-nine georeferenced groundwater samples were collected and analysed for major ions. The ionic sequence based on relative proportions was Na+ > Mg2+ > Ca2+ > SO4 2- > HCO3 - > Cl- > CO3 2- > BO3 3- > K+. High Na+, Mg2+ and Ca2+ were generally associated with basaltic alluvial formation, whereas pH, electrical conductivity (EC) and total dissolved salts (TDS) were found to be higher in granitic formations. High standard deviation for EC, TDS, Na+, Ca2+ and Mg2+ indicated the dispersion of ionic concentration throughout the study area. Four major hydrochemical facies identified were Na-Mg-HCO3 type; Mg-Na-HCO3 type; Na-Mg-Ca-SO4 and Mg-Na-Ca-SO4 type. The graphical plots indicated that the groundwater chemistry was influenced by rock-water interaction, silicate weathering and reverse ion exchange. Sodium-dominated waters might have impeded the hydraulic properties of soils as a result of long-term irrigation.

Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments

Science.gov (United States)

Jackson, W. Andrew; Böhlke, J. K.; Andraski, Brian J.; Fahlquist, Lynne; Bexfield, Laura; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta; Betancourt, Julio; Stonestrom, David; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.

2015-09-01

Natural perchlorate (ClO4-) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4- compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4- in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4- to the more well-studied atmospherically deposited anions NO3- and Cl- as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4- is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10-1 to 106 μg/kg. Generally, the ClO4- concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3- and ClO4- co-occur at molar ratios (NO3-/ClO4-) that vary between ∼104 and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4- reduction, as indicated in part by NO3- isotope data. In contrast, much larger ranges of Cl-/ClO4- and Cl-/NO3- ratios indicate Cl- varies independently from both ClO4- and NO3-. The general lack of correlation between Cl- and ClO4- or NO3- implies that Cl- is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a NO3-/ClO4- molar ratio ∼103. The relative

Study on Applicability of Conceptual Hydrological Models for Flood Forecasting in Humid, Semi-Humid Semi-Arid and Arid Basins in China

Directory of Open Access Journals (Sweden)

Guangyuan Kan

2017-09-01

Full Text Available Flood simulation and forecasting in various types of watersheds is a hot issue in hydrology. Conceptual hydrological models have been widely applied to flood forecasting for decades. With the development of economy, modern China faces with severe flood disasters in all types of watersheds include humid, semi-humid semi-arid and arid watersheds. However, conceptual model-based flood forecasting in semi-humid semi-arid and arid regions is still challenging. To investigate the applicability of conceptual hydrological models for flood forecasting in the above mentioned regions, three typical conceptual models, include Xinanjiang (XAJ, mix runoff generation (MIX and northern Shannxi (NS, are applied to 3 humid, 3 semi-humid semi-arid, and 3 arid watersheds. The rainfall-runoff data of the 9 watersheds are analyzed based on statistical analysis and information theory, and the model performances are compared and analyzed based on boxplots and scatter plots. It is observed the complexity of drier watershed data is higher than that of the wetter watersheds. This indicates the flood forecasting is harder in drier watersheds. Simulation results indicate all models perform satisfactorily in humid watersheds and only NS model is applicable in arid watersheds. Model with consideration of saturation excess runoff generation (XAJ and MIX perform better than the infiltration excess-based NS model in semi-humid semi-arid watersheds. It is concluded more accurate mix runoff generation theory, more stable and efficient numerical solution of infiltration equation and rainfall data with higher spatial-temporal resolution are main obstacles for conceptual model-based flood simulation and forecasting.

Predicting the future impact of droughts on ungulate populations in arid and semi-arid environments.

Directory of Open Access Journals (Sweden)

Clare Duncan

Full Text Available Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21(st century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change.

Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments

Science.gov (United States)

Jackson, W Andrew; Böhlke, John Karl; Andraski, Brian J.; Fahlquist, Lynne S.; Bexfield, Laura M.; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil C.; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta J.; Betancourt, Julio L.; Stonestrom, David A.; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.

2015-01-01

Natural perchlorate (ClO4−) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4− compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4− in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4− to the more well-studied atmospherically deposited anions NO3−and Cl− as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4− is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10−1to 106 μg/kg. Generally, the ClO4− concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3− and ClO4− co-occur at molar ratios (NO3−/ClO4−) that vary between ∼104and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4− reduction, as indicated in part by NO3− isotope data. In contrast, much larger ranges of Cl−/ClO4− and Cl−/NO3−ratios indicate Cl− varies independently from both ClO4− and NO3−. The general lack of correlation between Cl− and ClO4− or NO3− implies that Cl− is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a

Qualitative-quantitative characteristic of bird community of middle course alluvium of the Vah River (Piestany - Nove Mesto); Kvalitativno-kvantitativna charakteristika ornitocenoz aluvia stredneho toku Vahu (Piestany - Nove Mesto nad Vahom)

Energy Technology Data Exchange (ETDEWEB)

Lacko, J. [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra ekologie, 84215 Bratislava (Slovakia); Topercer, J. [Botanicka zahrada Univerzity Komenskeho v Bratislave, pracovisko Blatnica, 03815 Blatnica pri Martine (Slovakia)

2013-04-16

The research focuses on the analysis of structure and dynamics of bird communities in two transects on the Vah river alluvium between cities Piestany and Nove Mesto nad Vahom. The research is aimed on the analysis of species composition, distribution and multitude of aquatic and wetland birds, on the analysis of their seasonal dynamics, inter-annual variability in species composition, diversity and others indicators of birds in these transects. The secondary aim is to find out the main types of disturbances, their intensity, antropogenous effects and others chosen environment variables in these transects of Vah river alluvium. We will utilize statistical analyses from these environmental variables and explain their impact on bird communities of this area. From these findings suitable management measures for the conservation or improvement of conservation status of target species will be derived. (authors)

Aridity and grazing as convergent selective forces: an experiment with an Arid Chaco bunchgrass.

Science.gov (United States)

Quiroga, R Emiliano; Golluscio, Rodolfo A; Blanco, Lisandro J; Fernández, Roberto J

2010-10-01

It has been proposed that aridity and grazing are convergent selective forces: each one selects for traits conferring resistance to both. However, this conceptual model has not yet been experimentally validated. The aim of this work was to experimentally evaluate the effect of aridity and grazing, as selective forces, on drought and grazing resistance of populations of Trichloris crinita, a native perennial forage grass of the Argentinean Arid Chaco region. We collected seeds in sites with four different combinations of aridity and grazing history (semiarid/ subhumid x heavily grazed/lightly grazed), established them in pots in a common garden, and subjected the resulting plants to different combinations of drought and defoliation. Our results agreed with the convergence model. Aridity has selected T. crinita genotypes that respond better to drought and defoliation in terms of sexual reproduction and leaf growth, and that can evade grazing due to a lower shoot: root ratio and a higher resource allocation to reserves (starch) in stem bases. Similarly, grazing has selected genotypes that respond better to drought and defoliation in terms of sexual reproduction and that can evade grazing due to a lower digestibility of leaf blades. These results allow us to extend concepts of previous models in plant adaptation to herbivory to models on plant adaptation to drought. The only variable in which we obtained a result opposite to predictions was plant height, as plants from semiarid sites were taller (and with more erect tillers) than plants from subhumid sites; we hypothesize that this result might have been a consequence of the selection exerted by the high solar radiation and soil temperatures of semiarid sites. In addition, our work allows for the prediction of the effects of dry or wet growing seasons on the performance of T. crinita plants. Our results suggest that we can rely on dry environments for selecting grazing-resistant genotypes and on high grazing pressure

VOC-Arid Integrated Demonstration guide to preparation of demonstration documents

International Nuclear Information System (INIS)

Jensen, E.J.; Brouns, T.M.; Koegler, K.J.; McCabe, G.H.; Morris, F.A.

1994-06-01

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

A Tool for the Evaluation of Irrigation Water Quality in the Arid and Semi-Arid Regions

Directory of Open Access Journals (Sweden)

Lucia Bortolini

2018-02-01

Full Text Available In the Mediterranean arid and semi-arid regions, large amounts of low quality waters could be used for crop irrigation, but the adoption of articulated classifications with too rigid quality limits can often reduce the recoverable quantities of water and make the monitoring of water quality too much expensive. Therefore, an evaluation of irrigation water quality based on only a few crucial parameters, which consider the crop species to be irrigated and the type of irrigation system and management adopted, can be an easy and flexible method for maximizing the reuse of wastewater and low-quality water for agricultural purposes. In this view, an irrigation water quality tool (IWQT was developed to support farmers of arid and semi-arid regions on evaluating the use of low quality water for crop irrigation. The most significant and cheapest parameters of irrigation water quality were identified and clustered in three quality classes according to their effects on crop yield and soil fertility (agronomic quality indicators, human health (hygiene and health quality indicators, and irrigation systems (management quality indicators. According to IWQT parameters, a tool reporting a series of recommendations, including water treatment types, was implemented to guide farmers on the use of low quality irrigation water.

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.

The ARID1B phenotype: what we have learned so far.

Science.gov (United States)

Santen, Gijs W E; Clayton-Smith, Jill

2014-09-01

Evidence is now accumulating from a number of sequencing studies that ARID1B not only appears to be one of the most frequently mutated intellectual disability (ID) genes, but that the range of phenotypes caused by ARID1B mutations seems to be extremely wide. Thus, it is one of the most interesting ID genes identified so far in the exome sequencing era. In this article, we review the literature surrounding ARID1B and attempt to delineate the ARID1B phenotype. The vast majority of published ARID1B patients have been ascertained through studies of Coffin-Siris syndrome (CSS), which leads to bias when documenting the frequencies of phenotypic features. Additional observations of those individuals ascertained through exome sequencing studies helps in delineation of the broader clinical phenotype. We are currently establishing an ARID1B consortium, aimed at collecting ARID1B patients identified through genome-wide sequencing strategies. We hope that this endeavor will eventually lead to a more comprehensive view of the ARID1B phenotype. © 2014 Wiley Periodicals, Inc.

Determinants of tree water use across a floodplain in arid, subtropical northwest Australia

Science.gov (United States)

Grierson, Pauline; McLean, Elizabeth; Iles, Jordan; Skrzypek, Grzegorz; Brand, Melinda; O'Donnell, Alison; Siebers, Andre; Dogramaci, Shawan

2017-04-01

Riparian zones of ephemeral streams in hot arid regions are subject to unpredictable and generally short-lived flood periods. However, droughts tend to be longer and more severe than floods in their ecological impact as low water availability in surficial alluvium and on the floodplain results in hydrological stress. Resolving how riparian and floodplain vegetation respond to highly variable flow regimes remains a fundamental challenge for estimating water budgets in arid regions, particularly where water tables are subject to groundwater abstraction. Here, we investigated patterns of water use by a range of tree species (Eucalyptus camaldulensis, E. victrix, Acacia citrinoviridis, A. coriacea, Hakea lorea, Atalaya hemiglauca) across a floodplain in the Pilbara region of northwest Australia and assessed vegetation responsiveness to both temporal and spatial variation in water supply. We sought to disentangle the varying contributions of soil water, groundwater and surface water to tree water use to determine the ecological implications of changes in hydrologic connectivity resulting from both seasonal water deficits and anthropogenic management. Diurnal and seasonal dynamics of water use were assessed using sapflux measurements coupled with observations of changing source availability. Source utilization was examined using water stable isotope compositions of xylem, soil, rain, surface water and groundwater. Depending on distance from the stream channel and time since last rainfall, we found that small trees were primarily accessing shallow soil water of meteoric origin while larger eucalypts accessed water deeper in the profile (either stored soil water or groundwater), especially as surface soils dried out. However, tree species were highly variable in their diurnal patterns of water use,including some evidence of nocturnal sapflux in A. coriacea adjacent to streams. Sapflux rates also varied almost four-fold among species but generally declined with increasing

Interaction between aeschynomene spp and rhizobiaceae strains from soils degraded by alluvium mining process

International Nuclear Information System (INIS)

Orozco, F H; Medina M; Restrepo, L R; Cuartas, A M

2001-01-01

The interaction between isolated bacterial from indigenous legumes of degraded soils by alluvium mining process and different species of aeschynomene was evaluated under nursery conditions. An essay was made in material from mining zone and the experimental design was random blocks with 21 treatment and four repetitions. The results were measured by dry weight of biomass and nodules, foliar nitrogen contains and percentage of occupation in the nodules by strains evaluated. In general terms, evaluated plants showed high specificity by the treatments. Specie of A. Americana was the best, because of its precocity and high production of biomass and nitrogen. Both types of A. falcata responded well to an isolated of rhizobium, while A. americana and A. villosa were better with strains of bradyrhizobium. Nitrogen concentration in all species of aeschynomene was very different. A. villosa presented higher concentration (28-34 9 kg - 1). We found a significant correlation for dry weight between nodules and biomass (r 0.82-0.93 P<0.001). We also found important difference among size of nodules of the species evaluated; it was independent of inoculated strain

Shallow Horizontal GCHP Effectiveness in Arid Climate Soils

Science.gov (United States)

North, Timothy James

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

Application of Isotope techniques in the arid and semi-arid zone hydrology

International Nuclear Information System (INIS)

Gonfiantini, R.; Louvat, D.; Aranyossy, J.F.

1993-01-01

The paper presents a brief introduction on the scientific background of isotope hydrology,and after, explains the applications of environment isotope techniques in groundwater hydrology of the arid and semi-arid zones. It includes the study of aquifer recharge and discharge, identification of palaeorecharge, groundwater movement and age in unconfined and confined aquifers, and interconnections between aquifers. The contribution of isotopes is highlighted with many examples of field case studies, with emphasis on studies carried out with IAEA support. Finally, a short description of IAEA program on isotope hydrology is given, with a list of regional projects supported through the IAEA Technical Cooperation program, and of Coordinated Research Programs. The latter give the modern research trends in isotope application to hydrology and hydrosphere environmental studies. (author). 2 tabs., 25 figs., 69 refs

Evaluation of dissolved oxygen and organic substances concentrations in water of the nature reserve Alluvium Zitavy

International Nuclear Information System (INIS)

Palaticka, A.; Noskovic, J.; Babosova, M.

2007-01-01

In 2006 concentrations of dissolved oxygen and organic substances were evaluated in water in the Nature Reserve Alluvium Zitavy (indirect method based on their oxidation by K 2 Cr 2 0 7 was used). The results are represented in mg of O 2 · dm -3 . Taking of samples took place in 6 sampling sites in regular month intervals. Based on obtained data and according to the standard STN 75 7221 (Water quality -The classification of the water surface quality) water in individual sampling sites was ranked into the classes of the .water surface quality. From the data it is clear that the concentrations of dissolved oxygen and organic substances in the Nature Reserve Alluvium Zitavy changed in dependence on sampling sites and time. The highest mean concentrations of dissolved oxygen in dependence on sampling time were found out in spring months and the lowest concentrations in summer months. They ranged from 1.6 mg 0 2 · dm -3 (July) to 9.0 mg O 2 · dm -3 (March). Falling dissolved oxygen values can be related to successive increase of water temperature, thus good conditions were created for decomposition of organic matter by microorganisms in water and sediments in which they use dissolved oxygen. In dependence on sampling place the highest mean concentration of dissolved oxygen was in sampling site No. 4 (6.0 mg 0 2 · dm -3 ) which is situated in the narrowest place in the NR. The lowest value was in sampling site No. 2 (3.6 mg 0 2 · dm -3 ) which is a typical wetland ecosystem. High mean values of COD Cr in dependence on sampling time were determined in summer months and low values during winter moths. Dependence of COD Cr values on sampling site was also manifested. The lowest mean value was obtained in sampling site No. 4 (59.5 mg · dm -3 ) and the highest value in sampling site No. 5 (97.1 mg · dm -3 ) which is also a typical wetland. Based on the results and according to the STN 75 7221 we ranked water in all sampling sites into the 5 th class of the water

ARID1B alterations identify aggressive tumors in neuroblastoma.

Science.gov (United States)

Lee, Soo Hyun; Kim, Jung-Sun; Zheng, Siyuan; Huse, Jason T; Bae, Joon Seol; Lee, Ji Won; Yoo, Keon Hee; Koo, Hong Hoe; Kyung, Sungkyu; Park, Woong-Yang; Sung, Ki W

2017-07-11

Targeted panel sequencing was performed to determine molecular targets and biomarkers in 72 children with neuroblastoma. Frequent genetic alterations were detected in ALK (16.7%), BRCA1 (13.9%), ATM (12.5%), and PTCH1 (11.1%) in an 83-gene panel. Molecular targets for targeted therapy were identified in 16 of 72 patients (22.2%). Two-thirds of ALK mutations were known to increase sensitivity to ALK inhibitors. Sequence alterations in ARID1B were identified in 5 of 72 patients (6.9%). Four of five ARID1B alterations were detected in tumors of high-risk patients. Two of five patients with ARID1B alterations died of disease progression. Relapse-free survival was lower in patients with ARID1B alterations than in those without (p = 0.01). In analysis confined to high-risk patients, 3-year overall survival was lower in patients with an ARID1B alteration (33.3 ± 27.2%) or MYCN amplification (30.0 ± 23.9%) than in those with neither ARID1B alteration nor MYCN amplification (90.5 ± 6.4%, p = 0.05). These results provide possibilities for targeted therapy and a new biomarker identifying a subgroup of neuroblastoma patients with poor prognosis.

Gardens on the Arid Climate

Science.gov (United States)

Eka Saputra, Weldy

2017-12-01

Bahrain is located in the climate of the arid zone which rainfall is low and irregular. This paper discusses the approaches which response to the local context that has been implemented by the government of Bahrain to sustain the quality of the public garden in the arid climate, turning to green. Generally, the approach is an improvement in the central treatment of waste water system plant that used to irrigate the landscaping, agriculture as well as for industry use. These approaches are not the only technologically, but also involves the participation of community to achieve sustainable garden in this country.

Hazard Analysis of Arid and Semi-Arid (ASAL) Regions of Kenya ...

African Journals Online (AJOL)

Objectives: The overall objective of this study was to prioritize hazards in the ASAL region. ... Health, local Government, and Provincial Administration, Environment and NGO. ... and country level to inform interventions and other developmental activities. Women ... Keywords: hazard, natural disaster, disaster risk, arid, Kenya ...

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.

Genotype-phenotype correlation of Coffin-Siris syndrome caused by mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A.

Science.gov (United States)

Kosho, Tomoki; Okamoto, Nobuhiko

2014-09-01

Coffin-Siris syndrome (CSS) is a rare congenital malformation syndrome, recently found to be caused by mutations in several genes encoding components of the BAF complex. To date, 109 patients have been reported with their mutations: SMARCB1 (12%), SMARCA4 (11%), SMARCE1 (2%), ARID1A (7%), ARID1B (65%), and PHF6 (2%). We review genotype-phenotype correlation of all previously reported patients with mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A through reassessment of their clinical and molecular findings. Cardinal features of CSS included variable degrees of intellectual disability (ID) predominantly affecting speech, sucking/feeding difficulty, and craniofacial (thick eyebrows, long eyelashes), digital (hypoplastic 5th fingers or toes, hypoplastic 5th fingernails or toenails), and other characteristics (hypertrichosis). In addition, patients with SMARCB1 mutations had severe neurodevelopmental deficits including severe ID, seizures, CNS structural abnormalities, and no expressive words as well as scoliosis. Especially, those with a recurrent mutation "p.Lys364del" represented strikingly similar phenotypes including characteristic facial coarseness. Patients with SMARCA4 mutations had less coarse craniofacial appearances and behavioral abnormalities. Patients with SMARCE1 mutations had a wide spectrum of manifestations from severe to moderate ID. Patients with ARID1A also had a wide spectrum of manifestations from severe ID and serous internal complications that could result in early death to mild ID. Mutations in SMARCB1, SMARCA4, and SMARCE1 are expected to exert dominant-negative or gain-of-function effects, whereas those in ARID1A are expected to exert loss-of-function effects. © 2014 Wiley Periodicals, Inc.

Herbivore-plant interactions and desertification in arid lands

Science.gov (United States)

Arid lands around the world have experienced or are currently experiencing degradation that is known as desertification. Animal-plant interactions that have an effect on desertification are among the most important function of animals in arid ecosystems. Desertification has been defined as land de...

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)

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

Science.gov (United States)

Sim, Joe C H; White, Susan M; Fitzpatrick, Elizabeth; Wilson, Gabrielle R; Gillies, Greta; Pope, Kate; Mountford, Hayley S; Torring, Pernille M; McKee, Shane; Vulto-van Silfhout, Anneke T; Jhangiani, Shalini N; Muzny, Donna M; Leventer, Richard J; Delatycki, Martin B; Amor, David J; Lockhart, Paul J

2014-03-27

Mutations in genes encoding components of the Brahma-associated factor (BAF) chromatin remodeling complex have recently been shown to contribute to multiple syndromes characterised by developmental delay and intellectual disability. ARID1B mutations have been identified as the predominant cause of Coffin-Siris syndrome and have also been shown to be a frequent cause of nonsyndromic intellectual disability. Here, we investigate the molecular basis of a patient with an overlapping but distinctive phenotype of intellectual disability, plantar fat pads and facial dysmorphism. High density microarray analysis of the patient demonstrated a heterozygous deletion at 6q25.3, which resulted in the loss of four genes including AT Rich Interactive Domain 1B (ARID1B). Subsequent quantitative real-time PCR analysis revealed ARID1B haploinsufficiency in the patient. Analysis of both patient-derived and ARID1B knockdown fibroblasts after serum starvation demonstrated delayed cell cycle re-entry associated with reduced cell number in the S1 phase. Based on the patient's distinctive phenotype, we ascertained four additional patients and identified heterozygous de novo ARID1B frameshift or nonsense mutations in all of them. 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 evidence in patient-derived cells that alterations in cell cycle contribute to the underlying pathogenesis of syndromes associated with ARID1B haploinsufficiency.

Water conservation for semi-arid rangelands

International Nuclear Information System (INIS)

Willis, W.O.

1983-01-01

Water deficiency is most often the cause for low forage production on rangelands in semi-arid and arid regions. Water conservation methods have been developed but additional research is needed to develop the best management practices for various climatic regions. Poor management is another major cause of low rangeland production. Better management, including the application of research findings, depends on attitudes, policies, adaptability of findings, resources for implementation and a good understanding of the governing biotic and abiotic factors. (author)

Spatial variability in alluvium properties at a low-level nuclear waste site

International Nuclear Information System (INIS)

Istok, J.D.; Blout, D.O.; Barker, L.; Johnejack, K.R.; Hammermeister, D.P.

1994-01-01

Geological and statistical models for the spatial variability of soil properties are needed to predict field-scale water flow and solute transport but only limited information is currently available on unsaturated soils below the root zone. Spatial variability of selected physical and hydrologic properties was quantified for fine- and coarse-grained alluvial deposits at a low-level nuclear waste disposal site on the Nevada Test Site. Gravimetric water content (w), bulk density (ρ b ), saturated hydraulic conductivity (K a ), and particle-size distribution were determined for vertical and horizontal core specimens and bulk samples collected from 183-m-long horizontal transects in two existing waste disposal trenches located on a single alluvial fan. The transects were approximately aligned parallel and perpendicular to the principal direction of sediment transport. Properties were modeled as either normally or lognormally distributed random variables. Sample coefficients of variation were smallest for ρ b and largest for log(K a ); a weak correlation was identified between log(K a ) and the grain-size parameter d 10 . Particle-size distributions for the fine- and coarse-grained materials were different and significant differences in the natural logarithm of saturated hydraulic conductivity, log(K a ), existed between coarse and fine layers in an excavation aligned with the principal direction of alluvium deposition but not in a perpendicular direction. 37 refs., 7 figs., 11 tabs

Pathways to Resilience in Semi-Arid Economies (PRISE)

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

rlarbey

PRISE Goal. This research will support the emergence of equitable, climate resilient economic development in semi-arid lands through research excellence and ... change in semi-arid areas, and how is the private sector adapting? 4. How do ... Role. Individual. Contact email. Lead Principal Investigator. Dr Tom Mitchell.

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

International Nuclear Information System (INIS)

1998-07-01

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

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.

Analysis of Water Use and Water Scarcity in Arid and Semi-arid Regions

Science.gov (United States)

Samayoa, S. D.

2017-12-01

Analysis of Water Use and Water Scarcity in Arid and Semi-arid Regions Susana Samayoa , Muhammed A. G. Chowdhury, Tushar Sinha Department of Environmental Engineering, Texas A & M University - Kingsville Freshwater sustainability in arid and semi-arid regions is highly uncertain under increasing demands due to population growth and urban development as well as limited water supply. In particular, six largest cities by population among the top twenty U.S. cities are located in Texas (TX), which also experience high variability in water availability due to frequent droughts and floods. Similarly, several regions in Arizona (AZ) are rapidly growing (e.g. Phoenix and Tucson) despite receiving scanty rainfall. Thus, the goal of this study is to analyze water use and water scarcity in watersheds within TX and AZ between 1985 and 2010. The water use data from U.S. Geological Survey (USGS) is analyzed by Hydrological Unit Code (HUC) - 8 within TX and AZ. Total freshwater use by county during 1985 and 2010 were converted into water use by HUC-8 using geospatial analysis. Water availability will be estimated by using a large scale Variable Infiltration Capacity (VIC) hydrologic model. The VIC model will be calibrated and validated for multiple basins located in Texas and Arizona. The VIC model simulated total streamflow will be aggregated across the 1/8 degree grids that are within each HUC-8 to estimate water supply. The excess water for upstream HUC-8s (= local supply minus demands) will be routed, in addition to locally generated streamflow, to estimate water availability in downstream HUC-8s. Water Scarcity Index, defined as the ratio of total freshwater demand to supply, will be estimated during 1985 and 2010 to evaluate the effects of water availability and demands on scarcity. Finally, water scarcity and use will be analyzed by HUC-8s within TX and AZ. Such information could be useful in water resources management and planning. Keywords: Water scarcity, water use

Accumulation of iron and arsenic in the Chandina alluvium of the lower delta plain, Southeastern Bangladesh

Science.gov (United States)

Zahid, A.; Hassan, M.Q.; Breit, G.N.; Balke, K.-D.; Flegr, M.

2009-01-01

Accumulations of iron, manganese, and arsenic occur in the Chandina alluvium of southeastern Bangladesh within 2.5 m of the ground surface. These distinctive orange-brown horizons are subhorizontal and consistently occur within 1 m of the contact of the aerated (yellow-brown) and water-saturated (gray) sediment. Ferric oxyhydroxide precipitates that define the horizons form by oxidation of reduced iron in pore waters near the top of the saturated zone when exposed to air in the unsaturated sediment. Hydrous Fe-oxide has a high specific surface area and thus a high adsorption capacity that absorbs the bulk of arsenic also present in the reduced pore water, resulting in accumulations containing as much as 280 ppm arsenic. The steep redox gradient that characterizes the transition of saturated and unsaturated sediment also favors accumulation of manganese oxides in the oxidized sediment. Anomalous concentrations of phosphate and molybdenum also detected in the ferric oxyhydroxide-enriched sediment are attributed to sorption processes. ?? Springer Science+Business Media B.V. 2008.

Aridity changes in the Tibetan Plateau in a warming climate

International Nuclear Information System (INIS)

Gao, Yanhong; Li, Xia; Xu, Jianwei; Ruby Leung, L.; Chen, Deliang

2015-01-01

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

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

Changes in precipitation recycling over arid regions in the Northern Hemisphere

Science.gov (United States)

Li, Ruolin; Wang, Chenghai; Wu, Di

2018-01-01

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.

Field evaluation of support practice (P-factor) for stone walls to control soil erosion in an arid area (Northern Jordan)

Science.gov (United States)

Gharaibeh, Mamoun; Albalasmeh, Ammar

2017-04-01

Stone walls have been adopted for long time to control water erosion in many Mediterranean countries. In soil erosion equations, the support practice factor (P-factor) for stone walls has not been fully studied or rarely taken into account especially in semi-arid and arid regions. Field studies were conducted to evaluate the efficiency of traditional stone walls and to quantify soil erosion in six sites in north and northeastern Jordan. Initial estimates using the Universal Soil Loss Equation (USLE) showed that rainfall erosion was reduced by 65% in areas where stone walls are present. Annual soil loss ranged from 5 to 15 t yr-1. The mean annual soil loss in the absence of stone walls ranged from 10-60 t ha-1 with an average value of 35 t ha-1. Interpolating the slope of thickness of A horizon provided an average initial estimate of 0.3 for P value.

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

VOCs in Arid soils: Technology summary

International Nuclear Information System (INIS)

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

Performance evaluation of constructed wetlands: A review of arid ...

African Journals Online (AJOL)

Aiming at environmental pollution control through the use of constructed wetlands systems (CWs) in arid and semi arid climatic region, a detailed review of CWs was undertaken. Given the practical application and simplicity of the technology, principles for building phytotechnology-ecohydrology environment used for ...

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.

A novel microduplication of ARID1B: Clinical, genetic, and proteomic findings.

Science.gov (United States)

Seabra, Catarina M; Szoko, Nicholas; Erdin, Serkan; Ragavendran, Ashok; Stortchevoi, Alexei; Maciel, Patrícia; Lundberg, Kathleen; Schlatzer, Daniela; Smith, Janice; Talkowski, Michael E; Gusella, James F; Natowicz, Marvin R

2017-09-01

Genetic alterations of ARID1B have been recently recognized as one of the most common mendelian causes of intellectual disability and are associated with both syndromic and non-syndromic phenotypes. The ARID1B protein, a subunit of the chromatin remodeling complex SWI/SNF-A, is involved in the regulation of transcription and multiple downstream cellular processes. We report here the clinical, genetic, and proteomic phenotypes of an individual with a unique apparent de novo mutation of ARID1B due to an intragenic duplication. His neurodevelopmental phenotype includes a severe speech/language disorder with full scale IQ scores 78-98 and scattered academic skill levels, expanding the phenotypic spectrum of ARID1B mutations. Haploinsufficiency of ARID1B was determined both by RNA sequencing and quantitative RT-PCR. Fluorescence in situ hybridization analysis supported an intragenic localization of the ARID1B copy number gain. Principal component analysis revealed marked differentiation of the subject's lymphoblast proteome from that of controls. Of 3426 proteins quantified, 1014 were significantly up- or down-regulated compared to controls (q constitutional haploinsufficiency of ARID1B causes syndromic and non-syndromic developmental disabilities. © 2017 Wiley Periodicals, Inc.

Emerging crops in the USDA arid lands germplasm collection

Science.gov (United States)

The USDA National Plant Germplasm System maintains collections of several emerging crops for arid lands at the National Arid Land Plant Genetic Resources Unit in Parlier, CA (NALPGRU). The guayule, jojoba, and prickly pear collections are most active in terms of current research and crop development...

Watershed Management in Arid Zones: A Prototype Short Course.

Science.gov (United States)

Thames, John L., Ed.; Fischer, John N., Ed.

Presented is information recommended for inclusion in a short course to help extend knowledge of water resource development and research techniques in arid and semi-arid regions. Information is particularly intended for applicability in developing nations. Included are considerations of livestock grazing, use of hydrologic data, vegetation…

Consistency between Sweat Rate and Wet Bulb Globe Temperature for the Assessment of Heat Stress of People Working Outdoor in Arid and Semi-arid Regions

Directory of Open Access Journals (Sweden)

Hamidreza Heidari

2018-01-01

Full Text Available Background: Heat stress is common among workers in arid and semi-arid areas. In order to take every preventive measure to protect exposed workers against heat-related disorders, it is crucial to choose an appropriate index that accurately relates environmental parameters to physiological responses. Objective: To investigate the consistency between 2 heat stress and strain indices, ie, sweat rate and wet bulb globe temperature (WBGT, for the assessment of heat stress of people working outdoor in arid and semi-arid regions in Iran. Methods: During spring and summer, 136 randomly selected outdoor workers were enrolled in this study. Using a defined protocol, the sweat rate of these workers was measured 3 times a day. Simultaneously, the environmental parameters including WBGT index were recorded for each working station. Results: The level of agreement between sweat rate and WBGT was poor (κ<0.2. Based on sweat rate, no case exceeding the reference value was observed during the study. WBGT overestimated the heat stress in outdoor workers compared to sweat rate. Conclusion: It seems that the sweat rate standards may need some modifications related to real condition of work in arid and semi-arid regions in Iran. Moreover, it seems that judging workers solely based on monitoring their sweat rate in such regions, can probably result in underestimation of heat stress.

An evaluation of Mesodon and other larger terrestrial gastropod shells for dating late Holocene and historic alluvium in the Midwestern USA

Science.gov (United States)

Rakovan, Monica T.; Rech, Jason A.; Pigati, Jeffery S.; Nekola, Jeffery C.; Wiles, Gregory C.

2013-01-01

Understanding the history of stream erosion and changes in channel morphology is important for managing and restoring unstable streams. One of the significant challenges in this type of research is establishing accurate dating of late Holocene and historic alluvium. Here we evaluate the potential of using 14C dating and amino acid racemization (AAR) to date large terrestrial gastropod shells that are often preserved within alluvial sediments. Many terrestrial gastropods incorporate old carbon from limestone or other carbonate rocks into their shells and therefore are unsuitable for radiocarbon dating. Recent studies, however, have shown that some taxa avoid this ‘limestone problem’ and can yield reliable 14C ages. In this study, we measured the 14C activity of specimens for the genera Mesodon, Ventridens, and Allogona collected live and from alluvial sequences dated independently by dendrochronology, 14C dating of wood, and/or 137Cs analyses. Mesodon zaletus contained old carbon in similar concentrations (up to ~ 30%) found in previous studies of other large taxa and should be avoided for 14C dating when possible. In contrast, shells of Ventridens ligera and Allogona profunda showed minimal limestone effects and therefore may be suitable for dating late Holocene alluvium. These results highlight the importance of taxonomic identification of gastropod taxa prior to their use for 14C dating and demonstrate that shell fragments that are not identifiable should be avoided. We also measured d/l ratios (n = 17) of aspartic and glutamic acid from eight different taxa of terrestrial gastropods recovered from four late Holocene and historic stratigraphic sequences. Average d/l ratios of aspartic and glutamic acid from historic sediments < 300 years old are lower in shells from younger stratigraphic units, indicating that AAR can be used to differentiate between multiple historic stratigraphic units.

Identification and functional characterization of a novel bipartite nuclear localization sequence in ARID1A

Energy Technology Data Exchange (ETDEWEB)

Bateman, Nicholas W. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); The John P. Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda 20889, MD (United States); Shoji, Yutaka [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids 49503, MI (United States); Conrads, Kelly A.; Stroop, Kevin D. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); Hamilton, Chad A. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); The John P. Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda 20889, MD (United States); Gynecologic Oncology Service, Department of Obstetrics and Gynecology, Walter Reed National Military Medical Center, 8901 Wisconsin Ave, MD, Bethesda, 20889 (United States); Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda 20814, MD (United States); Darcy, Kathleen M. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); The John P. Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda 20889, MD (United States); Maxwell, George L. [Department of Obstetrics and Gynecology, Inova Fairfax Hospital, Falls Church, VA 22042 (United States); Risinger, John I. [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids 49503, MI (United States); and others

2016-01-01

AT-rich interactive domain-containing protein 1A (ARID1A) is a recently identified nuclear tumor suppressor frequently altered in solid tumor malignancies. We have identified a bipartite-like nuclear localization sequence (NLS) that contributes to nuclear import of ARID1A not previously described. We functionally confirm activity using GFP constructs fused with wild-type or mutant NLS sequences. We further show that cyto-nuclear localized, bipartite NLS mutant ARID1A exhibits greater stability than nuclear-localized, wild-type ARID1A. Identification of this undescribed functional NLS within ARID1A contributes vital insights to rationalize the impact of ARID1A missense mutations observed in patient tumors. - Highlights: • We have identified a bipartite nuclear localization sequence (NLS) in ARID1A. • Confirmation of the NLS was performed using GFP constructs. • NLS mutant ARID1A exhibits greater stability than wild-type ARID1A.

Plan and Some Results of "Advanced Study on Precipitation Enhancement in Arid and Semi-Arid Regions"

Science.gov (United States)

Murakami, M.

2016-12-01

There are several technologies to secure water resources, including the desalination of seawater, recycling of industrial water and reuse of wastewater. However precipitation enhancement is the only way we can create a large amount of water for industrial use, for example, water for irrigation, provided we find clouds suitable for cloud seeding and apply appropriate and effective methods to increase precipitation. Therefore, rain enhancement research is critical in the quest for new water security options and innovative solutions in the UAE and other arid and semi-arid regions. The main objective of our project is to better evaluate, and ultimately improve, the effectiveness of rain enhancement in the UAE and other arid and semi-arid regions using hygroscopic and glaciogenic seeding techniques. One of the major questions regarding rain enhancement today is the effectiveness of hygroscopic seeding for warm and supercooled convective clouds. Our research will investigate the microphysical processes in seeded and unseeded clouds using a combination of laboratory experiments, numerical simulations and in-situ aircraft measurements in order to decipher the mechanism responsible for precipitation augmentation due to hygroscopic seeding. In our research, major elements of cloud seeding, e.g., assessment of seedability, development of optimal seeding methods and evaluation of seeding effects, will be investigated in the most efficient and realistic way, within three years, using mainly the numerical models with the sophisticated seeding scheme, which is developed on a basis of laboratory experiments and then validated against in-situ and remote sensing observations. In addition to the research plan, the outcomes of the research projects, which will be made available to the public at the end of the project and benefit the broader society, is discussed.

Isotope studies of a thick unsaturated zone in a semi-arid area of Southern Africa

International Nuclear Information System (INIS)

Butler, M.J.; Verhagen, B.Th.

2001-01-01

Unsaturated zone profiles ranging in depth from 8 m to 22 m were obtained by hand augering an aeolian sand cover in the southern reaches of the semi-arid Kalahari thirstland. Moisture contents were rather low (<3 wt.%); in situ moisture chloride concentrations, measured by selective ion electrode following elutriation, are generally <500 ppm. Deuterium in the moisture was measured mass spectrometrically by direct quantitative conversion to hydrogen on zinc metal of moist soil samples. A novel technique of direct equilibration was developed for oxygen-18 analysis. Neither a thermonuclear tritium peak nor a stable isotope evaporation inversion near the surface could be observed in any of the profiles. Remarkable differences both laterally and vertically are observed in most parameters measured between profiles taken a few tens of metres apart. At greater depths, these differences become less pronounced. Recharge estimates based on chloride differ markedly from those obtained from tritium. Although the stable isotope values of the underlying saturated zone are similar to moisture in the deeper sections of the unsaturated zone profiles, the markedly lower chloride concentrations point towards preferential or bypass flow as an important mechanism of ground water recharge in the area. This can be regarded as a benchmark site on account of the wealth of unsaturated zone data as well as the detailed and ongoing rainfall record. (author)

Cereals for the semi-arid tropics

International Nuclear Information System (INIS)

De Wet, J.M.J.

1989-01-01

The region of semi-arid tropics is the most famine prone area of the world. This region with nearly one billion people extends across some 20 million square kilometres. Major domesticated cereals adapted to semi-arid regions are sorghum (Sorghum bicolor (L.) Moench), foxtail millet (Setaria italica (L.) P. Beauv.) and pearl millet (Pennisetum glaucum (L.) R. Br.). Several minor cereals are grown as speciality crops, or harvested in the wild in times of severe drought and scarcity. Important in the African Sahel are the fonios Digitaria iburua Stapf, D. exilis (Kapist) Stapf and Brachiaria deflexa (Schumach). C.E. Hubbard. These species are aggressive colonizers and are commonly encouraged as weeds in cultivated fields. Sown genotypes differ from their close wild relatives primarily in the lack of efficient natural seed dispersal. The fonios lend themselves to rapid domestication. Several wild cereals extend well beyond the limits of agriculture into the Sahara. Commonly harvested are the perennial Stipagrostis pungens and Panicum turgidum, and the annual Cenchrus biflorus (kram-kram). Kram-kram yields well under extreme heat and drought stress, and holds promise as a domesticated cereal. Sauwi millet (Panicum sonorum) is promising cereal in arid northwestern Mexico. (author). 31 refs

Australia's arid-adapted butcherbirds experienced range expansions during Pleistocene glacial maxima.

Science.gov (United States)

Kearns, Anna M; Joseph, Leo; Toon, Alicia; Cook, Lyn G

2014-05-30

A model of range expansions during glacial maxima (GM) for cold-adapted species is generally accepted for the Northern Hemisphere. Given that GM in Australia largely resulted in the expansion of arid zones, rather than glaciation, it could be expected that arid-adapted species might have had expanded ranges at GM, as cold-adapted species did in the Northern Hemisphere. For Australian biota, however, it remains paradigmatic that arid-adapted species contracted to refugia at GM. Here we use multilocus data and ecological niche models (ENMs) to test alternative GM models for butcherbirds. ENMs, mtDNA and estimates of nuclear introgression and past population sizes support a model of GM expansion in the arid-tolerant Grey Butcherbird that resulted in secondary contact with its close relative--the savanna-inhabiting Silver-backed Butcherbird--whose contemporary distribution is widely separated. Together, these data reject the universal use of a GM contraction model for Australia's dry woodland and arid biota.

Growth and Nutrient Status of Introduced Black Locust (Robinia pseudoacacia L.) Afforestation in Arid and Semi Arid Areas of Iran

OpenAIRE

Moshki, A.; Lamersdorf, N. P.

2011-01-01

Under global climate change it is expected that many arid regions in the world will experience enhanced desertification in the next decades. Black locust (Robinia pseudoacacia L.) is a one commonly used species for afforestation projects in arid regions of Iran due to its soil rehabilitation capabilities. This study aims to characterize how Robinia growth parameters and nutrient status interacted and were influenced soil properties. The experiment was conducted at three Robinia plantations in...

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.

International Arid Lands Consortium: Better land stewardship in water and watershed management

Science.gov (United States)

Peter F. Ffolliott; James T. Fisher; Menachem Sachs; Darrell W. DeBoer; Jeffrey O. Dawson; Timothy E. Fulbright; John Tracy

2000-01-01

The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training for the development, management, and restoration of arid and semi-arid lands throughout the world. One activity of IALC members and cooperators is to support research and development and demonstration projects that enhance management of these fragile...

Spatiotemporal trends in mean temperatures and aridity index over Rwanda

Science.gov (United States)

Muhire, I.; Ahmed, F.

2016-01-01

This study aims at quantifying the trends in mean temperatures and aridity index over Rwanda for the period of 1961-1992, based on analysis of climatic data (temperatures, precipitations, and potential evapotranspiration). The analysis of magnitude and significance of trends in temperatures and aridity index show the degree of climate change and mark the level of vulnerability to extreme events (e.g., droughts) in different areas of the country. The study reveals that mean temperatures increased in most parts of the country, with a significant increase observed in the eastern lowlands and in the southwestern parts. The highlands located in the northwest and the Congo-Nile crest showed a nonsignificant increase in mean temperatures. Aridity index increased only in March, April, October, and November, corresponding with the rainy seasons. The remaining months of the year showed a decreasing trend. At an annual resolution, the highlands and the western region showed a rise in aridity index with a decreasing pattern over the eastern lowlands and the central plateau. Generally, the highlands presented a nonsignificant increase in mean temperatures and aridity index especially during the rainy seasons. The eastern lowlands showed a significant increase in mean temperatures and decreasing trends in aridity index. Therefore, these areas are bound to experience more droughts, leading to reduced water and consequent decline in agricultural production. On the other hand, the north highlands and southwest region will continue to be more productive.

Sensitivity of long-term bare soil infiltration simulations to hydraulic properties in an arid environment

International Nuclear Information System (INIS)

Stothoff, S.A.

1997-01-01

The suitability of Yucca Mountain, Nevada, for emplacement of a high-level nuclear waste geologic repository is currently being evaluated. Assessments of the repository performance suggest that the uncertainty in infiltration rates strongly affects predicted repository performance. Most of the ground surface over the potential repository footprint is characterized by shallow to deep colluvium/alluvium overlying densely fractured, welded tuffs. In order to identify characteristic behavior of infiltration that might be expected at the site, two idealizations of this situation are examined: an effectively semi-infinite column of alluvium and a two-layer column of alluvium over a fractured impermeable matrix. For each idealization the impact of hydraulic properties is assessed. Examining the sensitivity of bare soil simulator predictions for an effectively semi-infinite column, it is found that decreasing the air entry pressure while holding all other parameters at a fixed level tends to increase both the long-term average moisture content and the long-term average net infiltration flux for homogeneous media. In contrast, increasing the van Genuchten scale parameter (m = 1 - 1/n) or decreasing the porosity tends to decrease the average soil moisture but increase the infiltration. Most interestingly, three regimes are found for permeability. For relatively high permeabilities, there is a trend toward increasing average infiltration and increasing average moisture content with decreasing permeability. For relatively low permeabilities, vapor transport dominates over liquid transport, runoff and evaporation overwhelm infiltration, and the soil becomes very dry with essentially no infiltration flux Between the extreme cases of high and low permeability, there is a zone where decreasing permeability results in decreased infiltration but increased moisture content

Hierarchy of responses to resource pulses in arid and semi-arid ecosystems.

Science.gov (United States)

Schwinning, Susanne; Sala, Osvaldo E

2004-10-01

In arid/semi-arid ecosystems, biological resources, such as water, soil nutrients, and plant biomass, typically go through periods of high and low abundance. Short periods of high resource abundance are usually triggered by rainfall events, which, despite of the overall scarcity of rain, can saturate the resource demand of some biological processes for a time. This review develops the idea that there exists a hierarchy of soil moisture pulse events with a corresponding hierarchy of ecological responses, such that small pulses only trigger a small number of relatively minor ecological events, and larger pulses trigger a more inclusive set and some larger ecological events. This framework hinges on the observation that many biological state changes, where organisms transition from a state of lower to higher physiological activity, require a minimal triggering event size. Response thresholds are often determined by the ability of organisms to utilize soil moisture pulses of different infiltration depth or duration. For example, brief, shallow pulses can only affect surface dwelling organisms with fast response times and high tolerance for low resource levels, such as some species of the soil micro-fauna and -flora, while it takes more water and deeper infiltration to affect the physiology, growth or reproduction of higher plants. This review first discusses how precipitation, climate and site factors translate into soil moisture pulses of varying magnitude and duration. Next, the idea of the response hierarchy for ecosystem processes is developed, followed by an exploration of the possible evolutionary background for the existence of response thresholds to resource pulses. The review concludes with an outlook on global change: does the hierarchical view of precipitation effects in ecosystems provide new perspectives on the future of arid/semiarid lands?

Adaptation of metabolism and evaporative water loss along an aridity gradient.

Science.gov (United States)

Tieleman, B Irene; Williams, Joseph B; Bloomer, Paulette

2003-01-22

Broad-scale comparisons of birds indicate the possibility of adaptive modification of basal metabolic rate (BMR) and total evaporative water loss (TEWL) in species from desert environments, but these might be confounded by phylogeny or phenotypic plasticity. This study relates variation in avian BMR and TEWL to a continuously varying measure of environment, aridity. We test the hypotheses that BMR and TEWL are reduced along an aridity gradient within the lark family (Alaudidae), and investigate the role of phylogenetic inertia. For 12 species of lark, BMR and TEWL decreased along a gradient of increasing aridity, a finding consistent with our proposals. We constructed a phylogeny for 22 species of lark based on sequences of two mitochondrial genes, and investigated whether phylogenetic affinity played a part in the correlation of phenotype and environment. A test for serial independence of the data for mass-corrected TEWL and aridity showed no influence of phylogeny on our findings. However, we did discover a significant phylogenetic effect in mass-corrected data for BMR, a result attributable to common phylogenetic history or to common ecological factors. A test of the relationship between BMR and aridity using phylogenetic independent constrasts was consistent with our previous analysis: BMR decreased with increasing aridity.

Hydrological Response of Semi-arid Degraded Catchments in Tigray, Northern Ethiopia

Science.gov (United States)

Teka, Daniel; Van Wesemael, Bas; Vanacker, Veerle; Hallet, Vincent

2013-04-01

To address water scarcity in the arid and semi-arid part of developing countries, accurate estimation of surface runoff is an essential task. In semi-arid catchments runoff data are scarce and therefore runoff estimation using hydrological models becomes an alternative. This research was initiated in order to characterize runoff response of semi-arid catchments in Tigray, North Ethiopia to evaluate SCS-CN for various catchments. Ten sub-catchments were selected in different river basins and rainfall and runoff were measured with automatic hydro-monitoring equipments for 2-3 years. The Curve Number was estimated for each Hydrological Response Unit (HRU) in the sub-catchments and runoff was modeled using the SCS-CN method at λ = 0.05 and λ = 0.20. The result showed a significant difference between the two abstraction ratios (P =0.05, df = 1, n= 132) and reasonable good result was obtained for predicted runoff at λ = 0.05 (NSE = -0.69; PBIAS = 18.1%). When using the CN values from literature runoff was overestimated compared to the measured value (e= -11.53). This research showed the importance of using measured runoff data to characterize semi-arid catchments and accurately estimate the scarce water resource. Key words: Hydrological response, rainfall-runoff, degraded environments, semi-arid, Ethiopia, Tigray

Alterations in flowering strategies and sexual allocation of Caragana stenophylla along a climatic aridity gradient

OpenAIRE

Lina Xie; Hongyu Guo; Chengcang Ma

2016-01-01

Plant can alter reproductive strategies for adaptation to different environments. However, alterations in flowering strategies and sexual allocation for the same species growing in different environments still remain unclear. We examined the sexual reproduction parameters of Caragana stenophylla across four climatic zones from semi-arid, arid, very arid, to intensively arid zones in the Inner Mongolia Steppe, China. Under the relatively favorable climatic conditions of semi-arid zone, C. sten...

