Desert isotope hydrology: Water sources of the Sinai Desert     

Joel R Gat  Arie Issar 《Geochimica et cosmochimica acta》1974,38(7):1117-1131

The isotopic composition of groundwater sources of the Sinai Desert was surveyed. The results are characterized by a large spread in the oxygen-18 and deuterium abundances, compared to equivalent systems from less arid climates. The variability reflects differences in the altitude at which precipitation occurred, the evaporation from stagnant surface waters prior to their infiltration into the ground and admixtures of waters which are not of meteoric or recent origin. It is difficult to distinguish between water sources recharged by direct infiltration and others recharged through the intermediary of flood waters, on the basis of their isotope composition. The isotopio composition enables a clearcut distinction, however, between paleowaters and more recently recharged groundwaters. Among the conclusions: paleowaters play a central role in the deep aquifers of desert areas; direct rain recharge to aquifers is widespread; surface waters which have undergone extensive evaporation contribute their water to local perched aquifers which are found along their route.  相似文献   

Deuterium content of humic acids from marine and non-marine environments     

Arie Nissenbaum 《Marine Chemistry》1974,2(1):59-63

Deuterium values obtained for humic acids isolated from marine sediments from the NE Pacific are in the range of $\text{δ}\text{D}\text{= (?105 ± 5)‰}$, corresponding to values obtained for marine plankton from the same area. Soil humic acids have a much broader range of δD values (?57 to ?97‰), depending on the isotopic values of the precipitation and the isotopic composition of the parent plant precursor.Data obtained on hydrogen isotope distribution confirms previous hypotheses based on chemical analysis and on carbon isotopes, which indicated the authigenic nature of marine humates.  相似文献   

Triangulating Social Multimedia Content for Event Localization using Flickr and Twitter          下载免费PDF全文

George Panteras  Sarah Wise  Xu Lu  Arie Croitoru  Andrew Crooks  Anthony Stefanidis 《Transactions in GIS》2015,19(5):694-715

The analysis of social media content for the extraction of geospatial information and event‐related knowledge has recently received substantial attention. In this article we present an approach that leverages the complementary nature of social multimedia content by utilizing heterogeneous sources of social media feeds to assess the impact area of a natural disaster. More specifically, we introduce a novel social multimedia triangulation process that uses both Twitter and Flickr content in an integrated two‐step process: Twitter content is used to identify toponym references associated with a disaster; this information is then used to provide approximate orientation for the associated Flickr imagery, allowing us to delineate the impact area as the overlap of multiple view footprints. In this approach, we practically crowdsource approximate orientations from Twitter content and use this information to orient Flickr imagery accordingly and identify the impact area through viewshed analysis and viewpoint integration. This approach enables us to avoid computationally intensive image analysis tasks associated with traditional image orientation, while allowing us to triangulate numerous images by having them pointed towards the crowdsourced toponym location. The article presents our approach and demonstrates its performance using a real‐world wildfire event as a representative application case study.  相似文献   

Redefining the trophic importance of seagrasses for fauna in tropical Indo-Pacific meadows   总被引：2，自引：1，他引：1  

Jan Arie Vonk  Marjolijn J.A. Christianen  Johan Stapel 《Estuarine, Coastal and Shelf Science》2008,79(4):653-660

