Hydrologic processes in deep vadose zones in interdrainage arid environments

2004 ◽  
pp. 15-28 ◽  
Author(s):  
Michelle A. Walvoord ◽  
Bridget R. Scanlon
Keyword(s):  
Arid Environments ◽  
Hydrologic Processes

scholarly journals Modern isotope hydrology and controls on δD of plant leaf waxes at Lake El'gygytgyn, NE Russia

2012 ◽  
Vol 8 (4) ◽  
pp. 3719-3764 ◽  
Author(s):  
K. M. K. Wilkie ◽  
B. Chapligin ◽  
H. Meyer ◽  
S. Burns ◽  
S. Petsch ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Winter Precipitation ◽  
Mean Value ◽  
Great Promise ◽  
Arid Environments ◽  
Hydrologic Processes ◽  
Leaf Wax ◽  
Stable Isotopic ◽  
Lake El’Gygytgyn ◽  
Hydrogen Isotope Ratios

Abstract. Stable isotope data from lipid biomarkers and diatom silica recovered from lake sediment cores hold great promise for paleoclimate and paleohydrological reconstructions. However, these records rely on accurate calibration with modern precipitation and hydrologic processes. Here we investigate the stable isotopic composition of modern precipitation, streams, lake water and ice cover, and use these data to constrain isotope systematics of the Lake El'gygytgyn basin hydrology. Compound specific hydrogen isotope ratios determined from modern vegetation are compared with modern precipitation and lake core top sediments. Multi-species net (apparent) fractionation values between source water (precipitation) and leaf wax lipids (mean value is −105 ± 13‰) agree with previous results in arid environments and provide a basis for application of this proxy downcore. We conclude that although there may be some bias towards winter precipitation signal, overall leaf wax lipids record annual average precipitation within the El'gygytgyn Basin.

ACTION ON MATTER: THE HISTORY OF THE UNIQUELY AFRICAN TAMPER AND CONCAVE ANVIL POT-FORMING TECHNIQUE

2003 ◽  
Vol 1 (1) ◽  
pp. 3-35 ◽  
Author(s):  
Judy Sterner ◽  
Nicholas David
Keyword(s):  
Historical Development ◽  
Weight Ratio ◽  
High Volume ◽  
Efficient Production ◽  
Arid Environments ◽  
Historical Evidence ◽  
Culture History ◽  
History Of ◽  
And Diffusion

The publication, largely by ethnoarchaeologists, of new data on the tamper and concave anvil technique of pot-forming (TCA) permits a reassessment of this uniquely African technique, its toolkit, and its culture history. A survey, inspired by the technologie culturelle school, of its varied expressions in the southern Saharan, Sahelian and northern Sudan zones from Mali to Sudan and extending north into Egypt emphasises the potential of the technique for the efficient production of spherical water jars of high volume to weight ratio, much appreciated in arid environments. The technique is demanding and therefore practised for the most part by specialists. The origins and diffusion of the technique are assessed in the light of the ethnological, archaeological, linguistic, and historical evidence, and a four stage historical development is sketched.

Temperature-Profile Methods for Estimating Percolation Rates in Arid Environments

2003 ◽  
Vol 2 (1) ◽  
pp. 12 ◽  
Author(s):  
Jim Constantz ◽  
Scott W. Tyler ◽  
Edward Kwicklis
Keyword(s):  
Temperature Profile ◽  
Arid Environments

scholarly journals Extensive Variation in the Activities of Pseudocerastes and Eristicophis Viper Venoms Suggests Divergent Envenoming Strategies Are Used for Prey Capture

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 112
Author(s):  
Bianca op den Brouw ◽  
Francisco C. P. Coimbra ◽  
Lachlan A. Bourke ◽  
Tam Minh Huynh ◽  
Danielle H. W. Vlecken ◽  
...  
Keyword(s):  
Prey Capture ◽  
Anticoagulant Activity ◽  
Protein Composition ◽  
Coagulation Factors ◽  
Arid Environments ◽  
Factor X ◽  
Venom Protein ◽  
Research Attention ◽  
Future Assessment ◽  
Viper Venoms

Snakes of the genera Pseudocerastes and Eristicophis (Viperidae: Viperinae) are known as the desert vipers due to their association with the arid environments of the Middle East. These species have received limited research attention and little is known about their venom or ecology. In this study, a comprehensive analysis of desert viper venoms was conducted by visualising the venom proteomes via gel electrophoresis and assessing the crude venoms for their cytotoxic, haemotoxic, and neurotoxic properties. Plasmas sourced from human, toad, and chicken were used as models to assess possible prey-linked venom activity. The venoms demonstrated substantial divergence in composition and bioactivity across all experiments. Pseudocerastes urarachnoides venom activated human coagulation factors X and prothrombin and demonstrated potent procoagulant activity in human, toad, and chicken plasmas, in stark contrast to the potent neurotoxic venom of P. fieldi. The venom of E. macmahonii also induced coagulation, though this did not appear to be via the activation of factor X or prothrombin. The coagulant properties of P. fieldi and P. persicus venoms varied among plasmas, demonstrating strong anticoagulant activity in the amphibian and human plasmas but no significant effect in that of bird. This is conjectured to reflect prey-specific toxin activity, though further ecological studies are required to confirm any dietary associations. This study reinforces the notion that phylogenetic relatedness of snakes cannot readily predict venom protein composition or function. The significant venom variation between these species raises serious concerns regarding antivenom paraspecificity. Future assessment of antivenom is crucial.

scholarly journals A multiscale assessment of Red-tailed Hawk reproductive success relative to urban density and habitat type

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Justin H White ◽  
Jessi L Brown ◽  
Zachary E Ormsby
Keyword(s):  
Urban Areas ◽  
Urban Expansion ◽  
Habitat Type ◽  
Nesting Success ◽  
Arid Environments ◽  
Hatch Date ◽  
Urban Density ◽  
Landscape Characteristics ◽  
Suburban Areas ◽  
Breeding Seasons

Abstract Despite the unique threats to wildlife in urban areas, many raptors have established successfully reproducing urban populations. To identify variations in raptor breeding ecology within an urban area, we compared metrics of Red-tailed Hawk reproductive attempts to landscape characteristics in Reno and Sparks, NV, USA during the 2015 and 2016 breeding seasons. We used the Apparent Nesting Success and logistic exposure methods to measure nesting success of the Red-tailed Hawks. We used generalized linear models to relate nesting success and fledge rate to habitat type, productivity to hatch date (Julian day) and hatch date to urban density. Nesting success was 86% and 83% for the respective years. Nesting success increased in grassland-agricultural and shrub habitats and decreased in riparian habitat within the urban landscape. Productivity was 2.23 and 2.03 per nest for the breeding seasons. Fledge rates were 72% and 77%, respectively, and decreased in riparian areas. Nestlings hatched earlier with increased urban density and earliest in suburban areas, following a negative quadratic curve. Nesting success and productivity for this population were high relative to others in North America. Productivity increased in habitats where ground prey was more accessible. We suggest that suburban areas, if not frequently disturbed, provide sufficient resources to sustain Red-tailed Hawks over extended periods. As urban expansion continues in arid environments globally, we stress that researchers monitor reproductive output across the urban predator guild to elucidate patterns in population dynamics and adaptation.

Sign in / Sign up

Export Citation Format

Share Document