Radioactivity in groundwater along the borders of Oman and UAE

International Nuclear Information System (INIS)

Murad, A.; Alshamsi, D.; Al Shidi, F.; Al Kendi, R.; Aldahan, A.; Uppsala University, Uppsala

2014-01-01

Characterizing the quality and radioactivity of groundwater is vital as it represents valuable resource in arid regions. Here we present radioactivity level in groundwater collected from wells in a region along the border between Sultanate of Oman and United Arab Emirates (UAE). The aquifers are alluvium deposits (silt, sand and gravel) and the measured groundwater radioactivity (including 232 Th, 238 U, 235 U, 226 Ra, 222 Rn, gross-α and gross-β) indicates values below the WHO permissible limits for drinking water. The results also show large difference in radioactivity fingerprints, in particular for 226 Ra and 222 Rn within the investigated aquifers. The data further indicate lower radioactivity in groundwater of the alluviums compared to the carbonate aquifers in the region. This feature makes the alluvium aquifers valuable reservoirs that should be carefully exploited as a source of groundwater. As this is the first investigation on the radioactivity of groundwater in alluvial aquifers in the region, it suggests that other alluvial deposits, particularly those inland and far from the marine water intrusion or seepage from carbonate rocks would have low radioactivity fingerprints. (author)

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

International Nuclear Information System (INIS)

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

2009-01-01

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)

Essential Roles for ARID1B in Dendritic Arborization and Spine Morphology of Developing Pyramidal Neurons

Science.gov (United States)

Ka, Minhan; Chopra, Divyan A.; Dravid, Shashank M.

2016-01-01

De novo truncating mutations in ARID1B, a chromatin-remodeling gene, cause Coffin–Siris syndrome, a developmental disorder characterized by intellectual disability and speech impairment; however, how the genetic elimination leads to cognitive dysfunction remains unknown. Thus, we investigated the neural functions of ARID1B during brain development. Here, we show that ARID1B regulates dendritic differentiation in the developing mouse brain. We knocked down ARID1B expression in mouse pyramidal neurons using in utero gene delivery methodologies. ARID1B knockdown suppressed dendritic arborization of cortical and hippocampal pyramidal neurons in mice. The abnormal development of dendrites accompanied a decrease in dendritic outgrowth into layer I. Furthermore, knockdown of ARID1B resulted in aberrant dendritic spines and synaptic transmission. Finally, ARID1B deficiency led to altered expression of c-Fos and Arc, and overexpression of these factors rescued abnormal differentiation induced by ARID1B knockdown. Our results demonstrate a novel role for ARID1B in neuronal differentiation and provide new insights into the origin of cognitive dysfunction associated with developmental intellectual disability. SIGNIFICANCE STATEMENT Haploinsufficiency of ARID1B, a component of chromatin remodeling complex, causes intellectual disability. However, the role of ARID1B in brain development is unknown. Here, we demonstrate that ARID1B is required for neuronal differentiation in the developing brain, such as in dendritic arborization and synapse formation. Our findings suggest that ARID1B plays a critical role in the establishment of cognitive circuitry by regulating dendritic complexity. Thus, ARID1B deficiency may cause intellectual disability via abnormal brain wiring induced by the defective differentiation of cortical neurons. PMID:26937011

Impacts of Present and Future Climate Variability and Change on Agriculture and Forestry in the Arid and Semi-Arid Tropics

Energy Technology Data Exchange (ETDEWEB)

Sivakumar, M.V.K. [World Meteorological Organization WMO, 7bis Avenue de la Paix, 1211 Geneva 2 (Switzerland); Das, H.P. [India Meteorological Department, Shivaji Nagar, Pune, 411005 (India); Brunini, O. [Center for Ecology and Biophysics, 13.020-430-Campinas, Sao Paulo (Brazil)

2005-05-01

The arid and semi-arid regions account for approximately 30% of the world total area and are inhabited by approximately 20% of the total world population. Issues of present and future climate variability and change on agriculture and forestry in the arid and semi-arid tropics of the world were examined and discussion under each of these issues had been presented separately for Asia, Africa and Latin America. Several countries in tropical Asia have reported increasing surface temperature trends in recent decades. Although, there is no definite trend discernible in the long-term mean for precipitation for the tropical Asian region, many countries have shown a decreasing trend in rainfall in the past three decades. African rainfall has changed substantially over the last 60 yr and a number of theoretical, modelling and empirical analyses have suggested that noticeable changes in the frequency and intensity of extreme events, including floods may occur when there are only small changes in climate. Climate in Latin America is affected by the El Nino-southern oscillation (ENSO) phases and there is a close relationship between the increase and decrease of rainfall depending upon the warm or cold phases of the phenomenon. Over land regions of Asia, the projected area-averaged annual mean warming is likely to be 1.6 {+-} 0.2C in the 2020s, 3.1 {+-} 0.3C in the 2050s, and 4.6 {+-} 0.4C in the 2080s and the models show high uncertainty in projections of future winter and summer precipitation. Future annual warming across Africa is projected to range from 0.2C per decade to more than 0.5C per decade, while future changes in mean seasonal rainfall in Africa are less well defined. In Latin America, projections indicate a slight increase in temperature and changes in precipitation. Impacts of climate variability and changes are discussed with suitable examples. Agricultural productivity in tropical Asia is sensitive not only to temperature increases, but also to changes in the

Impacts of Present and Future Climate Variability and Change on Agriculture and Forestry in the Arid and Semi-Arid Tropics

International Nuclear Information System (INIS)

Sivakumar, M.V.K.; Das, H.P.; Brunini, O.

2005-01-01

The arid and semi-arid regions account for approximately 30% of the world total area and are inhabited by approximately 20% of the total world population. Issues of present and future climate variability and change on agriculture and forestry in the arid and semi-arid tropics of the world were examined and discussion under each of these issues had been presented separately for Asia, Africa and Latin America. Several countries in tropical Asia have reported increasing surface temperature trends in recent decades. Although, there is no definite trend discernible in the long-term mean for precipitation for the tropical Asian region, many countries have shown a decreasing trend in rainfall in the past three decades. African rainfall has changed substantially over the last 60 yr and a number of theoretical, modelling and empirical analyses have suggested that noticeable changes in the frequency and intensity of extreme events, including floods may occur when there are only small changes in climate. Climate in Latin America is affected by the El Nino-southern oscillation (ENSO) phases and there is a close relationship between the increase and decrease of rainfall depending upon the warm or cold phases of the phenomenon. Over land regions of Asia, the projected area-averaged annual mean warming is likely to be 1.6 ± 0.2C in the 2020s, 3.1 ± 0.3C in the 2050s, and 4.6 ± 0.4C in the 2080s and the models show high uncertainty in projections of future winter and summer precipitation. Future annual warming across Africa is projected to range from 0.2C per decade to more than 0.5C per decade, while future changes in mean seasonal rainfall in Africa are less well defined. In Latin America, projections indicate a slight increase in temperature and changes in precipitation. Impacts of climate variability and changes are discussed with suitable examples. Agricultural productivity in tropical Asia is sensitive not only to temperature increases, but also to changes in the nature

Coupled flow and salinity transport modelling in semi-arid environments

DEFF Research Database (Denmark)

Bauer-Gottwein, Peter; Held, R.J.; Zimmermann, S.

2006-01-01

Numerical groundwater modelling is used as the base for sound aquifer system analysis and water resources assessment. In many cases, particularly in semi-arid and arid regions, groundwater flow is intricately linked to salinity transport. A case in point is the Shashe River Valley in Botswana. A ...

SITE CHARACTERIZATION AND MONITORING DATA FROM THE AREA 5 PILOT WELLS

International Nuclear Information System (INIS)

2005-01-01

Three exploratory boreholes were drilled and completed to the uppermost alluvial aquifer in Area 5 of the Nevada Test Site, Nye County, Nevada, in 1992. The boreholes and associated investigations were part of the Area 5 Site Characterization Program developed to meet data needs associated with regulatory requirements applicable to the disposal of low-level, mixed, and high-specific-activity waste at this site. This series of boreholes was specifically designed to characterize the hydrogeology of the thick vadose zone and to help define the water quality and hydraulic properties of the uppermost aquifer. Wells UE5PW-1, UE5PW-2, and UE5PW-3 are located in a triangular array near the southeast, northeast, and northwest corners, respectively, of the approximately 2.6-square-kilometer Area 5 Radioactive Waste Management Site to give reasonable spatial coverage for sampling and characterization, and to help define the nearly horizontal water table. Two of the wells, UE5PW-1 and UE5PW-2, penetrated only unconsolidated alluvial materials. The third well, located closer to the margin of the basin, penetrated both alluvium and underlying ash-flow and bedded tuff units. The watertable was encountered at the elevation of approximately 734 meters. The results of laboratory testing of core and drill cuttings samples indicate that the mineralogical, material, and hydrologic properties of the alluvium are very similar within and between boreholes. Additional tests on the same core and drill cuttings samples indicate that hydrologic conditions within the alluvium are also similar between pilot wells. Both core and drill cuttings samples are dry (less than 10 percent water content by weight) throughout the entire unsaturated section of alluvium, and water content increases slightly with depth in each borehole. Water potential measurements on core samples show a large positive potential gradient (water tends to move upward, rather than downward) to a depth of approximately 30

Asynchronous glaciations in arid continental climate

Science.gov (United States)

Batbaatar, Jigjidsurengiin; Gillespie, Alan R.; Fink, David; Matmon, Ari; Fujioka, Toshiyuki

2018-02-01

Mountain glaciers at ∼26-19 ka, during the global Last Glacial Maximum near the end of the last 105 yr glacial cycle, are commonly considered on the basis of dating and field mapping in several well-studied areas to have been the largest of the late Quaternary and to have advanced synchronously from region to region. However, a numerical sensitivity model (Rupper and Roe, 2008) predicts that the fraction of ablation due to melting varies across Central Asia in proportion to the annual precipitation. The equilibrium-line altitude of glaciers across this region likely varies accordingly: in high altitude, cold and arid regions sublimation can ablate most of the ice, whereas glaciers fed by high precipitation cannot ablate completely due to sublimation alone, but extend downhill until higher temperatures there cause them to melt. We have conducted field studies and 10Be dating at five glaciated sites along a precipitation gradient in Mongolia to test the Rupper/Roe model. The sites are located in nearby 1.875 × 1.875° cells of the Rupper/Roe model, each with a different melt fraction, in this little-studied region. The modern environment of the sites ranges from dry subhumid in the north (47.7° N) to arid in the south (45° N). Our findings show that the maximum local advances in the dry subhumid conditions predated the global Last Glacial Maximum and were likely from MIS 3. However, we also found that at ∼8-7 ka a cirque glacier in one mountain range of the arid Gobi desert grew to a magnitude comparable to that of the local maximum extent. This Holocene maximum occurred during a regional pluvial period thousands of years after the retreat of the Pleistocene glaciers globally. This asynchronous behavior is not predicted by the prevailing and generally correct presumption that glacier advances are dominantly driven by temperature, although precipitation also plays a role. Our findings are consistent with and support the Rupper/Roe model, which calls for

More than ten million years of hyper-aridity recorded in the Atacama Gravels

Science.gov (United States)

Sun, Tao; Bao, Huiming; Reich, Martin; Hemming, Sidney R.

2018-04-01

The Atacama Desert's hyper-aridity is closely linked to the development of world-class copper and nitrate/iodine ores and to regional tectonics and global paleoclimate changes in the Cenozoic era. The timing when the hyper-aridity commenced remains controversial, with proposed ages ranging from Late Oligocene to Pleistocene. In this study, we provide an independent constraint on the initiation of Atacama hyper-aridity utilizing a 100-m deep profile within the Atacama Gravels and underneath porphyry copper deposit in Spence, northern Chile. The overall high concentration of sulfate (up to 10 wt%) and a multimodal distribution of water soluble salt (sulfates, chlorides and nitrates) indicate multiple generations of sedimentation and salt accumulation events under semi-arid to hyper-arid climate conditions. The multiple sulfate isotope compositions (Δ17O, δ18O, δ34S) of the upper section (-15.0 to -34.5 m) are close to those of modern hyperarid surface sulfates, while the lower section (-34.5 to -65 m) displays a depth dependent isotope trend that is best interpreted as marking a period of climate change from semi-arid to hyper-arid. When these data are combined with new chronological 40Ar/39Ar dates obtained from a volcanic ash layer at depth of -28.0 m, our results show that hyper-arid condition in the Atacama Desert was prevailing at least prior to 9.47 Ma and may go back as old as the middle Miocene.

[Effects of the grain size and thickness of dust deposits on soil water and salt movement in the hinterland of the Taklimakan Desert].

Science.gov (United States)

Sun, Yan-Wei; Li, Sheng-Yu; Xu, Xin-Wen; Zhang, Jian-Guo; Li, Ying

2009-08-01

By using mcirolysimeter, a laboratory simulation experiment was conducted to study the effects of the grain size and thickness of dust deposits on the soil water evaporation and salt movement in the hinterland of the Taklimakan Desert. Under the same initial soil water content and deposition thickness condition, finer-textured (grain size of dust deposits on soil water evaporation had an inflection point at the grain size 0.20 mm, i. e., increased with increasing grain size when the grain size was 0.063-0.20 mm but decreased with increasing grain size when the grain size was > 0.20 mm. With the increasing thickness of dust deposits, its inhibition effect on soil water evaporation increased, and there existed a logarithmic relationship between the dust deposits thickness and water evaporation. Surface soil salt accumulation had a negative correlation with dust deposits thickness. In sum, the dust deposits in study area could affect the stability of arid desert ecosystem.

An Overview of Biodegradation of LNAPLs in Coastal (Semi)-arid Environment.

KAUST Repository

Yadav, Brijesh Kumar; Hassanizadeh, S Majid

2011-01-01

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

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

Actinobacteria from Arid and Desert Habitats: Diversity and Biological Activity.

Science.gov (United States)

Mohammadipanah, Fatemeh; Wink, Joachim

2015-01-01

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 non-ribosomal 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 obtained from arid ecosystems

Actinobacteria from Arid and Desert Habitats: Diversity and Biological Activity

Science.gov (United States)

Mohammadipanah, Fatemeh; Wink, Joachim

2016-01-01

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 non-ribosomal 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 obtained from arid ecosystems

Problems and Prospects of SWAT Model Application on an Arid/Semi-arid Watershed in Arizona

Science.gov (United States)

Hydrological characteristics in the semi-arid southwest create unique challenges to watershed modelers. Streamflow in these regions is largely dependent on seasonal, short term, and high intensity rainfall events. The objectives of this study are: 1) to analyze the unique hydrolo...

Pathways to Resilience in Semi-Arid Economies | CRDI - Centre de ...

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

Pathways to Resilience in Semi-Arid Economies. How can populations become resilient to climate change while pursuing economic growth? This question is at the heart of a research project designed to support climate-resilient economic development in semi-arid lands. It will do so by addressing the conditions for ...

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, Paul C. D.

2016-01-01

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.

Distribution of greenhouse gases in hyper-arid and arid areas of northern Chile and the contribution of the high altitude wetland microbiome (Salar de Huasco, Chile).

Science.gov (United States)

Molina, Verónica; Eissler, Yoanna; Cornejo, Marcela; Galand, Pierre E; Dorador, Cristina; Hengst, Martha; Fernandez, Camila; Francois, Jean Pierre

2018-04-06

Northern Chile harbors different bioclimatic zones including hyper-arid and arid ecosystems and hotspots of microbial life, such as high altitude wetlands, which may contribute differentially to greenhouse gases (GHG) such as carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O). In this study, we explored ground level GHG distribution and the potential role of a wetland situated at 3800 m.a.s.l, and characterized by high solar radiation arid to hyper-arid zones. The microbiome from the water and sediments was described by high-throughput sequencing 16S rRNA and rDNA genes. The results indicate that GHG at ground level were variable along the elevation gradient potentially associated with different bioclimatic zones, reaching high values at the high Andean steppe and variable but lower values in the Atacama Desert and at the wetland. The water areas of the wetland presented high concentrations of CH 4 and CO 2 , particularly at the spring areas and in air bubbles below microbial mats. The microbial community was rich (> 40 phyla), including archaea and bacteria potentially active in the different matrices studied (water, sediments and mats). Functional microbial groups associated with GHG recycling were detected at low frequency, i.e., arid and arid areas of northern Chile are sites of GHG exchange associated with various bioclimatic zones and particularly in aquatic areas of the wetland where this ecosystem could represent a net sink of N 2 O and a source for CH 4 and CO 2 .

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.

SC-HTGR Performance Impact for Arid Sites

International Nuclear Information System (INIS)

Lommers, L.; Geschwindt, J.; Southworth, F.; Shahrokhi, F.

2014-01-01

The SC-HTGR provides high temperature steam which can support industrial process heat applications as well as high efficiency electricity generation. The increased generating efficiency resulting from using high steam temperature provides greater plant output than lower temperature concepts, and it also reduces the fraction of waste heat which must be rejected. This capability is particularly attractive for sites with little or no water for heat rejection. This high temperature capability provides greater flexibility for these sites, and it results in a smaller performance penalty than for lower temperature systems when dry cooling must be used. The performance of the SC-HTGR for a conventional site with wet cooling is discussed first. Then the performance for arid sites is evaluated. Dry cooling performance is evaluated for both moderately arid sites and very hot sites. Offdesign performance of the dry cooling system under extreme conditions is also considered. Finally, operating strategies are explored for sites where some cooling water may be available but only in very limited quantities. Results of these assessments confirm that the higher operating temperatures of the SC-HTGR are very beneficial for arid sites, providing significant advantages for both gross and net power generation. (author)

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.

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

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

International Nuclear Information System (INIS)

Khattak, M.I.

2005-01-01

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

Changes in the forest ecosystems in areas impacted by aridization in south-western Romania.

Science.gov (United States)

Pravalie, Remus; Sîrodoev, Igor; Peptenatu, Daniel

2014-01-06

In the past few decades, global climate change has accentuated the intensification of aridization in South-Western Romania, with direct and indirect consequences on the quality of forest ecosystems. In addition to qualitative deterioration, the quantitative changes brought about by intensive anthropic deforestation have created the conditions for a decline in the size of forest areas on vast tracts of land. The paper aims to analyze the qualitative and quantitative changes in the forest ecosystems in South-Western Romania, changes due to the synergic context of the global climate changes and the anthropic pressures of the past three decades. In order to capture the evolution of aridization in the study area, specific aridization indexes have been calculated, such as the De Martonne index and the UNEP aridity index. 1990 and 2011 satellite images have been used in order to quantify the qualitative changes. The results obtained indicated that, in the past two decades, the quality of the biomass declined as a result of the increase in the climatic aridity conditions (De Martonne si UNEP aridity index, indicating in the last decades, annual values under 15 mm/°C, and under 0.5 mm/mm, that means that the values situated under these thresholds, describe arid and semi-arid climate conditions). Also, the uncontrolled logging across vast surfaces caused the loss of forest ecosystems by 7% in the overall study area, during the last three decades. The severe effects of aridization meant, first of all, a significant decline in the quality of the ecosystem services supplied by forests. In the absence of viable actions to correct the present situation, the extremely undesirable consequences of an ecological and social nature will arise in the near future.

Effects of Gravel Bars on Nutrient Spiraling in Bedrock-Alluvium Streams

Science.gov (United States)

Iobst, B. R.; Carroll, E. P.; Furbish, D. J.

2007-05-01

The importance of the connection between nutrient transport and local stream geomorphology is becoming increasingly important. Studies have shown that the interconnectivity of nutrient cycles in the downstream direction is in part controlled by the distribution and size of gravel bars in low order streams, as hyporheic flow occurs dominantly through alternate and mid-channel gravel bars. For this investigation multiple gravel bars in a 3rd order bedrock-alluvium stream were studied to determine general relationships between nutrient spiraling and hyporheic flow. The first goal was to understand (1) the extent to which water moves through hyporheic zones and (2) the basic chemistry of the hyporheic water. The second part of the study was to understand how nutrients, notably nitrogen, are affected in their cycling by the relatively long residence times encountered in gravel bars during hyporheic flow. Wells were installed along a 600 m reach of Panther Creek, KY in selected bars, as well as in a secondary location involving a grid installation pattern in one large bar. Results have shown that hyporheic flow through gravel bars is an important factor in influencing stream chemistry. Background water chemistry surveys have shown that certain parameters, specifically ammonium and nitrogen concentrations vary downstream, and that the dominant control over these changes is gravel bar location. Rhodamine WT was used in field tracer tests to track the travel times of water through bars as well as partitioning of water between the open channel and hyporheic flows. Further tests will be conducted utilizing a stable isotope study to determine how nitrogen is affected by hyporheic flow, and what implications this has for nutrient transport. We expect results to show that the spacing and size of gravel bars is a dominant control in key nutrient spiraling parameters, namely uptake lengths and overall nitrogen cycling rates. This has implications for how natural systems will

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. © 2013 John Wiley & Sons Ltd.

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

Background: Mutations in genes encoding components of the Brahma-associated factor (BAF) chromatin remodeling complex have recently been shown to contribute to multiple syndromes characterised by developmental delay and intellectual disability. ARID1B mutations have been identified as the predomi......Background: Mutations in genes encoding components of the Brahma-associated factor (BAF) chromatin remodeling complex have recently been shown to contribute to multiple syndromes characterised by developmental delay and intellectual disability. ARID1B mutations have been identified...

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.

Deep Soil Recharge in Arid and Semi-Arid Regions: New Evidences in MU-US Sandy Land of China

Science.gov (United States)

Cheng, Y.; Yang, W.; Zhan, H.

2017-12-01

Precipitation induced recharge is an important source of groundwater budget but it is very difficult to quantify in arid and semiarid regions. In this study, a newly invented lysimeter was used to monitor deep soil recharge (DSR) under 200 cm depth in MU-US sandy land in western China under three kinds of landforms (mobile dune, semi-fixed dune, and fixed dune). We found that the annual DSRs in such three different kinds of landforms varied significantly. Specifically, the annual DSRs were 224.1 mm (50.5% of the annual precipitation), 71.1 mm (50.5% of the annual precipitation), and 1.3 mm (0.3% of the annual precipitation) in mobile dune, semi-fixed dune, and fixed dune, respectively. We also found that vegetation coverage and precipitation pattern significantly affected DSR. A 24-hr precipitation event with the precipitation amount greater than 8 mm was able to infiltrate soil deeper than 200 cm and contributed to ground water recharge directly. Vegetation was a dominant factor influencing infiltration in the fixed sand dune. Our research revealed that precipitation induced DSR in arid and semi-arid regions was a complex process that required long-term monitoring and innovative system analysis of interrelated factors such as precipitation strength and pattern, meteorological parameters, and dynamic soil moisture. Key words: Precipitation pattern, sand dune groundwater, deep soil recharge, infiltration.

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

Arid1b haploinsufficient mice reveal neuropsychiatric phenotypes and reversible causes of growth impairment.

Science.gov (United States)

Celen, Cemre; Chuang, Jen-Chieh; Luo, Xin; Nijem, Nadine; Walker, Angela K; Chen, Fei; Zhang, Shuyuan; Chung, Andrew S; Nguyen, Liem H; Nassour, Ibrahim; Budhipramono, Albert; Sun, Xuxu; Bok, Levinus A; McEntagart, Meriel; Gevers, Evelien F; Birnbaum, Shari G; Eisch, Amelia J; Powell, Craig M; Ge, Woo-Ping; Santen, Gijs We; Chahrour, Maria; Zhu, Hao

2017-07-11

Sequencing studies have implicated haploinsufficiency of ARID1B , a SWI/SNF chromatin-remodeling subunit, in short stature (Yu et al., 2015), autism spectrum disorder (O'Roak et al., 2012), intellectual disability (Deciphering Developmental Disorders Study, 2015), and corpus callosum agenesis (Halgren et al., 2012). In addition, ARID1B is the most common cause of Coffin-Siris syndrome, a developmental delay syndrome characterized by some of the above abnormalities (Santen et al., 2012; Tsurusaki et al., 2012; Wieczorek et al., 2013). We generated Arid1b heterozygous mice, which showed social behavior impairment, altered vocalization, anxiety-like behavior, neuroanatomical abnormalities, and growth impairment. In the brain, Arid1b haploinsufficiency resulted in changes in the expression of SWI/SNF-regulated genes implicated in neuropsychiatric disorders. A focus on reversible mechanisms identified Insulin-like growth factor (IGF1) deficiency with inadequate compensation by Growth hormone-releasing hormone (GHRH) and Growth hormone (GH), underappreciated findings in ARID1B patients. Therapeutically, GH supplementation was able to correct growth retardation and muscle weakness. This model functionally validates the involvement of ARID1B in human disorders, and allows mechanistic dissection of neurodevelopmental diseases linked to chromatin-remodeling.

Soil, plant, and structural considerations for surface barriers in arid environments: Application of results from studies in the Mojave Desert near Beatty, Nevada

Science.gov (United States)

Andraski, Brian J.; Prudic, David E.; ,

1997-01-01

The suitability of a waste-burial site depends on hydrologic processes that can affect the near-surface water balance. In addition, the loss of burial trench integrity by erosion and subsidence of trench covers may increase the likelihood of infiltration and percolation, thereby reducing the effectiveness of the site in isolating waste. Although the main components of the water balance may be defined, direct measurements can be difficult, and actual data for specific locations are seldom available. A prevalent assumption is that little or no precipitation will percolate to buried wastes at an arid site. Thick unsaturated zones, which are common to arid regions, are thought to slow water movement and minimize the risk of waste migration to the underlying water table. Thus, reliance is commonly placed on the natural system to isolate contaminants at waste-burial sites in the arid West.Few data are available to test assumptions about the natural soil-water flow systems at arid sites, and even less is known about how the natural processes are altered by construction of a waste-burial facility. The lack of data is the result of technical complexity of hydraulic characterization of the dry, stony soils, and insufficient field studies that account for the extreme temporal and spatial variations in precipitation, soils, and plants in arid regions. In 1976, the U.S. Geological Survey (USGS) began a long-term study at a waste site in the Mojave Desert. This paper summarizes the findings of ongoing investigations done under natural-site and waste-burial conditions, and discusses how this information may be applied to the design of surface barriers for waste sites in arid environments.The waste-burial site is in one of the most arid parts of the United States and is about 40 km northeast of Death Valley, near Beatty, Nev. (Figure 1). Precipitation averaged 108 mm/yr during 1981-1992. The water table is 85-115 m below land surface (Fischer, 1992). Sediments are largely alluvial

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.

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.

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

Aridity of Central Asia through the Holocene

Science.gov (United States)

Aizen, E. M.; Aizen, V. B.; Mayewski, P. A.; Zhou, H.; Rodda, C.; Joswiak, D.; Takeuchi, N.; Fujita, K.; Kurbatov, A.; Grigholm, B. O.

2017-12-01

The dynamics of aridity in Central Asia for over the past 12,000 years has been analyzed using deep ice core records recovered from the Siberian Altai, Tien Shan and Pamir glaciers. An analysis of aridity in the 20-21 centuries based on the long-term meteorological observations complements the paleo- climate reconstruction. The goal of our research is to examine an aridity (at low and high temperatures) in Central Asia as a complex of characteristics including air temperature-precipitation relationship (Koppen, 1918, Geiger, 1961, Mezencev, 1973), intensity of dust loading and biomass burning. The stable isotope ratio, soluble ionic and insoluble particulate geochemical components and oxalate preserved in ice were considered in relation to climatic and environmental changes; and to determine the main aerosol sources using ground- and upper-level meteorological data. Multivariate statistical methods were employed for examination of the main geo-chemical components responsible for the preserved aridity variability. Insoluble particle concentrations preserved in the ice core were affected mainly by precipitation regimes and wind speed. Concentration of all size particles was found to be negatively correlated with monthly temperatures indicating low temperatures during the dry particle deposition. Two abrupt depletions in stable isotope records, i.e., Younger Dryas and Centurial Sever Drought (CSD), occurred during cold, dry, windy periods of intensified dust storms in large desert areas. When climate became colder and drier, the Central Asian deserts extended, wind speeds increased loading mineral dust to atmosphere, which formed inversion while the convection processes and precipitation occurrence were limited. Warmer and wetter conditions are associated with less dust loading that occurred during the Holocene climate optimum, medieval warm and modern warm periods. The sudden climate transitions are accompanied by the most intensifying mineral dust loading. From the

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

Evolution of Asian Interior Arid-Zone Biota: Evidence from the Diversification of Asian Zygophyllum (Zygophyllaceae)

Science.gov (United States)

Li, Hong-Lei; Yu, Sheng-Xiang; Zhang, Lin-Jing; Wang, Wei

2015-01-01

The Asian interior arid zone is the largest desert landform system in the Northern Hemisphere, and has high biodiversity. Little is currently known about the evolutionary history of its biota. In this study, we used Zygophyllum, an important and characteristic component of the Asian interior arid zone, to provide new insights into the evolution of this biota. By greatly enlarged taxon sampling, we present the phylogenetic analysis of Asian Zygophyllum based on two plastid and one nuclear markers. Our phylogenetic analyses indicate that Asian Zygophyllum and Sarcozygium form a clade and Sarcozygium is further embedded within the shrub subclade. An integration of phylogenetic, biogeographic, and molecular dating methods indicates that Zygophyllum successfully colonized the Asian interior from Africa in the early Oligocene, and Asian Zygophyllum became differentiated in the early Miocene and underwent a burst of diversification in the late Miocene associated with the expansion of Asian interior arid lands due to orogenetic and climatic changes. Combining diversification patterns of other important components of the Asian interior arid zone, we propose a multi-stage evolution model for this biota: the late Eocene–early Oligocene origin, the early Miocene expansion, and the middle-late Miocene rapid expansion to the whole Asian interior arid zone. This study also demonstrates that, for Zygophyllum and perhaps other arid-adapted organisms, arid biomes are evolutionary cradles of diversity. PMID:26393796

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.

Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment

Science.gov (United States)

de Melo Costa, Cíntia Carol; Maia, Alex Sandro Campos; Neto, José Domingues Fontenele; Oliveira, Steffan Edward Octávio; de Queiroz, João Paulo Araújo Fernandes

2014-03-01

The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands ( P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm2) and quantity per square centimeter (390 ± 9 cm-2). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m-2) and possessed the highest surface temperatures (39.47 ± 0.18 °C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

Kinetically limited weathering at low denudation rates in semi-arid climates

Science.gov (United States)

Vanacker, V.; Schoonejans, J.; Opfergelt, S.; Ameijeiras-Marino, Y.; Christl, M.

2016-12-01

On Earth, the Critical Zone supports terrestrial life, being the near-surface environment where interactions between the atmosphere, lithosphere, hydrosphere, and biosphere take place Quantitative understanding of the interaction between mechanical rock breakdown, chemical weathering, and physical erosion is essential for unraveling Earth's biogeochemical cycles. In this study, we explore the role of soil water balance on regulating soil chemical weathering under water deficit regimes. Weathering rates and intensities were evaluated for nine soil profiles located on convex ridge crests of three mountain ranges in the Spanish Betic Cordillera. We present and compare quantitative information on soil weathering, chemical depletion and total denudation that were derived based on geochemical mass balance, 10Be cosmogenic nuclides and U-series disequilibria. Soil production rates determined based on U-series isotopes (238U, 234U, 230Th and 226Ra) are of the same order of magnitude as 10Be-derived denudation rates, suggesting steady state soil thickness, in two out of three sampling sites. The chemical weathering intensities are relatively low (˜5 to 30% of the total denudation of the soil) and negatively correlated with the magnitude of the water deficit in soils. Soil weathering extents increase (nonlinearly) with soil thickness and decrease with increasing surface denudation rates, consistent with kinetically limited or controlled weathering. Our study suggests that soil residence time and water availability limit weathering processes in semi-arid climates, which has not been validated previously with field data. An important implication of this finding is that climatic regimes may strongly regulate soil weathering by modulating soil solute fluxes.

Survival and long-term growth of eucalypts on semi-arid sites in a ...

African Journals Online (AJOL)

1, which is comparable to volume obtained at more favourable aridity indices in the summer rainfall zone of South Africa and exceeds the growth rates obtained in several other arid zone studies globally. The E. grandis × E. camaldulensis ...

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.

Arid5b facilitates chondrogenesis by recruiting the histone demethylase Phf2 to Sox9-regulated genes

Science.gov (United States)

Hata, Kenji; Takashima, Rikako; Amano, Katsuhiko; Ono, Koichiro; Nakanishi, Masako; Yoshida, Michiko; Wakabayashi, Makoto; Matsuda, Akio; Maeda, Yoshinobu; Suzuki, Yutaka; Sugano, Sumio; Whitson, Robert H.; Nishimura, Riko; Yoneda, Toshiyuki

2013-11-01

Histone modification, a critical step for epigenetic regulation, is an important modulator of biological events. Sox9 is a transcription factor critical for endochondral ossification; however, proof of its epigenetic regulation remains elusive. Here we identify AT-rich interactive domain 5b (Arid5b) as a transcriptional co-regulator of Sox9. Arid5b physically associates with Sox9 and synergistically induces chondrogenesis. Growth of Arid5b-/- mice is retarded with delayed endochondral ossification. Sox9-dependent chondrogenesis is attenuated in Arid5b-deficient cells. Arid5b recruits Phf2, a histone lysine demethylase, to the promoter region of Sox9 target genes and stimulates H3K9me2 demethylation of these genes. In the promoters of chondrogenic marker genes, H3K9me2 levels are increased in Arid5b-/- chondrocytes. Finally, we show that Phf2 knockdown inhibits Sox9-induced chondrocyte differentiation. Our findings establish an epigenomic mechanism of skeletal development, whereby Arid5b promotes chondrogenesis by facilitating Phf2-mediated histone demethylation of Sox9-regulated chondrogenic gene promoters.

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

NARCIS (Netherlands)

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

2009-01-01

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

Birth of a biome: insights into the assembly and maintenance of the Australian arid zone biota.

Science.gov (United States)

Byrne, M; Yeates, D K; Joseph, L; Kearney, M; Bowler, J; Williams, M A J; Cooper, S; Donnellan, S C; Keogh, J S; Leys, R; Melville, J; Murphy, D J; Porch, N; Wyrwoll, K-H

2008-10-01

The integration of phylogenetics, phylogeography and palaeoenvironmental studies is providing major insights into the historical forces that have shaped the Earth's biomes. Yet our present view is biased towards arctic and temperate/tropical forest regions, with very little focus on the extensive arid regions of the planet. The Australian arid zone is one of the largest desert landform systems in the world, with a unique, diverse and relatively well-studied biota. With foci on palaeoenvironmental and molecular data, we here review what is known about the assembly and maintenance of this biome in the context of its physical history, and in comparison with other mesic biomes. Aridification of Australia began in the Mid-Miocene, around 15 million years, but fully arid landforms in central Australia appeared much later, around 1-4 million years. Dated molecular phylogenies of diverse taxa show the deepest divergences of arid-adapted taxa from the Mid-Miocene, consistent with the onset of desiccation. There is evidence of arid-adapted taxa evolving from mesic-adapted ancestors, and also of speciation within the arid zone. There is no evidence for an increase in speciation rate during the Pleistocene, and most arid-zone species lineages date to the Pliocene or earlier. The last 0.8 million years have seen major fluctuations of the arid zone, with large areas covered by mobile sand dunes during glacial maxima. Some large, vagile taxa show patterns of recent expansion and migration throughout the arid zone, in parallel with the ice sheet-imposed range shifts in Northern Hemisphere taxa. Yet other taxa show high lineage diversity and strong phylogeographical structure, indicating persistence in multiple localised refugia over several glacial maxima. Similar to the Northern Hemisphere, Pleistocene range shifts have produced suture zones, creating the opportunity for diversification and speciation through hybridisation, polyploidy and parthenogenesis. This review highlights

Spatial and temporal migration of a landfill leachate plume in alluvium

Science.gov (United States)

Masoner, Jason R.; Cozzarelli, Isabelle M.

2015-01-01

Leachate from unlined or leaky landfills can create groundwater contaminant plumes that last decades to centuries. Understanding the dynamics of leachate movement in space and time is essential for monitoring, planning and management, and assessment of risk to groundwater and surface-water resources. Over a 23.4-year period (1986–2010), the spatial extent of the Norman Landfill leachate plume increased at a rate of 7800 m2/year and expanded by 878 %, from an area of 20,800 m2 in 1986 to 203,400 m2 in 2010. A linear plume velocity of 40.2 m/year was calculated that compared favorably to a groundwater-seepage velocity of 55.2 m/year. Plume-scale hydraulic conductivity values representative of actual hydrogeological conditions in the alluvium ranged from 7.0 × 10−5 to 7.5 × 10−4 m/s, with a median of 2.0 × 10−4 m/s. Analyses of field-measured and calculated plume-scale hydraulic conductivity distributions indicate that the upper percentiles of field-measured values should be considered to assess rates of plume-scale migration, spreading, and biodegradation. A pattern of increasing Cl− concentrations during dry periods and decreasing Cl− concentrations during wet periods was observed in groundwater beneath the landfill. The opposite occurred in groundwater downgradient from the landfill; that is, Cl− concentrations in groundwater downgradient from the landfill decreased during dry periods and increased during wet periods. This pattern of changing Cl−concentrations in response to wet and dry periods indicates that the landfill retains or absorbs leachate during dry periods and produces lower concentrated leachate downgradient. During wet periods, the landfill receives more recharge which dilutes leachate in the landfill but increases leachate migration from the landfill and produces a more concentrated contaminant plume. This approach of quantifying plume expansion, migration, and concentration during variable hydrologic

Genetic Defects Underlie the Non-syndromic Autosomal Recessive Intellectual Disability (NS-ARID

Directory of Open Access Journals (Sweden)

Saleha Shamim

2017-05-01

Full Text Available Intellectual disability (ID is a neurodevelopmental disorder which appears frequently as the result of genetic mutations and may be syndromic (S-ID or non-syndromic (NS-ID. ID causes an important economic burden, for patient's family, health systems, and society. Identifying genes that cause S-ID can easily be evaluated due to the clinical symptoms or physical anomalies. However, in the case of NS-ID due to the absence of co-morbid features, the latest molecular genetic techniques can be used to understand the genetic defects that underlie it. Recent studies have shown that non-syndromic autosomal recessive (NS-ARID is extremely heterogeneous and contributes much more than X-linked ID. However, very little is known about the genes and loci involved in NS-ARID relative to X-linked ID, and whose complete genetic etiology remains obscure. In this review article, the known genetic etiology of NS-ARID and possible relationships between genes and the associated molecular pathways of their encoded proteins has been reviewed which will enhance our understanding about the underlying genes and mechanisms in NS-ARID.

The Impact of Urban Development in the Arid Zone and its Management.

Science.gov (United States)

Gat, J. R.

2002-05-01

From the experience in humid and semi-arid settings, the immediate impact of urbanization on the hydrological system is the interference with the natural direct infiltration pathways, resulting in a decrease of groundwater recharge as well as the possibility of surface flooding. In contrast, in the arid environment the limited rain amounts and number of rain events makes the contribution of rain of marginal importance in the city's water balance. The major impact of urbanization in the arid zone is the continuous excess of discharge of treated or untreated sewage or water spills, originating from the import of water to the city's water supply. Their effect can be advantageous if properly channeled. On the other hand, the polluting potential of these water excesses as well as the possibility of mobilizing stored salinity in the downstream locations is of concern, if the natural drainage network and its remediation capacity becomes overloaded. Further, since the arid zone hydrological cycle depends naturally on a discontinuous and episodal groundwater recharge pattern, the new situation requires the re-assessment of the eco-hydrological patterns in the downstream location.

Observational characteristics of cloud radiative effects over three arid regions in the Northern Hemisphere

Science.gov (United States)

Li, Jiandong; Wang, Tianhe; Habib, Ammara

2017-08-01

Cloud-radiation processes play an important role in regional energy budgets and surface temperature changes over arid regions. Cloud radiative effects (CREs) are used to quantitatively measure the aforementioned climatic role. This study investigates the characteristics of CREs and their temporal variations over three arid regions in central Asia (CA), East Asia (EA), and North America (NA), based on recent satellite datasets. Our results show that the annual mean shortwave (SW) and net CREs (SWCRE and NCRE) over the three arid regions are weaker than those in the same latitudinal zone of the Northern Hemisphere. In most cold months (November-March), the longwave (LW) CRE is stronger than the SWCRE over the three arid regions, leading to a positive NCRE and radiative warming in the regional atmosphere-land surface system. The cold-season mean NCRE at the top of the atmosphere (TOA) averaged over EA is 4.1 W m-2, with a positive NCRE from November to March, and the intensity and duration of the positive NCRE is larger than that over CA and NA. The CREs over the arid regions of EA exhibit remarkable annual cycles due to the influence of the monsoon in the south. The TOA LWCRE over arid regions is closely related to the high-cloud fraction, and the SWCRE relates well to the total cloud fraction. In addition, the relationship between the SWCRE and the low-cloud fraction is good over NA because of the considerable occurrence of low cloud. Further results show that the interannual variation of TOA CREs is small over the arid regions of CA and EA, but their surface LWCREs show certain decreasing trends that correspond well to their decreasing total cloud fraction. It is suggested that combined studies of more observational cloud properties and meteorological elements are needed for indepth understanding of cloud-radiation processes over arid regions of the Northern Hemisphere.

Synthetic Lethal Therapeutic Approaches for ARID1A-Mutated Ovarian Cancer

Science.gov (United States)

2017-10-01

Award Number: W81XWH-16-1-0496 TITLE: Synthetic lethal therapeutic approaches for ARID1A-mutated ovarian cancer PRINCIPAL INVESTIGATOR: Rugang...AND SUBTITLE Synthetic lethal therapeutic approaches for ARID1A-mutated ovarian cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-16-1-0496 5c...Release; Distribution Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Epithelial ovarian cancer (EOC) is the leading cause of death among gynecological

Jojoba, Simmondsia chinensis: an alternative for the economic development of the arid and semi arid zones of Mexico

Energy Technology Data Exchange (ETDEWEB)

Sepulveda Betancourt, J I; Parra Hake, H

1976-01-01

Simmondsia chinensis is, in spite of its name, a species indigenous to SE California and Arizona (US) and to the states of Sonora, Baja California Norte and Baja California Sur in Mexico. It is a shrubby forage plant that reaches a height of 1.5 m and can grow under conditions of extreme drought and high salinity provided that frost does not occur; it is thus suitable for many arid and semi-arid parts of Mexico as well as other similar regions of the world. The seed, traditionally associated with medicinal properties, was found in 1933 to produce a liquid wax with properties similar to those of sperm-whale oil, an increasingly scarce product used for the lubrication of machinery run at high temperatures and speeds. Some other uses for S. chinensis wax are listed, and silvicultural research on the species in progress in Baja California Sur and elsewhere is briefly described.

Jojoba, Simmondsia chinensis. An alternative for the economic development of the arid and semi arid zones of Mexico

Energy Technology Data Exchange (ETDEWEB)

Sepulveda Betancourt, J I; Parra Hake, H

1976-01-01

S. chinensis is, in spite of its name, a species indigenous to SE California and Arizona (US) and to the states of Sonora, Baja California Norte and Baja California Sur in Mexico. It is a shrubby forage plant that reaches a height of 1.5 m and can grow under conditions of extreme drought and high salinity provided that frost does not occur; it is thus suitable for many arid and semi-arid parts of Mexico as well as other similar regions of the world. The seed, traditionally associated with medicinal properties, was found in 1933 to produce a liquid wax with properties similar to those of sperm-whale oil, an increasingly scarce product used for the lubrication of machinery run at high temperatures and speeds. Some other uses for S. chinensis wax are listed, and silvicultural research on the species in progress in Baja California Sur and elsewhere is briefly described.

Socio-economic effect on socially-deprived communities of developing drinking water quality problems in arid and semi-arid area of central Rajasthan

Directory of Open Access Journals (Sweden)

I. Husain

2014-09-01

Full Text Available Rajasthan is well known for its Great Thar desert. Central Rajasthan has an arid to semi-arid environment. The area faces either scarcity of water or poor quality of drinking water. In some areas water is transported 2 km or more, which uses time, energy and money. Rich people have their own sources, which is restricted for use by others. Such conditions are affecting socially-deprived communities, both socially and economically. Groundwater is a major source of drinking water due to the unavailability of surface water. There is a lack of groundwater quality knowledge in the community and the data available is hard to understand by consumers. The CCME Water Quality Index is a tool to simplify the water quality report by rating the water on quality standards. It provides meaningful summaries of overall water quality and trends, which is accessible to non-technical lay people. In the present study the objective is to examine the groundwater quality of six districts (Ajmer, Bhilwara, Pali, Rajasamand, Nagaur and Jodhpur, centrally located in Rajasthan, with arid and semi-arid conditions. CCME WQI is also evaluated to produce quality data in a form to be understood by the community. A total of 4369 groundwater sources in 1680 villages from six districts (76 546 km2 were collected and examined. Results are outlined in the Bureau of Indian Standards (BIS: 10500, 2012 and 2952 sources are unsafe for drinking. According to CCME WQI groundwater of 93 villages is poor, 343 villages are marginal, and 369 villages are fair in quality. Toxicological studies of unsafe drinking water and their remedial measures are also discussed. A tentative correlation between prevailing water-borne diseases and quality parameter has also been shown

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)

Protocol for VOC-Arid ID remediation performance characterization

International Nuclear Information System (INIS)

Tegner, B.J.; Hassig, N.L.; Last, G.V.

1994-09-01

The Volatile Organic Compound-Arid Integrated Demonstration (VOC-Arid ID) is a technology development program sponsored by the US Department of Energy's Office of Technology Development that is targeted to acquire, develop, demonstrate, and deploy new technologies for the remediation of VOC contaminants in the soils and groundwaters of arid DOE sites. Technologies cannot be adequately evaluated unless sufficient site characterization and technology performance data have been collection and analyzed. The responsibility for identifying these data needs has been placed largely on the Principal Investigators (PIs) developing the remediation technology, who usually are not experts in site characterization or in identification of appropriate sampling, analysis, and monitoring techniques to support the field testing. This document provides a protocol for planning the collection of data before, during, and after a test of a new technology. This generic protocol provides the PIs and project managers with a set of steps to follow. The protocol is based on a data collection planning process called the Data Quality Objectives (DQO) process, which was originally developed by the US Environmental Protection Agency and has been expanded by DOE to support site cleanup decisions. The DQO process focuses on the quality and quantity of data required to make decision. Stakeholders to the decisions must negotiate such key inputs to the process as the decision rules that will be used and the acceptable probabilities of making decision errors

Isolation of microalgae species from arid environments and ...

African Journals Online (AJOL)

Isolation of microalgae species from arid environments and evaluation of their potentials for biodiesel production. ... African Journal of Biotechnology. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives.

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.

Water movement through a shallow unsaturated zone in an inland arid region: Field drip irrigation experiment under matrix potential control

Science.gov (United States)

Zhou, T.; Han, D.; Song, X.

2017-12-01

It is vital to study soil water movement in unsaturated zone for evaluating and improving current irrigation mode for prevention and control of soil secondary salinization, especially in inland arid area, where is characterized by strong evaporation, poor drainage system and shallow water table depth. In this study, we investigated the applicability of drip irrigation under matrix potential control during cotton growth seasons in an inland arid region of northwest China. Combined physical observation with stable isotopes tracing method, we studied soil water flow system and recharge sources of shallow groundwater in heavy (Pilot 1) and light (Pilot 2) saline-alkali cotton fields. Evaporation depths (about 50-60 cm) are about the same for both pilots, but infiltration depths (about 60 cm for Pilot 1 and 150 cm for Pilot 2) are very different due to different soil texture, soil structure and soil salt content. Middle layer (about 100 cm thick) is a critical barrier for water exchange between surface and deep layer. Irrigation water is the major source (about 79.6% for Pilot 1 and 81.6% for Pilot 2), while evapotranspiration is the major sink (about 80.7% for Pilot 1 and 83.1% for Pilot 2) of unsaturated zone. The increase of soil water storage is not enough to make up the water shortage of middle layer and thus drip irrigation water doesn't recharge into groundwater for both pilots. Water table rise (about 60 cm for Pilot 1 and 50 cm for Pilot 2) could be caused by lateral groundwater flow instead of vertical infiltration. This irrigation mode could retard the water table rise in this region. However, improving horizontal drainage system may be indispensable for sustainable agriculture development. The study can provide important basis for soil secondary salinization prevention and agricultural water management in inland arid areas.

Excessive reliance on afforestation in China's arid and semi-arid regions: Lessons in ecological restoration

Science.gov (United States)

Cao, Shixiong; Chen, Li; Shankman, David; Wang, Chunmei; Wang, Xiongbin; Zhang, Hong

2011-02-01

Afforestation is a primary tool for controlling desertification and soil erosion in China. Large-scale afforestation, however, has complex and poorly understood consequences for the structure and composition of future ecosystems. Here, we discuss the potential links between China's historical large-scale afforestation practices and the program's effects on environmental restoration in arid and semi-arid regions in northern China based on a review of data from published papers, and offer recommendations to overcome the shortcomings of current environmental policy. Although afforestation is potentially an important approach for environmental restoration, current Chinese policy has not been tailored to local environmental conditions, leading to the use of inappropriate species and an overemphasis on tree and shrub planting, thereby compromising the ability to achieve environmental policy goals. China's huge investment to increase forest cover seems likely to exacerbate environmental degradation in environmentally fragile areas because it has ignored climate, pedological, hydrological, and landscape factors that would make a site unsuitable for afforestation. This has, in many cases, led to the deterioration of soil ecosystems and decreased vegetation cover, and has exacerbated water shortages. Large-scale and long-term research is urgently needed to provide information that supports a more effective and flexible environmental restoration policy.

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

International Nuclear Information System (INIS)

Last, G.V.; Lenhard, R.J.; Bjornstad, B.N.; Evans, J.C.; Roberson, K.R.; Spane, F.A.; Amonette, J.E.; Rockhold, M.L.

1991-10-01

The Volatile Organic Compounds -- Arid Integrated Demonstration Program (VOC-Arid ID) is targeted at demonstration and testing of technologies for the evaluation and cleanup of volatile organic compounds and associated contaminants at arid DOE sites. The initial demonstration site is an area of carbon tetrachloride (CCl 4 ) contamination located near the center of the Hanford Site. The movement of CCl 4 and other volatile organic contaminants in the subsurface is very complex. The problem at the Hanford Site is further complicated by the concurrent discharge of other waste constituents including acids, lard oil, organic phosphates, and transuranic radionuclides. In addition, the subsurface environment is very complex, with large spatial variabilities in hydraulic properties. A thorough understanding of the problem is essential to the selection of appropriate containment, retrieval, and/or in situ remedial technologies. The effectiveness of remedial technologies depends on knowing where the contaminants are, how they are held up in a given physical and chemical subsurface environment; and knowing the physical, chemical, and microbiological changes that are induced by the various remedial technologies

Technology development for the design of waste repositories at arid sites: field studies of biointrusion and capillary barriers

International Nuclear Information System (INIS)

Nyhan, J.W.; Abeele, W.; Hakonson, T.; Lopez, E.A.