Fauna species living in seagrass meadows depend on different food sources, with seagrasses often being marginally important for higher trophic levels. To determine the food web of a mixed-species tropical seagrass meadow in Sulawesi, Indonesia, we analyzed the stable isotope (δ¹³C and δ¹⁵N) signatures of primary producers, particulate organic matter (POM) and fauna species. In addition invertebrates, both infauna and macrobenthic, and fish densities were examined to identify the important species in the meadow. The aims of this study were to identify the main food sources of fauna species by comparing isotopic signatures of different primary producers and fauna, and to estimate qualitatively the importance of seagrass material in the food web. Phytoplankton and water column POM were the most depleted primary food sources for δ¹³C (range −23.1 to −19.6‰), but no fauna species depended only on these sources for carbon. Epiphytes and Sargassum sp. had intermediate δ¹³C values (−14.2 to −11.9‰). Sea urchins, gastropods and certain fish species were the main species assimilating this material. Seagrasses and sedimentary POM had the least depleted values (−11.5 to −5.7‰). Between the five seagrass species significant differences in δ¹³C were measured. The small species Halophila ovalis and Halodule uninervis were most depleted, the largest species Enhalus acoroides was least depleted, while Thalassia hemprichii and Cymodocea rotundata had intermediate values. Fourteen fauna species, accounting for 10% of the total fauna density, were shown to assimilate predominantly (>50%) seagrass material, either directly or indirectly by feeding on seagrass consumers. These species ranged from amphipods up to the benthic top predator Taeniura lymma. Besides these species, about half of the 55 fauna species analyzed had δ¹³C values higher than the least depleted non-seagrass source, indicating they depended at least partly for their food on seagrass material. This study shows that seagrass material is consumed by a large number of fauna species and is important for a large portion of the food web in tropical seagrass meadows.  相似文献   

Laboratory examination of linearity in rainfall–runoff relationships     

Arie Ben-Zvi 《水文科学杂志》2020,65(10):1794-1801

ABSTRACT

Certain rainfall–runoff models, e.g. the unit hydrograph, assume linear relationships between the variables. These are proportionality of runoff discharges to (net) rainfall depth and linear summations of discharges resulting from (net) rainfalls during different time intervals or over different sectors of a watershed. This study examines the validity of these assumptions by use of an extensive two-dimensional laboratory experimentation. The results indicate that proportionality would be found under high rainfall intensity through a long duration. Spatial summations would more likely yield correct discharges in cases where rainfall duration is equal to, or is longer than, the time of concentration. Temporal summations may yield correct discharges when rainfall duration is longer than one half of the time of concentration. Here, the time of concentration is determined at the beginning of gradual approach of the discharge towards the equilibrium state.  相似文献   

The geochemical evolution of the Pleistocene Lake Lisan-Dead Sea system     

Amitai Katz  Yehoshua Kolodny  Arie Nissenbaum 《Geochimica et cosmochimica acta》1977,41(11):1609-1626

The geochemical history of Lake Lisan, the Pleistocene precursor of the Dead Sea, has been studied by geological, chemical and isotopic methods.Aragonite laminae from the Lisan Formation yielded (equivalent) Sr/Ca ratios in the range 0.5 × 10^?2?1 × 10^?2, Na/Ca ratios from 3.6 × 10^?3 to 9.2 × 10^?3, $\text{δ}{}^{18}\text{O}{}_{\mathrm{PDB}}$ values between 1.5 and 7%. and $\text{δ}{}^{13}\text{C}{}_{\mathrm{PDB}}$ from ?7.7 to 3.4%..The distribution coefficient of Na⁺ between aragonite and aqueous solutions, $\text{λ}{}^{\mathrm{A}}{}_{\mathrm{Na}}$, is experimentally shown to be very sensitive to salinity and nearly temperature independent. Thus, Na/Ca in aragonite serves as a paleosalinity indicator.Sr/Ca ratios and $\text{δ}{}^{18}\text{O}$ values in aragonite provide good long-term monitors of a lake's evolution. They show Lake Lisan to be well mixed, highly evaporated and saline. Except for a diluted surface layer, the salinity of the lake was half that of the present Dead Sea (15 vs 31%).Lake Lisan evolved from a small, yet deep, hypersaline Dead Sea-like, water body. This initial lake was rapidly filled-up to its highest stand by fresh waters and existed for about 40,000 yr before shrinking back to the present Dead Sea. The chemistry of Lake Lisan at its stable stand represented a material balance between a Jordan-like input, an original large mass of salts and a chemical removal of aragonite. The weighted average depth of Lake Lisan is calculated, on a geochemical basis, to have been at least 400, preferably 600 m.The oxygen isotopic composition of Lake Lisan water, which was higher by at least 3%. than that of the Dead Sea, was probably dictated by a higher rate of evaporation.Na/Ca ratios in aragonite, which correlate well with $\text{δ}{}^{13}\text{C}$ values, but change frequently in time, reflect the existence of a short lived upper water layer of varying salinity in Lake Lisan.  相似文献   