1986-03-01

The field research program involving the development of technology for arid shallow land burial (SLB) sites is described. Results of field testing of biointrusion barriers installed at an active low-level radioactive waste disposal site (Area G) at Los Alamos are presented. A second experiment was designed to test the ability of a capillary barrier to effectively convey water infiltrating a SLB trench around and away from underlying buried wastes. The performance of the capillary barrier was tested in the field for a barrier of known thickness (2 m), slope (10%), and slope length (2 m), and for one combination of porous materials [a crushed tuff-clay (2% w/w) mixture overlying Ottawa sand] subjected to a known water addition rate. The waste management implications of both studies are also discussed

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.

Optimized estimation and its uncertainties of gross primary production over oasis-desert ecosystems in an arid region of China

Science.gov (United States)

Wang, H.; Li, X.; Xiao, J.; Ma, M.

2017-12-01

Arid and semi-arid ecosystems cover more than one-third of the Earth's land surface, it is of great important to the global carbon cycle. However, the magnitude of carbon sequestration and its contribution to global atmospheric carbon cycle is poorly understood due to the worldwide paucity of measurements of carbon exchange in the arid ecosystems. Accurate and continuous monitoring the production of arid ecosystem is of great importance for regional carbon cycle estimation. The MOD17A2 product provides high frequency observations of terrestrial Gross Primary Productivity (GPP) over the world. Although there have been plenty of studies to validate the MODIS GPP products with ground based measurements over a range of biome types, few have comprehensively validated the performance of MODIS estimates in arid and semi-arid ecosystems. Thus, this study examined the performance of the MODIS-derived GPP comparing with the EC observed GPP at different timescales for the main arid ecosystems in the arid and semi-arid ecosystems in China, and optimized the performance of the MODIS GPP calculations by using the in-situ metrological forcing data, and optimization of biome-specific parameters with the Bayesian approach. Our result revealed that the MOD17 algorithm could capture the broad trends of GPP at 8-day time scales for all investigated sites on the whole. However, the GPP product was underestimated in most ecosystems in the arid region, especially the irrigated cropland and forest ecosystems, while the desert ecosystem was overestimated in the arid region. On the annual time scale, the best performance was observed in grassland and cropland, followed by forest and desert ecosystems. On the 8-day timescale, the RMSE between MOD17 products and in-situ flux observations of all sites was 2.22 gC/m2/d, and R2 was 0.69. By using the in-situ metrological data driven, optimizing the biome-based parameters of the algorithm, we improved the performances of the MODIS GPP calculation

Wind power variations under humid and arid meteorological conditions

International Nuclear Information System (INIS)

Şen, Zekâi

2013-01-01

Highlights: • It indicates the role of weather parameters’ roles in the wind energy calculation. • Meteorological variables are more significant in arid regions for wind power. • It provides opportunity to take into consideration air density variability. • Wind power is presented in terms of the wind speed, temperature and pressure. - Abstract: The classical wind power per rotor area per time is given as the half product of the air density by third power of the wind velocity. This approach adopts the standard air density as constant (1.23 g/cm 3 ), which ignores the density dependence on air temperature and pressure. Weather conditions are not taken into consideration except the variations in wind velocity. In general, increase in pressure and decrease in temperature cause increase in the wind power generation. The rate of increase in the pressure has less effect on the wind power as compared with the temperature rate. This paper provides the wind power formulation based on three meteorological variables as the wind velocity, air temperature and air pressure. Furthermore, from the meteorology point of view any change in the wind power is expressed as a function of partial changes in these meteorological variables. Additionally, weather conditions in humid and arid regions differ from each other, and it is interesting to see possible differences between the two regions. The application of the methodology is presented for two meteorology stations in Istanbul, Turkey, as representative of the humid regions and Al-Madinah Al-Monawwarah, Kingdom of Saudi Arabia, for arid region, both on daily record bases for 2010. It is found that consideration of air temperature and pressure in the average wind power calculation gives about 1.3% decrease in Istanbul, whereas it is about 13.7% in Al-Madinah Al-Monawwarah. Hence, consideration of meteorological variables in wind power calculations becomes more significant in arid regions

Aridity influences the recovery of vegetation and shrubland birds after wildfire

OpenAIRE

Puig Gironès, Roger; Brotons, Lluís; Pons Ferran, 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 numb...

Electromagnetic survey (TEM method) in Teradomari and examination of resistivity structure to be based on near surface information; Niigataken Teradomarimachi ni okeru denji tansa kekka (TEM ho) no doshitsu joho ni yoru kento

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, H; Mitsuhata, Y; Matsuo, K; Tanaka, H [Japan National Oil Corp., Tokyo (Japan). Technology Research Center; Wada, K [Mitsui Mineral Development Engineering Co. Ltd., Tokyo (Japan)

1996-10-01

TEM method was applied to estimate soil structure from resistivity change of underground water saturated stratum featured by slow S wave and fast P wave over 1500m/s. Vertical magnetic field was measured by underlaying a transmission loop of 60m{times}60m around a measuring point in Teradomari, Niigata prefecture, and by installing a magnetic sensor at the measuring point. From comparison of a soil profile with the resistivity profile obtained by TEM data, the former well consisted with the latter. The surface low resistivity stratum corresponded to alluvium from comparison of it with soil and logging data. This alluvium base with fast P wave over 1500m/s satisfied the condition of optimum blasting depth because of a saturated stratum in the surface base. The resistivity structure was related to a saturated stratum. Sand bed was thick at the interface between alluvium low ground and hill area, and from the analytical result, the depth of sand bed showing high resistivity was more shallow than that of the alluvium base, pointing out necessary notice in interpretation. Resistivity survey is promising as simple method for optimum blasting depth. 4 refs., 6 figs., 1 tab.

A simple formula for estimating global solar radiation in central arid deserts of Iran

International Nuclear Information System (INIS)

Sabziparvar, Ali A.

2008-01-01

Over the last two decades, using simple radiation models has been an interesting task to estimate daily solar radiation in arid and semi-arid deserts such as those in Iran, where the number of solar observation sites is poor. In Iran, most of the models used so far, have been validated for a few specific locations based on short-term solar observations. In this work, three different radiation models (Sabbagh, Paltridge, Daneshyar) have been revised to predict the climatology of monthly average daily solar radiation on horizontal surfaces in various cities in central arid deserts of Iran. The modifications are made by the inclusion of altitude, monthly total number of dusty days and seasonal variation of Sun-Earth distance. A new height-dependent formula is proposed based on MBE, MABE, MPE and RMSE statistical analysis. It is shown that the revised Sabbagh method can be a good estimator for the prediction of global solar radiation in arid and semi-arid deserts with an average error of less than 2%, that performs a more accurate prediction than those in the previous studies. The required data for the suggested method are usually available in most meteorological sites. For the locations, where some of the input data are not reported, an alternative approach is presented. (author)

In-situ arsenic removal during groundwater recharge through unsaturated alluvium

Science.gov (United States)

O'Leary, David; Izbicki, John; T.J. Kim,; Clark Ajawani,; Suarez, Donald; Barnes, Thomas; Thomas Kulp,; Burgess, Matthew K.; Tseng, Iwen

2015-01-01

OBJECTIVES The purpose of this study was to determine the feasibility and sustainability of in-situ removal of arsenic from water infiltrated through unsaturated alluvium. BACKGROUND Arsenic is naturally present in aquifers throughout the southwestern United States and elsewhere. In January 2006, the U.S. Environmental Protection Agency (EPA) lowered the Maximum Contaminant Level (MCL) for arsenic from 50 to 10 micrograms per liter (g/L). This raised concerns about naturally-occurring arsenic in groundwater. Although commercially available systems using sorbent iron or aluminum oxide resins are available to treat high-arsenic water, these systems are expensive to build and operate, and may generate hazardous waste. Iron and aluminum oxides occur naturally on the surfaces of mineral grains that compose alluvial aquifers. In areas where alluvial deposits are unsaturated, these oxides may sorb arsenic in the same manner as commercial resins, potentially providing an effective low-cost alternative to commercially engineered treatment systems. APPROACH The Antelope Valley within the Mojave Desert of southern California contains a shallow water-table aquifer with arsenic concentrations of 5 g/L, and a deeper aquifer with arsenic concentrations of 30 g/L. Water was pumped from the deep aquifer into a pond and infiltrated through an 80 m-thick unsaturated zone as part of field-scale and laboratory experiments to treat high-arsenic groundwater and recharge the shallow water table aquifer at the site. The field-scale recharge experiment included the following steps: 1) construction of a recharge pond 2) test drilling for sample collection and instrument installation adjacent to the pond 3) monitoring downward migration of water infiltrated from the pond 4) monitoring changes in selected trace-element concentrations as water infiltrated through the unsaturated zone Data from instruments within the borehole adjacent to the pond were supplemented with borehole and

CMI Remedy Selection for HE- and Barium-Contaminated Vadose Zone and Alluvium at LANL

Science.gov (United States)

Hickmott, D.; Reid, K.; Pietz, J.; Ware, D.

2008-12-01

A high explosives (HE) machining building outfall at Los Alamos National Laboratory's Technical Area 16 discharged millions of gallons of HE- and barium-contaminated water into the Canon de Valle watershed. The effluent contaminated surface soils, the alluvial aquifer, vadose zone waters, and deep-perched and regional groundwaters with HE and barium, frequently at levels greater than regulatory standards. Site characterization studies began in 1995 and included extensive monitoring of surface water, groundwater, soils, and subsurface solid media. Hydrogeologic and geophysical studies were conducted to help understand contaminant transport mechanisms and pathways. Results from the characterization studies were used to develop a site conceptual model. In 2000 the principal source area was removed. The ongoing Corrective Measure Study (CMS) and Corrective Measure Implementation (CMI) focus on residual vadose zone contamination and on the contaminated alluvial system. Regulators recently selected a CMI remedy that combined: 1) augmented source removal; 2) grouting of an HE- contaminated surge bed; 3) deployment of Stormwater Management System (SMS) stormfilters in contaminated springs; and 4) permeable reactive barriers (PRBs) in contaminated alluvium. The hydrogeologic conceptual model for the vadose zone and alluvial system as well as the status of the canyon as habitat for the Mexican Spotted Owl were key factors in selection of these minimal-environmental-impact remedies. The heterogeneous vadose zone, characterized by flow and contaminant transport in fractures and in surge beds, requires contaminant treatment at a point of discharge. The canyon PRB is being installed to capture water and contaminants prior to infiltration into the vadose zone. Pilot-scale testing of the SMS and lab-scale batch and column tests of a range of media suggest that granular activated carbon, zeolite, and gypsum may be effective media for removal of HE and/or barium from contaminated

Modeling of hydrological processes in arid agricultural regions

Directory of Open Access Journals (Sweden)

Jiang LI,Xiaomin MAO,Shaozhong KANG,David A. BARRY

2015-12-01

Full Text Available Understanding of hydrological processes, including consideration of interactions between vegetation growth and water transfer in the root zone, underpins efficient use of water resources in arid-zone agriculture. Water transfers take place in the soil-plant-atmosphere continuum, and include groundwater dynamics, unsaturated zone flow, evaporation/transpiration from vegetated/bare soil and surface water, agricultural canal/surface water flow and seepage, and well pumping. Models can be categorized into three classes: (1 regional distributed hydrological models with various land uses, (2 groundwater-soil-plant-atmosphere continuum models that neglect lateral water fluxes, and (3 coupled models with groundwater flow and unsaturated zone water dynamics. This review highlights, in addition, future research challenges in modeling arid-zone agricultural systems, e.g., to effectively assimilate data from remote sensing, and to fully reflect climate change effects at various model scales.

Introducing Pathways to Resilience in Semi-Arid Economies (PRISE ...

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

rlarbey

Equitable, climate resilient economic development in semi-arid .... manufacturing or services (apart from health, insurance and tourism). Further research ... evaluated, particularly economic impact assessments of adaptation both on existing.

Mutations in SWI/SNF chromatin remodeling complex gene ARID1B cause Coffin-Siris syndrome.

Science.gov (United States)

Santen, Gijs W E; Aten, Emmelien; Sun, Yu; Almomani, Rowida; Gilissen, Christian; Nielsen, Maartje; Kant, Sarina G; Snoeck, Irina N; Peeters, Els A J; Hilhorst-Hofstee, Yvonne; Wessels, Marja W; den Hollander, Nicolette S; Ruivenkamp, Claudia A L; van Ommen, Gert-Jan B; Breuning, Martijn H; den Dunnen, Johan T; van Haeringen, Arie; Kriek, Marjolein

2012-03-18

We identified de novo truncating mutations in ARID1B in three individuals with Coffin-Siris syndrome (CSS) by exome sequencing. Array-based copy-number variation (CNV) analysis in 2,000 individuals with intellectual disability revealed deletions encompassing ARID1B in 3 subjects with phenotypes partially overlapping that of CSS. Taken together with published data, these results indicate that haploinsufficiency of the ARID1B gene, which encodes an epigenetic modifier of chromatin structure, is an important cause of CSS and is potentially a common cause of intellectual disability and speech impairment.

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

The red edge in arid region vegetation: 340-1060 nm spectra

Science.gov (United States)

Ray, Terrill W.; Murray, Bruce C.; Chehbouni, A.; Njoku, Eni

1993-01-01

The remote sensing study of vegetated regions of the world has typically been focused on the use of broad-band vegetation indices such as NDVI. Various modifications of these indices have been developed in attempts to minimize the effect of soil background, e.g., SAVI, or to reduce the effect of the atmosphere, e.g., ARVI. Most of these indices depend on the so-called 'red edge,' the sharp transition between the strong absorption of chlorophyll pigment in visible wavelengths and the strong scattering in the near-infrared from the cellular structure of leaves. These broadband indices tend to become highly inaccurate as the green canopy cover becomes sparse. The advent of high spectral resolution remote sensing instrument such as the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) has allowed the detection of narrow spectral features in vegetation and there are reports of detection of the red edge even for pixels with very low levels of green vegetation cover by Vane et al. and Elvidge et al., and to characterize algal biomass in coastal areas. Spectral mixing approaches similar to those of Smith et al. can be extended into the high spectral resolution domain allowing for the analysis of more endmembers, and potentially, discrimination between material with narrow spectral differences. Vegetation in arid regions tends to be sparse, often with small leaves such as the creosote bush. Many types of arid region vegetation spend much of the year with their leaves in a senescent state, i.e., yellow, with lowered chlorophyll pigmentation. The sparseness of the leaves of many arid region plants has the dual effect of lowering the green leaf area which can be observed and of allowing more of the sub-shrub soil to be visible which further complicates the spectrum of a region covered with arid region vegetation. Elvidge examined the spectral characteristics of dry plant materials showing significant differences in the region of the red edge and the diagnostic ligno

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

THE SURFACE WATER STORAGE PROBLEM IN ARID REGIONS:

African Journals Online (AJOL)

H. Benfetta

2017-09-01

Sep 1, 2017 ... This dam is located in an arid zone where water resources are becoming increasingly scarce. It is situated 5 km ... Leakage leads to considerable losses of valuable, scarce water. ...... Detection of water leaks in the restraints ...

Full reflector thickness and isolation thickness on neutron transport

International Nuclear Information System (INIS)

Sakai, Tomohiro; Naito, Yoshitaka; Komuro, Yuichi.

1988-08-01

A method to determine ''full reflector thickness'' and ''isolation thickness'', which is utilized for criticality safety evaluation on nuclear fuel facilities, was proposed in this paper. Firstly, a calculation was tryed to obtain the two kinds of thicknesses from the result of criticality calculations for a specific case. Then, two simple equations which calculates the two kinds of thicknesses were made from the relation between reflector (or isolator) thickness and k eff , and one-group diffusion theory. Finally, we proposed a new method to determine the thicknesses. From the method we proposed, ''full reflector thickness'' and ''isolation thickness'' can be obtain using the equations and migration length of the reflector (or isolator) and infinite and effective multiplication factor of the fuel. (author)

Geochemical Weathering Increases Lead Bioaccessibility in Semi-Arid Mine Tailings

Science.gov (United States)

Hayes, Sarah M.; Webb, Sam M.; Bargar, John R.; O'Day, Peggy A.; Maier, Raina M.; Chorover, Jon

2012-01-01

Mine tailings can host elevated concentrations of toxic metal(loid)s that represent a significant hazard to surrounding communities and ecosystems. Eolian transport, capable of translocating small (micrometer-sized) particles, can be the dominant mechanism of toxic metal dispersion in arid or semi-arid landscapes. Human exposure to metals can then occur via direct inhalation or ingestion of particulates. The fact that measured doses of total lead (Pb) in geomedia correlate poorly with blood Pb levels highlights a need to better resolve the precise distribution of molecularly-speciated metal-bearing phases in the complex particle mixtures. Species distribution controls bioaccessibility, thereby directly impacting health risk. This study seeks to correlate Pb-containing particle size and mineral composition with lability and bioaccessibility in mine tailings subjected to weathering in a semi-arid environment. We employed X-ray absorption spectroscopy (XAS) and X-ray fluorescence (XRF), coupled with sequential chemical extractions, to study Pb speciation in tailings from the semi-arid Arizona Klondyke State Superfund Site. Representative samples ranging in pH from 2.6 to 5.4 were selected for in-depth study of Pb solid-phase speciation. The principle lead-bearing phase was plumbojarosite (PbFe6(SO4)4(OH)12), but anglesite (PbSO4) and iron oxide-sorbed Pb were also observed. Anglesite, the most bioavailable mineral species of lead identified in this study, was enriched in surficial tailings samples, where Pb concentrations in the clay size fraction were 2–3 times higher by mass relative to bulk. A mobile and bioaccessible Pb phase accumulates in surficial tailings, with a corresponding increase in risk of human exposure to atmospheric particles. PMID:22553941

Soil-atmosphere trace gas exchange in semiarid and arid zones.

Science.gov (United States)

Galbally, Ian E; Kirstine, Wayne V; Meyer, C P Mick; Wang, Ying Ping

2008-01-01

A review is presented on trace gas exchange of CH4, CO, N2O, and NOx arising from agriculture and natural sources in the world's semiarid and arid zones due to soil processes. These gases are important contributors to the radiative forcing and the chemistry of the atmosphere. Quantitative information is summarized from the available studies. Between 5 and 40% of the global soil-atmosphere exchange for these gases (CH4, CO, N2O, and NOx) may occur in semiarid and arid zones, but for each of these gases there are fewer than a dozen studies to support the individual estimates, and these are from a limited number of locations. Significant differences in the biophysical and chemical processes controlling these trace gas exchanges are identified through the comparison of semiarid and arid zones with the moist temperate or wet/dry savanna land regions. Therefore, there is a poorly quantified understanding of the contribution of these regions to the global trace gas cycles and atmospheric chemistry. More importantly, there is a poor understanding of the feedback between these exchanges, global change, and regional land use and air pollution issues. A set of research issues is presented.

LAMBERSART "LES CONQUERANTS" (DEULE VALLEY, NORTH OF FRANCE) : A WEICHSELIAN EARLY-PLENIGLACIAL SLOPE-BOTTOM VALLEY TRANSITION

NARCIS (Netherlands)

Deschodt, Laurent; Munaut, Andre-Valentin; Limondin-Lozouet, Nicole; Boulen, Muriel

2008-01-01

The Lambersart "les Conquerants" trench sequence is made of a Shelly loam topped by coarse alluviums. The whole is covered by several meters thick pleniglacial loess. The palynological and malacological data shows that this Shelly loam deposit occured during Early Glacial, in cold and moist

Environmental Effects of Irrigation in Arid and Semi-Arid Regions Efectos Ambientales del Riego en Regiones Áridas y Semi-Áridas en América Latina

Directory of Open Access Journals (Sweden)

Alicia Fernández Cirelli

2009-12-01

Full Text Available This article reviews the state of the art with respect to the environmental effects of irrigated agriculture on water and soil quality in arid and semi-arid regions on a field scale. Information is scarce and fragmentary. Examples in selected areas of other arid and semi-arid regions in the world clearly show the importance of studying the environmental impact of irrigation practices on water and soil quality. Studies mainly refer to waterlogging and salinization. As regards agrochemicals, fertilizers have been taken into account through nitrate leaching. The impact of micropollutants such as pesticides and heavy metals on water and soil quality is studied mainly by modeling. Pharmaceutical compounds emerge as pollutants when wastewater is used for irrigation without any previous treatment, situation which is now the object of new studies. There is an obvious need to study in-depth knowledge related to appropriate technologies for the use, treatment, and reuse of wastewater which is a valuable resource in arid and semi-arid regions.En este trabajo se presenta una revisión del estado del arte relativo a los efectos ambientales de la agricultura bajo riego en la calidad del agua y de los suelos en regiones semiáridas y áridas de América Latina a escala de campo. La información relevada es escasa y fragmentaria. Ejemplos en áreas seleccionadas de otras regiones del mundo muestran claramente la importancia del estudio del impacto ambiental de las prácticas de riego en la calidad de agua y del suelo. La mayor parte de los estudios se refieren a anegamiento y salinización de suelos. En relación a los agroquímicos, los fertilizantes han recibido mayor atención, en particular considerando la lixiviación de nitratos. El impacto de los microcontaminantes, como los pesticidas o los metales pesados, se ha estudiado mayormente a través de la aplicación de modelos. Los compuestos farmacéuticos surgen como contaminantes cuando las aguas servidas

Water and Solute Transport in Arid Vadose Zones: Innovations in Measurement and Analysis

International Nuclear Information System (INIS)

Tyler, S W.; Scanlon, Bridget R.; Gee, Glendon W.; Allison, G B.; Parlange, M. B.; Hopmans, J. W.

1999-01-01

Understanding the physics of flow and transport through the vadose zone has advanced significantly in the last three decades. These advances have been made primarily in humid regions or in irrigated agricultural settings. While some of the techniques are useful, many are not suited to arid regions. The fluxes of water and solutes typically found in arid regions are often orders of magnitude smaller than those found in agricultural settings, while the time scales for transport can be orders of magnitude larger. The depth over which transport must be characterized is also often much greater than in humid regions. Rather than relying on advances in applied tracers, arid-zone researchers have developed natural tracer techniques that are capable of quantifying transport over tens to thousands of years. Techniques have been developed to measure the hydraulic properties of sediments at all water contents, including the very dry range and at far greater depths. As arid and semiarid regions come under increased development pressures for such activities as hazardous- and radioactive-waste disposal, the development of techniques and the understanding of water and solute transport have become crucial components in defining the environmental impacts of activities at the landsurface

Evaluating steady-state soil thickness by coupling uranium series and 10Be cosmogenic radionuclides

Science.gov (United States)

Vanacker, Veerle; Schoonejans, Jerome; Opfergelt, Sophie; Granet, Matthieu; Christl, Marcus; Chabaux, Francois

2017-04-01

Within the Critical Zone, the development of the regolith mantle is controlled by the downwards propagation of the weathering front into the bedrock and denudation at the surface of the regolith by mass movements, water and wind erosion. When the removal of surface material is approximately balanced by the soil production, the soil system is assumed to be in steady-state. The steady state soil thickness (or so-called SSST) can be considered as a dynamic equilibrium of the system, where the thickness of the soil mantle stays relatively constant over time. In this study, we present and compare analytical data from two independent isotopic techniques: in-situ produced cosmogenic nuclides and U-series disequilibria to constrain soil development under semi-arid climatic conditions. The Spanish Betic Cordillera (Southeast Spain) was selected for this study, as it offers us a unique opportunity to analyze soil thickness steady-state conditions for thin soils of semiarid environments. Three soil profiles were sampled across the Betic Ranges, at the ridge crest of zero-order catchments with distinct topographic relief, hillslope gradient and 10Be-derived denudation rate. The magnitude of soil production rates determined based on U-series isotopes (238U, 234U, 230Th and 226Ra) is in the same order of magnitude as the 10Be-derived denudation rates, suggesting steady state soil thickness in two out of three sampling sites. The results suggest that coupling U-series isotopes with in-situ produced radionuclides can provide new insights in the rates of soil development; and also illustrate the potential frontiers in applying U-series disequilibria to track soil production in rapidly eroding landscapes characterized by thin weathering depths.

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 ...

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.

Human-environment interactions in arid Australia: a geoarchaeological approach

Science.gov (United States)

Fanning, Patricia C.; Holdaway, Simon J.; Rhodes, Edward J.

2010-05-01

The conventional approach to assessing the archaeological record in semi-arid regions of many parts of the world involves extensive survey of surface deposits thought to indicate the use of space by past peoples. However, such interpretations require a detailed understanding not only of how these deposits formed but also why they have survived. In summarizing more than a decade of research in western New South Wales, Australia, we argue that over much of semi-arid and arid Australia, archaeological ‘sites' are, in fact, accretion phenomena (or ‘palimpsests') that are not easily interpreted as the outcome of short-term behavioural events. Moreover, while the desert landscapes may appear to be unchanging, there is considerable variability in landsurface age, and hence the ‘availability' of archaeological surfaces. It cannot be assumed that stone artefact deposits, for example, from a similar location are of a similar age. To make behavioural inferences from these records, an approach is needed based on a geoarchaeological assessment of landscape potential, analyses able to detect human responses to environmental change, and analyses of artefacts that emphasise mobility rather than static settlement patterns. Landscape, paleoenvironmental and artifact assemblage data from our field area will be presented that demonstrates episodic occupation by highly mobile groups of people, most likely reacting to environmental changes and resource availability.

Are acid volatile sulfides (AVS) important trace metals sinks in semi-arid mangroves?

Science.gov (United States)

Queiroz, Hermano Melo; Nóbrega, Gabriel Nuto; Otero, Xose L; Ferreira, Tiago Osório

2018-01-01

Acid-volatile sulfides (AVS) formation and its role on trace metals bioavailability were studied in semi-arid mangroves. The semi-arid climatic conditions at the studied sites, marked by low rainfall and high evapotranspiration rates, clearly limited the AVS formation (AVS contents varied from 0.10 to 2.34μmolg -1 ) by favoring oxic conditions (Eh>+350mV). The AVS contents were strongly correlated with reactive iron and organic carbon (r=0.84; r=0.83 respectively), evidencing their dominant role for AVS formation under semi-arid conditions. On the other hand, the recorded ΣSEM/AVS values remained >1 evidencing a little control of AVS over the bioavailability of trace metals and, thus, its minor role as a sink for toxic metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Deficit irrigation and fertilization strategies to improve soil quality and alfalfa yield in arid and semi-arid areas of northern China.

Science.gov (United States)

Jia, Qianmin; Kamran, Muhammad; Ali, Shahzad; Sun, Lefeng; Zhang, Peng; Ren, Xiaolong; Jia, Zhikuan

2018-01-01

In the arid and semi-arid areas of northern China, overexploitation of fertilizers and extensive irrigation with brackish groundwater have led to soil degradation and large areas of farmland have been abandoned. In order to improve the soil quality of abandoned farmland and make reasonable use of brackish groundwater, we conducted field trials in 2013 and 2014. In our study, we used three fertilization modes (CF, chemical fertilizer; OM, organic manure and chemical fertilizer; NF, no fertilizer) and three deficit irrigation levels (I 0 : 0 mm; I 75 : 75 mm; I 150 : 150 mm). The results showed that the activities of soil urease, alkaline phosphatase, invertase, catalase, and dehydrogenase in the OM treatment were significantly improved compared with those in the CF and NF treatments under the three deficit irrigation levels. Compared with NF, the OM treatment significantly increased soil organic carbon (SOC), water-soluble carbon (WSC), total nitrogen, microbial biomass carbon and nitrogen (MBC and MBN), and soil respiration rate, and significantly decreased soil C:N and MBC:MBN ratios and the metabolic quotient, thus improving the soil quality of abandoned farmland. Furthermore, the OM treatment increased alfalfa plant height, leaf area index, leaf chlorophyll content, and biomass yield. Under the CF and OM fertilization modes, the activities of urease and catalase in I 150 were significantly higher than those in I 0 , whereas irrigating without fertilizer did not significantly increase the activity of these two enzymes. Regardless of fertilization, alkaline phosphatase activity increased with an increase in irrigation amount, whereas invertase activity decreased. The results showed that deficit irrigation with brackish groundwater under the OM treatment can improve soil quality. Over the two years of the study, maximum SOC, total nitrogen, WSC, MBC, and MBN were observed under the OM-I 150 treatment, and the alfalfa biomass yield of this treatment was also

Deficit irrigation and fertilization strategies to improve soil quality and alfalfa yield in arid and semi-arid areas of northern China

Directory of Open Access Journals (Sweden)

Qianmin Jia

2018-02-01

Full Text Available Background In the arid and semi-arid areas of northern China, overexploitation of fertilizers and extensive irrigation with brackish groundwater have led to soil degradation and large areas of farmland have been abandoned. In order to improve the soil quality of abandoned farmland and make reasonable use of brackish groundwater, we conducted field trials in 2013 and 2014. Methods In our study, we used three fertilization modes (CF, chemical fertilizer; OM, organic manure and chemical fertilizer; NF, no fertilizer and three deficit irrigation levels (I0: 0 mm; I75: 75 mm; I150: 150 mm. Results The results showed that the activities of soil urease, alkaline phosphatase, invertase, catalase, and dehydrogenase in the OM treatment were significantly improved compared with those in the CF and NF treatments under the three deficit irrigation levels. Compared with NF, the OM treatment significantly increased soil organic carbon (SOC, water-soluble carbon (WSC, total nitrogen, microbial biomass carbon and nitrogen (MBC and MBN, and soil respiration rate, and significantly decreased soil C:N and MBC:MBN ratios and the metabolic quotient, thus improving the soil quality of abandoned farmland. Furthermore, the OM treatment increased alfalfa plant height, leaf area index, leaf chlorophyll content, and biomass yield. Under the CF and OM fertilization modes, the activities of urease and catalase in I150 were significantly higher than those in I0, whereas irrigating without fertilizer did not significantly increase the activity of these two enzymes. Regardless of fertilization, alkaline phosphatase activity increased with an increase in irrigation amount, whereas invertase activity decreased. Discussion The results showed that deficit irrigation with brackish groundwater under the OM treatment can improve soil quality. Over the two years of the study, maximum SOC, total nitrogen, WSC, MBC, and MBN were observed under the OM-I150 treatment, and the alfalfa

Nuclear applications for the management of aquifers in the semi-arid region

International Nuclear Information System (INIS)

Simoes Filho, Fernando Lamego

2005-01-01

The semi-arid region of the Northeast of Brazil is characterized by a lack of superficial waters due to the low pluviometric precipitation and high evaporation rates. In addition to this, the precipitation events are irregular in time causing long periods of dryness or flooding with catastrophic consequences. Owing to adverse climatic conditions with recurrent droughts, intense pressure is being put on the use of groundwater resources. Groundwater occurrence on its turn depends on a series of geological and climatological characteristics that are very variable in the region. Because of this situation, groundwater is of strategical importance and represents a vital factor to its socioeconomic development. However, there is still insufficient knowledge of the basic aquifers characteristics leading to an over exploitation of the water resources. It is not surprising that, amongst other reasons, this situation contributes to the fact that areas with the lowest human development pattern are located in the semi-arid region of Brazil. Given the nature of hydrological problems that need to be addressed in semi-arid regions, nuclear/isotope techniques are increasingly recognized as indispensable tools for water resources assessment and development. However, information arising from these techniques has to cope with other hydrological methods in an integrated manner. The general objective was prospect nuclear technologies as tools for aquifer management, promoting sustainable use of groundwater in the semi-arid region. (author)

Association of ARID5B gene variants with acute lymphoblastic leukemia in Yemeni children.

Science.gov (United States)

Al-Absi, Boshra; Noor, Suzita M; Saif-Ali, Riyadh; Salem, Sameer D; Ahmed, Radwan H; Razif, Muhammad Fm; Muniandy, Sekaran

2017-04-01

Studies have shown an association between ARID5B gene polymorphisms and childhood acute lymphoblastic leukemia. However, the association between ARID5B variants and acute lymphoblastic leukemia among the Arab population still needs to be studied. The aim of this study was to investigate the association between ARID5B variants with acute lymphoblastic leukemia in Yemeni children. A total of 14 ARID5B gene single nucleotide polymorphisms (SNPs) were genotyped in 289 Yemeni children, of whom 136 had acute lymphoblastic leukemia and 153 were controls, using the nanofluidic Dynamic Array (Fluidigm 192.24 Dynamic Array). Using logistic regression adjusted for age and gender, the risks of acute lymphoblastic leukemia were presented as odds ratios and 95% confidence intervals. We found that nine SNPs were associated with acute lymphoblastic leukemia under additive genetic models: rs7073837, rs10740055, rs7089424, rs10821936, rs4506592, rs10994982, rs7896246, rs10821938, and rs7923074. Furthermore, the recessive models revealed that six SNPs were risk factors for acute lymphoblastic leukemia: rs10740055, rs7089424, rs10994982, rs7896246, rs10821938, and rs7923074. The gender-specific impact of these SNPs under the recessive genetic model revealed that SNPs rs10740055, rs10994982, and rs6479779 in females, and rs10821938 and rs7923074 in males were significantly associated with acute lymphoblastic leukemia risk. Under the dominant model, SNPs rs7073837, rs10821936, rs7896246, and rs6479778 in males only showed striking association with acute lymphoblastic leukemia. The additive model revealed that SNPs with significant association with acute lymphoblastic leukemia were rs10821936 (both males and females); rs7073837, rs10740055, rs10994982, and rs4948487 (females only); and rs7089424, rs7896246, rs10821938, and rs7923074 (males only). In addition, the ARID5B haplotype block (CGAACACAA) showed a higher risk for acute lymphoblastic leukemia. The haplotype (CCCGACTGC) was

Mutations in SWI/SNF chromatin remodeling complex gene ARID1B cause Coffin-Siris syndrome

NARCIS (Netherlands)

Santen, G.W.; Aten, E.; Sun, Y; Almomani, R.; Gilissen, C.F.; Nielsen, M.; Kant, S.G.; Snoeck, I.N.; Peeters, E.A.; Hilhorst-Hofstee, Y.; Wessels, M.W.; Hollander, N.S. den; Ruivenkamp, C.A.; van Ommen, G.J.; Breuning, M.H.; den Dunnen, J.T.; van Haeringen, A.; Kriek, M.

2012-01-01

We identified de novo truncating mutations in ARID1B in three individuals with Coffin-Siris syndrome (CSS) by exome sequencing. Array-based copy-number variation (CNV) analysis in 2,000 individuals with intellectual disability revealed deletions encompassing ARID1B in 3 subjects with phenotypes

Rainfall simulations as a tool for quantification of soil erosion processes caused by the trampling of sheep and goats in semi-arid and arid landscapes

Science.gov (United States)

Ruthenberg, Jonas; Tumbrink, Jonas; Wilms, Tobias; Peter, Klaus Daniel; Wirtz, Stefan; Ries, Johannes B.

2015-04-01

As there is a massive increase of livestock husbandry in semi-arid and arid landscapes, the investigation of trampling-induced soil erosion has become indispensable for a better understanding of erosive processes such as loosening and translocation of sediment, as well as the genesis of rill erosion and gully systems. Our work will support other studies focusing on desertification and land-use changes in the investigated landscapes. Up to this date, research on livestock-induced soil erosion, even in relation to other erosion processes such as aeolian and fluvial/pluvial sediment translocation, is very scarcely found in literature. The presented study on trampling-induced soil erosion by sheep and goats in arid and semi-arid landscapes aims to create a general understanding, an estimation and quantification of the influencing factors of these erosive processes. Within this study, we present the first results of several field rainfall experiments on rock fragment translocation as well as loosening and transportation of coarse and fine sediment depending on the motion sequence and the individual weight, size, and hoof beat of the animals. Furthermore, we conducted additional experiments to investigate the trampling-induced erosion processes for various other sediments, especially those in the range of clay, silt, and sand. To do so, we used a specially designed test plot, equipped with sediment traps on each side. For a clear and reliable analysis of the measured parameters, univariate as well as multivariate statistical methods have been used. For all field methods, we developed relevant statements concerning flock size. The rock fragment translocation experiments done so fare have shown that a flock of 45 sheep or goats moved 87 % of 320 spread out rock fragments with a mean translocation distance of 0.123 m when trampling across a test plot of 3.2 m^2. Besides that we found out that the soil surface was worked up in a way that the loosened fine sediment proved to

Hypogeous fungi from Southern Spanish semi-arid lands

NARCIS (Netherlands)

Honrubia, M.; Cano, A.; Molina-Niñirola, C.

1992-01-01

Six hypogeous fungi of Ascomycotina and Basidiomycotina have been studied from semiarid zones in Southern Spain. Melanogaster variegatus (Vitt.) Tul. is recorded for the first time from Spain. Picoa juniperi Vitt. and Terfezia claveryi Chat. are revealed as the most frequent species in semi-arid

Confirmation of an ARID2 defect in SWI/SNF-related intellectual disability.

Science.gov (United States)

Van Paemel, Ruben; De Bruyne, Pauline; van der Straaten, Saskia; D'hondt, Marleen; Fränkel, Urlien; Dheedene, Annelies; Menten, Björn; Callewaert, Bert

2017-11-01

We present a 4-year-old girl with delayed neuromotor development, short stature of prenatal onset, and specific behavioral and craniofacial features harboring an intragenic deletion in the ARID2 gene. The phenotype confirmed the major features of the recently described ARID2-related intellectual disability syndrome. However, our patient showed overlapping features with Nicolaides-Baraitser syndrome and Coffin-Siris syndrome, providing further arguments to reclassify these disorders as "SWI/SNF-related intellectual disability syndromes." © 2017 Wiley Periodicals, Inc.

[Effect of shifting sand burial on evaporation reduction and salt restraint under saline water irrigation in extremely arid region].

Science.gov (United States)

Zhang, Jian-Guo; Zhao, Ying; Xu, Xin-Wen; Lei, Jia-Qiang; Li, Sheng-Yu; Wang, Yong-Dong

2014-05-01

interface of shifting sand burial were much lower than that of shifting sand surface. 35 cm was the critical sand burial thickness for water-saving and salt restraint. In summary, sand burial had obvious inhibition effects on soil evaporation and salt accumulation, so maybe it could be used to save water and reduce salt accumulation in arid shifting desert areas.

Genesis and continuity of quaternary sand and gravel in glacigenic sediment at a proposed low-level radioactive waste disposal site in east-central Illinois

Science.gov (United States)

Troost, K.G.; Curry, B. Brandon

1991-01-01

The Illinois Department of Nuclear Safety has characterized the Martinsville Alternative Site (MAS) for a proposed low-level radioactive waste disposal facility. The MAS is located in east-central Illinois approximately 1.6 km (1 mi) north of the city of Martinsville. Geologic investigation of the 5.5-km2 (1380-acre) site revealed a sequence of chiefly Illinoian glacigenic sediments from 6 to 60 m (20-200 ft) thick overlying two major bedrock valleys carved in Pennsylvanian strata. Relatively permeable buried units include basal, preglacial alluvium; a complex of intraglacial and subglacial sediment; englacial deposits; and supraglacial fluvial deposits. Postglacial alluvium underlies stream valleys on and adjacent to the site. In most areas, the buried sand units are confined by low-permeability till, lacustrine sediment, colluvium, and loess. The distribution and thickness of the most extensive and continuous buried sand units have been modified considerably by subglacial erosion, and their distributions have been influenced by the buried bedrock valleys. The most continuous of the various sand units were deposited as preglacial and postglacial alluvium and are the uppermost and lowermost stratigraphic units at the alternative site. Sand units that were deposited in englacial or ice-marginal environments are less continuous. Aquifer pumping tests, potentiometric head data, and groundwater geochemistry analyses indicate minimal interaction of groundwater across localized interconnections of the permeable units. ?? 1991 Springer-Verlag New York Inc.

Progress and prospects of climate change impacts on hydrology in the arid region of northwest China.

Science.gov (United States)

Chen, Yaning; Li, Zhi; Fan, Yuting; Wang, Huaijun; Deng, Haijun

2015-05-01

The arid region of Northwest China, located in the central Asia, responds sensitively to global climate change. Based on the newest research results, this paper analyzes the impacts of climate change on hydrology and the water cycle in the arid region of Northwest China. The analysis results show that: (1) In the northwest arid region, temperature and precipitation experienced "sharply" increasing in the past 50 years. The precipitation trend changed in 1987, and since then has been in a state of high volatility, during the 21st century, the increasing rate of precipitation was diminished. Temperature experienced a "sharply" increase in 1997; however, this sharp increasing trend has turned to an apparent hiatus since the 21st century. The dramatic rise in winter temperatures in the northwest arid region is an important reason for the rise in the average annual temperature, and substantial increases in extreme winter minimum temperature play an important role in the rising average winter temperature; (2) There was a significant turning point in the change of pan evaporation in the northwest arid area in 1993, i.e., in which a significant decline reversed to a significant upward trend. In the 21st century, the negative effects of global warming and increasing levels of evaporation on the ecology of the northwest arid region have been highlighted; (3) Glacier change has a significant impact on hydrology in the northwest arid area, and glacier inflection points have appeared in some rivers. The melting water supply of the Tarim River Basin possesses a large portion of water supplies (about 50%). In the future, the amount of surface water will probably remain at a high state of fluctuation. Copyright © 2015 Elsevier Inc. All rights reserved.

De novo mutations in ARID1B associated with both syndromic and non-syndromic short stature.

Science.gov (United States)

Yu, Yongguo; Yao, RuEn; Wang, Lili; Fan, Yanjie; Huang, Xiaodong; Hirschhorn, Joel; Dauber, Andrew; Shen, Yiping

2015-09-16

Human height is a complex trait with a strong genetic basis. Recently, a significant association between rare copy number variations (CNVs) and short stature has been identified, and candidate genes in these rare CNVs are being explored. This study aims to evaluate the association between mutations in ARID1B gene and short stature, both the syndromic and non-syndromic form. Based on a case-control study of whole genome chromosome microarray analysis (CMA), three overlapping CNVs were identified in patients with developmental disorders who exhibited short stature. ARID1B, a causal gene for Coffin Siris syndrome, is the only gene encompassed by all three CNVs. A following retrospective genotype-phenotype analysis based on a literature review confirmed that short stature is a frequent feature in those Coffin-Siris syndrome patients with ARID1B mutations. Mutation screening of ARID1B coding regions was further conducted in a cohort of 48 non-syndromic short stature patients,andfour novel missense variants including two de novo mutations were found. These results suggest that haploinsufficient mutations of ARID1B are associated with syndromic short stature including Coffin-Siris syndrome and intellectual disability, while rare missense variants in ARID1B are associated with non-syndromic short stature. This study supports the notion that mutations in genes related to syndromic short stature may exert milder effect and contribute to short stature in the general population.

New Technologies to Reclaim Arid Lands User's Manual

Energy Technology Data Exchange (ETDEWEB)

W. K. Ostler

2002-10-01

Approximately 70 percent of all U.S. military training lands are located in arid and semi-arid areas. Training activities in such areas frequently adversely affect vegetation, damaging plants and reducing the resilience of vegetation to recover once disturbed. Fugitive dust resulting from a loss of vegetation creates additional problems for human health, increasing accidents due to decreased visibility, and increasing maintenance costs for roads, vehicles, and equipment. Under conventional technologies to mitigate these impacts, it is estimated that up to 35 percent of revegetation projects in arid areas will fail due to unpredictable natural environmental conditions, such as drought, and reclamation techniques that were inadequate to restore vegetative cover in a timely and cost-effective manner. New reclamation and restoration techniques are needed in desert ranges to help mitigate the adverse effects of military training and other activities to arid-land environments. In 1999, a cooperative effort between the U.S. Department of Energy (DOE), the US. Department of Defense (DoD), and selected university scientists was undertaken to focus on mitigating military impacts in arid lands. As arid lands are impacted due to DoD and DOE activities, biological and soil resources are gradually lost and the habitat is altered. A conceptual model of that change in habitat quality is described for varying levels of disturbance in the Mojave Desert. As the habitat quality degrades and more biological and physical resources are lost from training areas, greater costs are required to return the land to sustainable levels. The purpose of this manual is to assist land managers in recognizing thresholds associated with habitat degradation and provide reclamation planning and techniques that can reduce the costs of mitigation for these impacted lands to ensure sustainable use of these lands. The importance of reclamation planning is described in this manual with suggestions about

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.)

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

In arid and semi-arid agricultural areas, groundwater (GW) is an important water source of irrigation, in addition to surface water (SW). Groundwater pumping would significantly alter the regional hydrological regime, and therefore complicate the water resources management process. This study explored how to optimize the conjunctive use of SW and GW for agricultural irrigation at a basin scale, based on integrated SW-GW modeling and global optimization methods. The improved GSFLOW model was applied to the Heihe River Basin, the second largest inland river basin in China. Two surrogate-based global optimization approaches were implemented and compared, including the well-established DYCORS algorithm and a new approach we proposed named as SOIM, which takes radial basis function (RBF) and support vector machine (SVM) as the surrogate model, respectively. Both temporal and spatial optimizations were performed, aiming at maximizing saturated storage change of midstream part conditioned on non-reduction of irrigation demand, constrained by certain annual discharge for the downstream part. Several scenarios for different irrigation demand and discharge flow are designed. The main study results include the following. First, the integrated modeling not only provides sufficient flexibility to formulation of optimization problems, but also makes the optimization results more physically interpretable and managerially meaningful. Second, the surrogate-based optimization approach was proved to be effective and efficient for the complex, time-consuming modeling, and is quite promising for decision-making. Third, the strong and complicated SW-GW interactions in the study area allow significant water resources conservation, even if neither irrigation demand nor discharge for the downstream part decreases. Under the optimal strategy, considerable part of surface water division is replaced by 'Stream leakage-Pump' process to avoid non-beneficial evaporation via canals. Spatially

A mesic maximum in biological water use demarcates biome sensitivity to aridity shifts.

Science.gov (United States)

Good, Stephen P; Moore, Georgianne W; Miralles, Diego G

2017-12-01

Biome function is largely governed by how efficiently available resources can be used and yet for water, the ratio of direct biological resource use (transpiration, E T ) to total supply (annual precipitation, P) at ecosystem scales remains poorly characterized. Here, we synthesize field, remote sensing and ecohydrological modelling estimates to show that the biological water use fraction (E T /P) reaches a maximum under mesic conditions; that is, when evaporative demand (potential evapotranspiration, E P ) slightly exceeds supplied precipitation. We estimate that this mesic maximum in E T /P occurs at an aridity index (defined as E P /P) between 1.3 and 1.9. The observed global average aridity of 1.8 falls within this range, suggesting that the biosphere is, on average, configured to transpire the largest possible fraction of global precipitation for the current climate. A unimodal E T /P distribution indicates that both dry regions subjected to increasing aridity and humid regions subjected to decreasing aridity will suffer declines in the fraction of precipitation that plants transpire for growth and metabolism. Given the uncertainties in the prediction of future biogeography, this framework provides a clear and concise determination of ecosystems' sensitivity to climatic shifts, as well as expected patterns in the amount of precipitation that ecosystems can effectively use.

Atmospheric Nitrogen Deposition at Two Sites in an Arid Environment of Central Asia.

Science.gov (United States)

Li, Kaihui; Liu, Xuejun; Song, Wei; Chang, Yunhua; Hu, Yukun; Tian, Changyan

2013-01-01

Arid areas play a significant role in the global nitrogen cycle. Dry and wet deposition of inorganic nitrogen (N) species were monitored at one urban (SDS) and one suburban (TFS) site at Urumqi in a semi-arid region of central Asia. Atmospheric concentrations of NH3, NO2, HNO3, particulate ammonium and nitrate (pNH4 (+) and pNO3 (-)) concentrations and NH4-N and NO3-N concentrations in precipitation showed large monthly variations and averaged 7.1, 26.6, 2.4, 6.6, 2.7 µg N m(-3) and 1.3, 1.0 mg N L(-1) at both SDS and TFS. Nitrogen dry deposition fluxes were 40.7 and 36.0 kg N ha(-1) yr(-1) while wet deposition of N fluxes were 6.0 and 8.8 kg N ha(-1) yr(-1) at SDS and TFS, respectively. Total N deposition averaged 45.8 kg N ha(-1) yr(-1)at both sites. Our results indicate that N dry deposition has been a major part of total N deposition (83.8% on average) in an arid region of central Asia. Such high N deposition implies heavy environmental pollution and an important nutrient resource in arid regions.

Preliminary report on the geology and hydrology of Mortandad Canyon near Los Alamos, New Mexico, with reference to disposal of liquid low-level radioactive waste

Science.gov (United States)

Baltz, E.H.; Abrahams, J.H.; Purtyman, W.D.

1963-01-01

water levels and collect water samples from the alluvium. Twenty-three of the holes were cased to seal out water and were used as access tubes to accommodate a neutron-neutron probe for determining the moisture content of the alluvium and tuff. The source of recharge for the perched ground-water body in the alluvium in Mortandad Canyon is the precipitation in the drainage area of the canyon. During the winter of 1960-61, a snowpack 1-2 feet thick accumulated in the narrow shaded upper part of the canyon. The alluvium below the snowpack received some recharge because of diurnal melting during the winter. In March 1961 the snowmelt water saturated most of the thin alluvium in the upper part of the canyon, and a surface stream began to flow on the alluvium. The maximum flow of the stream was about 250 gpm (gallons per minute). Water from the stream infiltrated the alluvium at the front of the stream and in the reach upstream from the front. A ground-water mound was formed beneath the channel by water infiltrating from the stream. The front of the stream and the front of the ground-water mound advanced eastward to about the middle of the area studied. From this point eastward, the alluvium was thick enough to absorb and transmit the amount of flow in 1961. Late in April the front of the stream retreated, and by the first of May the flow stopped. During and after this period the ground-water mound decayed, and ground-water levels declined in the upper part of the canyon as water drained into the channel and downgradient through the alluvium. The amount of recharge was small in the wide lower part of the canyon during the period of study. The rise in ground-water levels and the increase in moisture content of the alluvium in the lower part of the canyon indicate that water moved downgradient by underflow through the alluvium from the recharge area in the upper part of the canyon. Moisture measurements indicate that only a little water moved into the underlyin

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...

Patchiness in semi-arid dwarf shrublands: evidence from satellite ...

African Journals Online (AJOL)

... Plants; Remote sensing; Rhigozum obovatum Burch; Satellite-derived vegetation indices; Woody species; patchiness; semi-arid; dwarf shrubland; shrublands; co2; assimilation; karoo; south africa; ndvi; satellite imagery; geochemical mound; rhigozum obovatum; eriocephalus ericoides; pentzia incana; vegetation; botany

Competitive Promoter-Associated Matrix Attachment Region Binding of the Arid3a and Cux1 Transcription Factors

Directory of Open Access Journals (Sweden)

Dongkyoon Kim

2017-12-01

Full Text Available Arid3a/Bright/Dril1 is a B cell-specific transactivator that regulates immunoglobulin heavy chain (IgH gene transcription by binding promoter and enhancer-associated matrix attachment regions (MARs within the IgH gene locus. Promoter MAR-mediated Arid3a transactivation is antagonized by direct competition of MAR binding by Cux1/CDP—a ubiquitously expressed repressor originally termed NF-μNR. We report that the NF-μNR complex includes Arid3a in B cells but not in non-B cells through mobility shift assays. The binding activity of NF-μNR and Arid3a in B cells is reciprocally altered during the cell division cycle and by the B cell mitogen lipopolysaccharide LPS. LPS treatment had no effect on Arid3a localization but increased its total abundance within the nucleus and cytoplasm. We show that this increased level of Arid3a is capable of displacing Cux from the MARs to facilitate IgH gene transcription. Finally, we showed that the MARs (termed Bf150 and Tx125 associated with the VH1 rearranged variable region expressed in the S107 murine plasmacytoma, can repress reporter gene transcription in non-B cells and that they can relieve the repression mediated by Eμ enhancer in B cells. These results have significant implications for early human development and demonstrate that MARs in IgH locus, NF-µNR and Arid3a regulate IgH gene expression in a concerted fashion. This paves the way for future studies examining the misregulation of this pathway in pediatric disease.

Relationship between seed bank expression, adult longevity and aridity in species of Chaetanthera (Asteraceae) in central Chile.

Science.gov (United States)

Arroyo, M T K; Chacon, P; Cavieres, L A

2006-09-01

Broad surveys have detected inverse relationships between seed and adult longevity and between seed size and adult longevity. However, low and unpredictable precipitation is also associated with seed bank (SB) expression in semi-arid and arid areas. The relationship between adult longevity, SB formation, seed mass and aridity is examined in annual and perennial herbs of Chaetanthera (Asteraceae) from the Chilean Mediterranean-type climate and winter-rainfall desert areas over a precipitation range of one order of magnitude. Seeds of 18 species and subtaxa (32 populations) were buried in field locations, and exhumed after two successive germination periods. Seeds not germinating in the field were tested in a growth chamber, and remnant intact seed tested for viability. Seed banks were classed as transient or persistent. The effect of life form, species, population and burial time on persistent SB size was assessed with factorial ANOVA. Persistent seed bank size was compared with the Martonne aridity index (shown to be a surrogate for inter-annual variation in precipitation) and seed size using linear regression. ANCOVA assessed the effect of life-form on SB size with aridity as covariate. Three species had a transient SB and 15 a persistent SB. ANOVA revealed a significant effect of life-form on SB size with annuals having larger SB size and greater capacity to form a persistent SB than perennials. Significant inter-population variation in SB size was found in 64% of cases. Seed mass was negatively correlated with persistent SB size. Persistent seed bank size was significantly correlated with the Martonne aridity index in the perennial and annual species, with species from more arid areas having larger persistent SBs. However, when aridity was considered as a covariate, ANCOVA revealed no significant differences between the annual and perennial herbs. Persistent seed bank size in Chaetanthera appears to reflect environmental selection rather than any trade-off with

Pleistocene Arid and Wet Climatic Variability: Imprint of Glacial Climate, Tectonics and Oceanographic Events in the Sediments of the se Indian Ocean, Western Australia

Science.gov (United States)

McHugh, C. M.; Castaneda, J.; Kominz, M. A.; Gallagher, S. J.; Gurnis, M.; Ishiwa, T.; Mamo, B. L.; Henderiks, J.; Christensen, B. A.; Groeneveld, J.; Yokoyama, Y.; Mustaque, S.; Iqbal, F.

2017-12-01

The interaction between the evolving tectonic configuration of the Indo Pacific region as a result of the northward migration of the Australian continent, and its collision with the Banda Arc began in the Late Miocene ( 8 Ma ago). This constriction played an important role in the diversion of the Indonesian Throughflow and initiation of the Leeuwin Current. These events coupled to Pleistocene glaciations left a significant imprint in the sediments offshore western Australia. The International Ocean Discovery Program Expedition 356 drilled in shelf depths of the Carnarvon and Perth Basins recovering a thick section of Pleistocene sediment from Sites U1461 (440 m thick) and U1460 (306 m), respectively. Analyses of the lithology (logs, grain size), chemistry (X-ray elemental analyses) and an initial age model constructed from biostratigraphy and radiocarbon ages were interpreted within the framework of multichannel seismic profiles. Radiocarbon ages provide control for MIS 1-4, and the identification of glacial cycles is based on shipboard biostratigraphy best developed for Site U1460. Arid and high productivity signals are linked with glacial stages. Wet conditions are associated with river discharge, terrigenous sediments and linked with interglacial stages. Except for one very pronounced interval the productivity signal during interglacials is low. High productivity during glacial stages is related to upwelling linked to the southward flowing Leeuwin Current. Comparison of the northernmost (U1461) with southernmost (U1460) sites reveals a strong arid and wet climatic variability beginning in the Pleistocene. This variability is most pronounced in the late Pleistocene post 0.8-1.0 Ma and can be correlated with glacial-interglacial cycles, especially in the more humid southern Site that was closer to the Subantarctic Front and influenced by the Westerlies. In Site U1461 we recovered the 135m thick Gorgon slide. Its occurrence at 1 Ma coincides with a rapid tectonic

Biocrust-forming mosses mitigate the impact of aridity on soil microbial communities in drylands: observational evidence from three continents.

Science.gov (United States)

Delgado-Baquerizo, Manuel; Maestre, Fernando T; Eldridge, David J; Bowker, Matthew A; Jeffries, Thomas C; Singh, Brajesh K

2018-04-02

Recent research indicates that increased aridity linked to climate change will reduce the diversity of soil microbial communities and shift their community composition in drylands, Earth's largest biome. However, we lack both a theoretical framework and solid empirical evidence of how important biotic components from drylands, such as biocrust-forming mosses, will regulate the responses of microbial communities to expected increases in aridity with climate change. Here we report results from a cross-continental (North America, Europe and Australia) survey of 39 locations from arid to humid ecosystems, where we evaluated how biocrust-forming mosses regulate the relationship between aridity and the community composition and diversity of soil bacteria and fungi in dryland ecosystems. Increasing aridity was negatively related to the richness of fungi, and either positively or negatively related to the relative abundance of selected microbial phyla, when biocrust-forming mosses were absent. Conversely, we found an overall lack of relationship between aridity and the relative abundance and richness of microbial communities under biocrust-forming mosses. Our results suggest that biocrust-forming mosses mitigate the impact of aridity on the community composition of globally distributed microbial taxa, and the diversity of fungi. They emphasize the importance of maintaining biocrusts as a sanctuary for soil microbes in drylands. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Understanding Flash Flood Generation in the Arid Region of the Dead Sea

Science.gov (United States)

Merz, R.; Hennig, H.; Rödiger, T.; Laronne, J. B.

2017-12-01

The arid region of the Dead Sea is prone by flash floods. Such flash floods in (semi-) arid regions are impressive. Generated within minutes, the peak unit discharge can be as high as 25 m³/s km². Floods are the main mechanism supplying water to alluvial aquifers, forming fluvial landscapes including canyons and often causing damage to humans, infrastructure, industry and tourism. Existing hydrological models in this region focus on peak discharges. However, these models are often based on simplified concepts and/or on concepts which were developed for humid regions. To more closely relate such models to local conditions, processes within catchments where floods occur require consideration. Therefore, a measurement network of rain gauges and level loggers to monitor runoff was installed in the beginning of the 2015/16 hydrological season in the tributaries of Wadi Arugot. The Arugot catchment is one of the largest ephemeral Wadis draining to the western shoreline of the Dead Sea at 450 m bsl. Due to the high gradient in elevation, the climate within the basin ranges from semiarid in the Judean Mountains, to hyper-arid near the Dead Sea with respective mean annual rainfall of 650 and 50 mm. The installed rain gauge network in the mountains is more dense compared to the Dead Sea area. Arid to semiarid catchments have different runoff generation processes compared to humid regions due local storm rainfall, low density of vegetation cover as well as patchy and shallow soil. These characteristics limit the contribution of groundwater flow, saturated overland flow and shallow subsurface flow, and therefore Hortonian overland flow is the most important contributor to overland flow. First analyses of the runoff data have shown that the storage capacity in the mountain area is lower compared to the more arid region. This is an evidence of high transmission losses in the coarse gravel wadi bed, therefore having a high permeability. The rain event duration and the amount of

A review of research on ecosystem of arid area using RS-GIS in China

Science.gov (United States)

Han, Hongling

2007-06-01

Arid area is classical mountain-oasis-desert ecosystem in North-west China. As the ecosystem has its nature geography character obviously, it has superior to research with remote-sensing and geography information system. The study on arid ecosystem in RS-GIS' way is focused on that the landscape spatial pattern of complex MODS ecosystem, the dynamic development of Land use/land cover, the security of ecological environment of eco-tone and so on. At the same time, the research on the single system is more and more, which has provided more ways and deeper fields of arid area using RS-GIS. Through the use of RS-GIS, desertification, oasis' development, urbanization etc. can be known, which would provide precaution for human-being and suitable ways to adjust the problems.

Analysis and evaluation of tillage on an alfisol in a 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

Diagnosis of GLDAS LSM based aridity index and dryland identification for socioeconomic aspect of water resources management

Science.gov (United States)

Ghazanfari, S.; Pande, S.; Hashemy, M.; Naseri M., M.

2012-04-01

Water resources scarcity plays an important role in socioeconomic aspect of livelihood pattern in dryland areas. Hydrological perspective of aridity is required for social and economic coping Strategies. Identification of dryland areas is crucial to guide policy aimed at intervening in water stressed areas and addressing its perennial livelihood or food insecurity. Yet, prevailing aridity indices are beset with methodological limitations that restrict their use in delineating drylands and, might be insuffient for decision making frameworks. Palmer's Drought Severity index (PDSI) reports relative soil moisture deviations from long term means, which does not allow cross comparisons, while UNEP's aridity index, the ratio of annual evaporative demand to rainfall supply, ignores site specific soil and vegetation characteristics that are needed for appropriate water balance assessment. We propose to refine UNEP's aridity index by accounting for site specific soil and vegetation to partition precipitation into competing demands of evaporation and runoff. We create three aridity indices at a 1 x 1 degree spatial resolution based on 3 decades of soil moisture time series from three GLDAS Land Surface Models (LSM's): VIC, MOSAIC and NOAH. We compare each LSM model aridity map with the UNEP aridity map which was created based on LSM data forcing. Our approach is to extract the first Eigen function from Empirical Orthogonal Function (EOF) analysis that represents the dominant spatial template of soil moisture conditions of the three LSM's. Frequency of non-exceedence of this dominant soil moisture mode for a location by all other locations is used as our proposed aridity index. The EOF analysis reveals that the first Eigen function explains, respectively, 33%, 43% and 47% of the VIC, NOAH and MOSAIC models. The temporal coefficients associated with the first OF (Orthogonal Function) for all three LSMS clearly show seasonality with a discrete jump in trend around the year 1999

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.

Aeolian dust nutrient contributions increase with substrate age in semi-arid ecosystems

Science.gov (United States)

Coble, A. A.; Hart, S. C.; Ketterer, M. E.; Newman, G. S.

2013-12-01

Rock-derived nutrients supplied by mineral weathering become depleted over time, and without an additional nutrient source the ecosystem may eventually regress or reach a terminal steady state. Previous studies have demonstrated that aeolian dust act as parent materials of soils and important nutrients to plants in arid regions, but the relative importance of these exogenous nutrients to the function of dry ecosystems during soil development is uncertain. Here, using strontium isotopes as a tracer and a well-constrained, three million year old substrate age gradient, we show that aeolian-derived nutrients become increasingly important to plant-available soil pools and tree (Pinus edulis) growth during the latter stages of soil development in a semi-arid climate. Furthermore, the depth of nutrient uptake increased on older substrates, suggesting that trees in arid regions acquire nutrients from greater depths as ecosystem development progresses presumably in response to nutrient depletion in the more weathered surface soils. Our results contribute to the unification of biogeochemical theory by demonstrating the similarity in roles of atmospheric nutrient inputs during ecosystem development across contrasting climates.

Leaf green-up in a semi-arid African savanna - separating tree and grass responses to environmental cues

CSIR Research Space (South Africa)

Archibald, S

2007-01-01

Full Text Available -arid African savanna - 583 Journal of Vegetation Science 18: 583-594, 2007 © IAVS; Opulus Press Uppsala. Leaf green-up in a semi-arid African savanna – separating tree and grass responses to environmental cues Archibald, S.1* & Scholes, R.J.1,2 1Natural... to identify tree and grass green-up dates in a semi-arid savanna system, and are there predictable environmental cues for green-up for each life form? Location: Acacia nigrescens/Combretum apiculatum savanna, Kruger National Park, South Africa (25° S, 31...

Hydropedological interpretation of arid soilscapes, South Africa

Science.gov (United States)

Tinnefeld, Martin; Van Tol, Jacobus; Le Roux, Pieter

2017-04-01

Hydropedological investigations in arid regions are scarce due to the low the low contribution of these areas to water resources. Infrequent rainfall and few flow events also complicates measurements hydrological studies. Hydropedological studies, relating soil morphological properties and their spatial distribution to hydrological response, have been studied in detail in semi-arid, temperate, and sub-humid regions. In this paper, we investigated the relation between soil morphological properties and selected hydrological properties of soils in an arid landscape. We also studied the spatial distribution of the morphological properties to conceptualise the hydrological behaviour of different soilscapes in the area. A total of 806 soil profiles, covering an area of 4836 ha in the Northern Cape Province of South Africa were described and classified. The geology is dominated by Dwyka tillite overlain by aeolian sands with scattered Dolerite buttes. Thirteen modal profiles, representing the dominant soils types were selected, sampled at horizon level, and analysed for pH, CEC, iron, manganese, carbonate content. In situ measurements of saturated and near saturated (tension) hydraulic conductivity (Ks) were conducted to determine the water conducting macroporosity (WCM). Undisturbed cores were collected on which water retention characteristics were determined under laboratory conditions. Results indicate that dry soil colour, degree of structure development and the presence, absence, and abundance of carbonates as well as the degree of precipitation, are important indicators of hydrological response. For example; grey soils typically have lower Ks with higher storage capacity than soils dominated by red colours, whereas abundant carbonate precipitations in the soil matrix have lower WCM due to clogging of macropores. The dominant soil distribution pattern indicates that rapid vertical flow, through and out of the pedon, might contribute to recharge of an accumulative

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

Woody plants in agro-ecosystems of semi-arid regions

NARCIS (Netherlands)

Breman, H.; Kessler, J.J.

1995-01-01

A quantitative analysis of the role of woody plants in semi-arid regions, focusing on the Sahel and Sudan zones in West-Africa, is given for the assessment of their benefits in agro-sylvopastoral land-use systems with productive and sustainability objectives.

Identification of suitable sites for rainwater harvesting structures in arid and semi-arid regions: A review

Directory of Open Access Journals (Sweden)

Ammar Adham

2016-06-01

Full Text Available Harvested rainwater is an alternative source of water in arid and semi-arid regions (ASARs around the world. Many researchers have developed and applied various methodologies and criteria to identify suitable sites and techniques for rainwater harvesting (RWH. Determining the best method or guidelines for site selection, however, is difficult. The main objective of this study was to define a general method for selecting suitable RWH sites in ASARs by assembling an inventory of the main methods and criteria developed during the last three decades. We categorised and compared four main methodologies of site selection from 48 studies published in scientific journals, reports of international organisations, or sources of information obtained from practitioners. We then identified three main sets of criteria for selecting RWH locations and the main characteristics of the most common RWH techniques used in ASARs. The methods were diverse, ranging from those based only on biophysical criteria to more integrated approaches including socio-economic criteria, especially after 2000. The most important criteria for the selection of suitable sites for RWH were slope, land use/cover, soil type, rainfall, distance to settlements/streams, and cost. The success rate of RWH projects tended to increase when these criteria were considered, but an objective evaluation of these selection methods is still lacking. Most studies now select RHW sites using geographic information systems in combination with hydrological models and multi-criteria analysis.

Arid site water balance: evapotranspiration modeling and measurements

International Nuclear Information System (INIS)

Gee, G.W.; Kirkham, R.R.

1984-09-01

In order to evaluate the magnitude of radionuclide transport at an aird site, a field and modeling study was conducted to measure and predict water movement under vegetated and bare soil conditions. Significant quantities of water were found to move below the roo of a shallow-rooted grass-covered area during wet years at the Hanford site. The unsaturated water flow model, UNSAT-1D, was resonably successful in simulating the transient behavior of the water balance at this site. The effects of layered soils on water balance were demonstrated using the model. Models used to evaluate water balance in arid regions should not rely on annual averages and assume that all precipitation is removed by evapotranspiration. The potential for drainage at arid sites exists under conditions where shallow rooted plants grow on coarse textured soils. This condition was observed at our study site at Hanford. Neutron probe data collected on a cheatgrass community at the Hanford site during a wet year indicated that over 5 cm of water drained below the 3.5-m depth. The unsaturated water flow model, UNSAT-1D, predicted water drainage of about 5 cm (single layer, 10 months) and 3.5 cm (two layers, 12 months) for the same time period. Additional field measurements of hydraulic conductivity will likely improve the drainage estimate made by UNSAT-1D. Additional information describing cheatgrass growth and water use at the grass site could improve model predictions of sink terms and subsequent calculations of water storage within the rooting zone. In arid areas where the major part of the annual precipitation occurs during months with low average potential evapotranspiration and where soils are vegetated but are coarse textured and well drained, significant drainage can occur. 31 references, 18 figures, 1 table

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.

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

International Nuclear Information System (INIS)

Jacobson, G.; Wischusen, J.; Cresswell, R.; Fifield, K.

1998-01-01

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

Water-quality data for the Missouri River and Missouri River alluvium near Weldon Spring, St. Charles County, Missouri, 1991--92

International Nuclear Information System (INIS)

Kleeschulte, M.J.

1993-01-01

This report contains the water-quality data collected at two cross sections across the Missouri River and from monitoring wells in the Missouri River alluvium near Defiance, Missouri. The sampling results indicate the general water composition from the Missouri River changes with different flow conditions. During low-base flow conditions, the water generally contained about equal quantities of calcium and sodium plus potassium and similar quantities of bicarbonate and sulfate. During high-base flow conditions, water from the river predominantly was a calcium bicarbonate type. During runoff conditions, the water from the river was a calcium bicarbonate type, and sulfate concentrations were larger than during high-base flow conditions but smaller than during low-base flow conditions. The total and dissolved uranium concentrations at both the upstream and downstream cross sections, as well as from the different vertical samples across the river, were similar during each sampling event. However, sodium, sulfate, nitrate, and total and dissolved uranium concentrations varied with different flow conditions. Sodium and sulfate concentrations were larger during low-base flow conditions than during high-base flow or runoff conditions, while nitrate concentrations decreased during low-base flow conditions. Both total and dissolved uranium concentrations were slightly larger during runoff events than during low-base or high-base flow conditions

Special waste form lysimeters-arid. Annual report, 1985

International Nuclear Information System (INIS)

Walter, M.B.; Graham, M.J.

1985-09-01

The Special Waste Form Lysimeters-Arid program was initiated to determine typical source terms generated by commercial solidified low-level nuclear waste in an arid climate. Waste-form leaching tests are being conducted at a field facility at the Hanford site near Richland, Washington. A similar program is being conducted at a humid site. The field facility consists of 10 lysimeters placed around a central instrument caisson. The waste samples from boiling water and pressurized water reactors were emplaced in 1984, and the lysimeters are being monitored for movement of contaminants and water. Solidifying agents being tested include vinyl ester-styrene, bitumen, and cement. Laboratory leaching and geochemical modeling studies are being conducted to predict expected leach rates at the field site and to aid field-data interpretation. Small samples of the solidified waste forms were made for use in the laboratory leaching studies that include standard leach tests and leaching of solidified waste forms in soil columns. Complete chemical and radionuclide analyses are being conducted on the solid and liquid portions of the wastes. 2 refs

Special Waste Form Lysimeters-Arid: annual report 1985

International Nuclear Information System (INIS)

Walter, M.B.; Graham, M.J.

1986-01-01

The Special Waste Form Lysimeters-Arid program was initiated to determine typical source terms generated by commercial solidified low-level nuclear waste in an arid climate. Waste-form leaching tests are being conducted at a field facility at the Hanford site near Richland, Washington. A similar program is being conducted at a humid site. The field facility consists of 10 lysimeters placed around a central instrument caisson. The waste samples from boiling water and pressurized water reactors were emplaced in 1984, and the lysimeters are being monitored for movement of contaminants and water. Solidifying agents being tested include vinyl ester-styrene, bitumen, and cement. Laboratory leaching and geochemical modeling studies are being conducted to predict expected leach rates at the field site and to aid field-data interpretation. Small samples of the solidified waste forms were made for use in the laboratory leaching studies that include standard leach tests and leaching of solidified waste forms in soil columns. Complete chemical and radionuclide analyses are being conducted on the solid and liquid portions of the wastes

Exploring the strategies for households to adapt to climate-change in arid and semiarid East Africa

NARCIS (Netherlands)

Ng'ang'a, Stanley K.

2018-01-01

In this thesis I set out to investigate how households cope and adapt to climate change in the context of arid and semi-arid areas of East Africa. This research fits well in the wider literature on the relationship between climate change and variability and household responses in term of coping

On the peculiarities of subsurface uranium concentrations in the arid regions

International Nuclear Information System (INIS)

Kochenov, A.V.; Chernikov, A.A.

1976-01-01

The general features of uranium distribution in the zone of hypergenesis of the area under investigation suggest a lack of accumulations due to climatic or landscape factors alone and formed at the expense of background near-clark contents of uranium in primary rocks. The low uranium concentrations in the debris layer of weathered crusts of acidic effusive rocks and granites as well as in salt marshes are of areal distribution and, in practice, never recorded as anomalies. The processes of salt formation in the area discussed appear, in the absence of organic matter in the sediments, to be insufficient by themselves for the accumulation of uranium from its near-clark contents in the primary rocks. At the same time the arid conditions are undoubtedly favorable for the formation and persistence of accumulative diffusion aureoles emphasizing and revealing on the surface the smallest and poorest primary concentrations of uranium. It is inadmissible to extrapolate the results of a study of one area to the entire variety of geomorphological conditions of the arid zone. The data reported show that care should be taken in interpreting uranium anomalies in arid areas, by all means taking account of the geological structure of the particular anomalous area and the uranium resources of the primary rocks

Agroecological and Social Transformations for Coexistence with Semi-Aridity in Brazil

Directory of Open Access Journals (Sweden)

Aldrin M. Pérez-Marin

2017-06-01

Full Text Available This article explores whether a shift in development paradigm resulted in coexistence with semi-aridity for residents of the Semi-Arid region of Brazil (SAB. If so, which strategies contributed and which conditions facilitated it? We conducted a comparative analysis of the transformations that occurred in 10 territories of the SAB during two time periods: PI (1973–2001 when “development” policies almost exclusively aimed to “combat drought and its effects”; and PII (2002–2016 when a concept of coexistence with semi-aridity informed policy making. Our study from the 10 territories of the SAB show significant changes between PI and PII. On average, there was a substantial improvement in Access to Water Infrastructure (+33%∆, Diversification of Production Systems (Animals +36%∆; Crops +61%∆, Management of Common Pool Resources (+45%∆, Involvement in Spaces of Political Organizing (+24%∆, and Access to Public Programs (+29%∆. As such, “coexistence” went from concept to action as a consequence of structural, agroecological, social, and management transformations in combination with a strengthening of mechanisms for community reciprocity. These were characterized by (a the creation of resource reserves for use during times of drought; (b the efficient use of available natural resources; and (c enhanced articulation between diverse actors.

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

NARCIS (Netherlands)

Pan, Xu; Song, Yao-Bin; Liu, Guo-Fang; Hu, Yu-Kun; Ye, Xue-Hua; Cornwell, W.K.; Prinzing, A.; Dong, Ming; Cornelissen, J.H.C.

2015-01-01

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

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

Science.gov (United States)

Jin, T. T.; Fu, B. J.; Liu, G. H.; Wang, Z.

2011-08-01

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 conditions, and the

New developments in the techniques of uranium exploration in Egypt. Case histories for exploration under arid conditions

International Nuclear Information System (INIS)

El-Shazly, E.M.; Meshref, W.M.; Ammar, A.A.; El-Ghawaby, M.A.; El-Kassas, I.A.; El-Rakaiby, M.M.

1977-01-01

Exploration for radioactive mineralizations and mineral accumulations in Egypt during the last five years involved the application of new techniques and their adaptation to the prevailing semi-arid to arid environment. The mobilization of uranium and thorium, and their daughter products in the oxidation zone, is greatly influenced by this particular environment. Exploration techniques employed include the use of airborne, space-borne, ground and sub-surface methodologies. Case histories for uranium exploration have been formulated through practical experience, which can be applied in the arid regions in different parts of the world where conditions are comparable to those of Egypt. (author)

HIC1 interacts with a specific subunit of SWI/SNF complexes, ARID1A/BAF250A

International Nuclear Information System (INIS)

Van Rechem, Capucine; Boulay, Gaylor; Leprince, Dominique

2009-01-01

HIC1, a tumor suppressor gene epigenetically silenced in many human cancers encodes a transcriptional repressor involved in regulatory loops modulating p53-dependent and E2F1-dependent cell survival and stress responses. HIC1 is also implicated in growth control since it recruits BRG1, one of the two alternative ATPases (BRM or BRG1) of SWI/SNF chromatin-remodeling complexes to repress transcription of E2F1 in quiescent fibroblasts. Here, through yeast two-hybrid screening, we identify ARID1A/BAF250A, as a new HIC1 partner. ARID1A/BAF250A is one of the two mutually exclusive ARID1-containing subunits of SWI/SNF complexes which define subsets of complexes endowed with anti-proliferative properties. Co-immunoprecipitation assays in WI38 fibroblasts and in BRG1-/- SW13 cells showed that endogenous HIC1 and ARID1A proteins interact in a BRG1-dependent manner. Furthermore, we demonstrate that HIC1 does not interact with BRM. Finally, sequential chromatin immunoprecipitation (ChIP-reChIP) experiments demonstrated that HIC1 represses E2F1 through the recruitment of anti-proliferative SWI/SNF complexes containing ARID1A.

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

Science.gov (United States)

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

2008-05-01

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

New Possibilities for High-Resolution, Large-Scale Ecosystem Assessment of the World's Semi-Arid Regions

Science.gov (United States)

Burney, J. A.; Goldblatt, R.

2016-12-01

Understanding drivers of land use change - and in particular, levels of ecosystem degradation - in semi-arid regions is of critical importance because these agroecosystems (1) are home to the world's poorest populations, almost all of whom depend on agriculture for their livelihoods, (2) play a critical role in the global carbon and climate cycles, and (3) have in many cases seen dramatic changes in temperature and precipitation, relative to global averages, over the past several decades. However, assessing ecosystem health (or, conversely, degradation) presents a difficult measurement problem. Established methods are very labor intensive and rest on detailed questionnaires and field assessments. High-resolution satellite imagery has a unique role semi-arid ecosystem assessment in that it can be used for rapid (or repeated) and very simple measurements of tree and shrub density, an excellent overall indicator for dryland ecosystem health. Because trees and large shrubs are more sparse in semi-arid regions, sub-meter resolution imagery in conjunction with automated image analysis can be used to assess density differences at high spatial resolution without expensive and time-consuming ground-truthing. This could be used down to the farm level, for example, to better assess the larger-scale ecosystem impacts of different management practices, to assess compliance with REDD+ carbon offset protocols, or to evaluate implementation of conservation goals. Here we present results comparing spatial and spectral remote sensing methods for semi-arid ecosystem assessment across new data sources, using the Brazilian Sertão as an example, and the implications for large-scale use in semi-arid ecosystem science.

Functionally relevant climate variables for arid lands: Aclimatic water deficit approach for modelling desert shrub distributions

Science.gov (United States)

Thomas E. Dilts; Peter J. Weisberg; Camie M. Dencker; Jeanne C. Chambers

2015-01-01

We have three goals. (1) To develop a suite of functionally relevant climate variables for modelling vegetation distribution on arid and semi-arid landscapes of the Great Basin, USA. (2) To compare the predictive power of vegetation distribution models based on mechanistically proximate factors (water deficit variables) and factors that are more mechanistically removed...

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

Seed germination, seedling traits, and seed bank of the tree Moringa peregrina (Moringaceae) in a hyper-arid environment.

Science.gov (United States)

Gomaa, Nasr H; Picó, F Xavier

2011-06-01

Water-limited hot environments are good examples of hyper-aridity. Trees are scarce in these environments but some manage to survive, such as the tree Moringa peregrina. Understanding how trees maintain viable populations in extremely arid environments may provide insight into the adaptive mechanisms by which trees cope with extremely arid weather conditions. This understanding is relevant to the current increasing aridity in several regions of the world. Seed germination experiments were conducted to assess variation in seed mass, seed germination, and seedling traits of Moringa peregrina plants and the correlations among these traits. A seed burial experiment was also designed to study the fate of M. peregrina seeds buried at two depths in the soil for two time periods. On average, seeds germinated in three days and seedling shoots grew 0.7 cm per day over three weeks. Larger seeds decreased germination time and increased seedling growth rates relative to smaller seeds. Seeds remained quiescent in the soil and germination was very high at both depths and burial times. The after-ripening time of Moringa peregrina seeds is short and seeds germinate quickly after imbibition. Plants of M. peregrina may increase in hyper-arid environments from seeds with larger mass, shorter germination times, and faster seedling growth rates. The results also illustrate the adjustment in allocation to seed biomass and correlations among seed and seedling traits that allows M. peregrina to be successful in coping with aridity in its environment.

Expression and methylation data from SLE patient and healthy control blood samples subdivided with respect to ARID3a levels

Directory of Open Access Journals (Sweden)

Julie M. Ward

2016-12-01

Full Text Available Previously published studies revealed that variation in expression of the DNA-binding protein ARID3a in B lymphocytes from patients with systemic lupus erythematosus (SLE correlated with levels of disease activity (“Disease activity in systemic lupus erythematosus correlates with expression of the transcription factor AT-rich-interactive domain 3A” (J.M. Ward, K. Rose, C. Montgomery, I. Adrianto, J.A. James, J.T. Merrill et al., 2014 [1]. The data presented here compare DNA methylation patterns from SLE peripheral blood mononuclear cells obtained from samples with high numbers of ARID3a expressing B cells (ARID3aH versus SLE samples with normal numbers of ARID3a+ B cells (ARID3aN. The methylation data is available at the gene expression omnibus (GEO repository, “Gene Expression Omnibus: NCBI gene expression and hybridization array data repository” (R. Edgar, M. Domrachev, A.E. Lash, 2002 [2]. Isolated B cells from SLE ARID3aH and ARID3aN B samples were also evaluated via qRT-PCR for Type I interferon (IFN signature and pathway gene expression levels by qRT-PCR. Similarly, healthy control B cells and B cells stimulated to express ARID3a with the TLR agonist, CpG, were also compared via qRT-PCR. Primers designed to detect 6 IFNa subtype mRNAs were tested in 4 IFNa, Epstein-Barr Virus-transformed B cell lines (“Reduced interferon-alpha production by Epstein-Barr virus transformed B-lymphoblastoid cell lines and lectin-stimulated lymphocytes in congenital dyserythropoietic anemia type I” (S.H. Wickramasinghe, R. Hasan, J. Smythe, 1997 [3]. The data in this article support the publication, “Human effector B lymphocytes express ARID3a and secrete interferon alpha” (J.M. Ward, M.L. Ratliff, M.G. Dozmorov, G. Wiley, J.M. Guthridge, P.M. Gaffney, J.A. James, C.F. Webb, 2016 [4].

Extending the clinical and genetic spectrum of ARID2 related intellectual disability. A case series of 7 patients.

Science.gov (United States)

Gazdagh, Gabriella; Blyth, Moira; Scurr, Ingrid; Turnpenny, Peter D; Mehta, Sarju G; Armstrong, Ruth; McEntagart, Meriel; Newbury-Ecob, Ruth; Tobias, Edward S; Joss, Shelagh

2018-04-23

In the last 3 years de novo sequence variants in the ARID2 (AT-rich interaction domain 2) gene, a subunit of the SWI/SNF complex, have been linked to intellectual disabilities in 3 case reports including one which describes frameshift mutations in ARID2 in 2 patients with features resembling Coffin-Siris syndrome. Coffin-Siris syndrome (CSS) is a rare congenital syndrome characterized by intellectual deficit, coarse facial features and hypoplastic or absent fifth fingernails and/or toenails among other features. Mutations in a number of different genes encoding SWI/SNF chromatin remodelling complex proteins have been described but the underlying molecular cause remains unknown in approximately 40% of patients with CSS. Here we describe 7 unrelated individuals, 2 with deletions of the ARID2 region and 5 with de novo truncating mutations in the ARID2 gene. Similarities to CSS are evident. Although hypertrichosis and hypoplasia of the fifth finger nail and distal phalanx do not appear to be common in these patients, toenail hypoplasia and the presence of Wormian bones might support the involvement of ARID2. Copyright © 2018. Published by Elsevier Masson SAS.

Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient.

Directory of Open Access Journals (Sweden)

Yizhao Chen

Full Text Available Water-use efficiency (WUE, defined as the ratio of net primary productivity (NPP to evapotranspiration (ET, is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS, to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES. The Aridity Index (AI was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999-2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH with 0.88 gC mm-1 and the lowest was in arid sub-region (AR with 0.22 gC mm-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.

Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient.

Science.gov (United States)

Chen, Yizhao; Li, Jianlong; Ju, Weimin; Ruan, Honghua; Qin, Zhihao; Huang, Yiye; Jeelani, Nasreen; Padarian, José; Propastin, Pavel

2017-01-01

Water-use efficiency (WUE), defined as the ratio of net primary productivity (NPP) to evapotranspiration (ET), is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS), to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES). The Aridity Index (AI) was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999-2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH) with 0.88 gC mm-1 and the lowest was in arid sub-region (AR) with 0.22 gC mm-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP) at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.

Modelling hydrologic and hydrodynamic processes in basins with large semi-arid wetlands

Science.gov (United States)

Fleischmann, Ayan; Siqueira, Vinícius; Paris, Adrien; Collischonn, Walter; Paiva, Rodrigo; Pontes, Paulo; Crétaux, Jean-François; Bergé-Nguyen, Muriel; Biancamaria, Sylvain; Gosset, Marielle; Calmant, Stephane; Tanimoun, Bachir

2018-06-01

Hydrological and hydrodynamic models are core tools for simulation of large basins and complex river systems associated to wetlands. Recent studies have pointed towards the importance of online coupling strategies, representing feedbacks between floodplain inundation and vertical hydrology. Especially across semi-arid regions, soil-floodplain interactions can be strong. In this study, we included a two-way coupling scheme in a large scale hydrological-hydrodynamic model (MGB) and tested different model structures, in order to assess which processes are important to be simulated in large semi-arid wetlands and how these processes interact with water budget components. To demonstrate benefits from this coupling over a validation case, the model was applied to the Upper Niger River basin encompassing the Niger Inner Delta, a vast semi-arid wetland in the Sahel Desert. Simulation was carried out from 1999 to 2014 with daily TMPA 3B42 precipitation as forcing, using both in-situ and remotely sensed data for calibration and validation. Model outputs were in good agreement with discharge and water levels at stations both upstream and downstream of the Inner Delta (Nash-Sutcliffe Efficiency (NSE) >0.6 for most gauges), as well as for flooded areas within the Delta region (NSE = 0.6; r = 0.85). Model estimates of annual water losses across the Delta varied between 20.1 and 30.6 km3/yr, while annual evapotranspiration ranged between 760 mm/yr and 1130 mm/yr. Evaluation of model structure indicated that representation of both floodplain channels hydrodynamics (storage, bifurcations, lateral connections) and vertical hydrological processes (floodplain water infiltration into soil column; evapotranspiration from soil and vegetation and evaporation of open water) are necessary to correctly simulate flood wave attenuation and evapotranspiration along the basin. Two-way coupled models are necessary to better understand processes in large semi-arid wetlands. Finally, such coupled

Seasonal behavioral responses of an arid-zone passerine in a hot environment.

Science.gov (United States)

Pattinson, Nicholas B; Smit, Ben

2017-10-01

Many arid-zone animals have to forage under extremely hot conditions to maintain water and energy balance. The effect of high air temperatures (T air ) on the behavioral patterns of small endothermic animals-characterized by their high energy and water demands-will provide a valuable framework for understanding species vulnerability to climate warming. We determined the seasonal behavioral responses to changes in T air in a~10-g arid-zone passerine, the rufous-eared warbler (Malcorus pectoralis), in the Karoo semi-desert, South Africa. Rufous-eared warblers showed significant temperature-dependence in their behavior in summer, but not in winter. During summer, the warblers frequently experienced T air exceeding 40°C in the shade. For all observations 36°C, the warblers showed reductions in preening (40% decrease), foraging effort (56% decrease), and foraging success (15% decrease), as well as a significant increase in time spent engaged in evaporative cooling behavior. Moreover, as T air increased the warblers shifted increasingly off the ground and out of the full sun, into microsites in the shade (131% increase) and in shrubs (23% increase). In this regard, behavior varied seasonally, with the time spent in the shade 23% higher, and foraging effort 28% higher, in summer compared to winter across a range of moderate T air (15-30°C). Our findings emphasize the link between behavior and temperature in small birds inhabiting hot, arid environments, as well as the importance of understanding these responses for predicting biologically meaningful responses (and hence, vulnerability) of arid-zone avian communities to climactic shifts. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment of the performance of water harvesting systems in semi-arid regions

Science.gov (United States)

Lasage, Ralph

2016-04-01

Water harvesting is widely practiced and has the potential to improve water availability for domestic and agricultural use in semi-arid regions. New funds are becoming available to stimulate the implementation of water harvesting projects, for meeting the Sustainable Development Goals and to help communities to adapt to climate change. For this, it is important to understand which factors determine the success of water harvesting techniques under different conditions. For this, we review the literature, including information on the crop yield impacts of water harvesting projects in semi-arid Africa and Asia. Results show that large water harvesting structures (> 500 m3) are less expensive than small structures, when taking into account investment costs, storage capacity and lifetimes. We also find that water harvesting improves crop yields significantly, and that the relative impact of water harvesting on crop yields is largest in low rainfall years. We also see that the governance, technical knowledge and initial investment are more demanding for the larger structures than for smaller structures, which may affect their spontaneous adoption and long term sustainability when managed by local communities. To support the selection of appropriate techniques, we present a decision framework based on case specific characteristics. This framework can also be used when reporting and evaluating the performance of water harvesting techniques, which is up to now quite limited in peer reviewed literature. Based on Bouma, J., Hegde, S.E., Lasage, R., (2016). Assessing the returns to water harvesting: A meta-analysis. Agricultural Water Management 163, 100-109. Lasage, R., Verburg P.H., (2015). Evaluation of small scale water harvesting techniques for semi-arid environments. Journal of Arid Environments 118, 48-57.

CONTROLLING FACTORS OF POTENTIAL EVAPOTRANSPIRATION ABOVE GRASSLAND IN HUMID AND ARID AREA

Directory of Open Access Journals (Sweden)

. Yanto

2013-05-01

Full Text Available Potential evapotranspiration (PET is an importance process in water balance studies controlled by a number of meteorological factors such as temperature, wind speed, atmospheric pressure, solar radiation, vapor pressure gradient, relative humidity and biological factors such as vegetation type, canopy height and plant density that varied in time-scale and in spatial scale. Of all those variables, determining the most controlling factors of evapotranspiration in humid and arid area is of interest of this paper. Two sites representing humid and arid area i.e. Fermi Prairie site in Illinois and Audubon Research Ranch in Arizona respectively were investigated in this study.  The flux data employed in this study was acquired from Ameriflux Netwotk. Penmann-Monteith formula is employed in to estimate evapotranspiration rate in both sites. The result shows that the PET is in dependence on the considered meteorological factor such as shortwave radiation, vapor pressure, air temperature, wind speed, net radiation and vapor pressure deficit. It is also can be inferred from the analysis that PET is also strongly controlled by vegetation factors represented as stomatal resistance. Keywords: Potential evapotranspiration, Penmann-Monteith, humid, arid.

Relation between century-scale Holocene arid intervals in tropical and temperate zones

Science.gov (United States)

Lamb, H. F.; Gasse, F.; Benkaddour, A.; El Hamouti, N.; van der Kaars, S.; Perkins, W. T.; Pearce, N. J.; Roberts, C. N.

1995-01-01

CLIMATE records from lake sediments in tropical Africa, Central America and west Asia show several century-scale arid intervals during the Holocene1-10. These may have been caused by temporary weakening of the monsoonal circulation associated with reduced northward heat transport by the oceans7 or by feedback processes stimulated by changes in tropical land-surface conditions10. Here we use a lake-sediment record from the montane Mediterranean zone of Morocco to address the question of whether these events were also felt in temperate continental regions. We find evidence of arid intervals of similar duration, periodicity and possibly timing to those in the tropics. But our pollen data show that the forest vegetation was not substantially affected by these events, indicating that precipitation remained adequate during the summer growing season. Thus, the depletion of the groundwater aquifer that imprinted the dry events in the lake record must have resulted from reduced winter precipitation. We suggest that the occurrence of arid events during the summer in the tropics but during the winter at temperate latitudes can be rationalized if they are both associated with cooler sea surface temperatures in the North Atlantic.

Characterization of lactic acid bacteria isolated from Algerian arid ...

African Journals Online (AJOL)

Diversity and density of lactic acid bacteria isolated from Algerian raw goats\\' milk in arid zones were studied by determination of morphological, cultural, physiological and biochemical characteristics. 206 lactic acid bacterial strains were isolated, with 115 of them belonging to lactic acid cocci and others to the genus, ...

Ground-water recharge in the arid and semiarid southwestern United States

Science.gov (United States)

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

2007-01-01

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

Do invasive riparian Tamarix alter hydrology of riparian areas of arid and semi-arid regions under climate change scenarios?

Science.gov (United States)

Bhattarai, M. P.; Acharya, K.; Chen, L.

2012-12-01

Competitiveness of riparian invasive species, Tamarix, in arid and semi-arid riparian areas of the southwestern United States under climate change scenario (SRES A2) was investigated. Tamarix has been replacing native vegetation along the riparian corridors of these areas for the past several decades and is thought to alter water balance. Changes in depth to groundwater, soil moisture distribution and flood frequency are critical in survival and growth of a facultative phreatophyte such as Tamarix. In this study, a fully coupled 2d surface flow and 3d subsurface flow hydrologic model, HydroGeoSphere, was used to simulate surface-subsurface hydrology of the lower Virgin River basin (4500 sq. km), located in Nevada, Utah and Arizona. The hydrologic model results, depth to groundwater and soil saturation, were then applied to the species distribution model, Maxent, along with other bioclimatic parameters to asses future Tamarix distribution probability. Simulations were made for the climate scenarios of the end of 21st centry conditions. Depth to groundwater is found to be the most important predictor variable to the Maxent model. Future Tamarix distribution range is not uniform across the basin. It is likely to decrease at lower elevations and increase in some higher elevation areas.

Climate-smart crop production in semi-arid areas through increased knowledge of varieties, environment and management factors

NARCIS (Netherlands)

Murungweni, C.; Wijk, van M.T.; Smaling, E.M.A.; Giller, K.E.

2016-01-01

In large regions of sub-Saharan Africa, semi-arid conditions are likely to increase with climate change, yet these regions are becoming more important to feed production zones due to increasing population pressure. A production system in the semi-arid south eastern Zimbabwe was studied to assess

Heterozygosity for ARID2 loss-of-function mutations in individuals with a Coffin-Siris syndrome-like phenotype.

Science.gov (United States)

Bramswig, Nuria C; Caluseriu, O; Lüdecke, H-J; Bolduc, F V; Noel, N C L; Wieland, T; Surowy, H M; Christen, H-J; Engels, H; Strom, T M; Wieczorek, D

2017-03-01

Chromatin remodeling is a complex process shaping the nucleosome landscape, thereby regulating the accessibility of transcription factors to regulatory regions of target genes and ultimately managing gene expression. The SWI/SNF (switch/sucrose nonfermentable) complex remodels the nucleosome landscape in an ATP-dependent manner and is divided into the two major subclasses Brahma-associated factor (BAF) and Polybromo Brahma-associated factor (PBAF) complex. Somatic mutations in subunits of the SWI/SNF complex have been associated with different cancers, while germline mutations have been associated with autism spectrum disorder and the neurodevelopmental disorders Coffin-Siris (CSS) and Nicolaides-Baraitser syndromes (NCBRS). CSS is characterized by intellectual disability (ID), coarsening of the face and hypoplasia or absence of the fifth finger- and/or toenails. So far, variants in five of the SWI/SNF subunit-encoding genes ARID1B, SMARCA4, SMARCB1, ARID1A, and SMARCE1 as well as variants in the transcription factor-encoding gene SOX11 have been identified in CSS-affected individuals. ARID2 is a member of the PBAF subcomplex, which until recently had not been linked to any neurodevelopmental phenotypes. In 2015, mutations in the ARID2 gene were associated with intellectual disability. In this study, we report on two individuals with private de novo ARID2 frameshift mutations. Both individuals present with a CSS-like phenotype including ID, coarsening of facial features, other recognizable facial dysmorphisms and hypoplasia of the fifth toenails. Hence, this study identifies mutations in the ARID2 gene as a novel and rare cause for a CSS-like phenotype and enlarges the list of CSS-like genes.

Ecotoxicology of organisms adapted to life in temporary freshwater ponds in arid and semi-arid regions.

Science.gov (United States)

Lahr, J

1997-01-01

Hot arid and semi-arid zones are characterized by an abundance of temporary ponds. Most of these depend on rain for their existence. These habitats are distinguished by fluctuating and unpredictable changes in their hydrological regime and of physical and chemical conditions.They contain a uniquely-adapted fauna that copes in different ways with changing and often extreme temperatures, oxygen levels, pH, salinity and turbidity. A classification is presented of the most distinctive adaptations,the various tactics that organisms apply to survive dry periods. The main strategies are dormancy (escape in time) and dispersal (escape in space). These adaptations may affect the impact of toxicants on individuals, populations and communities of temporary ponds. The physiological adaptations of species found in temporary ponds are likely to alter the sensitivity to pollutants of characteristic species. Results from laboratory experiments,for example, suggest that fairy shrimp (Branchiopoda, Anostraca) may react differently to heavy metals and pesticides as the standard test species Daphnia. Life history strategies influence recovery rates of populations after exposure to acutely toxic substances such as pesticides. It is also suggested that slow growth and decreased reproductive capacity of organisms caused by toxicants may, in ephemeral ponds, result in the failure of annual recruitment. Whether assemblages of organisms in temporary ponds are generally more vulnerable or more resilient than those in permanent waters or temperate regions could not be determined conclusively with the limited data available. Ecological concepts for studying the habitat and the development of risk assessment methods for temporary ponds are briefly discussed.

Lake Area Changes and Their Influence on Factors in Arid and Semi-Arid Regions along the Silk Road

Directory of Open Access Journals (Sweden)

Chao Tan

2018-04-01

Full Text Available In the context of global warming, the changes in major lakes and their responses to the influence factors in arid and semi-arid regions along the Silk Road are especially important for the sustainable development of local water resources. In this study, the areas of 24 lakes were extracted using MODIS NDVI data, and their spatial-temporal characteristics were analyzed. In addition, the relationship between lake areas and the influence factors, including air temperature, precipitation, evapotranspiration, land use and land cover change (LULCC and population density in the watersheds, were investigated. The results indicated that the areas of most lakes shrank, and the total area decreased by 22,189.7 km2 from 2001 to 2016, except for those of the lakes located on the Qinghai-Tibetan Plateau. The air temperature was the most important factor for all the lakes and increased at a rate of 0.113 °C/a during the past 16 years. LULCC and the increasing population density markedly influenced the lakes located in the middle to western parts of this study area. Therefore, our results connecting lake area changes in the study region highlight the great challenge of water resources and the urgency of implementation of the green policy in the One Belt and One Road Initiative through international collaboration.

Transport assessment - arid: measurement and prediction of water movement below the root zone

International Nuclear Information System (INIS)

Gee, G.W.; Kirkham, R.R.

1984-01-01

The amount of water transported below the root-zone and available for drainage (recharge) must be known in order to quantify the potential for leaching at low-level waste sites. Under arid site conditions, we quantified drainage by using weighing lysimeters containing sandy soil and measured 6 and 11 cm of drainage for a 1-yr period (June 1983-May 1984) from grass-covered and bare-soil surfaces, respectively. Precipitation during this period at our test site near Richland, Washington, was 25 cm. Similar drainage values were estimated from neutron probe measurements of water content profile changes in an adjacent grass-covered site. These data suggest that significant amounts of drainage can occur at arid sites when soils are coarse textured and precipitation occurs during fall and winter months. Model simulations predicted drainage values comparable to those measured with our weighing lysimeters. Long-term, 500- to 1000-yr predictions of leaching are possible with our model simulations. However, additional studies are needed to evaluate the effect of soil variability and stochastic rainfall inputs on drainage estimates, particularly for arid sites

First record of Chantransia macrospora Wood, 1887 (Batrachospermales, Rhodophyta in semi-arid northeastern Brazil

Directory of Open Access Journals (Sweden)

Janiele França Vasconcelos

2014-12-01

Full Text Available This study presents the first record of Chantransia macrospora in the state of Rio Grande do Norte, in the semi-arid region of northeastern Brazil. Analyses of periphytic algae revealed C. macrospora individuals associated in particular with shells of Melanoides tuberculatus, a non-native species, suggesting that C. macrospora have been introduced into systems associated with the gastropods. In this context, new records of C. macrospora are still expected for the Brazilian semi-arid region in the next years.