Book Review — R. Kandel: Water from heaven. The story of water from the Big Bang to the rise of civilization and beyond     

Arie?S.?IssarEmail author 《Hydrogeology Journal》2004,12(4):478-479

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Combining field and modelling techniques to assess rockfall dynamics on a protection forest hillslope in the European Alps   总被引：4，自引：0，他引：4  

Luuk K. A. Dorren  Bernhard Maier  Uif S. Putters  Arie C. Seijmonsbergen 《Geomorphology》2004,57(3-4):151-167

Adequate management of a mountain forest that protects downslope areas against impacts of rockfall requires insight into the dynamics of the hillslope environment. Therefore, we applied a combined approach, using field and modelling techniques, to assess the determining factors for rockfall source areas, rockfall tracks and rockfall runout zones on a forested slope in mountainous terrain. The first objective of this study was to understand why rockfall occurs in the study area. The second objective was to translate the knowledge obtained in the field into a model that simulates rockfall dynamics on a forested slope realistically. The third objective was to assess which hillslope characteristics primarily determine the distribution of active rockfall tracks. To achieve these objectives, we made a geomorphological map of the whole study area, and we measured the major discontinuity planes in the bedrock that are exposed in the rockfall source areas. Furthermore, a test site for simulation modelling within the larger study area was defined in which both a forest and a hillslope inventory were carried out. The available data and our developed rockfall simulation model allowed us to assess the slope characteristics that mainly determine the distribution of areas affected by rockfall. We found that in decreasing order of importance, both standing and felled trees, the surface roughness and rockfall resistant shrubs primarily determine the distribution of rockfall-affected areas. Simulation tests without a forest cover produced similar rockfall runout zones as fossil rockfall events identified in the field. We believe that the combined field and modelling approach is a prerequisite for understanding how forests can protect against rockfall.  相似文献   

Warming at 18,000 yr B.P. in the Tropical Andes     

Karin F. Helmens  Peter Kuhry  Nathaniel W. Rutter  Klaas Van Der Borg  Arie F. M. De Jong 《Quaternary Research》1996,45(3):289-299

Palynological, paleopedological, and glacial geomorphological evidence from the area of the high plain of Bogotá in the Colombian Eastern Cordillera indicates a significant climatic warming around 18,000¹⁴C yr B.P. Comparison of dated vegetation changes, pedogenic episodes, and glacier fluctuations provides the basis for defining the so-called “La Laguna Interstadial” that lasted from 19,500 to 17,000 yr B.P. During this interstadial period, mean annual temperatures in the tropical Andes were up to 4°C higher than during the preceding and following stadial periods, when full-glacial conditions prevailed and temperatures were up to 8°C colder than at present.  相似文献   

Methane derived organic matter and carbonates     

Arie Nissenbaum 《Organic Geochemistry》1984,5(4):187-192

¹³C depleted materials of three types are encountered in the south-eastern Mediterranean Coastal Plain of Israel and Northern Sinai. Sub-surface coarse carbonates associated with elemental sulfur have gd¹³C values of −50‰. Organic matter (humic substances and lipid soluble) in the Be'eri sulfur quarries have δ¹³C values of −80 to −90‰. Dissolved bicarbonate in groundwaters show δ¹³C values of −13 to −17‰.It is suggested that all these values can be explained by biogenic methane leaking from sub-surface reservoir which is oxidized under different depositional and environmental conditions.  相似文献