Evaporation as the transport mechanism of metals in arid regions

KAUST Repository

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

2014-01-01

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

Lead Thickness Measurements

International Nuclear Information System (INIS)

Rucinski, R.

1998-01-01

The preshower lead thickness applied to the outside of D-Zero's superconducting solenoid vacuum shell was measured at the time of application. This engineering documents those thickness measurements. The lead was ordered in sheets 0.09375-inch and 0.0625-inch thick. The tolerance on thickness was specified to be +/- 0.003-inch. The sheets all were within that thickness tolerance. The nomenclature for each sheet was designated 1T, 1B, 2T, 2B where the numeral designates it's location in the wrap and 'T' or 'B' is short for 'top' or 'bottom' half of the solenoid. Micrometer measurements were taken at six locations around the perimeter of each sheet. The width,length, and weight of each piece was then measured. Using an assumed pure lead density of 0.40974 lb/in 3 , an average sheet thickness was calculated and compared to the perimeter thickness measurements. In every case, the calculated average thickness was a few mils thinner than the perimeter measurements. The ratio was constant, 0.98. This discrepancy is likely due to the assumed pure lead density. It is not felt that the perimeter is thicker than the center regions. The data suggests that the physical thickness of the sheets is uniform to +/- 0.0015-inch.

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.

Modelling annual evapotranspiration in a semi-arid, African savanna ...

African Journals Online (AJOL)

Accurately measuring evapotranspiration (ET) is essential if we are to derive reasonable estimates of production and water use for semi-arid savannas. Estimates of ET are also important in defining the health of an ecosystem and the quantity of water used by the vegetation when preparing a catchment-scale water balance.

Adaptation at Scale in Semi-Arid Regions | IDRC - International ...

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

People living in Africa and South Asia's semi-arid regions face challenges that hinder their economic growth and development. This project seeks to find proactive, longer-term approaches to climate change adaptation in these vulnerable regions, while helping locals manage existing risks. Short-term focus must shift. So far ...

Determining Dry Matter Degradability of Some Semi-Arid Browse ...

African Journals Online (AJOL)

acer

ABSTRACT: The in vitro gas production of some semi-arid browse species were evaluated. The relationship between in ... between in vitro gas measured on incubation of browse leaves and that calculated from SCFA allows the prediction of SCFA from ... with concentrate feed (40% corn, 10% wheat offal, 10% palm kernel ...

Paclobutrazol biodegradation in unsaturated soil in the Semi-Arid ...

African Journals Online (AJOL)

Paclobutrazol (PBZ) is a plant growth regulator, increasing flowe ring and yield that is widely used in mango cultivation in the semi-arid northeastern Brazil. PBZ remains active in the soil for several years. However, it can severely affect the growth and development of subsequent crops, mainly by reducing vegetative vigor.

Rocks, climate and the survival of human societies in hyper-arid and arid environments - Are the human civilization in deserts at a permanent risk of collapse?

Science.gov (United States)

Yoav, Avni; Noa, Avriel-Avni

2017-04-01

The great challenges of living in the arid and hyper arid regions worldwide are the shortage of water, limited resources and the permanent uncertainty of the desert climate. These challenges are known as the main weaknesses of desert societies that are prone, according to the existing paradigm, to a permanent risk of collapse. However, in the Middle East deserts, human societies are known since prehistoric times and during the entire hyper-dry Holocene. This hints that the simple paradigm of desert societies' high vulnerability to harsh desert environments needs to be better examined. In this context we examine three case studies: 1. The Southern Sinai region in Egypt: In this region, the annual precipitation fluctuates between 20-50 mm/y. However, in this highly mountainous area, desert agriculture plots including orchards were constructed, located mainly around the byzantine monastery of Santa Katerina. During the last 1500 years, much of the water supply needed for humans and agriculture was generated from runoff developed on exposed granite rocks. 2. The southern Jordan region south of Petra: Much of this wide area connecting the deserts of the Arabian Peninsula and southern Jordan receive only 20-30 mm/y. However, the main caravan route established by the Arabian tribes during the first millennia BC managed to cross this land, supplying the water needs of many camels. Most of this water was stored in large cisterns dug into the sandstone rock formations exposed along the route, especially within the Disi Formation. 3. The Negev Highlands of southern Israel: This region is divided between the hyper arid region to the south, receiving 70-80 mm/y, and the arid region to the north receiving 90-130 mm/y. During the last two millennia, the hyper arid area was used for camel grazing and goats herds, while the northern sector was used for the construction of agriculture plots, agriculture farms and even desert towns. All these activities were sustained by runoff

Characteristics and influencing factors of crop coefficient for drip-irrigated cotton under plastic mulch conditions in arid environment

DEFF Research Database (Denmark)

Ai, Zhipin; Yang, Yonghui; Wang, Qinxue

2017-01-01

agronomy practice such as plastic mulching and drip irrigation in arid environments. This study calculated and analyzed Kc of a drip-irrigated and plastic-mulched cotton field in Aksu Oasis of the arid Tarim River Basin, China, and its relationships with several crop-, soil- and management variables......-mulched condition already published, the Kc of mulched cotton for the entire growth season decreased by 16 to 39%. The largest reductions in Kc due to plastic mulch were found in the initial and developmental growth stage. Kc could be calculated by a third-degree polynomial model in relation to RGD, which...... significantly increased Kc, i.e., 29% on average, partly due to arid advection. This study provided up-to-date and detailed information on cotton crop coefficient under plastic mulching and drip irrigation conditions in arid environment, and it is useful for improved management of agricultural water resources....

Performance comparison of land change modeling techniques for land use projection of arid watersheds

Directory of Open Access Journals (Sweden)

S.M. Tajbakhsh

2018-07-01

Full Text Available The change of land use/land cover has been known as an imperative force in environmental alteration, especially in arid and semi-arid areas. This research was mainly aimed to assess the validity of two major types of land change modeling techniques via a three dimensional approach in Birjand urban watershed located in an arid climatic region of Iran. Thus, a Markovian approach based on two suitability and transition potential mappers, i.e. fuzzy analytic hierarchy process and artificial neural network-multi layer perceptron was used to simulate land use map. Validation metrics, quantity disagreement, allocation disagreement and figure of merit in a three-dimensional space were used to perform model validation. Utilizing the fuzzy-analytic hierarchy processsimulation of total landscape in the target point 2015, quantity error, the figure of merit and allocation error were 2%, 18.5% and 8%, respectively. However, Artificial neural network-multi layer perceptron simulation led to a marginal improvement in figure of merit, i.e. 3.25%.

REUSE OF TREATED WASTEWATER IN AGRICULTURE: SOLVING WATER DEFICIT PROBLEMS IN ARID AREAS (REVIEW

Directory of Open Access Journals (Sweden)

Faissal AZIZ

2014-12-01

Full Text Available In the arid and semiarid areas, the availability and the management of irrigation water have become priorities of great importance. The successive years of drought, induced by climate change and population growth, increasingly reduced the amount of water reserved for agriculture. Consequently, many countries have included wastewater reuse as an important dimension of water resources planning. In the more arid areas wastewater is used in agriculture, releasing high resource of water supplies. In this context, the present work is a review focusing the reuse of treated wastewater in agriculture as an important strategy for solving water deficit problems in arid areas. Much information concerning the wastewater reuse in different regions of the world and in Morocco, the different wastewater treatment technologies existing in Morocco were discussed. The review focused also the fertilizing potential of wastewater in agriculture, the role of nutrients and their concentrations in wastewater and their advantages effects on plant growth and yield.

Comments on: The moisture from the air as water resource in arid region: hopes, doubt and facts

NARCIS (Netherlands)

Beysens, D.; Milimouk, I.; Nikolayev, V.; Berkowicz, S.M.; Muselli, M.; Heusinkveld, B.G.; Jacobs, A.F.G.

2006-01-01

Kogan and Trahtman [2003. The moisture from the air as water resource in arid region: hopes, doubts and facts. Journal of Arid Environments 53, 231¿240] analysed the functioning of a passive dew condenser built by F.I. Zibold in 1912 in Feodosia, and proposed a model to explain how thousands of

The simulation of naturally ventilated residential buildings in semi-arid regions

Energy Technology Data Exchange (ETDEWEB)

Ghiabaklou, Z.; Ballinger, J.A.; Prasad, D.K. [New South Wales Univ., Kensington, NSW (Australia). Solar Architecture Research Unit

1995-12-31

The most important consideration in hot arid and semi-arid zones is to reduce the internal day temperature and to maintain the interior spaces of buildings in a comfortable condition. An important contributor to errors in the thermal analysis of naturally ventilated buildings is inaccurate airflow predictions. These predictions are important for designers in regions where most buildings are naturally ventilated. Passive cooling by day and night natural ventilation in a single story residential building in Wagga Wagga, a semi-arid location in New South Wales has been compared and analyzed theoretically. A modified version of the computer simulation program CHEETAH, has been used to consider a building with continuous natural ventilation to simulate indoor air temperature. The aim of the study was to investigate the thermal behaviour of the building with continuous ventilation (24 hour/day) and the same building with only night time ventilation. Using night time ventilation in high mass buildings in such a climate, leads to a considerable decrease in room air temperature. Simulation results showed that increasing the effective area of windows is effective only when the wind blows. Using a steady averaged air change per hour can also cause a reduction in room air temperatures which results in different temperatures than the actual air changes per hour. (author). 3 figs., 4 refs.

Diversification and persistence at the arid-monsoonal interface: australia-wide biogeography of the Bynoe's gecko (Heteronotia binoei; Gekkonidae).

Science.gov (United States)

Fujita, Matthew K; McGuire, Jimmy A; Donnellan, Stephen C; Moritz, Craig

2010-08-01

Late Neogene aridification in the Southern Hemisphere caused contractions of mesic biota to refugia, similar to the patterns established by glaciation in the Northern Hemisphere, but these episodes also opened up new adaptive zones that spurred range expansion and diversification in arid-adapted lineages. To understand these dynamics, we present a multilocus (nine nuclear introns, one mitochondrial gene) phylogeographic analysis of the Bynoe's gecko (Heteronotia binoei), a widely distributed complex spanning the tropical monsoon, coastal woodland, and arid zone biomes in Australia. Bayesian phylogenetic analyses, estimates of divergence times, and demographic inferences revealed episodes of diversification in the Pliocene, especially in the tropical monsoon biome, and range expansions in the Pleistocene. Ancestral habitat reconstructions strongly support recent and independent invasions into the arid zone. Our study demonstrates the varied responses to aridification in Australia, including localized persistence of lineages in the tropical monsoonal biome, and repeated invasion of and expansion through newly available arid-zone habitats. These patterns are consistent with those found in other arid environments in the Southern Hemisphere, including the South African succulent karoo and the Chilean lowlands, and highlight the diverse modes of diversification and persistence of Earth's biota during the glacial cycles of the Pliocene and Pleistocene.

Relationship Between Job Burnout and Neuroendocrine Indicators in Soldiers in the Xinjiang Arid Desert: A Cross-Sectional Study

Directory of Open Access Journals (Sweden)

Ning Tao

2015-12-01

Full Text Available The purpose of this study was to explore the relationship between job burnout and neuroendocrine indicators in soldiers living in a harsh environment. Three hundred soldiers stationed in the arid desert and 600 in an urban area were recruited. They filled in the Chinese Maslach Burnout Inventory questionnaire. One hundred soldiers were randomly selected from each group to measure their levels of noradrenaline, serotonin, heat shock protein (HSP-70, adrenocorticotropic hormone, and serum cortisol. Job burnout was more common in soldiers from urban areas than those from rural areas. Job burnout was significantly higher among soldiers stationed in the arid desert than those in urban areas. For soldiers in the arid desert, the levels of HSP-70, serum cortisol, and adrenocorticotropic hormone were significantly higher than in soldiers in urban areas. Correlation analyses showed that the degree of job burnout was weakly negatively correlated with the level of HSP-70. Being an only child, HSP-70 levels, cortisol levels, and ACTH levels were independently associated with job burnout in soldiers stationed in the arid desert. A higher level of job burnout in soldiers stationed in arid desert and a corresponding change in neuroendocrine indicators indicated a correlation between occupational stress and neurotransmitters.

Hydrological modeling in semi-arid region using HEC-HMS model ...

African Journals Online (AJOL)

The purpose of this study is to simulate rainfall-runoff in the semi-arid region of ... the frequency storm is used for the meteorological model, the SCS curve number is ... SCS unit hydrograph method have been applied to simulate the runoff rate.

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).

Productivity of selected plant species adapted to arid regions. [Crassulacean metabolizing plants; Agave deserti and Ferocactus acanthodes

Energy Technology Data Exchange (ETDEWEB)

Nobel, P.S.

1980-01-01

The biomass potential of selected arid region species for alcohol production merits careful consideration. The basis for this interest is the current low agronomic use of arid lands and the potential productivity of certain species adapted to these lands. Plants displaying Crassulacean acid metabolism (CAM) are particularly interesting with reference to biomass for fuel in regions with low rainfall, because plants with this photosynthetic process are strikingly efficient in water requirements. For CAM plants, CO/sub 2/ fixation occurs primarily at night, when tissue surface temperature and hence transpirational water loss is less than daytime values. For Agave deserti in the Sonoran desert, the water-use efficiency (mass of CO/sub 2/ fixed/mass of water transpired) over an entire year is an order of magnitude or more larger than for C-3 and C-4 plants. This indicates how well adapted CAM species are to arid regions. The potential productivity per unit land area of CAM plants is fairly substantial and, therefore, of considerable economic interest for arid areas where growth of agricultural plants is minimal.

Projected and Observed Aridity and Climate Change in the East Coast of South India under RCP 4.5

Science.gov (United States)

Ramachandran, A.; Praveen, Dhanya; Jaganathan, R.; Palanivelu, K.

2015-01-01

In the purview of global warming, the present study attempts to project changes in climate and quantify the changes in aridity of two coastal districts in south India under the RCP 4.5 trajectory. Projected climate change output generated by RegCM 4.4 model, pertaining to 14 grid points located within the study area, was analyzed and processed for this purpose. The meteorological parameters temperature and precipitations were used to create De Martonne Aridity Index, to assess the spatial distribution of aridity. The original index values ranged from 13.7 to 16.4 mm/°C, characterizing this area as a semidry climate. The outcome from the changed scenario analysis under RCP 4.5 showed that, during the end of the 21st century, the aridity may be increased more as the index values tend to reduce. The increasing trend in the drying phenomenon may be attributed to the rising of mean annual temperatures. PMID:26771002

Optimizing cooling systems in Egyptian arid urbans

International Nuclear Information System (INIS)

Medhat, Ahmed A.; Khalil, Essam E.

2006-01-01

Present study is devoted to climatic and site oriented investigations that were carried out in a new rural development in the Upper-Egypt. Bioclimatic classifications considered Upper Egypt region, near Sudan border, as a Hot and Dry climatic region. [1]. that is affected by solar heat intensities that can reach 900 W/m2 for a period ranged from 5-to-7 hours per day with the presence of study storms. Cooling season extends up to eight months per year having Upper-day-bulb temperature ranged from 400 degree centigrade - to - 470 degree centigrade while Lower-dry-bulb-temperature ranged from 280 degree centigrade - to - 320 degree centigrade with the relative humidity ranged from 10%-to-37% RH. [2]. Site surveys and field experimental and analyses of the commonly used cooling systems were investigated, evaluated and optimized for optimum indoor comfort conditions at efficient energy efficiency. [3]. Extensive analyses were performed based on Psychrometric formulae to evaluate the impact of energy consumptions related to different cooling systems such as direct expansion, chilled water, and evaporative systems. the present study enables the critical investigations of the influence of arid outdoor conditions and the required indoor thermal parameters on the energy efficiencies of HVAC-system. This work; focuses on the suggestion of suitable system that should be implemented by local energy codes in these arid urban.(Author)

Meaningful traits for grouping plant species across arid ecosystems.

Science.gov (United States)

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

2016-05-01

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

Uranium isotopes in carbonate aquifers of arid region setting

International Nuclear Information System (INIS)

Alshamsi, D.M.; Murad, A.A.

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 238 U and 235 U 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 235 U 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 concentrations suggests that in lithologically comparable aquifers, climate may influence the concentration of uranium in subtropical to arid regions. (author)

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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

CSIR Research Space (South Africa)

O'Farrell, PJ

2009-01-01

Full Text Available . Grassl. Soc. S. Afr. 8, 126–130. 7. Wilhite D.A. and Glantz M.H. (1985). Understanding the drought phenome- non: the role of definitions. Water Int. 10(3), 111–120. 8. Le Houerou H.N. (1996). Climate change, drought and desertification. J. Arid....E. and Tainton N.M. (1996). Range management: optimising forage production and quality. Bull. Grassl. Soc. S. Afr. 7 (1), 36–43. 13. Scoones I. (1992). Coping with drought – responses of herders and livestock in contrasting savanna environments in southern...

Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico

OpenAIRE

Roth-Monzón, Andrea J.; Mendoza-Hernández, Andrés Alberto; Flores-Villela, Oscar

2018-01-01

Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of...

Determining termite diversity in arid Namibian rangelands – a ...

African Journals Online (AJOL)

Three methods of sampling termite diversity in arid rangelands were tested in Namibia during the wet (March) and dry (October) seasons of 1998. Six sites were chosen: one pair on each of three farms representing a gradient of land use intensity. At each site, two adjacent plots of 1 ha each were sampled: one plot by a ...

Transport assessment - arid: measurement and prediction of water movement below the root zone

International Nuclear Information System (INIS)

Gee, G.W.; Kirkham, R.R.

1984-09-01

The amount of water transported below the root-zone and available for drainage (recharge) must be known in order to quantify the potential for leaching at low-level waste sites. Under arid site conditions, we quantified drainage by using weighing lysimeters containing sandy soil and measured 6 and 11 cm of drainage for a 1-yr period (June 1983-May 1984) from grass-covered and bare-soil surfaces, respectively. Precipitation during this period at our test site near Richland, Washington, was 25 cm. Similar drainage values were estimated from neutron probe measurements of water content profile changes in an adjacent grass-covered site. These data suggest that significant amounts of drainage can occur at arid sites when soils are coarse textured and precipitation occurs during fall and winter months. Model simulations predicted drainage values comparable to those measured with our weighing lysimeters. Long-term, 500- to 1000-yr predictions of leaching are possible with our model simulations. However, additional studies are needed to evaluate the effect of soil variability and stochastic rainfall inputs on drainage estimates, particularly for arid sites. 15 references, 9 figures, 1 table

Microscopic investigations of palynological features of convolvulaceous species from arid zone of Pakistan.

Science.gov (United States)

Ashfaq, Shomaila; Zafar, Muhammad; Ahmad, Mushtaq; Sultana, Shazia; Bahadur, Siraj; Khan, Adeel; Shah, Amin

2018-02-01

The pollen morphology of some species of glamorous family Convolvulaceae from arid zones of Pakistan has been evaluated. The pollen grains were acetolyzed, measured, described qualitatively, and illustrated using Light microscopy and scanning electron microscopy (SEM). The examined species have differences in shape, size, polarity and exine ornamentation, confirming the eurypalynous character. The pollen types varies from psilate to echinate and colpi to tricolporate, tetracolporate and pantocolporate. Exine ornamentation was exposed as perforate, reticulate and echinate. Spine morphology and exine sculpture are vital for the distinction of species. Pollen fertility shows that selected plants species are well-known in the Arid Zone. A taxonomic key is prepared to use these variations in the identification of species. Statistical analysis by using the Software XLSTAT exhibited that some morphological features is the main characters in identification of the taxa. These studied taxa were separated from each other using cluster Analysis. Our results constructed on MVSP ver. 3.22 software analyses that show morphological explanation; thus, the results highlight the importance of pollen morphology in the identification and characterization of species of the family convolvulacae in arid zone. © 2017 Wiley Periodicals, Inc.

Evaporation as the transport mechanism of metals in arid regions

NARCIS (Netherlands)

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

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

The flexible loop L1 of the H3K4 demethylase JARID1B ARID domain has a crucial role in DNA-binding activity

International Nuclear Information System (INIS)

Yao, Wenming; Peng, Yu; Lin, Donghai

2010-01-01

JARID1B, a member of the JmjC demethylase family, has a crucial role in H3K4me3 demethylation. The ARID domain is a potential DNA-binding domain of JARID1B. Previous studies indicate that a GC-rich DNA motif is the specific target of the ARID domain. However, the details of the interaction between the ARID domain and duplex DNA require further study. Here, we utilized NMR spectroscopy to assign the backbone amino acids and mapped the DNA-binding sites of the human JARID1B ARID domain. Perturbations to 1 H- 15 N correlation spectra revealed that the flexible loop L1 of ARID was the main DNA-binding interface. EMSA and intrinsic fluorescence experiments demonstrated that mutations on loop L1 strongly reduced the DNA-binding activity of JARID1B ARID. Furthermore, transfection of mutant forms resulted in a distinct loss of intrinsic H3K4 demethylase activity, implying that the flexible loop L1 made a major contribution to sustaining the DNA-binding ability of JARID1B ARID domain.

Recent changes in continentality and aridity conditions over the Middle East and North Africa region, and their association with circulation patterns

KAUST Repository

El Kenawy, Ahmed M.

2016-05-30

A long-term (1960-2013) assessment of the variability of continentality and aridity conditions over the Middle East and North Africa (MENA) region was undertaken. Monthly gridded temperature and precipitation data from the Climate Research Unit (CRU) (TS3.22 version) were used to compute the Johansson Continentality Index (JCI) and the Marsz Oceanity Index (MOI). In addition, the De Martonne index and the Pinna index were employed to assess recent changes in aridity conditions. All indices revealed a statistically significant increase in continental influences over the region, particularly in the Nile Basin and the Fertile Crescent. For aridity, the results suggested a generally statistically insignificant increase, with the most rapid changes occurring over the most humid regions (i.e. the Ethiopian Highlands and the Fertile Crescent). In order to explain the observed changes in the continentality and aridity conditions, we assessed the relationship between aridity and continentality indices and a wide range of large-scale circulation patterns. Results indicate that the spatial variability of continentality (as well as aridity) was closely coupled with the Atlantic modes of variability, e.g. the Eastern Atlantic pattern and the Atlantic Meridional Mode, compared to those of the Mediterranean Sea and the Indian Ocean. The results of this work highlight change processes in 2 important climate features in one of the hottest regions on Earth. Improving our understanding of the spatio-temporal characteristics of climate continentality and aridity has implications for a diversity of socio-political, economic, hydrological, and ecological activities in the MENA region.

Recent changes in continentality and aridity conditions over the Middle East and North Africa region, and their association with circulation patterns

KAUST Repository

El Kenawy, Ahmed M.; McCabe, Matthew; Vicente-Serrano, Sergio M.; Robaa, Sayed M.; Lopez-Moreno, Juan I.

2016-01-01

A long-term (1960-2013) assessment of the variability of continentality and aridity conditions over the Middle East and North Africa (MENA) region was undertaken. Monthly gridded temperature and precipitation data from the Climate Research Unit (CRU) (TS3.22 version) were used to compute the Johansson Continentality Index (JCI) and the Marsz Oceanity Index (MOI). In addition, the De Martonne index and the Pinna index were employed to assess recent changes in aridity conditions. All indices revealed a statistically significant increase in continental influences over the region, particularly in the Nile Basin and the Fertile Crescent. For aridity, the results suggested a generally statistically insignificant increase, with the most rapid changes occurring over the most humid regions (i.e. the Ethiopian Highlands and the Fertile Crescent). In order to explain the observed changes in the continentality and aridity conditions, we assessed the relationship between aridity and continentality indices and a wide range of large-scale circulation patterns. Results indicate that the spatial variability of continentality (as well as aridity) was closely coupled with the Atlantic modes of variability, e.g. the Eastern Atlantic pattern and the Atlantic Meridional Mode, compared to those of the Mediterranean Sea and the Indian Ocean. The results of this work highlight change processes in 2 important climate features in one of the hottest regions on Earth. Improving our understanding of the spatio-temporal characteristics of climate continentality and aridity has implications for a diversity of socio-political, economic, hydrological, and ecological activities in the MENA region.

Choroidal thickness in Malaysian eyes with full-thickness macular holes

Directory of Open Access Journals (Sweden)

Chew Y Tan

2018-02-01

Full Text Available AIM: To compare choroidal thickness at the macula in eyes with unilateral idiopathic full-thickness macular holes(FTMHwith that of unaffected fellow eyes, and eyes of normal control patients.METHODS: Cross-sectional study. Thirty patients with unilateral idiopathic FTMH and thirty age, sex, and race-matched controls were recruited. Axial lengths were measured using laser interferometry. Enhanced depth imaging optical coherence tomography images were obtained using Heidelberg spectral-domain optical coherence tomography. Choroidal thickness was measured at the fovea, and at 1 mm and 2 mm nasally, temporally, superiorly and inferiorly from the center of the fovea. Statistical analysis was performed using independent and paired t-tests, chi-square tests, and Pearson correlation tests(PRESULTS: The mean subfoveal choroidal thickness was 201.0±44.0 μm in the FTMH group, 225.3±51.4 μm in the fellow eye group and 262.3±70.3 μm in the control group. The choroid was thinner in FTMH eyes at all locations when compared to control eyes(PPP>0.05. Choroidal thickness was generally highest subfoveally and lowest nasally. Subfoveal choroidal thickness was negatively correlated with age(r=-0.278, P=0.032, and axial length(r=-0.328, P=0.011.CONCLUSION: Choroidal thickness is lower in both eyes of patients with unilateral FTMH compared to healthy control eyes.

Ecology and functional roles of biological soil crusts in semi-arid ecosystems of Spain

Science.gov (United States)

Maestre, Fernando T.; Bowker, Matthew A.; Cantón, Yolanda; Castillo-Monroy, Andrea P.; Cortina, Jordi; Escolar, Cristina; Escudero, Adrián; Lázaro, Roberto; Martínez, Isabel

2015-01-01

Biological soil crusts (BSCs), composed of lichens, cyanobacteria, mosses, liverworts and microorganisms, are key biotic components of arid and semi-arid ecosystems worldwide. Despite they are widespread in Spain, these organisms have been historically understudied in this country. This trend is beginning to change as a recent wave of research has been identifying BSCs as a model ecological system. Many studies and research projects carried out in Spain have explored the role of BSCs on water, carbon and nitrogen fluxes, the interactions between BSCs and vascular plants, their dynamics after disturbances, and their response to global change, among other topics. In this article we review the growing body of research on BSCs available from semi-arid areas of Spain, highlighting its importance for increasing our knowledge on this group of organisms. We also discuss how it is breaking new ground in emerging research areas on the ecology of BSCs, and how it can be use to guide management and restoration efforts. Finally, we provide directions for future research on the ecology of BSCs in Spain and abroad. PMID:25908884

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.

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

2012-05-01

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.

Plant-Microbe Interactions and Water Management in Arid and Saline Soils

KAUST Repository

Daffonchio, Daniele; Hirt, Heribert; Berg, Gabriele

2014-01-01

Drought and salinity are major factors limiting agriculture in many regions in the world, and their importance is predicted to even increase in the near future in parallel with the ongoing global warming and climate changes. Soil and rhizosphere microbes are potential resources for counteracting such abiotic stresses in plants. The knowledge on the roles of root microorganisms in retaining soil humidity and promoting plant growth under such abiotic stresses is analyzed in this chapter. The importance of microbial diversity in the rhizosphere for alleviating drought and salinity effects on the plant physiology is discussed in the light of “Desert Farming”, the general crop management practice that is frequently used in arid regions. The plant growth promoting functional services exerted by microorganisms within the rhizosphere in arid soils are presented in relation to the plant response under water stress.

Plant-Microbe Interactions and Water Management in Arid and Saline Soils

KAUST Repository

Daffonchio, Daniele

2014-12-05

Drought and salinity are major factors limiting agriculture in many regions in the world, and their importance is predicted to even increase in the near future in parallel with the ongoing global warming and climate changes. Soil and rhizosphere microbes are potential resources for counteracting such abiotic stresses in plants. The knowledge on the roles of root microorganisms in retaining soil humidity and promoting plant growth under such abiotic stresses is analyzed in this chapter. The importance of microbial diversity in the rhizosphere for alleviating drought and salinity effects on the plant physiology is discussed in the light of “Desert Farming”, the general crop management practice that is frequently used in arid regions. The plant growth promoting functional services exerted by microorganisms within the rhizosphere in arid soils are presented in relation to the plant response under water stress.

Spatial distribution of overland flow and sediment yield in semi-arid rangelands

International Nuclear Information System (INIS)

Sarah, P.; Lavee, H.

2009-01-01

Feedbacks and mutual links exist among soil, vegetation and water; they enable co-evolution of these features within eco-geomorphic systems, These relations are fragile, especially in semi-arid areas where grazing is the main land use. The simples subdivision of the surface of many semi-arid rangelands is into a two-component mosaic pattern comprising shrub patches interspersed with open spaces, with the former acting s skinks for water and other resources, and the latter as sources. However close observations in areas under grazing in the northern Negev region of Israel suggested that the spatial patterns of surface components is more complicated, and that the open space between shrubs consists of two components: herbaceous areas, separated by trampling routes that support no vegetation. (Author)

Crop Upgrading Strategies and Modelling for Rainfed Cereals in a Semi-Arid Climate—A Review

Directory of Open Access Journals (Sweden)

Festo Richard Silungwe

2018-03-01

Full Text Available Spatiotemporal rainfall variability and low soil fertility are the primary crop production challenges facing poor farmers in semi-arid environments. However, there are few solutions for addressing these challenges. The literature provides several crop upgrading strategies (UPS for improving crop yields, and biophysical models are used to simulate these strategies. However, the suitability of UPS is limited by systemization of their areas of application and the need to cope with the challenges faced by poor farmers. In this study, we reviewed 187 papers from peer-reviewed journals, conferences and reports that discuss UPS suitable for cereals and biophysical models used to assist in the selection of UPS in semi-arid areas. We found that four UPS were the most suitable, namely tied ridges, microdose fertilization, varying sowing dates, and field scattering. The DSSAT, APSIM and AquaCrop models adequately simulate these UPS. This work provides a systemization of crop UPS and models in semi-arid areas that can be applied by scientists and planners.

Effects of enhanced ultraviolet radiation-B on maize in arid regions of middle-high elevation

International Nuclear Information System (INIS)

Zhang Lei; Wang Lianxi; Li Fusheng

2009-01-01

[Objective]The experiment aimed to explore the influence of enhanced ultraviolet radiation-B on maize in arid regions of middle-high elevation for correct assessing the influence of enhanced ultraviolet radiation-B on maize and providing scientific reference to make proper countermeasures.[Method] The location test in field and lift lamp of UV-B were used to observe the changes of maize height , leaf area and number of green leaves under influences of different UV-B radiation. [Result]In arid regions of middle-high elevation, enhanced ultraviolet radiation-B could dwarf maize plant, decrease leaf area, decline number of green leaves and yield. The reason of decreasing leaf area was that enhanced ultraviolet radiation-B shortened leaf length and leaf width while the reason of declining yield was that yield components were all negatively influenced and with the increase of ultraviolet radiation-B, the yield declined dramatically.[Conclusion]The result of this experiment would be good for maize production in arid regions of middle-high elevation

Temporal variations of isotopes in arid rain storms

International Nuclear Information System (INIS)

Adar, E.M.; Dodi, A.; Geyh, M.A.; Yair, A.

1999-01-01

The distribution of isotopes in rainfall has long been used to elaborate on hydrological systems. Both isotopic composition of stable isotopes (oxygen-18 and deuterium) and tritium content are used to illuminate on sources of groundwater recharge and as tracers upon which groundwater fluxes are assessed. As runoff is concerned, stable isotopes have been used to identify flow paths and the precise location of the rain storm which produced the floods. Analyses of stable isotopes in arid storms in the Negev desert revealed clear discrepancy between the spatial isotopic composition in floods versus the spatial and temporal isotopic composition in rainfall. In addition, simple water balance revealed that the entire flood volume is equivalent to a very small portion of the rain storm, suggesting that a specific flood is produced by a very short and intensive portion of the rainfall. Therefore, knowledge of the weighted isotopic average of a rainfall can not serve as an adequate input function for modeling of desert floods. Since in arid environment, floods are considered as major source of groundwater recharge it also can not be used as input function for modeling of groundwater systems. This paper summarizes detailed isotopic study of short segments (∼2 mm each) of desert rainstorms as sampled in the Negev desert, Israel

Contribution to the study of the zonal variation of the climate aridity in central northern Sahara (Algeria)

Science.gov (United States)

Benseghier-Hadjaidji, Fatiha; Talbi, Nadjib; Derridj, Arezki

2018-05-01

The environment degradation at the level of all its compartments which we notice at present, calls us to the risks that it would underestimate the climatic and consequently bioclimatic crisis there, in the North as in the South of the Mediterranean region. To protect the environment is not a luxury. In this respect, we wondered about the zonal variation of the climate aridity at the level of three bordering climatic stations: El-Oued, Touggourt and Ouargla. These are distant from 160 km on average some of the others. For that purpose, we based ourselves on the statistical tool the software "instat +" for the estimation of the ETP (PM) and afterward the determination of the pluvio-evapotranspiration "quotient P/ETP". For this analysis, the climatic data spread out over a period of 20 years. The results allowed to specify the aridity degree of the studied zone. So, they reveal a mitigation of the aridity of the climate in Touggourt and El-Oued while the hyper-aridity distinguishes well the Ouargla region. This approach contributes to a better knowledge of the dry ecosystems. This is important to indicate it to turn better in the eremologic search later.

Spatial patterns and natural recruitment of native shrubs in a semi-arid sandy land.

Science.gov (United States)

Wu, Bo; Yang, Hongxiao

2013-01-01

Passive restoration depending on native shrubs is an attractive approach for restoring desertified landscapes in semi-arid sandy regions. We sought to understand the relationships between spatial patterns of native shrubs and their survival ability in sandy environments. Furthermore, we applied our results to better understand whether passive restoration is feasible for desertified landscapes in semi-arid sandy regions. The study was conducted in the semi-arid Mu Us sandy land of northern China with the native shrub Artemisia ordosica. We analyzed population structures and patterns of A. ordosica at the edges and centers of land patches where sand was stabilized by A. ordosica-dominated vegetation. Saplings were more aggregated than adults, and both were more aggregated at the patch edges than at the patch centers. At the patch edges, spatial association of the saplings with the adults was mostly positive at distances 0.3-6.6 m, and turned from positive to neutral, and even negative, at other distances. At the patch centers, the saplings were spaced almost randomly around the adults, and their distances from the adults did not seem to affect their locations. A greater number of A. ordosica individuals emerged at the patch edges than at the patch centers. Such patterns may have resulted from their integrative adjustment to specific conditions of soil water supply and sand drift intensity. These findings suggest that in semi-arid sandy regions, native shrubs that are well-adapted to local environments may serve as low-cost and competent ecological engineers that can promote the passive restoration of surrounding patches of mobile sandy land.

Calibration and evaluation of the FAO56-Penman-Monteith, FAO24-radiation, and Priestly-Taylor reference evapotranspiration models using the spatially measured solar radiation across a large arid and semi-arid area in southern Iran

Science.gov (United States)

Didari, Shohreh; Ahmadi, Seyed Hamid

2018-05-01

Crop evapotranspiration (ET) is one of the main components in calculating the water balance in agricultural, hydrological, environmental, and climatological studies. Solar radiation (Rs) supplies the available energy for ET, and therefore, precise measurement of Rs is required for accurate ET estimation. However, measured Rs and ET and are not available in many areas and they should be estimated indirectly by the empirical methods. The Angström-Prescott (AP) is the most popular method for estimating Rs in areas where there are no measured data. In addition, the locally calibrated coefficients of AP are not yet available in many locations, and instead, the default coefficients are used. In this study, we investigated different approaches for Rs and ET calculations. The daily measured Rs values in 14 stations across arid and semi-arid areas of Fars province in south of Iran were used for calibrating the coefficients of the AP model. Results revealed that the calibrated AP coefficients were very different and higher than the default values. In addition, the reference ET (ET o ) was estimated by the FAO56 Penman-Monteith (FAO56 PM) and FAO24-radiation methods by using the measured Rs and were then compared with the measured pan evaporation as an indication of the potential atmospheric demand. Interestingly and unlike many previous studies, which have suggested the FAO56 PM as the standard method in calculation of ET o , the FAO24-radiation with the measured Rs showed better agreement with the mean pan evaporation. Therefore, the FAO24-radiation with the measured Rs was used as the reference method for the study area, which was also confirmed by the previous studies based on the lysimeter data. Moreover, the accuracy of calibrated Rs in the estimation of ET o by the FAO56 PM and FAO24-radiation was investigated. Results showed that the calibrated Rs improved the accuracy of the estimated ET o by the FAO24-radiation compared with the FAO24-radiation using the measured

Retreating or standing: Responses of forest species and steppe species to climate change in arid eastern central Asia

Science.gov (United States)

Hong-Xiang Zhang; Ming-Li Zhang; Stewart C. Sanderson

2013-01-01

The temperature in arid Eastern Central Asia is projected to increase in the future, accompanied by increased variability of precipitation. To investigate the impacts of climate change on plant species in this area, we selected two widespread species as candidates, Clematis sibirica and C. songorica, from montane coniferous forest and arid steppe habitats respectively...

Possible stakeholder concerns regarding volatile organic compound in arid soils integrated demonstration technologies not evaluated in the stakeholder involvement program

International Nuclear Information System (INIS)

Peterson, T.

1995-12-01

The Volatile Organic Compounds in Arid Soils Integrated Demonstration (VOC-Arid ID) supported the demonstration of a number of innovative technologies, not all of which were evaluated in the integrated demonstration's stakeholder involvement program. These technologies have been organized into two categories and the first category ranked in order of priority according to interest in the evaluation of the technology. The purpose of this report is to present issues stakeholders would likely raise concerning each of the technologies in light of commentary, insights, data requirements, concerns, and recommendations offered during the VOC-Arid ID's three-year stakeholder involvement, technology evaluation program. A secondary purpose is to provide a closeout status for each of the technologies associated with the VOC-Arid ID. This report concludes with a summary of concerns and requirements that stakeholders have for all innovative technologies

Coffin-Siris Syndrome with obesity, macrocephaly, hepatomegaly and hyperinsulinism caused by a mutation in the ARID1B gene.

Science.gov (United States)

Vals, Mari-Anne; Õiglane-Shlik, Eve; Nõukas, Margit; Shor, Riina; Peet, Aleksandr; Kals, Mart; Kivistik, Paula Ann; Metspalu, Andres; Õunap, Katrin

2014-11-01

Coffin-Siris Syndrome (CSS, MIM 135900) is a rare genetic disorder, and mutations in ARID1B were recently shown to cause CSS. In this study, we report a novel ARID1B mutation identified by whole-exome sequencing in a patient with clinical features of CSS. We identified a novel heterozygous frameshift mutation c.1584delG in exon 2 of ARID1B (NM_020732.3) predicting a premature stop codon p.(Leu528Phefs*65). Sanger sequencing confirmed the c.1584delG mutation as a de novo in the proband and that it was not present either in her parents, half-sister or half-brother. Clinically, the patient presented with extreme obesity, macrocephaly, hepatomegaly, hyperinsulinism and polycystic ovarian syndrome (PCOS), which have previously not been described in CSS patients. We suggest that obesity, macrocephaly, hepatomegaly and/or PCOS may be added to the list of clinical features of ARID1B mutations, but further clinical reports are required to make a definite conclusion.

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

Energy exploration in the Australian arid zone: constraints and environmental consequences

Energy Technology Data Exchange (ETDEWEB)

Buckley, R C

1982-03-01

The main constraints on energy exploration in the Australian arid zone are logistic, with limited additional constraints from Aboriginal reserves. The main consequence is increased access, with possible introduction of weeds and expansion of tourism and cattle grazing in consequence.

First record of Chantransia macrospora Wood, 1887 (Batrachospermales, Rhodophyta in semi-arid northeastern Brazil

Directory of Open Access Journals (Sweden)

Janiele França Vasconcelos

2014-08-01

Full Text Available http://dx.doi.org/10.5007/2175-7925.2014v27n4p129 This study presents the first record of Chantransia macrospora in the state of Rio Grande do Norte, in the semi-arid region of northeastern Brazil. Analyses of periphytic algae revealed C. macrospora individuals associated in particular with shells of Melanoides tuberculatus, a non-native species, suggesting that C. macrospora have been introduced into systems associated with the gastropods. In this context, new records of C. macrospora are still expected for the Brazilian semi-arid region in the next years.

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

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 Sedimentgefuege und

Realization of daily evapotranspiration in arid ecosystems based on remote sensing techniques

Science.gov (United States)

Elhag, Mohamed; Bahrawi, Jarbou A.

2017-03-01

Daily evapotranspiration is a major component of water resources management plans. In arid ecosystems, the quest for an efficient water budget is always hard to achieve due to insufficient irrigational water and high evapotranspiration rates. Therefore, monitoring of daily evapotranspiration is a key practice for sustainable water resources management, especially in arid environments. Remote sensing techniques offered a great help to estimate the daily evapotranspiration on a regional scale. Existing open-source algorithms proved to estimate daily evapotranspiration comprehensively in arid environments. The only deficiency of these algorithms is the course scale of the used remote sensing data. Consequently, the adequate downscaling algorithm is a compulsory step to rationalize an effective water resources management plan. Daily evapotranspiration was estimated fairly well using an Advance Along-Track Scanner Radiometer (AATSR) in conjunction with (MEdium Resolution Imaging Spectrometer) MERIS data acquired in July 2013 with 1 km spatial resolution and 3 days of temporal resolution under a surface energy balance system (SEBS) model. Results were validated against reference evapotranspiration ground truth values using standardized Penman-Monteith method with R2 of 0.879. The findings of the current research successfully monitor turbulent heat fluxes values estimated from AATSR and MERIS data with a temporal resolution of 3 days only in conjunction with reliable meteorological data. Research verdicts are necessary inputs for a well-informed decision-making processes regarding sustainable water resource management.

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.

ARID5B polymorphism confers an increased risk to acquire specific MLL rearrangements in early childhood leukemia

Science.gov (United States)

2014-01-01

Background Acute leukemia in early age (EAL) is characterized by acquired genetic alterations such as MLL rearrangements (MLL-r). The aim of this case-controlled study was to investigate whether single nucleotide polymorphisms (SNPs) of IKZF1, ARID5B, and CEBPE could be related to the onset of EAL cases (diagnosis). Methods The SNPs (IKZF1 rs11978267, ARID5B rs10821936 and rs10994982, CEBPE rs2239633) were genotyped in 265 cases [169 acute lymphoblastic leukemia (ALL) and 96 acute myeloid leukaemia (AML)] and 505 controls by Taqman allelic discrimination assay. Logistic regression was used to evaluate the association between SNPs of cases and controls, adjusted on skin color and/or age. The risk was determined by calculating odds ratios (ORs) with 95% confidence interval (CI). Results Children with the IKZF1 SNP had an increased risk of developing MLL-germline ALL in white children. The heterozygous/mutant genotype in ARID5B rs10994982 significantly increased the risk for MLL-germline leukemia in white and non-white children (OR 2.60, 95% CI: 1.09-6.18 and OR 3.55, 95% CI: 1.57-8.68, respectively). The heterozygous genotype in ARID5B rs10821936 increased the risk for MLL-r leukemia in both white and non-white (OR 2.06, 95% CI: 1.12-3.79 and OR 2.36, 95% CI: 1.09-5.10, respectively). Furthermore, ARID5B rs10821936 conferred increased risk for MLL-MLLT3 positive cases (OR 7.10, 95% CI:1.54-32.68). Our data do not show evidence that CEBPE rs2239633 confers increased genetic susceptibility to EAL. Conclusions IKZF1 and CEBPE variants seem to play a minor role in genetic susceptibility to EAL, while ARID5B rs10821936 increased the risk of MLL-MLLT3. This result shows that genetic susceptibility could be associated with the differences regarding MLL breakpoints and partner genes. PMID:24564228

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

Science.gov (United States)

Mary I. Williams; R. Kasten Dumroese; Deborah S. Page-Dumroese; Stuart P. Hardegree

2016-01-01

Direct seeding is a common large-scale restoration practice for revegetating arid and semi-arid lands, but success can be limited by moisture and temperature. Seed coating technologies that use biochar may have the potential to overcome moisture and temperature limitations on native plant germination and growth. Biochar is a popular agronomic tool for improving soil...

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

Science.gov (United States)

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

2014-09-15

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

Forecasting the Depletion of Transboundary Groundwater Resources in Hyper-Arid Environments

Science.gov (United States)

Mazzoni, A.; Heggy, E.

2014-12-01

The increase in awareness about the overexploitation of transboundary groundwater resources in hyper-arid environments that occurred in the last decades has highlighted the need to better map, monitor and manage these resources. Climate change, economic and population growth are driving forces that put more pressure on these fragile but fundamental resources. The aim of our approach is to address the question of whether or not groundwater resources, especially non-renewable, could serve as "backstop" water resource during water shortage periods that would probably affect the drylands in the upcoming 100 years. The high dependence of arid regions on these resources requires prudent management to be able to preserve their fossil aquifers and exploit them in a more sustainable way. We use the NetLogo environment with the FAO Aquastat Database to evaluate if the actual trends of extraction, consumption and use of non-renewable groundwater resources would remain feasible with the future climate change impacts and the population growth scenarios. The case studies selected are three: the Nubian Sandstone Aquifer System, shared between Egypt, Libya, Sudan and Chad; the North Western Sahara Aquifer System, with Algeria, Tunisia and Libya and the Umm Radhuma Dammam Aquifer, in its central part, shared between Saudi Arabia, Qatar and Bahrain. The reason these three fossil aquifers were selected are manifold. First, they represent properly transboundary non-renewable groundwater resources, with all the implications that derive from this, i.e. the necessity of scientific and socio-political cooperation among riparians, the importance of monitoring the status of shared resources and the need to elaborate a shared management policy. Furthermore, each country is characterized by hyper-arid climatic conditions, which will be exacerbated in the next century by climate change and lead to probable severe water shortage periods. Together with climate change, the rate of population

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

Distribution of ticks infesting ruminants and risk factors associated with high tick prevalence in livestock farms in the semi-arid and arid agro-ecological zones of Pakistan.

Science.gov (United States)

Rehman, Abdul; Nijhof, Ard M; Sauter-Louis, Carola; Schauer, Birgit; Staubach, Christoph; Conraths, Franz J

2017-04-19

Tick infestation is the major problem for animal health that causes substantial economic losses, particularly in tropical and subtropical countries. To better understand the spatial distribution of tick species and risk factors associated with tick prevalence in livestock in Pakistan, ticks were counted and collected from 471 animals, including 179 cattle, 194 buffaloes, 80 goats and 18 sheep, on 108 livestock farms in nine districts, covering both semi-arid and arid agro-ecological zones. In total, 3,807 ticks representing four species were collected: Hyalomma anatolicum (n = 3,021), Rhipicephalus microplus (n = 715), Hyalomma dromedarii (n = 41) and Rhipicephalus turanicus (n = 30). The latter species is reported for the first time from the study area. Rhipicephalus microplus was the predominant species in the semi-arid zone, whereas H. anatolicum was the most abundant species in the arid zone. The overall proportion of tick-infested ruminants was 78.3% (369/471). It was highest in cattle (89.9%), followed by buffaloes (81.4%), goats (60.0%) and sheep (11.1%). The median tick burden significantly differed among animal species and was highest in cattle (median 58), followed by buffaloes (median 38), goats (median 19) and sheep (median 4.5). Female animals had significantly higher tick burdens than males and, in large ruminants, older animals carried more ticks than younger animals. The intensity of infestation was significantly lower in indigenous animals compared to exotic and crossbred cows. Analysis of questionnaire data revealed that the absence of rural poultry, not using any acaricides, traditional rural housing systems and grazing were potential risk factors associated with a higher tick prevalence in livestock farms. Absence of rural poultry, not performing acaricide treatments, traditional rural housing systems and grazing were important risk factors associated with higher tick prevalence in livestock farms. Age, gender, breed and animal

Experimental Studies on Earthen Architecture Sites Consolidated with BS Materials in Arid Regions

Directory of Open Access Journals (Sweden)

Dong Zhao

2016-01-01

Full Text Available This paper takes the preservation works on the archaeological sites of Gaochang Ruins, Xinjiang, as background. Based on the soil characteristics analysis on the archaeological sites, experimental studies were conducted on the consolidation effect of the BS-10 consolidation material on the archaeological sites of adobe and rammed earth. The results showed the following:, after consolidation, the wind erosion resistance of the soil on the archaeological sites was substantially increased, and the wind erosion modulus was reduced by 5~8 times; the soil exhibited fine grid structure and significantly reduced degree of permeability, while still maintaining the moisture exchange between inside and outside the soil; there is excellent ageing resistance; the resistance to freezing and thawing was closely related to the soil water content and had little influence in arid regions; the water resistance was improved and could satisfy the requirements for consolidating the sites in arid regions; the unconfined compressive strength was improved moderately, which was the key direction of improvement in the future, and the consolidated soil did not form duricrust on the surface and had good bonding strength with the internal parts. The BS-10 material can meet the consolidation requirements for the earthen archaeological sites in arid regions of northwest China.

Do Red Edge and Texture Attributes from High-Resolution Satellite Data Improve Wood Volume Estimation in a Semi-Arid Mountainous Region?

DEFF Research Database (Denmark)

Schumacher, Paul; Mislimshoeva, Bunafsha; Brenning, Alexander

2016-01-01

to overcome this issue. However, clear recommendations on the suitability of specific proxies to provide accurate biomass information in semi-arid to arid environments are still lacking. This study contributes to the understanding of using multispectral high-resolution satellite data (RapidEye), specifically...... red edge and texture attributes, to estimate wood volume in semi-arid ecosystems characterized by scarce vegetation. LASSO (Least Absolute Shrinkage and Selection Operator) and random forest were used as predictive models relating in situ-measured aboveground standing wood volume to satellite data...

Isotopic composition of rainfall and runoff in a small arid basin with implications for deep percolation

International Nuclear Information System (INIS)

Dody, A.

1995-08-01

The aim of this work was to characterize the isotopic composition of potential recharge in an arid rocky watershed. Unique field observations were obtained from an arid watershed in the Negev Highlands, Israel, through utilization of the dynamic variations in the isotopic composition of rainfall and runoff. The hydrological system's inputs are rainfall and its isotopic composition. Rainfall and runoff were sampled in eight storms. High variability in the isotopic composition of rainfall was observed during any single rainstorm. The isotopic distribution in the runoff at the outlet of the basin appeared often not to be correlated to the isotopic patterns of the associated rain storm. A new mathematical model was developed to describe these physical processes. The model called A Double-Component Kinematic Wave Flow and Transport Approach, was designated to assess the dynamic isotopic distribution in arid rain storms and runoff. This model simulates the transport of rainfall into overland flow and runoff in an arid rocky watershed with uniformly distributed shallow depression storage. A numerical solution for the problem was developed, to estimate the depression storage parameters. The model also reflects the isotopic memory effect due to the depression storage between sequential rain showers. A good agreement between the observed and computed hydrograph and the change of the δ 18O values in runoff in time confirms the validity of the model. (author) 138 figs., 125 refs

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

Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico.

Science.gov (United States)

Roth-Monzón, Andrea J; Mendoza-Hernández, Andrés Alberto; Flores-Villela, Oscar

2018-01-01

Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of Nopala de Villagrán, Mexico, and analyze its biodiversity in relation to the seasons, vegetation and microhabitat. During a year of fieldwork, we found 24 species in the area, most of them of low abundance, and one of which was recorded for the first time for the state of Hidalgo. We documented five amphibian species and 19 reptile species. We also found that observed species richness was higher in the rainy season and in xeric scrub vegetation, although only the season differences were significant according to rarefaction curves. Our findings highlight the importance of seasonality and vegetation type for the species that inhabit this semi-arid region. This study broadens our understanding of the importance of semi-arid regions and, by extension, that of other areas with similar characteristics.

Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico

Directory of Open Access Journals (Sweden)

Andrea J. Roth-Monzón

2018-01-01

Full Text Available Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of Nopala de Villagrán, Mexico, and analyze its biodiversity in relation to the seasons, vegetation and microhabitat. During a year of fieldwork, we found 24 species in the area, most of them of low abundance, and one of which was recorded for the first time for the state of Hidalgo. We documented five amphibian species and 19 reptile species. We also found that observed species richness was higher in the rainy season and in xeric scrub vegetation, although only the season differences were significant according to rarefaction curves. Our findings highlight the importance of seasonality and vegetation type for the species that inhabit this semi-arid region. This study broadens our understanding of the importance of semi-arid regions and, by extension, that of other areas with similar characteristics.

Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico

Science.gov (United States)

Mendoza-Hernández, Andrés Alberto; Flores-Villela, Oscar

2018-01-01

Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of Nopala de Villagrán, Mexico, and analyze its biodiversity in relation to the seasons, vegetation and microhabitat. During a year of fieldwork, we found 24 species in the area, most of them of low abundance, and one of which was recorded for the first time for the state of Hidalgo. We documented five amphibian species and 19 reptile species. We also found that observed species richness was higher in the rainy season and in xeric scrub vegetation, although only the season differences were significant according to rarefaction curves. Our findings highlight the importance of seasonality and vegetation type for the species that inhabit this semi-arid region. This study broadens our understanding of the importance of semi-arid regions and, by extension, that of other areas with similar characteristics. PMID:29312825

Effect of high ambient temperature on behavior of sheep under semi-arid tropical environment.

Science.gov (United States)

De, Kalyan; Kumar, Davendra; Saxena, Vijay Kumar; Thirumurugan, Palanisamy; Naqvi, Syed Mohammed Khursheed

2017-07-01

High environmental temperature is a major constraint in sheep production under semi-arid tropical environment. Behavior is the earliest indicator of animal's adaptation and responses to the environmental alteration. Therefore, the objective of this study was to assess the effects of high ambient temperature on the behavior of sheep under a semi-arid tropical environment. The experiment was conducted for 6 weeks on 16 Malpura cross (Garole × Malpura × Malpura (GMM)) rams. The rams were divided equally into two groups, designated as C and T. The rams of C were kept in comfortable environmental conditions served as control. The rams of T were exposed to a different temperature at different hours of the day in a climatic chamber, to simulate a high environmental temperature of summer in semi-arid tropic. The behavioral observations were taken by direct instantaneous observation at 15-min intervals for each animal individually. The feeding, ruminating, standing, and lying behaviors were recorded twice a week from morning (0800 hours) to afternoon (1700 hours) for 6 weeks. Exposure of rams to high temperature (T) significantly (P behavior of sheep which is directed to circumvent the effect of the stressor.

Effect of high ambient temperature on behavior of sheep under semi-arid tropical environment

Science.gov (United States)

De, Kalyan; Kumar, Davendra; Saxena, Vijay Kumar; Thirumurugan, Palanisamy; Naqvi, Syed Mohammed Khursheed

2017-07-01

High environmental temperature is a major constraint in sheep production under semi-arid tropical environment. Behavior is the earliest indicator of animal's adaptation and responses to the environmental alteration. Therefore, the objective of this study was to assess the effects of high ambient temperature on the behavior of sheep under a semi-arid tropical environment. The experiment was conducted for 6 weeks on 16 Malpura cross (Garole × Malpura × Malpura (GMM)) rams. The rams were divided equally into two groups, designated as C and T. The rams of C were kept in comfortable environmental conditions served as control. The rams of T were exposed to a different temperature at different hours of the day in a climatic chamber, to simulate a high environmental temperature of summer in semi-arid tropic. The behavioral observations were taken by direct instantaneous observation at 15-min intervals for each animal individually. The feeding, ruminating, standing, and lying behaviors were recorded twice a week from morning (0800 hours) to afternoon (1700 hours) for 6 weeks. Exposure of rams to high temperature (T) significantly ( P animals of T spent significantly ( P behavior of sheep which is directed to circumvent the effect of the stressor.

Can behaviour buffer the impacts of climate change on an arid-zone ...

African Journals Online (AJOL)

Can behaviour buffer the impacts of climate change on an arid-zone bird? ... These could include reduced opportunity for foraging, breeding or territorial defence, each ... We investigated patterns of microclimate use and foraging behaviour by ...

Photochemically induced carbon dioxide production as a mechanism for carbon loss from plant litter in arid ecosystems

Science.gov (United States)

Brandt, L. A.; Bohnet, C.; King, J. Y.

2009-06-01

We investigated the potential for abiotic mineralization to carbon dioxide (CO2) via photodegradation to account for carbon (C) loss from plant litter under conditions typical of arid ecosystems. We exposed five species of grass and oak litter collected from arid and mesic sites to a factorial design of ultraviolet (UV) radiation (UV pass, UV block), and sterilization under dry conditions in the laboratory. UV pass treatments produced 10 times the amount of CO2 produced in UV block treatments. CO2 production rates were unaffected by litter chemistry or sterilization. We also exposed litter to natural solar radiation outdoors on clear, sunny days close to the summer solstice at midlatitudes and found that UV radiation (280-400 nm) accounted for 55% of photochemically induced CO2 production, while shortwave visible radiation (400-500 nm) accounted for 45% of CO2 production. Rates of photochemically induced CO2 production on a per-unit-mass basis decreased with litter density, indicating that rates depend on litter surface area. We found no evidence for leaching, methane production, or facilitation of microbial decomposition as alternative mechanisms for significant photochemically induced C loss from litter. We conclude that abiotic mineralization to CO2 is the primary mechanism by which C is lost from litter during photodegradation. We estimate that CO2 production via photodegradation could be between 1 and 4 g C m-2 a-1 in arid ecosystems in the southwestern United States. Taken together with low levels of litter production in arid systems, photochemical mineralization to CO2 could account for a significant proportion of annual carbon loss from litter in arid ecosystems.

Catchment management in semi-arid area of central South Africa ...

African Journals Online (AJOL)

This accentuates the need for wise decisions by catchment management agencies (CMAs), especially in water-scarce semi-arid areas. ... A financial analysis also showed that gross margin of option, expressed as R/ m3 of rainwater utilised, was estimated to be between 0.0234 to 0.0254 under Option 1 and 0.0354 for ...

Variation in nest predation among arid-zone birds | Lloyd | Ostrich ...

African Journals Online (AJOL)

I examined the nesting habits and success of 11 co-existing species in an arid, sub-tropical habitat in South Africa. Nesting success ranged from 3.5% to 75.4% among species, with predation by mammals and snakes accounting for 94% of nest losses. Differences in predator avoidance behaviour (deserting the nest vs ...

Estimating the water table under the Radioactive Waste Management Site in Area 5 of the Nevada Test Site: The Dupuit-Forcheimer approximation

International Nuclear Information System (INIS)

Lindstrom, F.T.; Barker, L.E.; Cawlfield, D.E.; Daffern, D.D.; Dozier, B.L.; Emer, D.F.; Strong, W.R.

1992-01-01

To adequately manage the low level nuclear waste (LLW) repository in Area 5 of the Nevada Test Site (NTS), a knowledge of the water table under the site is paramount. The estimated thickness of the arid intermountain basin alluvium is roughly 900 feet. Very little reliable water table data for Area 5 currently exists. The Special Projects Section of the Reynolds Electrical ampersand Engineering Co., Inc. Waste Management Department is currently formulating a long-range drilling and sampling plan in support of a Resource Conservation Recovery Act (RCRA) Part B permit waiver for groundwater monitoring and liner systems. An estimate of the water table under the LLW repository, called the Radioactive Waste Management Site (RWMS) in Area 5, is needed for the drilling and sampling plan. Very old water table elevation estimates at about a dozen widely scattered test drill holes, as well as water wells, are available from declassified US Geological Survey, Lawrence Livermore National Laboratory, and Los Alamos National Laboratory drilling logs. A three-dimensional steady-state water-flow equation for estimating the water table elevation under a thick, very dry vadose zone is developed using the Dupuit assumption. A prescribed positive vertical downward infiltration/evaporation condition is assumed at the atmosphere/soil interface. An approximation to the square of the elevation head, based upon multivariate cubic interpolation methods, is introduced. The approximate is forced to satisfy the governing elliptic (Poisson) partial differential equation over the domain of definition. The remaining coefficients are determined by interpolating the water table at eight ''boundary point.'' Several realistic scenarios approximating the water table under the RWMS in Area 5 of the NTS are discussed

Isotope hydrology applied to evaluation of groundwater in arid areas

International Nuclear Information System (INIS)

Froehlich, K.; Geyh, M.A.; Verhagen, B.T.; Wirth, K.

1987-01-01

Capture of underground water in arid or semi-arid areas in developing countries is essential to safeguarding life. In order to realize in time, or to prevent, endangerment of exploitable groundwater resources due to pollution or excess exploitation, isotope hydrology offers low-cost methods that are applied along with other methods. Their results contribute to determine the origin, mixing, residence time (or age), and pollution of endangered groundwater resources. The research report in hand uses the results of hydrochemical analyses and isotope hydrological data from hydrogeological studies made over some years by the Bundesanstalt fuer Geowissenschaften und Rohstoffe in six selected countries: Jordan, Cyprus, Brazil, Sudan, Djibouti, Senegal. It also uses data of recent analyses of the years 1985 and 1986. Data evaluation is done applying modern, qualitative and quantitative methods of interpretation. The available long-term series of isotopic data are scanned for any early information on water quality deterioration that is not otherwise detected. The information thus obtained is a prerequisite of urgently needed measures for protecting the groundwater reserves. (orig./HP) [de

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.

Bacterial polyextremotolerant bioemulsifiers from arid soils improve water retention capacity and humidity uptake in sandy soil

KAUST Repository

Raddadi, Noura

2018-05-31

Water stress is a critical issue for plant growth in arid sandy soils. Here, we aimed to select bacteria producing polyextremotolerant surface-active compounds capable of improving water retention and humidity uptake in sandy soils.From Tunisian desert and saline systems, we selected eleven isolates able to highly emulsify different organic solvents. The bioemulsifying activities were stable with 30% NaCl, at 4 and 120 °C and in a pH range 4-12. Applications to a sandy soil of the partially purified surface-active compounds improved soil water retention up to 314.3% compared to untreated soil. Similarly, after 36 h of incubation, the humidity uptake rate of treated sandy soil was up to 607.7% higher than untreated controls.Overall, results revealed that polyextremotolerant bioemulsifiers of bacteria from arid and desert soils represent potential sources to develop new natural soil-wetting agents for improving water retention in arid soils.

Bacterial polyextremotolerant bioemulsifiers from arid soils improve water retention capacity and humidity uptake in sandy soil

KAUST Repository

Raddadi, Noura; Giacomucci, Lucia; Marasco, Ramona; Daffonchio, Daniele; Cherif, Ameur; Fava, Fabio

2018-01-01

Water stress is a critical issue for plant growth in arid sandy soils. Here, we aimed to select bacteria producing polyextremotolerant surface-active compounds capable of improving water retention and humidity uptake in sandy soils.From Tunisian desert and saline systems, we selected eleven isolates able to highly emulsify different organic solvents. The bioemulsifying activities were stable with 30% NaCl, at 4 and 120 °C and in a pH range 4-12. Applications to a sandy soil of the partially purified surface-active compounds improved soil water retention up to 314.3% compared to untreated soil. Similarly, after 36 h of incubation, the humidity uptake rate of treated sandy soil was up to 607.7% higher than untreated controls.Overall, results revealed that polyextremotolerant bioemulsifiers of bacteria from arid and desert soils represent potential sources to develop new natural soil-wetting agents for improving water retention in arid soils.

Bacterial polyextremotolerant bioemulsifiers from arid soils improve water retention capacity and humidity uptake in sandy soil.

Science.gov (United States)

Raddadi, Noura; Giacomucci, Lucia; Marasco, Ramona; Daffonchio, Daniele; Cherif, Ameur; Fava, Fabio

2018-05-31

Water stress is a critical issue for plant growth in arid sandy soils. Here, we aimed to select bacteria producing polyextremotolerant surface-active compounds capable of improving water retention and humidity uptake in sandy soils. From Tunisian desert and saline systems, we selected eleven isolates able to highly emulsify different organic solvents. The bioemulsifying activities were stable with 30% NaCl, at 4 and 120 °C and in a pH range 4-12. Applications to a sandy soil of the partially purified surface-active compounds improved soil water retention up to 314.3% compared to untreated soil. Similarly, after 36 h of incubation, the humidity uptake rate of treated sandy soil was up to 607.7% higher than untreated controls. Overall, results revealed that polyextremotolerant bioemulsifiers of bacteria from arid and desert soils represent potential sources to develop new natural soil-wetting agents for improving water retention in arid soils.

Coffin–Siris Syndrome with obesity, macrocephaly, hepatomegaly and hyperinsulinism caused by a mutation in the ARID1B gene

Science.gov (United States)

Vals, Mari-Anne; Õiglane-Shlik, Eve; Nõukas, Margit; Shor, Riina; Peet, Aleksandr; Kals, Mart; Kivistik, Paula Ann; Metspalu, Andres; Õunap, Katrin

2014-01-01

Coffin–Siris Syndrome (CSS, MIM 135900) is a rare genetic disorder, and mutations in ARID1B were recently shown to cause CSS. In this study, we report a novel ARID1B mutation identified by whole-exome sequencing in a patient with clinical features of CSS. We identified a novel heterozygous frameshift mutation c.1584delG in exon 2 of ARID1B (NM_020732.3) predicting a premature stop codon p.(Leu528Phefs*65). Sanger sequencing confirmed the c.1584delG mutation as a de novo in the proband and that it was not present either in her parents, half-sister or half-brother. Clinically, the patient presented with extreme obesity, macrocephaly, hepatomegaly, hyperinsulinism and polycystic ovarian syndrome (PCOS), which have previously not been described in CSS patients. We suggest that obesity, macrocephaly, hepatomegaly and/or PCOS may be added to the list of clinical features of ARID1B mutations, but further clinical reports are required to make a definite conclusion. PMID:24569609

Structure and Function of Ephemeral Streams in the Arid and Semiarid Southwest: Implications for Conservation and Management

Science.gov (United States)

2015-07-24

Respondents should be aware that notwithstanding any other provision of law , no person shall be subject to any penalty for failing to comply with a collection...stream channels in southern Arizona that span three aridity zones and a range of geomorphic conditions (Fig. 3.1, Table 3.1).We calculated aridity...in the field until they were transported to lab freezers. We later thawed samples and measured and identified all macroinvertebrates to the family

COCKROACHES, PESTICIDE USE, AND CHILDREN'S PULMONARY FUNCTION IN AN ARID COMMUNITY

Science.gov (United States)

Cockroaches, pesticide use, and children's pulmonary function in an arid communityErik Svendsen1, Mary Ross1, Melissa Gonzales2, Debra Walsh1, Scott Rhoney1, Gina Terrill1, Lucas Neas11US EPA, Chapel Hill, NC; 2University of New MexicoThe El Paso Children's He...

Spatial patterns of grasses and shrubs in an arid grassland environment

Science.gov (United States)

In the Chihuahuan Desert of Mexico and New Mexico, shrub invasion is a common problem, and once-abundant grassland ecosystems are being replaced by shrub-dominated habitat. The spatial arrangement of grasses and shrubs in these arid grasslands can provide better insight into community dynamics and c...

Transport Assessment - Arid Task: model verification studies - FY 1983. Annual report

International Nuclear Information System (INIS)

Jones, T.L.; Kirkham, R.R.; Gibson, D.

1983-08-01

The current focus of the Transport Assessment- Arid Task is the evaluation of evaporation and transpiration submodels used in water flow models. Models will be evaluated by how accurately they simulate field water balance data. To date we have: (1) selected four evaporation models to be tested, (2) constructed an evaporation test case, and (3) started collection of data for a transpiration test case. Evaluation of the evaporation models will be completed during FY83, with results published in September. The evaporation test case contains data describing soil water content, water storage, as well as drainage rates observed in the unvegetated lysimeters of the BWTF. For example, data show deep drainage accounted for 8% of the natural precipitation, but rose to 25% after irrigation doubled total precipitation. This year, deep drainage was also observed in vegetated soils. These results refute a commonly held assumption that evapotranspiration eliminates deep drainage in arid soils

Vegetation monitoring on semi-arid grasslands unglazed by domestic livestock

Science.gov (United States)

Linda Kennedy; Dan Robinett

2013-01-01

The Research Ranch is an 8000-acre sanctuary and research facility in the semi-arid grasslands of southeastern Arizona, USA. Cattle were removed from the property in 1968 to provide a reference area by which various land uses, such as grazing and exurbanization, could be evaluated. Vegetation transects were established in 2000 and 2003 on several ecological sites in...

Rates of wood and dung disintegration in arid South African ...

African Journals Online (AJOL)

Dead shrubs lying on the soil surface in an arid shrubland in the southern Karoo have half-lives of 9 to 18 years depending on wood density which varies among species. Dung pellets of sheep and springbok can remain intact on the soil surface in Karoo shrubland and desert grassland for five years or more. Highlights the ...

Semi-arid development: competitiveness factors in biodiesel productive chain

OpenAIRE

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

2009-01-01

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

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

Science.gov (United States)

Walvoord, Michelle Ann; Andraski, Brian J.; Krabbenhoft, D.P.; Striegl, Robert 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.

Isotopic composition of rainfall and runoff in a small arid basin with implications for deep percolation

Energy Technology Data Exchange (ETDEWEB)

Dody, A [Ben-Gurion Univ. of the Negev, Beersheba (Israel)

1995-08-01

The aim of this work was to characterize the isotopic composition of potential recharge in an arid rocky watershed. Unique field observations were obtained from an arid watershed in the Negev Highlands, Israel, through utilization of the dynamic variations in the isotopic composition of rainfall and runoff. The hydrological system`s inputs are rainfall and its isotopic composition. Rainfall and runoff were sampled in eight storms. High variability in the isotopic composition of rainfall was observed during any single rainstorm. The isotopic distribution in the runoff at the outlet of the basin appeared often not to be correlated to the isotopic patterns of the associated rain storm. A new mathematical model was developed to describe these physical processes. The model called A Double-Component Kinematic Wave Flow and Transport Approach, was designated to assess the dynamic isotopic distribution in arid rain storms and runoff. This model simulates the transport of rainfall into overland flow and runoff in an arid rocky watershed with uniformly distributed shallow depression storage. A numerical solution for the problem was developed, to estimate the depression storage parameters. The model also reflects the isotopic memory effect due to the depression storage between sequential rain showers. A good agreement between the observed and computed hydrograph and the change of the {delta}{sup 18O} values in runoff in time confirms the validity of the model. (author) 138 figs., 125 refs.

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.

Correlation of alluvial deposits at the Nevada Test Site

International Nuclear Information System (INIS)

Grothaus, B.; Howard, N.

1977-01-01

Because characteristics of rock layers and problems in drilling must be studied before radioactive waste can be safely contained, an evaluation was made of methods for correlating alluvial deposits at Yucca Flat of the Nevada Test Site (NTS). Although correlation of Tertiary volcanic tuff beds at the NTS has been successfully achieved, correlation of stratigraphic zones in the overlying alluvium has posed technical difficulties. We have evaluated several methods for correlating alluvial deposits from drillholes, including electric resistivity logs (E logs), visual examination of sidewall samples and comparison of their carbonate (CO 2 ) content, downhole stereo photography for identifying debris flow deposits, caliche age-dating, and specific yield and permeability measurements of deposits. For predicting the thickness of zones having similar physical properties in the alluvium, E log measurements were found to be the most useful of these methods

Quality of urban runoff in wet and dry seasons: a case study in a semi-arid zone.

Science.gov (United States)

Ortiz-Hernández, Joyce; Lucho-Constantino, Carlos; Lizárraga-Mendiola, Liliana; Beltrán-Hernández, Rosa Icela; Coronel-Olivares, Claudia; Vázquez-Rodríguez, Gabriela

2016-12-01

Urban runoff (UR) is a promising new resource that may alleviate growing tensions in numerous arid and semi-arid regions of the world. However, it is precisely in these zones that the available UR quality characteristics are scarcer. This work aims to evaluate a wide set of parameters to establish a detailed approach to both the quality of UR in a midsized city in Central Mexico and the feasibility of using UR to recharge aquifers. UR from an institutional land use site was sampled during wet and dry seasons and assessed for suspended solids, organic matter, nutrients, microorganisms, metals, and persistent organic chemicals (i.e., polycyclic aromatic hydrocarbons, PAH). The results were analyzed using multivariate statistical methods to identify relationships among the variables, the sampling sites and the seasons. The soil erosion and the leaching of materials due to the water flow through vegetated areas were identified as the most influencing factor on the quality of the site runoff in both dry and wet seasons. Additionally, data were more heterogeneous during the dry season, and higher pollutant concentrations were found both during the dry season and in more pervious zones. We consider UR a promising water source for recharging aquifers in arid and semi-arid zones if a program is implemented that can integrate an adequate runoff treatment system, soil protection, and other non-structural measures.

Characterisation of rainfall at a semi-arid ecotope in the Limpopo ...

African Journals Online (AJOL)

Detailed knowledge of rainfall regime is an important prerequisite for agricultural planning. Despite the importance of rain-fed agriculture to food security in the semi-arid regions of South Africa, studies to understand the spatial and temporal variability of rainfall are not widely documented. Twenty-three years (1983 to 2005) ...

Adaptations to life on arid islands of South Africa: renal performance ...

African Journals Online (AJOL)

Morphological parameters of the mammalian kidney can provide information on the extent to which an animal is able to regulate water relations within its body and cope with arid conditions. Certain groups of mammals, such as rabbits and hares, show a flexible phenotype (phenotypic plasticity) with respect to renal ...

Static and dynamic through thickness lamina properties of thick laminates

NARCIS (Netherlands)

Lahuerta, F.; Nijssen, R.P.L.; Van der Meer, F.P.; Sluys, L.J.

2015-01-01

Thick laminates are increasingly present in large composites structures such as wind turbine blades. Different factors are suspected to be involved in the decreased static and dynamic performance of thick laminates. These include the effect of self-heating, the scaling effect, and the manufacturing

Future Freshwater Stress on Small Islands: Population, Aridity and Global Warming Targets

Science.gov (United States)

Karnauskas, K. B.; Schleussner, C. F.; Donnelly, J. P.; Anchukaitis, K. J.

2017-12-01

Small island developing states (SIDS) face multiple threats from anthropogenic climate change, including potential changes in freshwater resource availability. Future freshwater stress, including geographic and seasonal variability, has important implications for climate change adaptation scenarios for vulnerable human populations living on islands across the world ocean. Due to a mismatch in spatial scale between SIDS landforms and the horizontal resolution of global climate models (GCMs), SIDS are mostly unaccounted for in GCMs that are used to make future projections of global climate change and its regional impacts. Specific approaches are required to address this gap between broad-scale model projections and regional, policy-relevant outcomes. Here we apply a recently developed methodology to project future changes in aridity in combination with population projections associated with different shared socioeconomic pathways (SSPs) to evaluate overall changes in freshwater stress in SIDS at warming levels of 1.5°C and 2°C above pre-industrial levels. By accounting for evaporative demand a posteriori, we reveal a robust yet spatially variable tendency towards increasing aridity for 16 million people living on islands by mid-century. Although about half of the islands are projected to experience increased rainfall—predominantly in the deep tropics—projected changes in evaporation are more uniform, shifting the global distribution of changes in island freshwater balance towards greater aridity. In many cases, the magnitude of projected drying is comparable to the amplitude of the estimated observed interannual variability, with important consequences for extreme events. While we find that future population growth will dominate changes in projected freshwater stress especially towards the end of the century, projected changes in aridity are found to compound freshwater stress for the vast majority of SIDS. Particularly across the Caribbean region, a

Assessing Riparian Vegetation Condition and Function in Disturbed Sites of the Arid Northwestern Mexico

Directory of Open Access Journals (Sweden)

Lara Cornejo-Denman

2018-01-01

Full Text Available Transformation or modification of vegetation distribution and structure in arid riparian ecosystems can lead to the loss of ecological function. Mexico has 101,500,000 ha of arid lands, however there is a general lack of information regarding how arid riparian ecosystems are being modified. To assess these modifications, we use eight sites in the San Miguel River (central Sonora to analyze (1 riparian vegetation composition, structure and distribution using field sampling and remote sensing data from Unmanned Aerial Vehicles (UAV; (2 productivity (proxies, using vegetation indices derived from satellite data; and (3 variability posed by riparian vegetation and vegetation adjacent to riparian habitats. The development of a simple yet informative Anthropogenic-disturbance Index (ADI allowed us to classify and describe each study site. We found sharp differences in vegetation composition and structure between sites due to the absence/presence of obligate-riparian species. We also report significant difference between EVI (Enhanced Vegetation Index values for the dry season among vegetation types that develop near the edges of the river but differ in composition, suggesting that land cover changes form obligate-riparian to facultative-riparian species can lead to a loss in potential productivity. Finally, our tests suggest that sites with higher disturbance present lower photosynthetic activity.

Coprophilous Mucorales (ex Zygomycota from three areas in the semi-arid of Pernambuco, Brazil

Directory of Open Access Journals (Sweden)

Carlos Alberto Fragoso de Souza

Full Text Available Abstract Mucorales comprises fungi commonly isolated as saprobes from soil, dung, stored grains and plants. Although these fungi have been studied in several countries, there are relatively a few reports of them in semi-arid areas. Therefore, the aims of the present study were to assess and compare the Mucorales communities in dung from different species and breeds of herbivores in the semi-arid of Pernambuco, based on the frequency of occurrence and species richness of these fungi. Samples of dung collected in the cities of Arcoverde, Serra Talhada and Sertânia were incubated in moist chambers in triplicate. Altogether, 24 taxa of Mucorales distributed in the genera Absidia, Circinella, Cunninghamella, Lichtheimia, Mucor, Pilobolus, Rhizopus and Syncephalastrum were identified. The highest species richness was found in sheep excrement. Mucor circinelloides f. griseo-cyanus was the most common taxon, followed by M. ramosissimus. The similarity of the composition of Mucorales species was greatest between the excrements of Guzerá and Sindi breeds (bovine. All mucoralean species isolated are being cited for the first time from animal dung found in Caatinga and a new species of Mucor was recorded. An identification key for species of Mucorales from dung in the semi-arid region of Brazil is provided.

The Environmental Fluctuations of some Bioactive Nutraceutical Compounds in Zilla spinosa Inhabiting Arid Habitats

Directory of Open Access Journals (Sweden)

Hemmat Ibrahim KHATTAB

2017-12-01

Full Text Available Zilla spinosa is one of the dominated woody perennial shrubs widespread in the Egyptian Red sea coastal desert, belonging to family Brassicacea. Z. spinosa is used as a folk medicine and for heating by local people. Z. spinosa inhabits arid habitats exposed to adverse climatic changes which influence the production of the bioactive natural products. The natural secondary products have significant importance for plant acclimatization to the arid habitats beside their significant practical application in medicinal, nutritive and industrial purposes. The accumulation levels of some natural products including phenols, tannins, glucosinolates, flavonoids, saponins, proanthocyanidins and cardiac glycosides were measured in Z. spinosa inhabiting different locations of Wadi Hagul during spring and summer seasons. The results of the current study showed that Z. spinosa grown in the adverse environment has adapted to cope with extreme temperature, water deficit and geoclimate changes especially in summer, by enhancing the accumulation of some antioxidant compounds including phenols, tannins, glucosinolates, flavonoids, saponins, cardiac glycosides, concomitant with increments in the total antioxidant capacity and PAL activity. Consequently, Z. spinosa shrubs inhabiting the arid environment is a promising new source of saponins, glucosinolates, cardiac glycosides, phenols and flavonoids which could participate in drug development and exploration of alternative strategies to increase productivity of wild plants.

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.

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...

Utilization of Indigenous Technical Knowledge (ITK'S) in Arid and Semi-Arid Regions of Eastern Kenya: A Coping Strategy to Shocks of Market Utilization

International Nuclear Information System (INIS)

Ndubi, J

2002-01-01

Most of the farmers in the arid and semi arid are poorly endowed with resources. Market liberalisation and withdrawal of government support (subsidies) in accessing some of the modern technologies has led to decreased use of most of the modern recommended technologies due to their high prices. A a coping strategy most of the resources poor farmers have turned to utilization of the indigenous technology to sustain their agricultural production. The main objective of this paper is to document the indigenous technologies utilized by farmers, explore the possibility of refining/calibrating and up-scaling them and the advantages and disadvantages of utilizing them as identified by the farmers. The method for data collection was by use of interviews the farmers who were stratified in terms of gender and age sets (young, middle aged and old) and data analysed by use of qualitative methods. The results indicate that, most farmers do utilize indigenous technology in crops, livestock pests, diseases, soil and water conservation as cropping strategies to increase input prices due to market liberalization and withdrawal of government subsidies. It was also observed that, there is need for scientists to calibrate the most important practices for improved adoption and up-scaling of the main indigenous technologies within and outside the study areas

Arbuscular mycorrhizal fungi in a semi-arid, limestone mining-impacted area of Brazil

Directory of Open Access Journals (Sweden)

Thaís Teixeira-Rios

2013-12-01

Full Text Available The main goal of this study was to determine the diversity and activity of arbuscular mycorrhizal fungi (AMF in an area degraded by limestone mining within the semi-arid region of Brazil known as the caatinga (shrublands. Near a limestone quarry, we selected two areas of caatinga (preserved and degraded for study. The number of glomerospores did not differ significantly between the two areas. There was a trend toward the most probable number of infective propagules being higher in the degraded area. Twenty AMF taxa were identified in the two sampled areas, species richness, diversity and evenness being higher in the preserved area. Two species of Racocetra represent new records for the semi-arid region of Brazil. Glomerospore production and AMF species richness were unaffected by mining activity in the study area.

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.

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

Science.gov (United States)

Oliver, Paul M; Couper, Patrick J; Pepper, Mitzy

2014-01-01

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.

Spatial variation in the flux of atmospheric deposition and its ecological effects in arid Asia

Science.gov (United States)

Jiao, Linlin; Wang, Xunming; Li, Danfeng

2018-06-01

Atmospheric deposition is one of the key land surface processes, and plays important roles in regional ecosystems and global climate change. Previous studies have focused on the magnitude of and the temporal and spatial variations in the flux of atmospheric deposition, and the composition of atmospheric deposition on a local scale. However, there have been no comprehensive studies of atmospheric deposition on a regional scale and its ecological effects in arid Asia. The temporal and spatial patterns, composition of atmospheric deposition, and its potential effects on regional ecosystems in arid Asia are investigated in this study. The results show that the annual deposition flux is high on the Turan Plain, Aral Sea Desert, and Tarim Basin. The seasonal deposition flux also varies remarkably among different regions. The Tarim Basin shows higher deposition flux in both spring and summer, southern Mongolian Plateau has a higher deposition flux in spring, and the deposition flux of Iran Plateau is higher in summer. Multiple sources of elements in deposited particles are identified. Calcium, iron, aluminum, and magnesium are mainly derived from remote regions, while zinc, copper and lead have predominantly anthropogenic sources. Atmospheric deposition can provide abundant nutrients to vegetation and consequently play a role in the succession of regional ecosystems by affecting the structure, function, diversity, and primary production of the vegetation, especially the exotic or short-lived opportunistic species in arid Asia. Nevertheless, there is not much evidence of the ecological effects of atmospheric deposition on the regional and local scale. The present results may help in further understanding the mechanism of atmospheric deposition as well as providing a motivation for the protection of the ecological environment in arid Asia.

Effects of fishing technique on assessing species composition in aquatic systems in semi-arid Brazil

Directory of Open Access Journals (Sweden)

ESF Medeiros

Full Text Available In most ecological field research, appropriate sampling is critical for the understanding of processes underlying fish populations and communities, and is even more important in heterogeneous environments such as the aquatic systems of the semi-arid region of Brazil. This study intends to make a contribution to the development of sampling programs and gear selection in aquatic systems of semi-arid Brazil by evaluating the effects of different fishing techniques on the assessment of richness and composition of the fish fauna in selected aquatic environments. Six sites were selected to represent typical artificial (reservoirs and natural (intermittent streams environments and four different types of sampling gear were applied to each site during four occasions. The present study shows that when selecting sampling techniques to be used in aquatic systems in semi-arid Brazil, one must consider the objectives of the study, e.g. ecological or taxonomic, in order to decide on inclusion of rare species in the sampling population. Also, the effect of the sampling gear on natural abundances of fish must be considered given that some sampling techniques are highly detrimental to fish population numbers.

Is the future blue-green or brown? The effects of extreme events on phytoplankton dynamics in a semi-arid man-made lake

NARCIS (Netherlands)

Meideiros, L.D.C.; Mattos, A.; Lurling, M.F.L.L.W.; Becker, V.

2015-01-01

In arid and semi-arid regions, a hydrological regime characterized by an annual cycle of drought and rainy seasons changes the volume and retention time of reservoirs. Such changes affect the limnological characteristics and lead to changes on phytoplankton community. Phytoplankton seasonal

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

Through thickness property variations in a thick plate AA7050 friction stir welded joint

International Nuclear Information System (INIS)

Canaday, Clinton T.; Moore, Matthew A.; Tang, Wei; Reynolds, A.P.

2013-01-01

In this study, moderately thick (32 mm) AA7050 plates were joined by friction stir welding (FSW). Various methods were used to characterize the welded joints, including nugget grain size measurements at different locations through the thickness, micro-hardness indentation through nugget, thermo-mechanically affected zone (TMAZ), and heat affected zone (HAZ) at different cross section heights, and residual stress measurement using the cut compliance method with full thickness and partial thickness specimens. All testing results are consistent with the presence of a strong gradient in peak temperature through the plate thickness during FSW.

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.

Use of carbon isotope analysis to understand semi-arid erosion dynamics and long-term semi-arid land degradation.

Science.gov (United States)

Turnbull, Laura; Brazier, Richard E; Wainwright, John; Dixon, Liz; Bol, Roland

2008-06-01

Many semi-arid areas worldwide are becoming degraded, in the form of C(4) grasslands being replaced by C(3) shrublands, which causes an increase in surface runoff and erosion, and altered nutrient cycling, which may affect global biogeochemical cycling. The prevention or control of vegetation transitions is hindered by a lack of understanding of their temporal and spatial dynamics, particularly in terms of interactions between biotic and abiotic processes. This research investigates (1) the effects of soil erosion on the delta(13)C values of soil organic matter (SOM) throughout the soil profile and its implications for reconstructing vegetation change using carbon-isotope analysis and (2) the spatial properties of erosion over a grass-shrub transition to increase understanding of biotic-abiotic interactions by using delta(13)C signals of eroded material as a sediment tracer. Results demonstrate that the soils over grass-shrub transitions are not in steady state. A complex interplay of factors determines the input of SOM to the surface horizon of the soil and its subsequent retention and turnover through the soil profile. A positive correlation between event runoff and delta(13)C signatures of eroded sediment was found in all plots. This indicates that the delta(13)C signatures of eroded sediment may provide a means of distinguishing between changes in erosion dynamics over runoff events of different magnitudes and over different vegetation types. The development of this technique using delta(13)C signatures of eroded sediment provides a new means of furthering existing understanding of erosion dynamics over vegetation transitions. This is critical in terms of understanding biotic-abiotic feedbacks and the evolution of areas subject to vegetation change in semi-arid environments. John Wiley & Sons, Ltd

Aerobiological importance and allergic sensitization to Amaranthaceae under arid climate conditions.

Science.gov (United States)

Elvira-Rendueles, Belén; Zapata, Juan J; Miralles, Juan C; Moreno, José M; García-Sánchez, Antonio; Negral, Luis; Moreno-Grau, Stella

2017-04-01

Species of the Amaranthaceae family are abundant in the Southeast of Spain, one of the driest areas in Europe. The Amaranthaceae include species of interest from the point of view of allergic diseases. With the expansion of aridity, many species belonging to this family will be favoured. The objectives of this study were: first, to define the prevalence of sensitization to Amaranthaceae pollen in allergic patients in the Southeast of Spain; second, to present the aerobiological features of this taxon; and, finally, to demarcate those periods of increased risk of suffering allergic symptoms with the aim of improving the diagnosis and prevention of hay fever. Skin prick tests with extracts of pollen were performed on patients with symptoms of respiratory allergy referred for consultation for the first time in Almería and Murcia. Samples of the atmospheric bioaerosol were taken using a Lanzoni VPPS 2000 volumetric sampler, samples treatment and subsequent counts being carried out according to the methodology approved by the Spanish Aerobiological Network. The statistical significance of the correlation between aerobiological and meteorological data from this arid region in 2010-2014 was determined. The aerobiological study revealed the presence of two distinct peaks responsible for pollen symptoms. The flowering of this taxon is especially noteworthy in the city of Cartagena, where it supposes 94% of the total pollen collected in these periods. This situation converts Amaranthaceae pollen in the second leading cause of hay fever in the Southeast of Spain. With the expansion of aridity, an increase in the presence of these species is expected. Bearing in mind their prevalence in the spring and summer/autumn periods and their extensive presence in the bioaerosol, this makes data from Southeastern Spanish a benchmark with respect to the aerobiology of this type of pollen. Copyright © 2017 Elsevier B.V. All rights reserved.

Uranium-series dated authigenic carbonates and Acheulian sites in southern Egypt

International Nuclear Information System (INIS)

Szabo, B.J.; McHugh, W.P.; Schaber, G.G.; Breed, C.S.; Haynes, C.V.

1989-01-01

Field investigations in southern Egypt have yielded Acheulian artifacts in situ in authigenic carbonate deposits (CaCO 3 -cemented alluvium) along the edges of now-aggraded paleovalleys (Wadi Arid and Wadi Safsaf). Uranium-series dating of 25 carbonate samples from various localities as far apart as 70 kilometers indicates that widespread carbonate deposition occurred about 45, 141 and 212 ka (thousand years ago). Most of the carbonate appears to have been precipitated from groundwater, which suggests that these three episodes of deposition may be related to late Pleistocene humid climates that facilitated human settlement in this now hyperarid region. Carbonate cements from sediments containing Acheulian artifacts provide a minimum age of 212 ka for early occupation of the paleovalleys. 16 refs., 3 figs., 2 tabs

Non-contact radiation thickness gauge

International Nuclear Information System (INIS)

Tsujii, T.; Okino, T.

1983-01-01

A noncontact thickness gauge system for measuring the thickness of a material comprising a source of radiation, a detector for detecting the amount of radiation transmitted through the material which is a function of the absorptance and thickness of the material, a memory for storing the output signals of the detector and curve-defining parameters for a plurality of quadratic calibration curves which correspond to respective thickness ranges, and a processor for processing the signals and curve defining parameters to determine the thickness of the material. Measurements are made after precalibration to obtain calibration curves and these are stored in the memory, providing signals representative of a nominal thickness and an alloy compensation coefficient for the material. The calibration curve corresponding to a particular thickness range is selected and the curve compensated for drift; the material is inserted into the radiation path and the detector output signal processed with the compensated calibration curve to determine the thickness of the material. (author)

Genotype-phenotype correlation of Coffin-Siris syndrome caused by mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A

NARCIS (Netherlands)

Kosho, T.; Okamoto, N.; Bon, B.W. van; Vulto-van Silfhout, A.T.; et al.,

2014-01-01

Coffin-Siris syndrome (CSS) is a rare congenital malformation syndrome, recently found to be caused by mutations in several genes encoding components of the BAF complex. To date, 109 patients have been reported with their mutations: SMARCB1 (12%), SMARCA4 (11%), SMARCE1 (2%), ARID1A (7%), ARID1B

Genotype-Phenotype Correlation of Coffin-Siris Syndrome Caused by Mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A

NARCIS (Netherlands)

Kosho, Tomoki; Okamoto, Nobuhiko; Imai, Yoko; Ohashi, Hirofumi; van Eerde, Albertien M.; Chrzanowska, Krystyna; Clayton-Smith, Jill; Kingston, Helen; Mari, Francesca; Aggarwal, Shagun; Mowat, David; Niikawa, Norio; Hiraki, Yoko; Matsumoto, Naoya; Fukushima, Yoshimitsu; Josifova, Dragana; Dean, John; Smigiel, Robert; Sakazume, Satoru; Silengo, Margherita; Tinschert, Sigrid; Kawame, Hiroshi; Yano, Shoji; Yamagata, Takanori; van Bon, Bregje W. M.; Vulto-van Silfhout, Anneke T.; Ben-Omran, Tawfeg; Bigoni, Stefania; Alanay, Yasemin; Miyake, Noriko; Tsurusaki, Yoshinori; Matsumoto, Naomichi; Santen, Gijs W. E.; Wieczorek, Dagmar; Wollnik, Bernd; Hennekam, Raul C. M.

2014-01-01

Coffin-Siris syndrome (CSS) is a rare congenital malformation syndrome, recently found to be caused by mutations in several genes encoding components of the BAF complex. To date, 109 patients have been reported with their mutations: SMARCB1 (12%), SMARCA4 (11%), SMARCE1 (2%), ARID1A (7%), ARID1B

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 \

Spatial heterogeneity of physicochemical properties explains differences in microbial composition in arid soils from Cuatro Cienegas, Mexico

Directory of Open Access Journals (Sweden)

Silvia Pajares

2016-09-01

Full Text Available Arid ecosystems are characterized by high spatial heterogeneity, and the variation among vegetation patches is a clear example. Soil biotic and abiotic factors associated with these patches have also been well documented as highly heterogeneous in space. Given the low vegetation cover and little precipitation in arid ecosystems, soil microorganisms are the main drivers of nutrient cycling. Nonetheless, little is known about the spatial distribution of microorganisms and the relationship that their diversity holds with nutrients and other physicochemical gradients in arid soils. In this study, we evaluated the spatial variability of soil microbial diversity and chemical parameters (nutrients and ion content at local scale (meters occurring in a gypsum-based desert soil, to gain knowledge on what soil abiotic factors control the distribution of microbes in arid ecosystems. We analyzed 32 soil samples within a 64 m2 plot and: (a characterized microbial diversity using T-RFLPs of the bacterial 16S rRNA gene, (b determined soil chemical parameters, and (c identified relationships between microbial diversity and chemical properties. Overall, we found a strong correlation between microbial composition heterogeneity and spatial variation of cations (Ca2, K+ and anions (HCO ${}_{3}^{-}$ 3 − , Cl−, SO ${}_{4}^{2-}$ 4 2 − content in this small plot. Our results could be attributable to spatial differences of soil saline content, favoring the patchy emergence of salt and soil microbial communities.

Analysis of the Current Nutrient Management Practices in Semi-Arid Areas of Eastern Kenya: A Nutmon Approach

International Nuclear Information System (INIS)

Karuku, A.M.

2002-01-01

Declining soil fertility caused mainly by continuous cultivation without adequate replenishment of nutrients, is a major factor contributing to low crop yields in the arid and semi arid areas of Kenya. Development of appropriate nutrient management strategies for suitable agricultural production in these areas is, therefore, a priority issue. in the study reported here, analyses of the current nutrient management practices were carried out using the nutrient monitoring (NUTMON) approach in order to create farm house-hold awareness on nutrient management aspects. The procedure involved participatory soil and nutrient flow maps and soil sampling at farm level. laboratory analysis of the soil samples was later carried out. Structured questionnaires were used for systematic collection of information on farm management practices in order to quantify flows of materials with emphasis on soil nutrients and cash. Results of the laboratory soil analysis were also presented to the farmers and discussed during feedback sessions. The test was carried out in three places namely, Kibwezi, Kasikeu and Kiomo. In all the three clusters, off-farm income was an important component of the total family income. Farm net cash flow was highest in Kibwezi cluster due to horticultural crop production activities. Household net cash flow was highest in Kasikeu, largely originating from off-farm income. It was concluded that NUTMON methodology appeared a suitable tool for the diagnostic of the farming system analysis and design in the arid and semi-arid lands of Kenya

Thickness filters for gradient based multi-material and thickness optimization of laminated composite structures

DEFF Research Database (Denmark)

Sørensen, Rene; Lund, Erik

2015-01-01

This paper presents a new gradient based method for performing discrete material and thickness optimization of laminated composite structures. The novelty in the new method lies in the application of so-called casting constraints, or thickness filters in this context, to control the thickness...... variation throughout the laminate. The filters replace the layerwise density variables with a single continuous through-the-thickness design variable. Consequently, the filters eliminate the need for having explicit constraints for preventing intermediate void through the thickness of the laminate....... Therefore, the filters reduce both the number of constraints and design variables in the optimization problem. Based upon a continuous approximation of a unit step function, the thickness filters are capable of projecting discrete 0/1 values to the underlying layerwise or ”physical” density variables which...

Effects of rainfall on bird reproduction in a semi-arid Neotropical region

Directory of Open Access Journals (Sweden)

Liana Monique Paiva Cavalcanti

Full Text Available ABSTRACT In semi-arid ecosystems, birds commonly use rainfall as a reliable environmental cue to adjust the timing and strength of their reproductive activity. Here we evaluate this hypothesis for a community of birds in the Caatinga (the semi-arid region of northeastern Brazil, using brood patch information and nest abundance. Sampling occurred every 14 days between September 2012 and August 2013 (brood patch, and every three or four days during the reproductive period (nests. Abundance of brood patches and nests were correlated, and all brood patches were recorded between March and July (4.5 to 5.0 months. We recorded three peaks of brood patch abundance: the first 28 days after the first rains, the second 14 days after the second rainfall peak, and the third synchronously with the third rainy period. These results indicate that intra-annual variation in local rainfall has the potential to account for variations in the timing and intensity of reproduction in the studied birds.

1 Title page Title: Groundwater quality in a semi-arid region of India ...

Indian Academy of Sciences (India)

64

Groundwater quality in a semi-arid region of India - suitability for drinking, ... concentration ranges from 0.1 to 4.4 mg/L and 39% of the total samples measured ..... on identifying local priorities and implementing proper management is very.

Competing effects of groundwater withdrawals and climate change on water availability in semi-arid India

Science.gov (United States)

Sishodia, R. P.; Shukla, S.

2017-12-01

India, a global leader in groundwater use (250 km3/yr), is experiencing groundwater depletion. There has been a 130-fold increase in number of irrigation wells since 1960. Anticipated future increase in groundwater demand is likely to exacerbate the water availability in the semi-arid regions of India. Depending on the direction of change, future climate change may either worsen or enhance the water availability. This study uses an integrated hydrologic modeling approach (MIKE SHE MIKE 11) to compare and combine the effects of future (2040-2069) increased groundwater withdrawals and climate change on surface and groundwater flows and availability for an agricultural watershed in semi-arid south India. Modeling results showed that increased groundwater withdrawals in the future resulted in reduced surface flows (25%) and increased frequency and duration (90 days/yr) of well drying. In contrast, projected future increase in rainfall (7-43%) under the changed climate showed increased groundwater recharge (15-67%) and surface flows (9-155%). Modeling results suggest that the positive effects of climate change may enhance the water availability in this semi-arid region of India. However, in combination with increased withdrawals, climate change was shown to increase the well drying and reduce the water availability especially during dry years. A combination of management options such as flood to drip conversion, energy subsidy reductions and water storage can support increased groundwater irrigated area in the future while mitigating the well drying. A cost-benefit analysis showed that dispersed water storage and flood to drip conversion can be highly cost-effective in this semi-arid region. The study results suggest that the government and management policies need to be focused towards an integrated management of demand and supply to create a sustainable food-water-energy nexus in the region.

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

International Nuclear Information System (INIS)

Edmunds, W.M.; Walton, N.R.G.

1980-01-01

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

Feasibility of groundwater recharge dam projects in arid environments

Science.gov (United States)

Jaafar, H. H.

2014-05-01

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

Comparison of 120- and 140-μm SMILE Cap Thickness Results in Eyes With Thick Corneas.

Science.gov (United States)

Liu, Manli; Zhou, Yugui; Wu, Xianghua; Ye, Tiantian; Liu, Quan

2016-10-01

To evaluate clinical outcomes after small incision lenticule extraction (SMILE) with different cap thicknesses in thick corneas. Forty patients with central corneal thickness of more than 560 μm were recruited in this prospective, randomized, masked, paired-eye study. Patients were randomized to receive SMILE with a 120-μm cap thickness in 1 eye and 140-μm cap thickness in the other. Uncorrected and corrected distance visual acuity (CDVA), contrast sensitivity (CS), higher-order aberrations (HOAs), and morphologic modifications of corneal architecture were measured during the 3-month follow-up period. Postoperative refractive outcomes, visual outcomes, CS, and the changes in HOAs were similar between both groups. The persistence of brightly reflective particles in the corneal interface layer was 1388.6 ± 219.5/mm in eyes with 120-μm cap thickness and 54.7 ± 8.6/mm in eyes with 140-μm cap thickness (P line at the interface layer almost disappeared in all eyes with 140-μm cap thickness, and it still persisted in 43% of the fellow eyes at 3 months postoperatively. The anterior surfaces of lenticules in the 140-μm cap thickness group exhibited more smoothness than in the 120-μm cap thickness group. There was a lower level corneal wound-healing response after SMILE with a 140-μm cap thickness than with a 120-μm cap thickness, although the thickness of cap creation did not affect visual outcomes by 3 months postoperatively.

Coprophilous Mucorales (ex Zygomycota) from three areas in the semi-arid of Pernambuco, Brazil.

Science.gov (United States)

Souza, Carlos Alberto Fragoso de; Lima, Diogo Xavier; Gurgel, Luciana M S; Santiago, André Luiz Cabral Monteiro de Azevedo

Mucorales comprises fungi commonly isolated as saprobes from soil, dung, stored grains and plants. Although these fungi have been studied in several countries, there are relatively a few reports of them in semi-arid areas. Therefore, the aims of the present study were to assess and compare the Mucorales communities in dung from different species and breeds of herbivores in the semi-arid of Pernambuco, based on the frequency of occurrence and species richness of these fungi. Samples of dung collected in the cities of Arcoverde, Serra Talhada and Sertânia were incubated in moist chambers in triplicate. Altogether, 24 taxa of Mucorales distributed in the genera Absidia, Circinella, Cunninghamella, Lichtheimia, Mucor, Pilobolus, Rhizopus and Syncephalastrum were identified. The highest species richness was found in sheep excrement. Mucor circinelloides f. griseo-cyanus was the most common taxon, followed by M. ramosissimus. The similarity of the composition of Mucorales species was greatest between the excrements of Guzerá and Sindi breeds (bovine). All mucoralean species isolated are being cited for the first time from animal dung found in Caatinga and a new species of Mucor was recorded. An identification key for species of Mucorales from dung in the semi-arid region of Brazil is provided. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Land–Atmosphere Exchange of Water and Heat in the Arid Mountainous Grasslands of Central Asia during the Growing Season

Directory of Open Access Journals (Sweden)

Xiaotao Huang

2017-09-01

Full Text Available Arid grassland ecosystems are widely distributed across Central Asia. However, there is a lack of research and observations of the land–atmosphere exchange of water and heat in the arid grasslands in this region, particularly over complex surfaces. In this study, systematic observations were conducted from 2013 to 2015 using an HL20 Bowen ratio and TDR300 and WatchDog1400 systems to determine the characteristics of these processes during the growing season (April–October of the arid mountainous grasslands of this region. (1 The latent heat flux (Le was lower than the sensible heat flux (He overall, and a small transient decrease in Le was observed before its daytime maximum; daily comparative variations in both fluxes were closely related to vegetation growth. (2 Evapotranspiration (ET showed substantial variation across different years, seasons and months, and monthly variations in ET were closely related to vegetation growth. Water condensation (Q was low and relatively stable. Relatively high levels of soil water were measured in spring followed by a decreasing trend. The land–atmosphere exchange of water and heat during the growing season in this region was closely associated with phenology, available precipitation and terrain. This study provides data support for the scientific management of arid mountainous grasslands.

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

OpenAIRE

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 Netherlands). ... Zie: Summary

Endemic shrubs in temperate arid and semiarid regions of northern China and their potentials for rangeland restoration.

Science.gov (United States)

Chu, Jianmin; Yang, Hongxiao; Lu, Qi; Zhang, Xiaoyan

2015-06-03

Some endemic shrubs in arid and semiarid ecosystems are in danger of extinction, and yet they can play useful roles in maintaining or restoring these ecosystems, thus practical efforts are needed to conserve them. The shrubs Amygdalus pedunculata Pall., Amygdalus mongolica (Maxim.) Ricker and Ammopiptanthus mongolicus (Maxim. ex Kom.) Cheng f. are endemic species in arid and semiarid regions of northern China, where rangeland desertification is pronounced due to chronic overgrazing. In this study, we tested the hypothesis that these endemic shrubs have developed adaptations to arid and semiarid environments and could play critical roles as nurse species to initiate the process of rangeland recovery. Based on careful vegetation surveys, we analysed the niches of these species in relation to precipitation, temperature and habitats. All sampling plots were categorized by these endemics and sorted by the non-metric multidimensional scaling method. Species ratios of each life form and species co-occurrence rates with the endemics were also evaluated. Annual average temperature and annual precipitation were found to be the key factors determining vegetation diversity and distributions. Amygdalus pedunculata prefers low hills and sandy land in temperate semiarid regions. Amygdalus mongolica prefers gravel deserts of temperate semiarid regions. Ammopiptanthus mongolicus prefers sandy land of temperate arid regions. Communities of A. pedunculata have the highest diversity and the largest ratios of long-lived grass species, whereas those of A. mongolicus have the lowest diversity but the largest ratios of shrub species. Communities of A. mongolica are a transition between the first two community types. These findings demonstrate that our focal endemic shrubs have evolved adaptations to arid and semiarid conditions, thus they can be nurse plants to stabilize sand ground for vegetation restoration. We suggest that land managers begin using these shrub species to restore

Predictive models of threatened plant species distribution in the Iberian arid south-east

OpenAIRE

Benito, Blas M.

2013-01-01

Poster on the distribution of three rare, endemic and endangered annual plants of arid zones in the south-eastern Iberian peninsula. Presented in the workshop "Predictive Modelling of Species Distribution: New Tools for the XXI Century (Baeza, Spain, november 2005).

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.

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

Science.gov (United States)

Oliver, Paul M; Couper, Patrick J; Pepper, Mitzy

2015-01-01

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.

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

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......-arid savanna sites; half-hourly GPP and Reco peaked at -43μmol CO2m-2s-1 and 20μmol CO2m-2s-1, and daily GPP and Reco peaked at -15gCm-2 and 12gCm-2, respectively. Possible explanations for the high CO2 fluxes are a high fraction of C4 species, alleviated water stress conditions, and a strong grazing pressure...

The SPACE 1.0 model: a Landlab component for 2-D calculation of sediment transport, bedrock erosion, and landscape evolution

Science.gov (United States)

Shobe, Charles M.; Tucker, Gregory E.; Barnhart, Katherine R.

2017-12-01

Models of landscape evolution by river erosion are often either transport-limited (sediment is always available but may or may not be transportable) or detachment-limited (sediment must be detached from the bed but is then always transportable). While several models incorporate elements of, or transition between, transport-limited and detachment-limited behavior, most require that either sediment or bedrock, but not both, are eroded at any given time. Modeling landscape evolution over large spatial and temporal scales requires a model that can (1) transition freely between transport-limited and detachment-limited behavior, (2) simultaneously treat sediment transport and bedrock erosion, and (3) run in 2-D over large grids and be coupled with other surface process models. We present SPACE (stream power with alluvium conservation and entrainment) 1.0, a new model for simultaneous evolution of an alluvium layer and a bedrock bed based on conservation of sediment mass both on the bed and in the water column. The model treats sediment transport and bedrock erosion simultaneously, embracing the reality that many rivers (even those commonly defined as bedrock rivers) flow over a partially alluviated bed. SPACE improves on previous models of bedrock-alluvial rivers by explicitly calculating sediment erosion and deposition rather than relying on a flux-divergence (Exner) approach. The SPACE model is a component of the Landlab modeling toolkit, a Python-language library used to create models of Earth surface processes. Landlab allows efficient coupling between the SPACE model and components simulating basin hydrology, hillslope evolution, weathering, lithospheric flexure, and other surface processes. Here, we first derive the governing equations of the SPACE model from existing sediment transport and bedrock erosion formulations and explore the behavior of local analytical solutions for sediment flux and alluvium thickness. We derive steady-state analytical solutions for

Research summary: characterization of radionuclide and moisture movement through arid region sediments

International Nuclear Information System (INIS)

Gee, G.W.; Jones, T.L.; Rai, D.

1981-09-01

This project has the task of understanding the movement of moisture and radionuclides under arid region conditions. This understanding will be used to maximize the isolation of low level waste from the environment. Specific objectives include: field monitoring of moisture and radionuclide transport at an arid region site; assessment of the interaction of radionuclides with unsaturated soils in arid regions; evaluation of radionuclide transport in unsaturated soils by appropriate mathematical models; and assessment of the importance of upward migration of radionuclides by evaporation and diffusion processes. The Burial Waste Test Facility (BWTF) located near Richland, Washington, on the Department of Energy (DOE) Hanford Site has been monitored for water content and radionuclide transport for the past two years. Tritium movement has been observed to depths of 7.6 m in both irrigated and nonirrigated lysimeters. Laboratory tests were conducted to determine how leachate from uranium tailings interacts with geologic materials. Acid leach tailings and tailings solution and geologic materials typical of mill site tailing pits were physically and chemically characterized. Investigation was made of the sorption characteristics of heavy metals and radionuclides on the geologic materials under low and neutral pH conditions. From solubility tests conducted at Pacific Northwest Laboratory, thermodynamic considerations predicted that for the Eh-pH range of natural aqueous environment, the dominant species of Pu is likely to be Pu(V) in relatively oxidizing environments and Pu(III) in reducing environments. Radionuclide transport through unsaturated media was investigated by using two solute transport models to describe the transport of tritium and strontium-85 in laboratory columns. A new approach was used to analyze radon emissions from uranium mill tailings

Native-plant amendments and topsoil addition enhance soil function in post-mining arid grasslands.

Science.gov (United States)

Kneller, Tayla; Harris, Richard J; Bateman, Amber; Muñoz-Rojas, Miriam

2018-04-15

One of the most critical challenges faced in restoration of disturbed arid lands is the limited availability of topsoil. In post-mining restoration, alternative soil substrates such as mine waste could be an adequate growth media to alleviate the topsoil deficit, but these materials often lack appropriate soil characteristics to support the development and survival of seedlings. Thus, addition of exogenous organic matter may be essential to enhance plant survival and soil function. Here, we present a case study in the arid Pilbara region (north-west Western Australia), a resource-rich area subject to intensive mining activities. The main objective of our study was to assess the effects of different restoration techniques such as soil reconstruction by blending available soil materials, sowing different compositions of plant species, and addition of a locally abundant native soil organic amendment (Triodia pungens biomass) on: (i) seedling recruitment and growth of Triodia wiseana, a dominant grass in Australian arid ecosystems, and (ii) soil chemical, physical, and biological characteristics of reconstructed soils, including microbial activity, total organic C, total N, and C and N mineralisation. The study was conducted in a 12-month multifactorial microcosms setting in a controlled environment. Our results showed that the amendment increased C and N contents of re-made soils, but these values were still lower than those obtained in the topsoil. High microbial activity and C mineralisation rates were found in the amended waste that contrasted the low N mineralisation but this did not translate into improved emergence or survival of T. wiseana. These results suggest a short- or medium-term soil N immobilisation caused by negative priming effect of fresh un-composted amendment on microbial communities. We found similar growth and survival rates of T. wiseana in topsoil and a blend of topsoil and waste (50:50) which highlights the importance of topsoil, even in a

Effects of added organic matter and water on soil carbon sequestration in an arid region.

Directory of Open Access Journals (Sweden)

Liming Lai

Full Text Available It is generally predicted that global warming will stimulate primary production and lead to more carbon (C inputs to soil. However, many studies have found that soil C does not necessarily increase with increased plant litter input. Precipitation has increased in arid central Asia, and is predicted to increase more, so we tested the effects of adding fresh organic matter (FOM and water on soil C sequestration in an arid region in northwest China. The results suggested that added FOM quickly decomposed and had minor effects on the soil organic carbon (SOC pool to a depth of 30 cm. Both FOM and water addition had significant effects on the soil microbial biomass. The soil microbial biomass increased with added FOM, reached a maximum, and then declined as the FOM decomposed. The FOM had a more significant stimulating effect on microbial biomass with water addition. Under the soil moisture ranges used in this experiment (21.0%-29.7%, FOM input was more important than water addition in the soil C mineralization process. We concluded that short-term FOM input into the belowground soil and water addition do not affect the SOC pool in shrubland in an arid region.

Thickness-Dependent Bioelectrochemical and Energy Applications of Thickness-Controlled Meso-Macroporous Antimony-Doped Tin Oxide

Directory of Open Access Journals (Sweden)

Daniel Mieritz

2018-04-01

Full Text Available Coatings of hierarchically meso-macroporous antimony-doped tin oxide (ATO enable interfacing adsorbed species, such as biomacromolecules, with an electronic circuit. The coating thickness is a limiting factor for the surface coverage of adsorbates, that are electrochemically addressable. To overcome this challenge, a carbon black-based templating method was developed by studying the composition of the template system, and finding the right conditions for self-standing templates, preventing the reaction mixture from flowing out of the mask. The thicknesses of as-fabricated coatings were measured using stylus profilometry to establish a relationship between the mask thickness and the coating thickness. Cyclic voltammetry was performed on coatings with adsorbed cytochrome c to check whether the entire coating thickness was electrochemically addressable. Further, bacterial photosynthetic reaction centers were incorporated into the coatings, and photocurrent with respect to coating thickness was studied. The template mixture required enough of both carbon black and polymer, roughly 7% carbon black and 6% poly(ethylene glycol. Coatings were fabricated with thicknesses approaching 30 µm, and thickness was shown to be controllable up to at least 15 µm. Under the experimental conditions, photocurrent was found to increase linearly with the coating thickness, up to around 12 µm, above which were diminished gains.

Active old-field restoration in the most arid lands of the Great Basin

Science.gov (United States)

Restoration of former agricultural fields can be challenging, especially in arid systems, where factors such as wind erosion, water stress, soil alteration, and competition from weeds can strongly affect plant establishment and growth. Experiments were conducted in two former agricultural fields in ...

Semi-arid Northeast Brazil: integrated modelling of regional development and global change impacts

NARCIS (Netherlands)

Krol, Martinus 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

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.

The use of soil quality indicators to assess soil functionality in restored semi-arid ecosystems

Science.gov (United States)

Muñoz-Rojas, Miriam; Erickson, Todd E.; Dixon, Kingsley W.; Merritt, David J.

2016-04-01

Keywords: Pilbara, 1-day CO2 test, microbial activity, mine restoration, soil health, ecosystem services. Introduction Semi-arid and arid environments are highly vulnerable to land degradation and their restoration has commonly showed low rates of success (James et al., 2013). A systematic knowledge of soil functionality is critical to successful restoration of degraded ecosystems since approximately 80% of ecosystem services can be connected to soil functions. The assessment of soil functionality generally involves the evaluation of soil properties and processes as they relate to the ability of soil to function effectively as a component of a healthy ecosystem (Costantini et al., 2015) Using soil quality indicators may be a valuable approach to assess functionality of topsoil and novel substrates used in restoration (Muñoz-Rojas et al., 2014; 2015). A key soil chemical indicator is soil organic C, that has been widely used as an attribute of soil quality because of the many functions that it provides and supports (Willaarts et al., 2015). However, microbial indicators can be more sensitive to disturbances and could be a valuable addition in soil assessment studies in restoration programs. Here, we propose a set of soil quality indicators to assess the soil status in restored soils (topsoil and waste material) of semi-arid environments. The study was conducted during March 2015 in the Pilbara biogeographical region (northwestern Australia) at an iron ore mine site rehabilitated in 2011. Methods Soil samples were collected from two sub-areas with different soil materials used as growth media: topsoil retrieved from nearby stockpiles and a lateritic waste material utilised for its erosive stability and physical competence. An undisturbed natural shrub-grassland ecosystem dominated by Triodia spp. and Acacia spp. representative of the restored area was selected as the analogue reference site. Soil physicochemical analysis were undertaken according to standard methods

Use of composts in revegetating arid lands

Energy Technology Data Exchange (ETDEWEB)

Brandt, C.A.; Hendrickson, P.L.

1991-09-01

Compost has been suggested as a soil amendment for arid lands at the US Department of Energy's Hanford Site in southeastern Washington State. The operating contractor of the site, Westinghouse Hanford Company, requested that the Pacific Northwest Laboratory conduct a literature review to compile additional information on the use of compost amendments and their benefits. This report provides background information on the factors needed for plant growth and the consequences of severe soil disturbance. This report also discussed the characteristics of composts relative to other amendments and how they each affect plant growth. Finally,regulatory requirements that could affect land application of sludge-based compost on the Hanford Site are reviewed.

Increased water use efficiency does not prevent growth decline of Pinus canariensis in a semi-arid treeline ecotone in Tenerife, Canary Islands (Spain).

Science.gov (United States)

Brito, Patricia; Grams, Thorsten E E; Matysssek, Rainer; Jimenez, Maria S; Gonzalez-Rodríguez, Agueda M; Oberhuber, Walter; Wieser, Gerhard

2016-09-01

Intrinsic water-use efficiency of Pinus canariensis (Sweet ex Spreng.) growing at a semi-arid treeline has increased during the past 37 years. Tree-ring width by contrast has declined, likely caused by reduced stomatal conductance due to increasing aridity. Rising atmospheric CO 2 concentration ( C a ) has been related to tree growth enhancement accompanied by increasing intrinsic water-use-efficiency (iWUE). Nevertheless, the extent of rising C a on long-term changes in iWUE and growth has remained poorly understood to date in Mediterranean treeline ecosystems. This study aimed to examine radial growth and physiological responses of P. canariensis in relation to rising C a and increasing aridity at treeline in Tenerife, Canary Islands, Spain. We evaluated temporal changes in secondary growth (tree-ring width; TRW) and tree ring stable C isotope signature for assessing iWUE from 1975 through 2011. Precipitation was the main factor controlling secondary growth. Over the last 36 years P. canariensis showed a decline in TRW at enhanced iWUE, likely caused by reduced stomatal conductance due to increasing aridity. Our results indicate that increasing aridity has overridden the potential CO 2 fertilization on tree growth of P. canariensis at its upper distribution limit.

Diversity of avian haemosporidians in arid zones of northern Venezuela.

Science.gov (United States)

Belo, Nayara O; Rodríguez-Ferraro, Adriana; Braga, Erika M; Ricklefs, Robert E

2012-07-01

Arid zones of northern Venezuela are represented by isolated areas, important from an ornithological and ecological perspective due to the occurrence of restricted-range species of birds. We analysed the prevalence and molecular diversity of haemosporidian parasites of wild birds in this region by screening 527 individuals (11 families and 20 species) for parasite mitochondrial DNA. The overall prevalence of parasites was 41%, representing 17 mitochondrial lineages: 7 of Plasmodium and 10 of Haemoproteus. Two parasite lineages occurred in both the eastern and western regions infecting a single host species, Mimus gilvus. These lineages are also present throughout northern and central Venezuela in a variety of arid and mesic habitats. Some lineages found in this study in northern Venezuela have also been observed in different localities in the Americas, including the West Indies. In spite of the widespread distributions of some of the parasite lineages found in northern Venezuela, several, including some that are relatively common (e.g. Ven05 and Ven06), have not been reported from elsewhere. Additional studies are needed to characterize the host and geographical distribution of avian malaria parasite lineages, which will provide a better understanding of the influence of landscape, vector abundance and diversity, and host identity on haemosporidian parasite diversity and prevalence.

Simulated Optimum Sowing Date for Forage Pearl Millet Cultivars in Multilocation Trials in Brazilian Semi-Arid Region.

Science.gov (United States)

Santos, Rafael D; Boote, Kenneth J; Sollenberger, Lynn E; Neves, Andre L A; Pereira, Luiz G R; Scherer, Carolina B; Gonçalves, Lucio C

2017-01-01

Forage production is primarily limited by weather conditions under dryland production systems in Brazilian semi-arid regions, therefore sowing at the appropriate time is critical. The objectives of this study were to evaluate the CSM-CERES-Pearl Millet model from the DSSAT software suite for its ability to simulate growth, development, and forage accumulation of pearl millet [ Pennisetum glaucum (L.) R.] at three Brazilian semi-arid locations, and to use the model to study the impact of different sowing dates on pearl millet performance for forage. Four pearl millet cultivars were grown during the 2011 rainy season in field experiments conducted at three Brazilian semi-arid locations, under rainfed conditions. The genetic coefficients of the four pearl millet cultivars were calibrated for the model, and the model performance was evaluated with experimental data. The model was run for 14 sowing dates using long-term historical weather data from three locations, to determine the optimum sowing window. Results showed that performance of the model was satisfactory as indicated by accurate simulation of crop phenology and forage accumulation against measured data. The optimum sowing window varied among locations depending on rainfall patterns, although showing the same trend for cultivars within the site. The best sowing windows were from 15 April to 15 May for the Bom Conselho location; 12 April to 02 May for Nossa Senhora da Gloria; and 17 April to 25 May for Sao Bento do Una. The model can be used as a tool to evaluate the effect of sowing date on forage pearl millet performance in Brazilian semi-arid conditions.

Effects of tillage on runoff from a bare clayey soil on a semi-arid ...

African Journals Online (AJOL)

arid areas. However, by adopting appropriate soil management practices, the runoff can be harnessed for improving crop yields. The main objective of this study was to quantify rainfall-runoff relationships under in-field rainwater harvesting ...

The surface water storage problem in arid regions: a case study of ...

African Journals Online (AJOL)

Most dams lose capacity as a result of three principal phenomena: leakage, sedimentation and evaporation. The study of these phenomena is particularly important as they can also endanger the dam's stability. Here, we examine the case of the Gargar dam in western Algeria. This dam is located in an arid zone where ...

Seawater as Alternative to Freshwater in Pretreatment of Date Palm Residues for Bioethanol Production in Coastal and/or Arid Areas

DEFF Research Database (Denmark)

Fang, Chuanji; Thomsen, Mette Hedegaard; Brudecki, Grzegorz P

2015-01-01

The large water consumption (1.9-5.9 m3 water per m3 of biofuel) required by biomass processing plants has become an emerging concern, which is particularly critical in arid/semiarid regions. Seawater, as a widely available water source, could be an interesting option. This work was to study the ...... be a promising alternative to freshwater for lignocellulose biorefineries in coastal and/or arid/semiarid areas....

Paleohydrology of the southern Great Basin, with special reference to water table fluctuations beneath the Nevada Test Site during the late(?) Pleistocene

Science.gov (United States)

Winograd, Isaac Judah; Doty, Gene C.

1980-01-01

Knowledge of the magnitude of water-table rise during Pleistocene pluvial climates, and of the resultant shortening of groundwater flow path and reduction in unsaturated zone thickness, is mandatory for a technical evaluation of the Nevada Test Site (NTS) or other arid zone sites as repositories for high-level or transuranic radioactive wastes. The distribution of calcitic veins filling fractures in alluvium, and of tufa deposits between the Ash Meadows spring discharge area and the Nevada Test Site indicates that discharge from the regional Paleozoic carbonate aquifer during the Late( ) Pleistocene pluvial periods may have occurred at an altitude about 50 meters higher than at present and 14 kilometers northeast of Ash Meadows. Use of the underflow equation (relating discharge to transmissivity, aquifer width, and hydraulic gradient), and various assumptions regarding pluvial recharge, transmissivity, and altitude of groundwater base level, suggest possible rises in potentiometric level in the carbonate aquifer of about -90 meters beneath central Frenchman Flat. During Wisconsin time the rise probably did not exceed 30 meters. Water-level rises beneath Frenchman Flat during future pluvials are unlikely to exceed 30 meters and might even be 10 meters lower than modern levels. Neither the cited rise in potentiometric level in the regional carbonate aquifer, nor the shortened flow path during the Late( ) Pleistocene preclude utilization of the NTS as a repository for high-level or transuranic-element radioactive wastes provided other requisite conditions are met as this site. Deep water tables, attendant thick (up to several hundred meter) unsaturated zones, and long groundwater flow paths characterized the region during the Wisconsin Stage and probably throughout the Pleistocene Epoch and are likely to so characterize it during future glacial periods. (USGS)

The paradigm of paraglacial megafans of the San Juan river basin, Central Andes, Argentina

Science.gov (United States)

Suvires, Graciela M.

2014-11-01

The spatial distribution and several morphometric characteristics of the Quaternary alluvial fans of the San Juan River, in the province of San Juan, at the Central and Western part of Argentina, have been studied to classify them as paraglacial megafans, as well to ratify its depositional environmental conditions. The high sedimentary load exported by San Juan river from the Central Andes to the foreland depressions is estimated about 3,682,200 hm3. The large alluvial fans of Ullum-Zonda and Tulum valleys were deposited into deep tectonic depressions, during the Upper Pleistocene deglaciation stages. The outcome of collecting remotely sensed data, map and DEM data, geophysical data and much fieldwork gave access to morphometric, morphographic and morphogenetic data of these alluvial fans. The main drainage network was mapped on processed images using QGis (vers.2.0.1). Several fan morphometric parameters were measured, such as the size, the shape, the thickness, the surface areas and the sedimentary volume of exported load. The analyzed fans were accumulated in deep tectonic depressions, where the alluvium fill reaches 700 to 1200 m thick. Such fans do not reach the large size that other world megafans have, and this is due to tectonic obstacles, although the sedimentary fill average volume surpasses 514,000 hm3. The author proposes to consider Ullum-Zonda and Tulum alluvial fans as paraglacial megafans. According to the stratigraphic relationships of the tropical South American Rivers, the author considers that the San Juan paraglacial megafans would have occurred in the period before 24 ka BP , possibly corresponding to Middle Pleniglacial (ca 65-24ka BP). They record colder and more humid conditions compared with the present arid and dry conditions.

Autonomous Sea-Ice Thickness Survey

Science.gov (United States)

2016-06-01

the conductivity of an infinitely thick slab of sea ice. Ice thickness, Hice, is then obtained by subtracting the height of the ...Thickness Survey of Sea Ice Runway” ERDC/CRREL SR-16-4 ii Abstract We conducted an autonomous survey of sea -ice thickness using the Polar rover Yeti...efficiency relative to manual surveys routinely con- ducted to assess the safety of roads and runways constructed on the sea ice. Yeti executed the

PRESERVATION OF ARCHAEOLOGICAL MATERIALS IN ARID ENVIRONMENTS RELEVANT TO YUCCA MOUNTAIN

International Nuclear Information System (INIS)

N. Chapman, A. Dansie, C. McCombie

2006-01-01

The objective of this study was to evaluate archaeological materials from underground openings or shallow burial in arid environments relevant to Yucca Mountain and to draw conclusions about how their state and their environment of preservation could be of relevance to design and operational aspects of the high-level waste repository. The study has evaluated materials from cultures in the arid regions of the ancient Middle East and compared them with the preservation of ancient materials in dry cave sites in the Great Basin desert area of Nevada. The emphasis has been on materials found in undisturbed underground openings such as caves and un-backfilled tombs. Long-term preservation of such materials in underground openings and the stability of the openings themselves provide useful analogue information that serves as a reference point for considering the operation and evolution of the Yucca Mountain repository. Being able to shed light, by close physical and environmental analogy, on what happens in underground openings over many thousands of years provides valuable underpinning to illustrations of expected system performance and offers pointers towards optimizing repository system and operational design

Archaeology of Arid Environments Points to Management Options for Yucca Mountain

International Nuclear Information System (INIS)

N. Chapman; A. Dansie; C. McCombie

2006-01-01

As with all planned repositories for spent fuel, the critical period over which Yucca Mountain needs to provide isolation is the first hundreds to thousands of years after the fuel is emplaced, when it is at its most hazardous. Both the original and the proposed new EPA standards highlight the central importance of this performance period by focusing on repository behavior during the first 10,000 years. Archaeology has a lot to tell us about the behavior of materials and structures over this time period. There have been numerous studies of archaeological artifacts in conditions relevant to the groundwater saturated environments that are a feature of most international geological disposal concepts, but relatively few in arid environments like that of the Nevada desert. However, there is much information to be gleaned, not only from classic archaeological areas in the Middle East and around the Mediterranean but also, perhaps surprisingly to some, from Nevada itself. Our recent study evaluated archaeological materials from underground openings and shallow burial in arid environments relevant to Yucca Mountain, drawing conclusions about how their state and their environment of preservation could help to assess design and operational options for the high-level waste repository

Thickness evaluation using a new relationship between film density and penetrated thickness in radiography

International Nuclear Information System (INIS)

Lee, Sung Sik; Kim, Young H.

2005-01-01

In order to improve the accuracies in the thickness evaluation using radiography, a new relationship between film density and penetrated thickness has been proposed, and experimental verification of the proposed relationship was carried out by using the X- and γ-ray radiographs of two carbon steel step wedges. A new parameter, the logarithmic gradient of film density, was defined in order to express the characteristics of the radiographic film for wider range of film density. A new relationship between the film density and the penetrated thickness were formulated using the logarithmic gradient of the film density. In experiment, the logarithmic gradient of the film density was independent on both the exposure and the film density and measured for the radiographic film used in the present work from the slope of the fitting lines for the same penetrated thickness. Experimental results verifies the accuracy of the proposed relationship between film density and the penetrated thickness for the range of film density from 1.0 to 3.5. The thickness can be more accurately determined by using the proposed relationship and the parameters determined by experiment. It is also found that the γ-ray having simple energy spectrum is more appropriate radiation source for the evaluation of the thickness from the film density of the radiograph

Changes in semi-arid plant species associations along a livestock grazing gradient.

Directory of Open Access Journals (Sweden)

Hugo Saiz

Full Text Available In semi-arid ecosystems, vegetation is heterogeneously distributed, with plant species often associating in patches. These associations between species are not constant, but depend on the particular response of each species to environmental factors. Here, we investigated how plant species associations change in response to livestock grazing in a semi-arid ecosystem, Cabo de Gata-Níjar Natural Park in South East Spain. We established linear point-intercept transects at four sites with different grazing intensity, and recorded all species at each point. We investigated plant associations by comparing the number of times that each pair of species occurred at the same spatial point (co-occurrences, with the expected number of times based on species abundances. We also assessed associations for each shrub and grass species by considering all their pairs of associations and for the whole plant community by considering all pairs of associations on each site. At all sites, the plant community had a negative pattern of association, with fewer co-occurrences than expected. Negative association in the plant community increased at maximum grazing intensity. Most species associated as expected, particularly grass species, and positive associations were most important at intermediate grazing intensities. No species changed its type of association along the grazing gradient. We conclude that in the present plant community, grazing-resistant species compete among themselves and segregate in space. Some shrub species act as refuges for grazing-sensitive species that benefit from being spatially associated with shrub species, particularly at intermediate grazing intensities where positive associations were highest. At high grazing intensity, these shrubs can no longer persist and positive associations decrease due to the disappearance of refuges. Spatial associations between plant species and their response to grazing help identify the factors that organize

Isotope and radiation techniques for efficient water and fertilizer use in semi-arid regions

International Nuclear Information System (INIS)

1986-04-01

The Joint FAO/IAEA Division carried out a coordinated research programme, which was concerned with the efficiency of water and fertilizer uses in semi-arid farming systems. The present publication is a summary of the individual contributions from Belgium, Chile, Ivory Coast, Cyprus, France, India, Israel, Romania, Senegal, Sri Lanka and the United States of America, over the period 1978-1984. Water and fertilizer uptake by crops are dynamic processes affected by several factors of the soil-plant-atmosphere system. The neutron moisture meters were used not only to measure soil water contents but also to understand water dynamics under field conditions. Nitrogen is the most limiting nutrient in many semi-arid regions, and as its absorption is very much related to water dynamics in the soil, experiments using N-15 labelled fertilizer were carried out, which are presented in this report

Impacts of urbanization on nitrogen cycling and aerosol, surface and groundwater transport in semi-arid regions

Science.gov (United States)

Lohse, K. A.; Gallo, E.; Carlson, M.; Riha, K. M.; Brooks, P. D.; McIntosh, J. C.; Sorooshian, A.; Michalski, G. M.; Meixner, T.

2011-12-01

Semi-arid regions are experiencing disproportionate increases in human population and land transformation worldwide, taxing limited water resources and altering nitrogen (N) biogeochemistry. How the redistribution of water and N by urbanization affects semi-arid ecosystems and downstream water quality (e.g. drinking water) is unclear. Understanding these interactions and their feedbacks will be critical for developing science-based management strategies to sustain these limited resources. This is especially true in the US where some of the fastest growing urban areas are in semi-arid ecosystems, where N and water cycles are accelerated, and intimately coupled, and where runoff from urban ecosystems is actively managed to augment a limited water supply to the growing human population. Here we synthesize several ongoing studies from the Tucson Basin in Arizona and examine how increasing urban land cover is altering rainfall-runoff relationships, groundwater recharge, water quality, and long range transport of atmospheric N. Studies across 5 catchments varying in impervious land cover showed that only the least impervious catchment responded to antecedent moisture conditions while hydrologic responses were not statistically related to antecedent rainfall conditions at more impervious sites. Regression models indicated that rainfall depth, imperviousness, and their combined effect control discharge and runoff ratios (p channel characteristics and infrastructure controlled runoff chemistry. Groundwater studies showed nonpoint source contamination of CFCs and associated nitrate in areas of rapid recharge along ephemeral channels. Aerosol measurements indicate that both long-range transport of N and N emissions from Tucson are being transported and deposited at high elevation in areas that recharge regional groundwater. Combined, our findings suggest that urbanization in semi-arid regions results in tradeoffs in the redistribution of water and N that have important

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,

Influence of hydraulic and geomorphologic components of a semi-arid watershed on depleted-uranium transport

International Nuclear Information System (INIS)

Becker, N.M.

1991-01-01

Investigations were undertaken to determine the fate and transport of depleted uranium away from high explosive firing sites at Los Alamos National Laboratory in north-central New Mexico. Investigations concentrated on a small, semi-arid watershed which drains 5 firing sites. Sampling for uranium in spring/summer/fall runoff, snowmelt runoff, in fallout, and in soil and in sediments revealed that surface water is the main transport mechanism. Although the watershed is less than 8 km 2 , flow discontinuity was observed between the divide and the outlet; flow discontinuity occurs in semi-arid and arid watersheds, but was unexpected at this scale. This region, termed a discharge sink, is an area where all flow infiltrates and all sediment, including uranium, deposits during nearly all flow events; it is estimated that the discharge sink has provided the locale for uranium detention during the last 23 years. Mass balance calculations indicate that over 90% of uranium expended still remains at or nearby the firing sites. Leaching experiments determined that uranium can rapidly dissolve from the solid phase. It is postulated that precipitation and runoff which percolate vertically through uranium-contaminated soil and sediment are capable of transporting uranium in the dissolved phase to deeper strata. This may be the key transport mechanism which moves uranium out of the watershed

Disentangling The Thick Concept Argument

DEFF Research Database (Denmark)

Blomberg, Olle

2007-01-01

Critics argue that non-cognitivism cannot adequately account for the existence and nature of some thick moral concepts. They use the existence of thick concepts as a lever in an argument against non-cognitivism, here called the Thick Concept Argument (TCA). While TCA is frequently invoked...

Application of Industrial XRF Coating Thickness Analyzer for Phosphate Coating Thickness on Steel

Directory of Open Access Journals (Sweden)

Aleksandr Sokolov

2018-03-01

Full Text Available The results of industrial application of an online X-ray fluorescence coating thickness analyzer for measuring the thickness of phosphate coatings on moving steel strips are considered in the article. The target range of coating thickness to be measured is from tens to hundreds of mg/m2 in a measurement time of 10 s. The measurement accuracy observed during long-duration factory acceptance test was 10–15%. The coating thickness analyzer consists of two XRF gauges, mounted above and below the steel strip and capable of moving across the moving strip system for their suspension and relocation and electronic control unit. Fully automated software was developed to automatically and continuously (24/7 control both gauges, scanning both sides of the steel strip, and develop and test methods for measuring new coatings. It allows performing offline storage and retrieval of the measurement results, remotely controlling the analyzer components and measurement modes from a control room. The developed XRF coating thickness analyzer can also be used for real-time measurement of other types of coatings, both metallic and non-metallic.

Modelling dynamic water redistribution patterns in arid catchments in the Negev Desert of Israel

NARCIS (Netherlands)

Buis, E.; Veldkamp, A.

2008-01-01

In arid climate regions, redistribution of runoff water is highly relevant for vegetation development. The process of water redistribution at catchment scale is studied with the landscape process model LAPSUS, mainly used for erosion and sedimentation modelling. LAPSUS, formerly applied in

Gonadal mosaicism in ARID1B gene causes intellectual disability and dysmorphic features in three siblings.

Science.gov (United States)

Ben-Salem, Salma; Sobreira, Nara; Akawi, Nadia A; Al-Shamsi, Aisha M; John, Anne; Pramathan, Thachillath; Valle, David; Ali, Bassam R; Al-Gazali, Lihadh

2016-01-01

The gene encoding the AT-rich interaction domain-containing protein 1B (ARID1B) has recently been shown to be one of the most frequently mutated genes in patients with intellectual disability (ID). The phenotypic spectrums associated with variants in this gene vary widely ranging for mild to severe non-specific ID to Coffin-Siris syndrome. In this study, we evaluated three children from a consanguineous Emirati family affected with ID and dysmorphic features. Genomic DNA from all affected siblings was analyzed using CGH array and whole-exome sequencing (WES). Based on a recessive mode of inheritance, homozygous or compound heterozygous variants shared among all three affected children could not be identified. However, further analysis revealed a heterozygous variant (c.4318C>T; p.Q1440*) in the three affected children in an autosomal dominant ID causing gene, ARID1B. This variant was absent in peripheral blood samples obtained from both parents and unaffected siblings. Therefore, we propose that the most likely explanation for this situation is that one of the parents is a gonadal mosaic for the variant. To the best of our knowledge, this is the first report of a gonadal mosaicism inheritance of an ARID1B variant leading to familial ID recurrence. © 2015 Wiley Periodicals, Inc.

INTEGRATION OF SATELLITE RAINFALL DATA AND CURVE NUMBER METHOD FOR RUNOFF ESTIMATION UNDER SEMI-ARID WADI SYSTEM

Directory of Open Access Journals (Sweden)

E. O. Adam

2017-11-01

Full Text Available The arid and semi-arid catchments in dry lands in general require a special effective management as the scarcity of resources and information which is needed to leverage studies and investigations is the common characteristic. Hydrology is one of the most important elements in the management of resources. Deep understanding of hydrological responses is the key towards better planning and land management. Surface runoff quantification of such ungauged semi-arid catchments considered among the important challenges. A 7586 km2 catchment under investigation is located in semi-arid region in central Sudan where mean annual rainfall is around 250 mm and represent the ultimate source for water supply. The objective is to parameterize hydrological characteristics of the catchment and estimate surface runoff using suitable methods and hydrological models that suit the nature of such ungauged catchments with scarce geospatial information. In order to produce spatial runoff estimations, satellite rainfall was used. Remote sensing and GIS were incorporated in the investigations and the generation of landcover and soil information. Five days rainfall event (50.2 mm was used for the SCS CN model which is considered the suitable for this catchment, as SCS curve number (CN method is widely used for estimating infiltration characteristics depending on the landcover and soil property. Runoff depths of 3.6, 15.7 and 29.7 mm were estimated for the three different Antecedent Moisture Conditions (AMC-I, AMC-II and AMC-III. The estimated runoff depths of AMCII and AMCIII indicate the possibility of having small artificial surface reservoirs that could provide water for domestic and small household agricultural use.

Diversification patterns of pebble-mimic dragons are consistent with historical disruption of important habitat corridors in arid Australia.

Science.gov (United States)

Shoo, L P; Rose, R; Doughty, P; Austin, J J; Melville, J

2008-08-01

The pebble-mimic dragon lineage of Tympanocryptis is widely distributed in the stony, or 'gibber', deserts of Australia but is noticeably absent from intersecting areas of sand deserts. Past fluctuations in the extent and configuration of sandy desert habitat barriers are likely to have been an import factor promoting genetic differentiation in this group. We sequenced a approximately 1400bp region of mitochondrial DNA and a approximately 1400bp nuclear gene (RAG-1) to investigate phylogeographic structuring of species of pebble-mimic dragons. Our topology indicates an early split in this lineage between eastern and western parts of the arid zone that probably dates to the mid-Miocene. This split corresponds directly with large expanses of contemporary sandy habitat in the form of Great Sandy and Great Victoria Deserts. Our data indicate that this biogeographic barrier established very early on in the development of the arid zone and has persisted to present. Additional genetic structuring in the absence of recognized barriers suggests that an expanded view of potential habitat barriers in the arid zone is required.

Implementation of a multiangle soil moisture retrieval model using RADARSAT-2 imagery over arid Juyanze, northwest China

Science.gov (United States)

Yang, Liping; Li, Yanfei; Li, Qi; Sun, Xiaohui; Kong, Jinling; Wang, Le

2017-07-01

Accurate retrieval of soil moisture is important for understanding regional environmental changes and sustainable development in arid regions. Through numerical simulation and regression analysis based on advanced integral equation model (AIEM), the study aims to establish a multiangle soil moisture retrieval model based on RADARSAT-2 image in arid Juyanze. A combined roughness parameter Rs was established, and then the influences of roughness and soil moisture on the backscattering simulations were discussed. Finally, the empirical multiangle soil moisture retrieval model was implemented and validated in Juyanze. Inversion results show that the model has favorable validity. The coefficient of determination R2 between the inferred and measured soil moisture is 0.775 with a root-mean-square error (rmse) of 0.626%, implying better retrieval accuracy. Soil moisture varies from about 0.1% to 25% and is no more than 10% in most parts of this region, which is in reasonable agreement with the factual circumstances. The model directly relates the Fresnel reflection coefficient and soil moisture and is independent of ground roughness measurements. With a wider angular range, it has great potential for soil moisture evaluation in arid regions.

Cranial vault thickness in primates: Homo erectus does not have uniquely thick vault bones.

Science.gov (United States)

Copes, Lynn E; Kimbel, William H

2016-01-01

Extremely thick cranial vaults have been noted as a diagnostic characteristic of Homo erectus since the first fossil of the species was identified, but relatively little work has been done on elucidating its etiology or variation across fossils, living humans, or extant non-human primates. Cranial vault thickness (CVT) is not a monolithic trait, and the responsiveness of its layers to environmental stimuli is unknown. We obtained measurements of cranial vault thickness in fossil hominins from the literature and supplemented those data with additional measurements taken on African fossil specimens. Total CVT and the thickness of the cortical and diploë layers individually were compared to measures of CVT in extant species measured from more than 500 CT scans of human and non-human primates. Frontal and parietal CVT in fossil primates was compared to a regression of CVT on cranial capacity calculated for extant species. Even after controlling for cranial capacity, African and Asian H. erectus do not have uniquely high frontal or parietal thickness residuals, either among hominins or extant primates. Extant primates with residual CVT thickness similar to or exceeding H. erectus (depending on the sex and bone analyzed) include Nycticebus coucang, Perodicticus potto, Alouatta caraya, Lophocebus albigena, Galago alleni, Mandrillus sphinx, and Propithecus diadema. However, the especially thick vaults of extant non-human primates that overlap with H. erectus values are composed primarily of cortical bone, while H. erectus and other hominins have diploë-dominated vault bones. Thus, the combination of thick vaults comprised of a thickened diploë layer may be a reliable autapomorphy for members of the genus Homo. Copyright © 2015 Elsevier Ltd. All rights reserved.

In vitro antagonistic activity, plant growth promoting traits and phylogenetic affiliation of rhizobacteria associated with wild plants grown in arid soil

OpenAIRE

El-Sayed, Wael S.; Akhkha, Abdellah; El-Naggar, Moustafa Y.; Elbadry, Medhat

2014-01-01

The role of plant growth-promoting rhizobacteria (PGPR) in adaptation of plants in extreme environments is not yet completely understood. For this study native bacteria were isolated from rhizospeheric arid soils and evaluated for both growth-promoting abilities and antagonistic potential against phytopathogenic fungi and nematodes. The phylogentic affiliation of these representative isolates was also characterized. Rhizobacteria associated with 11 wild plant species from the arid soil of Alm...

Environment, safety, health, and quality plan for the TRU- Contaminated Arid Soils Project of the Landfill Stabilization Focus Area Program

International Nuclear Information System (INIS)

Watson, L.R.

1995-06-01

The Landfill Stabilization Focus Area (LSFA) is a program funded by the US Department of Energy Office of Technology Development. LSFA supports the applied research, development, demonstration, testing, and evaluation of a suite of advanced technologies that together form a comprehensive remediation system for the effective and efficient remediation of buried waste. The TRU-Contaminated Arid Soils project is being conducted under the auspices of the LSFA Program. This document describes the Environment, Safety, Health, and Quality requirements for conducting LSFA/Arid Soils activities at the Idaho National Engineering Laboratory. Topics discussed in this report, as they apply to LSFA/Arid Soils operations, include Federal, State of Idaho, and Environmental Protection Agency regulations, Health and Safety Plans, Quality Program, Data Quality Objectives, and training and job hazard analysis. Finally, a discussion is given on CERCLA criteria and system and performance audits as they apply to the LSFA Program

CMIP5 land surface models systematically underestimate inter-annual variability of net ecosystem exchange in semi-arid southwestern North America.

Science.gov (United States)

MacBean, N.; Scott, R. L.; Biederman, J. A.; Vuichard, N.; Hudson, A.; Barnes, M.; Fox, A. M.; Smith, W. K.; Peylin, P. P.; Maignan, F.; Moore, D. J.

2017-12-01

Recent studies based on analysis of atmospheric CO2 inversions, satellite data and terrestrial biosphere model simulations have suggested that semi-arid ecosystems play a dominant role in the interannual variability and long-term trend in the global carbon sink. These studies have largely cited the response of vegetation activity to changing moisture availability as the primary mechanism of variability. However, some land surface models (LSMs) used in these studies have performed poorly in comparison to satellite-based observations of vegetation dynamics in semi-arid regions. Further analysis is therefore needed to ensure semi-arid carbon cycle processes are well represented in global scale LSMs before we can fully establish their contribution to the global carbon cycle. In this study, we evaluated annual net ecosystem exchange (NEE) simulated by CMIP5 land surface models using observations from 20 Ameriflux sites across semi-arid southwestern North America. We found that CMIP5 models systematically underestimate the magnitude and sign of NEE inter-annual variability; therefore, the true role of semi-arid regions in the global carbon cycle may be even more important than previously thought. To diagnose the factors responsible for this bias, we used the ORCHIDEE LSM to test different climate forcing data, prescribed vegetation fractions and model structures. Climate and prescribed vegetation do contribute to uncertainty in annual NEE simulations, but the bias is primarily caused by incorrect timing and magnitude of peak gross carbon fluxes. Modifications to the hydrology scheme improved simulations of soil moisture in comparison to data. This in turn improved the seasonal cycle of carbon uptake due to a more realistic limitation on photosynthesis during water stress. However, the peak fluxes are still too low, and phenology is poorly represented for desert shrubs and grasses. We provide suggestions on model developments needed to tackle these issues in the future.

Plant-associated microbiomes in arid lands: diversity, ecology and biotechnological potential

KAUST Repository

Soussi, Asma; Ferjani, Raoudha; Marasco, Ramona; Guesmi, Amel; Cherif, Hanene; Rolli, Eleonora; Mapelli, Francesca; Ouzari, Hadda Imene; Daffonchio, Daniele; Cherif, Ameur

2015-01-01

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.

the relationships of the avifauna of the south west arid area of africa

African Journals Online (AJOL)

Some years ago, I discussed (Winterbottom 1959) the limits of the zoogeographical district well named by Chapin (1923) the South West Arid and extended it eastward to include the highveld grasslands of the Transvaal and Orange Free State which Chapin had excluded. Later, I (Winter- bottom 1966) considered its ...

Tear progression of symptomatic full-thickness and partial-thickness rotator cuff tears as measured by repeated MRI.

Science.gov (United States)

Kim, Yang-Soo; Kim, Sung-Eun; Bae, Sung-Ho; Lee, Hyo-Jin; Jee, Won-Hee; Park, Chang Kyun

2017-07-01

The purpose of this study was to analyse the natural course of symptomatic full-thickness and partial-thickness rotator cuff tears treated non-operatively and to identify risk factors affecting tear enlargement. One hundred and twenty-two patients who received non-surgical treatment for a partial- or full-thickness supraspinatus tear were included in this study. All rotator cuff tears were diagnosed with magnetic resonance imaging (MRI), and the same modality was used for follow-up studies. Follow-up MRI was performed after at least a 6-month interval. We evaluated the correlation between tear enlargement and follow-up duration. Eleven risk factors were analysed by both univariate and multivariate analyses to identify factors that affect enlargement of rotator cuff tears. The mean follow-up period was 24.4 ± 19.5 months. Out of 122 patients, 34 (27.9%) patients had an initial full-thickness tear and 88 (72.1%) patients had a partial-thickness tear. Considering all patients together, tear size increased in 51/122 (41.8%) patients, was unchanged in 65/122 (53.3%) patients, and decreased in 6/122 (4.9%) patients. Tear size increased for 28/34 (82.4%) patients with full-thickness tears and 23/88 (26.1%) patients with partial-thickness tears. From the two groups which were followed over 12 months, a higher rate of enlargement was observed in full-thickness tears than in partial-thickness tears (6-12 months, n.s.; 12-24 months, P = 0.002; over 24 months, P rotator cuff tears and 23/88 (26.1%) of symptomatic partial-thickness tears increased in size over a follow-up period of 6-100 months. Full-thickness tears showed a higher rate of enlargement than partial-thickness tears regardless of the follow-up duration. Univariate and multivariate analyses suggested that full-thickness tear was the most reliable risk factor for tear enlargement. The clinical relevance of these observations is that full-thickness rotator cuff tears treated conservatively should be

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.

Physiological characteristics of three wild sonchus species to prolonged drought tolerance in arid regions

International Nuclear Information System (INIS)

Jia, P.Y.; Hu, Y.; Zhang, L.X.; Wu, G.L.

2018-01-01

Drought is one of the main abiotic factors determining plants growth and productivity in arid and semiarid regions. Understanding the physiological responses of wild plants to drought in different growth stages is essential to evaluate their ability of drought tolerance and allow identification and selection of valuable tolerant plants to be cultivated and introduced in arid and semiarid regions. Three wild Sonchus species, Sonchus oleraceus L., Sonchus wightianus DC. and Sonchus uliginosus M. B. were compared regarding some physiological indexes in leaves such as antioxidant enzymes (superoxide dismutase and peroxidase), malondialdehyde, osmotic solutes (proline, soluble sugar and soluble protein), photosynthetic pigments (total chlorophyll, chlorophyll a, chlorophyll b and carotenoid) under the natural condition at seeding stage, flowering stage and maturation stage respectively. Comparing to S. uliginosus and S. wightianus, S. oleraceus had the higher peroxidase (POD) and superoxide dismutase (SOD) activities and total chlorophyll (Chla+b) and carotenoid (Car) content in three growth stages, and the higher proline content at flowering and maturation stage and the lower malondialdehyde (MDA) content at seeding stage and flowering stage. But the ratio of Chla/Chlb and Car/Chla+b in S. uliginosus were significantly higher than that in S. oleraceus and S. wightianus. These findings suggested that S. oleraceus had the higher tolerance to prolonged drought than S. wightianus and S. uliginosus due to the better capacity to prevent oxidative damage to cellular components and osmoregulation and photosynthetic ability and S. uliginosus were more photo-protected under drought. The research results were instructive for cultivation and introduction of S. oleraceus in arid and semiarid regions. (author)

climatology of air mass trajectories and aerosol optical thickness ...

African Journals Online (AJOL)

George

We present in this paper a climatological study of back trajectories of air masses ... obtained by inversion of photometric measurements of AERONET network. ... the arid Sahel region adjacent in the north to the Sahara ... the city a strategic position in the study of the .... atmospheric emergencies, diagnostic case studies and.

Influence of slice thickness on the determination of left ventricular wall thickness and dimension by magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Ohnishi, Shusaku; Fukui, Sugao; Atsumi, Chisato and others

1989-02-01

Wall thickness of the ventricular septum and left ventricle, and left ventricular cavity dimension were determined on magnetic resonance (MR) images with slices 5 mm and 10 mm in thickness. Subjects were 3 healthy volunteers and 7 patients with hypertension (4), hypertrophic cardiomyopathy (one) or valvular heart disease (2). In visualizing the cardiac structures such as left ventricular papillary muscle and right and left ventricles, 5 mm-thick images were better than 10 mm-thick images. Edges of ventricular septum and left ventricular wall were more clearly visualized on 5 mm-thick images than 10 mm-thick images. Two mm-thick MR images obtained from 2 patients yielded the most excellent visualization in end-systole, but failed to reveal cardiac structures in detail in end-diastole. Phantom studies revealed no significant differences in image quality of 10 mm and 5 mm in thickness in the axial view 80 degree to the long axis. In the axial view 45 degree to the long axis, 10 mm-thick images were inferior to 5 mm-thick images in detecting the edge of the septum and the left ventricular wall. These results indicate that the selection of slice thickness is one of the most important determinant factors in the measurement of left ventricular wall thickness and cavity dimension. (Namekawa, K).

Influence of slice thickness on the determination of left ventricular wall thickness and dimension by magnetic resonance imaging

International Nuclear Information System (INIS)

Ohnishi, Shusaku; Fukui, Sugao; Atsumi, Chisato

1989-01-01

Wall thickness of the ventricular septum and left ventricle, and left ventricular cavity dimension were determined on magnetic resonance (MR) images with slices 5 mm and 10 mm in thickness. Subjects were 3 healthy volunteers and 7 patients with hypertension (4), hypertrophic cardiomyopathy (one) or valvular heart disease (2). In visualizing the cardiac structures such as left ventricular papillary muscle and right and left ventricles, 5 mm-thick images were better than 10 mm-thick images. Edges of ventricular septum and left ventricular wall were more clearly visualized on 5 mm-thick images than 10 mm-thick images. Two mm-thick MR images obtained from 2 patients yielded the most excellent visualization in end-systole, but failed to reveal cardiac structures in detail in end-diastole. Phantom studies revealed no significant differences in image quality of 10 mm and 5 mm in thickness in the axial view 80 degree to the long axis. In the axial view 45 degree to the long axis, 10 mm-thick images were inferior to 5 mm-thick images in detecting the edge of the septum and the left ventricular wall. These results indicate that the selection of slice thickness is one of the most important determinant factors in the measurement of left ventricular wall thickness and cavity dimension. (Namekawa, K)

La réhabilitation des terres arides de Baringo au Kenya | CRDI ...

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

9 févr. 2011 ... Lorsque le personnel de la fiducie de bienfaisance Rehabilitation of Arid Environments (RAE) a entendu parler d'un taureau qui mangeait des cactus, il l'a acheté pour l'amener dans le district afin qu'il montre aux bovins affamés comment eux aussi pouvaient se nourrir de ces plantes grasses, une fois que ...

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 ...

Integrated Scenarios of Regional Development in Two Semi-Arid States of North-Eastern Brazil

NARCIS (Netherlands)

Döll, Petra; Krol, Martinus S.

2002-01-01

Scenario analysis of the future is an important tool for supporting sustainability-oriented regional planning. To assist regional planning in two federal states in semi-arid North-eastern Brazil, Ceará and Piauí, we developed integrated qualitative¿quantitative scenarios that show potential

Rainfall-interception-evaporation-runoff relationships in a semi-arid catchment, northern Limpopo basin, Zimbabwe

NARCIS (Netherlands)

Love, D.; Uhlenbrook, S.; Corzo Perez, G.; Twomlow, S.; Zaag, van der P.

2010-01-01

Characterizing the response of a catchment to rainfall, in terms of the production of runoff vs the interception, transpiration and evaporation of water, is the first important step in understanding water resource availability in a catchment. This is particularly important in small semi-arid

Fluvial system response to Late Devensian (Weichselian) aridity, Baston, Lincolnshire, England

Science.gov (United States)

Briant, Rebecca M.; Coope, G. Russell; Preece, Richard C.; Keen, David H.; Boreham, Steve; Griffiths, Huw I.; Seddon, Mary B.; Gibbard, Philip L.

2004-07-01

Little is known about the impact of Late Devensian (Weichselian) aridity on lowland British landscapes, largely because they lack the widespread coversand deposits of the adjacent continent. The concentration of large interformational ice-wedge casts in the upper part of many Devensian fluvial sequences suggests that fluvial activity may have decreased considerably during this time. The development of optically stimulated luminescence (OSL) dating enables this period of ice-wedge cast formation to be constrained for the first time in eastern England, where a marked horizon of ice-wedge casts is found between two distinctive dateable facies associations. Contrasts between this horizon and adjacent sediments show clear changes in environment and fluvial system behaviour in response to changing water supply, in line with palaeontological evidence. In addition to providing chronological control on the period of ice-wedge formation, the study shows good agreement of the radiocarbon and OSL dating techniques during the Middle and Late Devensian, with direct comparison of these techniques beyond 15 000 yr for the first time in Britain. It is suggested that aridity during the Late Devensian forced a significant decrease in fluvial activity compared with preceding and following periods, initiating a system with low peak flows and widespread permafrost development. Copyright

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

Science.gov (United States)

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-d...

The hydraulic geometry of narrow and deep channels; evidence for flow optimisation and controlled peatland growth

Science.gov (United States)

Nanson, Rachel A.; Nanson, Gerald C.; Huang, He Qing

2010-04-01

At-a-station and bankfull hydraulic geometry analyses of peatland channels at Barrington Tops, New South Wales, Australia, reveal adjustments in self-forming channels in the absence of sediment load. Using Rhodes ternary diagram, comparisons are made with hydraulic geometry data from self-forming channels carrying bedload in alluvial settings elsewhere. Despite constraints on channel depths caused at some locations by the restricted thickness of peat, most stations have cohesive, near-vertical, well-vegetated banks, and width/depth (w/d) ratios of ∼ 2 that are optimal for sediment-free flow. Because banks are strong, resist erosion and can stand nearly vertical, and depth is sometimes constrained, adjustments to discharge are accommodated largely by changes in velocity. These findings are consistent with the model of maximum flow efficiency and the overarching least action principle in open channels. The bankfull depth of freely adjusting laterally active channels in clastic alluvium is well known to be related to the thickness of floodplain alluvium and a similar condition appears to apply to these swamps that grow in situ and are formed almost entirely of organic matter. The thickness of peat in these swamps rarely exceeds that required to form a bankfull channel of optimum w/d ratio for the transport of sediment-free water. Swamp vegetation is highly dependent on proximity to the water table. To maintain a swamp-channel and associated floodplain system, the channels must flow with sufficient water much of the time; they not only offer an efficient morphology for flow but do so in a way that enables bankfull conditions to occur many times a year. They also prevent the swamp from growing above a level linked to the depth of the channel. Once the channel attains the most efficient cross section, further growth of the swamp vertically is restricted by enhanced flow velocities and limited flow depths. This means that the volume of peat in such swamps is determined

Evolutionary refugia and ecological refuges: key concepts for conserving Australian arid zone freshwater biodiversity under climate change

Science.gov (United States)

Davis, Jenny; Pavlova, Alexandra; Thompson, Ross; Sunnucks, Paul

2013-01-01

Refugia have been suggested as priority sites for conservation under climate change because of their ability to facilitate survival of biota under adverse conditions. Here, we review the likely role of refugial habitats in conserving freshwater biota in arid Australian aquatic systems where the major long-term climatic influence has been aridification. We introduce a conceptual model that characterizes evolutionary refugia and ecological refuges based on our review of the attributes of aquatic habitats and freshwater taxa (fishes and aquatic invertebrates) in arid Australia. We also identify methods of recognizing likely future refugia and approaches to assessing the vulnerability of arid-adapted freshwater biota to a warming and drying climate. Evolutionary refugia in arid areas are characterized as permanent, groundwater-dependent habitats (subterranean aquifers and springs) supporting vicariant relicts and short-range endemics. Ecological refuges can vary across space and time, depending on the dispersal abilities of aquatic taxa and the geographical proximity and hydrological connectivity of aquatic habitats. The most important are the perennial waterbodies (both groundwater and surface water fed) that support obligate aquatic organisms. These species will persist where suitable habitats are available and dispersal pathways are maintained. For very mobile species (invertebrates with an aerial dispersal phase) evolutionary refugia may also act as ecological refuges. Evolutionary refugia are likely future refugia because their water source (groundwater) is decoupled from local precipitation. However, their biota is extremely vulnerable to changes in local conditions because population extinction risks cannot be abated by the dispersal of individuals from other sites. Conservation planning must incorporate a high level of protection for aquifers that support refugial sites. Ecological refuges are vulnerable to changes in regional climate because they have little

Seawater as Alternative to Freshwater in Pretreatment of Date Palm Residues for Bioethanol Production in Coastal and/or Arid Areas.

Science.gov (United States)

Fang, Chuanji; Thomsen, Mette Hedegaard; Brudecki, Grzegorz P; Cybulska, Iwona; Frankaer, Christian Grundahl; Bastidas-Oyanedel, Juan-Rodrigo; Schmidt, Jens Ejbye

2015-11-01

The large water consumption (1.9-5.9 m(3) water per m(3) of biofuel) required by biomass processing plants has become an emerging concern, which is particularly critical in arid/semiarid regions. Seawater, as a widely available water source, could be an interesting option. This work was to study the technical feasibility of using seawater to replace freshwater in the pretreatment of date palm leaflets, a lignocellulosic biomass from arid regions, for bioethanol production. It was shown that leaflets pretreated with seawater exhibited lower cellulose crystallinity than those pretreated with freshwater. Pretreatment with seawater produced comparably digestible and fermentable solids to those obtained with freshwater. Moreover, no significant difference of inhibition to Saccharomyces cerevisiae was observed between liquids from pretreatment with seawater and freshwater. The results showed that seawater could be a promising alternative to freshwater for lignocellulose biorefineries in coastal and/or arid/semiarid areas. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Soil quality improvement for crop production in semi-arid West Africa

OpenAIRE

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 The results show that adoption of improved soil fertility technologies such as composting by farmers is determined by soil fertility status, access to the market and social reasons. Organic amendment...

Sources and controls for the mobility of arsenic in oxidizing groundwaters from loess-type sediments in arid/semi-arid dry climates - evidence from the Chaco-Pampean plain (Argentina).

Science.gov (United States)

Nicolli, Hugo B; Bundschuh, Jochen; García, Jorge W; Falcón, Carlos M; Jean, Jiin-Shuh

2010-11-01

In oxidizing aquifers, arsenic (As) mobilization from sediments into groundwater is controlled by pH-dependent As desorption from and dissolution of mineral phases. If climate is dry, then the process of evaporative concentration contributes further to the total concentration of dissolved As. In this paper the principal As mobility controls under these conditions have been demonstrated for Salí River alluvial basin in NW Argentina (Tucumán Province; 7000 km(2)), which is representative for other basins or areas of the predominantly semi-arid Chaco-Pampean plain (1,000,000 km(2)) which is one of the world's largest regions affected by high As concentrations in groundwater. Detailed hydrogeochemical studies have been performed in the Salí River basin where 85 groundwater samples from shallow aquifers (42 samples), deep samples (26 samples) and artesian aquifers (17 samples) have been collected. Arsenic concentrations range from 11.4 to 1660 μg L(-1) leaving 100% of the investigated waters above the provisional WHO guideline value of 10 μg L(-1). A strong positive correlation among As, F, and V in shallow groundwaters was found. The correlations among those trace elements and U, B and Mo have less significance. High pH (up to 9.2) and high bicarbonate (HCO(3)) concentrations favour leaching from pyroclastic materials, including volcanic glass which is present to 20-25% in the loess-type aquifer sediments and yield higher trace element concentrations in groundwater from shallow aquifers compared to deep and artesian aquifers. The significant increase in minor and trace element concentrations and salinity in shallow aquifers is related to strong evaporation under semi-arid climatic conditions. Sorption of As and associated minor and trace elements (F, U, B, Mo and V) onto the surface of Fe-, Al- and Mn-oxides and oxi-hydroxides, restricts the mobilization of these elements into groundwater. Nevertheless, this does not hold in the case of the shallow unconfined

Corneal thickness: measurement and implications.

Science.gov (United States)

Ehlers, Niels; Hjortdal, Jesper

2004-03-01

The thickness of the cornea was reported in more than 100-year-old textbooks on physiological optics (Helmholtz, Gullstrand). Physiological interest was revived in the 1950s by David Maurice, and over the next 50 years, this 'simple' biological parameter has been studied extensively. Several techniques for its measurement have been described and physiological and clinical significance have been studied. In this review, the different methods and techniques of measurement are briefly presented (optical, ultrasound). While the corneal thickness of many animals are the same over a considerable part of the surface, in the human cornea anterior and posterior curvature are not concentric giving rise to a problem of definition. Based on this the precision and accuracy of determining the central corneal thickness are discussed. Changes in corneal thickness reflects changes in function of the boundary layers, in particular the endothelial barrier. The absolute value of thickness is of importance for the estimation of IOP but also in diagnosis of corneal and systemic disorders. Finally it is discussed to what extent the thickness is a biometric parameter of significance, e.g. in the progression of myopia or in the development of retinal detachment.

A late Holocene record of arid events from the Cuzco region, Peru

Science.gov (United States)

Chepstow-Lusty, Alex; Frogley, Michael R.; Bauer, Brian S.; Bush, Mark. B.; Tupayachi Herrera, Alfredo

2003-09-01

The small recently infilled lake basin of Marcacocha (13°13S, 72°12W, 3355 m) in the Cuzco region of Peru has a morphology and location that renders it extremely sensitive to environmental change. A record of vegetation, human impact and climatic change during the past 4200 yr has been obtained from a highly organic core taken from the centre of the basin. Sustained arid episodes that affected the Peruvian Andes may be detectable using the proxy indicator of sedge (Cyperaceae) pollen abundances. As the lake-level was lowered during sustained drier conditions, the local catchment was colonised by Cyperaceae, whereas during lake floods, they retreated or were submerged and pollen production was correspondingly reduced. Drier episodes during prehistoric times occurred around 900 bc, 500 bc, ad 100 and ad 550, with a longer dry episode occurring from ad 900 to 1800. Evidence from the independently derived Quelccaya ice-core record and the archaeological chronology for the Cuzco region appears to support the climatic inferences derived from the sedge data. Many of these aridity episodes appear to correspond with important cultural changes in the Cuzco region and elsewhere in the Central Andes. Copyright

Pipeline monitoring with interferometry in non-arid regions

Energy Technology Data Exchange (ETDEWEB)

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

2005-07-01

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

Extreme precipitation variability, forage quality and large herbivore diet selection in arid environments

Science.gov (United States)

Cain, James W.; Gedir, Jay V.; Marshal, Jason P.; Krausman, Paul R.; Allen, Jamison D.; Duff, Glenn C.; Jansen, Brian; Morgart, John R.

2017-01-01

Nutritional ecology forms the interface between environmental variability and large herbivore behaviour, life history characteristics, and population dynamics. Forage conditions in arid and semi-arid regions are driven by unpredictable spatial and temporal patterns in rainfall. Diet selection by herbivores should be directed towards overcoming the most pressing nutritional limitation (i.e. energy, protein [nitrogen, N], moisture) within the constraints imposed by temporal and spatial variability in forage conditions. We investigated the influence of precipitation-induced shifts in forage nutritional quality and subsequent large herbivore responses across widely varying precipitation conditions in an arid environment. Specifically, we assessed seasonal changes in diet breadth and forage selection of adult female desert bighorn sheep Ovis canadensis mexicana in relation to potential nutritional limitations in forage N, moisture and energy content (as proxied by dry matter digestibility, DMD). Succulents were consistently high in moisture but low in N and grasses were low in N and moisture until the wet period. Nitrogen and moisture content of shrubs and forbs varied among seasons and climatic periods, whereas trees had consistently high N and moderate moisture levels. Shrubs, trees and succulents composed most of the seasonal sheep diets but had little variation in DMD. Across all seasons during drought and during summer with average precipitation, forages selected by sheep were higher in N and moisture than that of available forage. Differences in DMD between sheep diets and available forage were minor. Diet breadth was lowest during drought and increased with precipitation, reflecting a reliance on few key forage species during drought. Overall, forage selection was more strongly associated with N and moisture content than energy content. Our study demonstrates that unlike north-temperate ungulates which are generally reported to be energy-limited, N and moisture

An automated microlysimeter to study dew formation and evaporation in arid and semiarid regions

NARCIS (Netherlands)

Heusinkveld, B.G.; Berkowicz, S.M.; Jacobs, A.F.G.; Holtslag, A.A.M.; Hillen, W.C.A.M.

2006-01-01

The development of a simple and low-cost portable weighing microlysimeter that makes use of a load cell for automated recording and for studying daily dew formation, rate of accumulation, and subsequent evaporation in arid or semiarid regions during rainless seasons is presented. The sampling cup is

Agroforestry parkland species diversity : uses and management in semi-arid West-Africa (Burkina Faso)

NARCIS (Netherlands)

Nikiema, A.

2005-01-01

Agroforestry parkland in semi-arid West Africa is a rural land use system, which allows farmers to grow annual crops in combination with useful trees. In addition to cereals, tree products such as vegetables, fruits, vegetable oil, firewood, fodder, and medicines are obtained from the parklands.

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

Three-dimensional primate molar enamel thickness.

Science.gov (United States)

Olejniczak, Anthony J; Tafforeau, Paul; Feeney, Robin N M; Martin, Lawrence B

2008-02-01

Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary assessments of fossil primate teeth for nearly 90 years. Despite the frequency with which enamel thickness is discussed in paleoanthropological discourse, methods used to attain information about enamel thickness are destructive and record information from only a single plane of section. Such semidestructive planar methods limit sample sizes and ignore dimensional data that may be culled from the entire length of a tooth. In light of recently developed techniques to investigate enamel thickness in 3D and the frequent use of enamel thickness in dietary and phylogenetic interpretations of living and fossil primates, the study presented here aims to produce and make available to other researchers a database of 3D enamel thickness measurements of primate molars (n=182 molars). The 3D enamel thickness measurements reported here generally agree with 2D studies. Hominoids show a broad range of relative enamel thicknesses, and cercopithecoids have relatively thicker enamel than ceboids, which in turn have relatively thicker enamel than strepsirrhine primates, on average. Past studies performed using 2D sections appear to have accurately diagnosed the 3D relative enamel thickness condition in great apes and humans: Gorilla has the relatively thinnest enamel, Pan has relatively thinner enamel than Pongo, and Homo has the relatively thickest enamel. Although the data set presented here has some taxonomic gaps, it may serve as a useful reference for researchers investigating enamel thickness in fossil taxa and studies of primate gnathic biology.

Simulations for Making On-farm Decisions in Relation to ENSO in Semi-arid Areas, South Africa

Science.gov (United States)

Tesfuhuney, W. A.; Crespo, O. O.; Walker, S. S.; Steyn, S. A.

2017-12-01

The study was employed to investigate and improve on-farm decision making on planting dates and fertilization by relating simulated yield and seasonal outlook information. The Agricultural Production Systems SIMulator model (APSIM) was used to explore ENSO/SOI effects for small-scale farmers to represent weather conditions and soil forms of semi-arid areas of Bothaville, Bethlehem and Bloemfontein regions in South Africa. The relationships of rainfall and SOI anomalies indicate a positive correlation, signifies ENSO/SOI as seasonal outlooks for study areas. Model evaluation results showed higher degree of bias (RMSEs/RMSE value of 0.88-0.98). The D-index of agreement in the range 0.61-0.71 indicate the ability of the APSIM-Maize model is an adequate tool in evaluating relative changes in maize yield in relation to various management practices and seasonal variations. During rainy, La Niño years (SOI > +5), highest simulated yields were found for Bethlehem in November with addition of 100 - 150 kg ha-1 N fertilization and up to 50 kg ha-1 for both Bothaville and Bloemfontein. With respect to various levels of fertilization, the dry El Niño years (SOI risk for dryland farming in semi-arid regions. Key word: Semi-arid; APSIM; SOI; El Niño / La Niña; On-farm Decisions

the relationships of the avifauna of the south west arid area of africa

African Journals Online (AJOL)

came from the north; zoological facts suggest that African birds must have evolved within the continent, with .... discovered one in central Tanganyika, appears to have evolved in the South West Arid but to have left these ... seems to me that leucotis is more similar, in size and plumage pattern, to verticalis than to australis.

Evaluation of methods for delineating riparian zones in a semi-arid montane watershed

Science.gov (United States)

Jessica A. Salo; David M. Theobald; Thomas C. Brown

2016-01-01

Riparian zones in semi-arid, mountainous regions provide a disproportionate amount of the available wildlife habitat and ecosystem services. Despite their importance, there is little guidance on the best way to map riparian zones for broad spatial extents (e.g., large watersheds) when detailed maps from field data or high-resolution imagery and terrain data...

Detection and differentiation of pollution in urban surface soils using magnetic properties in arid and semi-arid regions of northwestern China.

Science.gov (United States)

Wang, Bo; Xia, Dunsheng; Yu, Ye; Jia, Jia; Xu, Shujing

2014-01-01

Increasing urbanization and industrialization over the world has caused many social and environmental problems, one of which drawing particular concern is the soil pollution and its ecological degradation. In this study, the efficiency of magnetic methods for detecting and discriminating contaminates in the arid and semi-arid regions of northwestern China was investigated. Topsoil samples from six typical cities (i.e. Karamay, Urumqi, Lanzhou, Yinchuan, Shizuishan and Wuhai) were collected and a systematic analysis of their magnetic properties was conducted. Results indicate that the topsoil samples from the six cities were all dominated by coarse low-coercivity magnetite. In addition, the average magnetite contents in the soils from Urumqi and Lanzhou were shown to be much higher than those from Karamay, Yinchuan, Shizuishan and Wuhai, and they also have relatively higher χlf and χfd% when compared with cities in eastern China. Moreover, specific and distinctive soil pollution signals were identified at each sampling site using the combined various magnetic data, reflecting distinct sources. Industrial and traffic-derived pollution was dominant in Urumqi and Lanzhou, in Yinchuan industrial progress was observed to be important with some places affected by vehicle emission, while Karamay, Shizuishan and Wuhai were relatively clean. The magnetic properties of these latter three cities are significantly affected by both anthropogenic pollution and local parent materials from the nearby Gobi desert. The differences in magnetic properties of topsoil samples affected by mixed industrial and simplex traffic emissions are not obvious, but significant differences exist in samples affected by simplex industrial/vehicle emissions and domestic pollution. The combined magnetic analyses thus provide a sensitive and powerful tool for classifying samples according to likely sources, and may even provide a valuable diagnostic tool for discriminating among different cities

Modern sedimentary facies, depositional environments, and major controlling processes on an arid siliciclastic coast, Al qahmah, SE Red Sea, Saudi Arabia

Science.gov (United States)

Nabhan, Abdullah I.; Yang, Wan

2018-04-01

The facies and environments along the arid siliciclastic coast of Red Sea in Al Qahmah, Saudi Arabia are studied to establish a depositional model for interpretation of ancient rocks deposited in rift settings. Field and petrographic studies of 151 sediment samples in an area of 20 km2 define seven main facies types: beach, washover fan, tidal channel, dune, sabkha, delta, and wadi (seasonal stream). The wadi and delta facies are composed of poorly to moderately well-sorted, gravelly, medium-to-fine sands. Delta-front sands are redistributed by southward longshore currents to form a beach. Beach facies is composed of well-to-moderately sorted fine sands with minor gravels, which contain high concentrations of magnetite, ilmenite, garnet, pyroxene, amphibole, epidote, titanite, and apatite grains, indicating strong winnowing. Crabs and other burrowers destroy primary sedimentary structures and mix sediments in foreshore and backshore of the beaches. Wind and storm surge rework foreshore and backshore sediments to form washover fans. Sabkha facies occurs extensively in supratidal depressions behind beach, are flooded by rainstorms and spring tide, and capped by a 5-cm-thick crust composed of interlaminated halite, quartz, albite, minor gypsum and biotite, and rarely calcium carbonate. Halite occurs as thin sheets and gypsum as nodules with a chicken-wire structure. Clastic fraction in sabkha sediments ranges from coarse silt to coarse sand with moderate sorting, and is transported by currents and wind. Tidal inlets and tidal creeks assume abandoned wadis and are filled by muddy sand. Sand dunes and sand sheets are 1-7 m high and widely distributed due to variable wind directions. Fine-grained dune sands are moderately well sorted, whereas sheet sands are coarser and poorly sorted due to vegetation baffling. Most eolian sands are sourced from beach deposits. This suite of complex riverine, wave, tidal, wind, chemical, and biological processes form the facies mosaic

Sedimentology and paleoecology of an Eocene Oligocene alluvial lacustrine arid system, Southern Mexico

Science.gov (United States)

Beraldi-Campesi, Hugo; Cevallos-Ferriz, Sergio R. S.; Centeno-García, Elena; Arenas-Abad, Concepción; Fernández, Luis Pedro

2006-10-01

A depositional model of the Eocene-Oligocene Coatzingo Formation in Tepexi de Rodríguez (Puebla, Mexico) is proposed, based on facies analysis of one of the best-preserved sections, the Axamilpa Section. The sedimentary evolution is interpreted as the retrogradation of an alluvial system, followed by the progressive expansion of an alkaline lake system, with deltaic, palustrine, and evaporitic environments. The analysis suggests a change towards more arid conditions with time. Fossils from this region, such as fossil tracks of artiodactyls, aquatic birds and cat-like mammals, suggest that these animals traversed the area, ostracods populated the lake waters, and plants grew on incipient soils and riparian environments many times throughout the history of the basin. The inferred habitat for some fossil plants coincides with the sedimentological interpretation of an arid to semiarid climate for that epoch. This combined sedimentological-paleontological study of the Axamilpa Section provides an environmental context in which fossils can be placed and brings into attention important biotic episodes, like bird and camelid migrations or the origin of endemic but extinct plants in this area.

Thickly Syndetical Sensitivity of Topological Dynamical System

Directory of Open Access Journals (Sweden)

Heng Liu

2014-01-01

Full Text Available Consider the surjective continuous map f:X→X, where X is a compact metric space. In this paper we give several stronger versions of sensitivity, such as thick sensitivity, syndetic sensitivity, thickly syndetic sensitivity, and strong sensitivity. We establish the following. (1 If (X,f is minimal and sensitive, then (X,f is syndetically sensitive. (2 Weak mixing implies thick sensitivity. (3 If (X,f is minimal and weakly mixing, then it is thickly syndetically sensitive. (4 If (X,f is a nonminimal M-system, then it is thickly syndetically sensitive. Devaney chaos implies thickly periodic sensitivity. (5 We give a syndetically sensitive system which is not thickly sensitive. (6 We give thickly syndetically sensitive examples but not cofinitely sensitive ones.

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,

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

Recovery of rangelands : the functioning of soil seed banks in a semi-arid African savanna

NARCIS (Netherlands)

Tessema, Z.K.

2011-01-01

Rangelands in Africa provide important forage resources for herbivores; particularly perennial grasses provide grazing for domestic and wild herbivores. However, semi-arid African rangelands experience severe vegetation and soil degradation due to heavy grazing, causing negative impacts

Biomass and biomass water use efficiency in oilseed crop (Brassica juncea L.) under semi-arid microenvironments

International Nuclear Information System (INIS)

Adak, Tarun; Kumar, Gopal; Chakravarty, N.V.K.; Katiyar, R.K.; Deshmukh, P.S.; Joshi, H.C.

2013-01-01

Biomass production in arid and semi-arid regions requires a special attention owing to spatiotemporal scarcity of irrigation water wherein improved water use efficiency (WUE) of the crop is targeted. Under field conditions, the crop undergoes dynamic changes in near ground or within-canopy microenvironments. This changed microclimatic condition may have an impact on phenological response of the oilseed crop which in turn would affect biomass productivity, economic seed yield and water use efficiency of the crop. Henceforth, quantification of biomass production and its WUE of oilseed Brassica crop is essentially required owing to have better understanding of the crop water requirement under the era of climate change. Following a 2 years field experiment, it was revealed that the changes in leaf area index were explained by about 68–74%. The best fit polynomial third order regression analysis indicated >93% prediction in biomass production as a function of time factor. Improved biomass partitioning into economic sinks was also observed. Small scale change in near ground microenvironment may reduce the prediction of biomass variability to the extent of 3%. The mean ET variations were observed as 2.4, 1.5 and 3.2 mm day −1 during the critical phenological stages. Mean seed yield, biomass WUE and seed yield WUE ranged between 2.71 and 2.87 Mg ha −1 , 11.4 and 13.1 g m −2 mm −1 and 19.3 and 22.9 kg ha −1 mm −1 respectively. Variations in both biomass and seed yield water use efficiencies due to small scale change in near ground microclimates were revealed. -- Highlights: ► Assessing biomass productivity and its water use efficiency under arid and semi-arid regions is important. ► Under field conditions, the crop undergoes dynamic changes in near ground or within-canopy microenvironments. ► We have estimated changes in seasonal ET, within-canopy micrometeorological dynamics. ► Biomass productivity, partitioning and water use efficiencies were

Potential sites for a spent unreprocessed fuel facility (SURFF), southwesten part of the Nevada Test Site

International Nuclear Information System (INIS)

Hoover, D.L.; Eckel, E.B.; Ohl, J.P.

1978-01-01

In the absence of specific criteria, the topography, geomorphology, and geology of Jackass Flats and vicinity in the southwestern part of the Nevada Test Site are evaluated by arbitrary guidelines for a Spent Unreprocessed Fuel Facility. The guidelines include requirements for surface slopes of less than 5%, 61 m of alluvium beneath the site, an area free of active erosion or deposition, lack of faults, a minimum area of 5 km 2 , no potential for flooding, and as many logistical support facilities as possible. The geology of the Jackass Flats area is similar to the rest of the Nevada Test Site in topographic relief (305-1,200 m), stratigraphy (complexly folded and faulted Paleozoic sediments overlain by Tertiary ash-flow tuffs and lavas overlain in turn by younger alluvium), and structure (Paleozoic thrust faults and folds, strike-slip faults, proximity to volcanic centers, and Basin and Range normal faults). Of the stratigraphic units at the potential Spent Unreprocessed Fuel Facility site in Jackass Flats, only the thickness and stability of the alluvium are of immediate importance. Basin and Range faults and a possible extension of the Mine Mountain fault need further investigation. The combination of a slope map and a simplified geologic and physiographic map into one map shows several potential sites for a Spent Unreprocessed Fuel Facility in Jackass Flats. The potential areas have slopes of less than 5% and contain only desert pavement or segmented pavement--the two physiographic categories having the greatest geomorphic and hydraulic stability. Before further work can be done, specific criteria for a Spent Unreprocessed Fuel Facility site must be defined. Following criteria definition, potential sites will require detailed topographic and geologic studies, subsurface investigations (including geophysical methods, trenching, and perhaps shallow drilling for faults in alluvium), detailed surface hydrologic studies, and possibly subsurface hydrologic studies

Development of land degradation spectral indices in a semi-arid Mediterranean ecosystem

Science.gov (United States)

Chabrillat, Sabine; Kaufmann, Hermann J.; Palacios-Orueta, Alicia; Escribano, Paula; Mueller, Andreas

2004-10-01

The goal of this study is to develop remote sensing desertification indicators for drylands, in particular using the capabilities of imaging spectroscopy (hyperspectral imagery) to derive soil and vegetation specific properties linked to land degradation status. The Cabo de Gata-Nijar Natural Park in SE Spain presents a still-preserved semiarid Mediterranean ecosystem that has undergone several changes in landscape patterns and vegetation cover due to human activity. Previous studies have revealed that traditional land uses, particularly grazing, favoured in the Park the transition from tall arid brush to tall grass steppe. In the past ~40 years, tall grass steppes and arid garrigues increased while crop field decreased, and tall arid brushes decreased but then recovered after the area was declared a Natural Park in 1987. Presently, major risk is observed from a potential effect of exponential tourism and agricultural growth. A monitoring program has been recently established in the Park. Several land degradation parcels presenting variable levels of soil development and biological activity were defined in summer 2003 in agricultural lands, calcareous and volcanic areas, covering the park spatial dynamics. Intensive field spectral campaigns took place in Summer 2003 and May 2004 to monitor inter-annual changes, and assess the landscape spectral variability in spatial and temporal dimension, from the dry to the green season. Up to total 1200 field spectra were acquired over ~120 targets each year in the land degradation parcels. The targets were chosen to encompass the whole range of rocks, soils, lichens, and vegetation that can be observed in the park. Simultaneously, acquisition of hyperspectral images was performed with the HyMap sensor. This paper presents preliminary results from mainly the field spectral campaigns. Identifying sources of variability in the spectra, in relation with the ecosystem dynamics, will allow the definition of spectral indicators of

High Spatial Resolution Visual Band Imagery Outperforms Medium Resolution Spectral Imagery for Ecosystem Assessment in the Semi-Arid Brazilian Sertão

Directory of Open Access Journals (Sweden)

Ran Goldblatt

2017-12-01

Full Text Available Semi-arid ecosystems play a key role in global agricultural production, seasonal carbon cycle dynamics, and longer-run climate change. Because semi-arid landscapes are heterogeneous and often sparsely vegetated, repeated and large-scale ecosystem assessments of these regions have to date been impossible. Here, we assess the potential of high-spatial resolution visible band imagery for semi-arid ecosystem mapping. We use WorldView satellite imagery at 0.3–0.5 m resolution to develop a reference data set of nearly 10,000 labeled examples of three classes—trees, shrubs/grasses, and bare land—across 1000 km 2 of the semi-arid Sertão region of northeast Brazil. Using Google Earth Engine, we show that classification with low-spectral but high-spatial resolution input (WorldView outperforms classification with the full spectral information available from Landsat 30 m resolution imagery as input. Classification with high spatial resolution input improves detection of sparse vegetation and distinction between trees and seasonal shrubs and grasses, two features which are lost at coarser spatial (but higher spectral resolution input. Our total tree cover estimates for the study area disagree with recent estimates using other methods that may underestimate treecover because they confuse trees with seasonal vegetation (shrubs and grasses. This distinction is important for monitoring seasonal and long-run carbon cycle and ecosystem health. Our results suggest that newer remote sensing products that promise high frequency global coverage at high spatial but lower spectral resolution may offer new possibilities for direct monitoring of the world’s semi-arid ecosystems, and we provide methods that could be scaled to do so.

The complementary relationship in estimation of regional evapotranspiration: An enhanced Advection-Aridity model

Science.gov (United States)

Michael T. Hobbins; Jorge A. Ramirez; Thomas C. Brown

2001-01-01

Long-term monthly evapotranspiration estimates from Brutsaert and Stricker’s Advection-Aridity model were compared with independent estimates of evapotranspiration derived from long-term water balances for 139 undisturbed basins across the conterminous United States. On an average annual basis for the period 1962-1988 the original model, which uses a Penman wind...

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

Education and "Thick" Epistemology

Science.gov (United States)

Kotzee, Ben

2011-01-01

In this essay Ben Kotzee addresses the implications of Bernard Williams's distinction between "thick" and "thin" concepts in ethics for epistemology and for education. Kotzee holds that, as in the case of ethics, one may distinguish between "thick" and "thin" concepts of epistemology and, further, that this distinction points to the importance of…

Relationship between macular ganglion cell complex thickness and macular outer retinal thickness: a spectral-domain optical coherence tomography study.

Science.gov (United States)

Kita, Yoshiyuki; Kita, Ritsuko; Takeyama, Asuka; Anraku, Ayako; Tomita, Goji; Goldberg, Ivan

2013-01-01

To assess the relationship between macular ganglion cell complex and macular outer retinal thicknesses. Case-control study. Forty-two normal eyes and 91 eyes with primary open-angle glaucoma were studied. Spectral-domain optical coherence tomography (RTVue-100) was used to measure the macular ganglion cell complex and macular outer retinal thickness. Ganglion cell complex to outer retinal thickness ratio was also calculated. The relationships between the ganglion cell complex and outer retinal thicknesses and between the ganglion cell complex to outer retinal thickness ratio and outer retinal thickness were evaluated. There was a positive correlation between ganglion cell complex and outer retinal thicknesses in the normal group and the glaucoma group (r = 0.53, P variation in the outer retinal thickness. Therefore, when determining the ganglion cell complex, it seems necessary to consider the outer retinal thickness as well. We propose the ratio as a suitable parameter to account for individual variations in outer retinal thickness. © 2013 The Authors. Clinical and Experimental Ophthalmology © 2013 Royal Australian and New Zealand College of Ophthalmologists.

An overview of nitrate sources and operating processes in arid and semiarid aquifer systems.

Science.gov (United States)

Gutiérrez, Mélida; Biagioni, Richard N; Alarcón-Herrera, Maria Teresa; Rivas-Lucero, Bertha A

2018-05-15

Nitrate concentration in most aquifers in arid and semi-arid areas has increased in the past several decades as a result of human activities. Under the predominantly oxic conditions of these aquifers, denitrification is inhibited, allowing nitrate, a soluble and stable form of nitrogen (N), to accumulate. Because of its close association with municipal and agricultural wastes, nitrate is commonly used as an indicator of anthropogenic contamination. Aquifers affected by agricultural waste may contain salts from irrigation returns and herbicides in addition to nitrates. Preventing leakage from soil to deeper parts of the aquifer is thus a priority in the sustainable management of aquifers in arid and semiarid areas. Studies report a wide range of nitrate concentrations distributed non-uniformly within the aquifer, with roughly 40% and 20% of sampled wells exceeding 50mg/L nitrate in shallow and deep parts of the aquifer respectively. In aquifers at risk of becoming contaminated, nitrate isotopes (δ 15 N, δ 18 O, Δ 17 O) can be used to identify the source of nitrogen as mineral or organic fertilizer, sewage, or atmospheric deposition. A variety of mathematical models (crop, hydrological, geochemical, or a combination of them) have been successful in identifying best practices that minimize N leakage without negatively affecting crop yield. In addition, field research in crop management, e.g., conservation agriculture, has yielded promising results in determining the adequate dosage and time of application of fertilizers to reduce N losses. Examples of key dryland aquifers impacted by nitrate are discussed, and some of the most pressing challenges to achieve sustainability are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods.

Science.gov (United States)

Amidon, William H; Fisher, G Burch; Burbank, Douglas W; Ciccioli, Patricia L; Alonso, Ricardo N; Gorin, Andrew L; Silverhart, Perri H; Kylander-Clark, Andrew R C; Christoffersen, Michael S

2017-06-20

Although Earth's climate history is best known through marine records, the corresponding continental climatic conditions drive the evolution of terrestrial life. Continental conditions during the latest Miocene are of particular interest because global faunal turnover is roughly synchronous with a period of global glaciation from ∼6.2-5.5 Ma and with the Messinian Salinity Crisis from ∼6.0-5.3 Ma. Despite the climatic and ecological significance of this period, the continental climatic conditions associated with it remain unclear. We address this question using erosion rates of ancient watersheds to constrain Mio-Pliocene climatic conditions in the south-central Andes near 30° S. Our results show two slowdowns in erosion rate, one from ∼6.1-5.2 Ma and another from 3.6 to 3.3 Ma, which we attribute to periods of continental aridity. This view is supported by synchrony with other regional proxies for aridity and with the timing of glacial ‟cold" periods as recorded by marine proxies, such as the M2 isotope excursion. We thus conclude that aridity in the south-central Andes is associated with cold periods at high southern latitudes, perhaps due to a northward migration of the Southern Hemisphere westerlies, which disrupted the South American Low Level Jet that delivers moisture to southeastern South America. Colder glacial periods, and possibly associated reductions in atmospheric CO 2 , thus seem to be an important driver of Mio-Pliocene ecological transitions in the central Andes. Finally, this study demonstrates that paleo-erosion rates can be a powerful proxy for ancient continental climates that lie beyond the reach of most lacustrine and glacial archives.

Water repellency and infiltration of biological soil crusts on an arid and a temperate dunes

Science.gov (United States)

Fischer, Thomas; Yair, Aaron; Geppert, Helmut; Veste, Maik

2014-05-01

Biological soil crusts (BSCs) play an important role in many ecosystems and in all climates. We studies hydrological properties of BSCs under arid and temperate climates. The arid study site was located near Nizzana, in the northwestern Negev, Israel and the temperate site was near Lieberose, Brandenburg, Germany. BSCs were sampled at each site near the dune crest, at the center of the dune slope and at the dune base. Using principal component analysis (PCA), we studied the relationships between hydraulic properties and the molecular structure of organic matter using repellency indices, microinfiltrometry, and 13C-CP/MAS-NMR. The soil texture was finer and water holding capacities (WHCs) were higher in Nizzana, whereas surface wettability was reduced in Lieberose. At both sites, BSCs caused extra WHC compared to the mineral substrate. Infiltration after wetting along both catenas generally reached a maximum after 10 min and decreased after 30 min. Carbohydrates were the dominating components in all of the BSCs studied, where the relative peak areas of carbohydrate-derived structures (60-110 ppm) amounted to 28-46% and to 10-14% of total C-peak areas, respectively. PCA revealed that the WHC of the substrate was closely related to the amount of silt and clay, whereas the BSC induced extra WHC was closely related to carbohydrates. It was further found that water repellency was positively related to carbohydrate C, but negatively related to alkyl C. Infiltration kinetics was attributed to polysaccharide hydration and swelling. Our findings support the hypothesis that hydraulic properties of BSCs are determined by extracellular polymeric substances (EPS) and soil texture. Hydraulic properties in BSCs result from the combination of chemical properties related to C compounds mainly dominated by carbohydrates and physical surface properties related to texture, porosity and water holding capacity. References Fischer, T., Yair, A., Veste, M., Geppert, H. (2013) Hydraulic

Efficiency of water and fertilizer use in semi-arid regions

International Nuclear Information System (INIS)

1976-01-01

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

Use of buffy coat thick films in detecting malaria parasites in patients with negative conventional thick films.

Science.gov (United States)

Duangdee, Chatnapa; Tangpukdee, Noppadon; Krudsood, Srivicha; Wilairatana, Polrat

2012-04-01

To determine the frequency of malaria parasite detection from the buffy coat blood films by using capillary tube in falciparum malaria patients with negative conventional thick films. Thirty six uncomplicated falciparum malaria patients confirmed by conventional thick and thin films were included in the study. The patients were treated with artemisinin combination therapy at Hospital for Tropical Diseases, Bangkok, Thailand for 28 day. Fingerpricks for conventional blood films were conducted every 6 hours until negative parasitemia, then daily fingerpricks for parasite checks were conducted until the patients were discharged from hospital. Blood samples were also concurrently collected in 3 heparinized capillary tubes at the same time of fingerpricks for conventional blood films when the prior parasitemia was negative on thin films and parasitemia was lower than 50 parasites/200 white blood cells by thick film. The first negative conventional thick films were compared with buffy coat thick films for parasite identification. Out of 36 patients with thick films showing negative for asexual forms of parasites, buffy coat films could detect remaining 10 patients (27.8%) with asexual forms of Plasmodium falciparum. The study shows that buffy coat thick films are useful and can detect malarial parasites in 27.8% of patients whose conventional thick films show negative parasitemia.

Development of an arid site closure plan

International Nuclear Information System (INIS)

Nyhan, J.W.; Barnes, F.J.

1987-01-01

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

Greening reclamation of arid region

Energy Technology Data Exchange (ETDEWEB)

Kamichika, Makio [Tottori Univ. (Japan)

1989-01-20

Arid regions occupy a third of the whole land in the world, and desertification in the rimland makes a problem become more acute. It is also a problem that the large part of such areas is distributed in developing countries. Desertification is defined as a phenomenon, by which the ecological system is degenerated by the change of weather conditions and the pressure of human beings and livestock, and productivity of land is markedly deteriorated. In order to prevent desertification and to promote greening reclamation and agricultural development, it is necessary to analyze desertification mechanism in detail. Artificial factors are overpopulation, too much pasturage, and conversion of grassland into farmland. Natural environmental factors are weather conditions, water resources, soil conditions, etc. It is also important for greening reclamation and development of farm land to evaluate the amount of meteorological resources (such as water resources, energy resources, etc.) and to search for the possibility of their utilization. Because of major condition to grow plants is water environment, investigation and development of water resources are important. If a project ignores the cycle of the ecological system, it might be in danger of retrogradation toward desertification. 8 refs., 10 figs., 4 tabs.

Seasonal variation in water uptake patterns of three plant species based on stable isotopes in the semi-arid Loess Plateau.

Science.gov (United States)

Wang, Jian; Fu, Bojie; Lu, Nan; Zhang, Li

2017-12-31

Water is a limiting factor and significant driving force for ecosystem processes in arid and semi-arid areas. Knowledge of plant water uptake pattern is indispensable for understanding soil-plant interactions and species coexistence. The 'Grain for Green' project that started in 1999 in the Loess Plateau of China has led to large scale vegetation change. However, little is known about the water uptake patterns of the main plant species that inhabit in this region. In this study, the seasonal variations in water uptake patterns of three representative plant species, Stipa bungeana, Artemisia gmelinii and Vitex negundo, that are widely distributed in the semi-arid area of the Loess Plateau, were identified by using dual stable isotopes of δ 2 H and δ 18 O in plant and soil water coupled with a Bayesian mixing model MixSIAR. The soil water at the 0-120cm depth contributed 79.54±6.05% and 79.94±8.81% of the total water uptake of S. bungeana and A. gmelinii, respectively, in the growing season. The 0-40cm soil contributed the most water in July (74.20±15.20%), and the largest proportion of water (33.10±15.20%) was derived from 120-300cm soils in August for A. gmelinii. However, V. negundo obtained water predominantly from surface soil horizons (0-40cm) and then switched to deep soil layers (120-300cm) as the season progressed. This suggested that V. negundo has a greater degree of ecological plasticity as it could explore water sources from deeper soils as the water stress increased. This capacity can mainly be attributed to its functionally dimorphic root system. V. negundo may have a competitive advantage when encountering short-term drought. The ecological plasticity of plant water use needs to be considered in plant species selection and ecological management and restoration of the arid and semi-arid ecosystems in the Loess Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of the Ti-Nanolayer Thickness on the Self-Lift-off of Thick GaN Epitaxial Layers

International Nuclear Information System (INIS)

Yugov, A. A.; Malahov, S. S.; Donskov, A. A.; Duhnovskii, M. P.; Knyazev, S. N.; Kozlova, Yu. P.; Yugova, T. G.; Belogorokhov, I. A.

2016-01-01

The effect of the type of substrate, sapphire substrate (c- and r-orientation) or GaN/Al_2O_3 template (c- and r-orientations), on the nitridation of an amorphous titanium nanolayer is shown. The effect of the titanium-nanolayer thickness on thick GaN epitaxial layer self-separation from the substrate is revealed. The titanium-nanolayer thickness at which thick GaN layer is reproducibly self-separated is within 20–40 nm.

Contour hedgerows and grass strips in erosion and runoff control in semi-arid Kenya

NARCIS (Netherlands)

Kinama, J.M.; Stigter, C.J.; Ong, C.K.; Ng'ang'a, J.K.; Gichuki, F.N.

2007-01-01

Most early alley cropping studies in semi-arid Kenya were on fairly flat land while there is an increase in cultivated sloping land. The effectiveness of aging contour hedgerows and grass strips for erosion control on an about 15% slope of an Alfisol was compared. The five treatments were Senna

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

Thick film hydrogen sensor

Science.gov (United States)

Hoffheins, Barbara S.; Lauf, Robert J.

1995-01-01

A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.