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Gazella leptoceros (F. Cuvier, 1842) is a monotypic African gazelle, most commonly called the slender-horned gazelle. It is one of 21 species in the genus Gazella and is distinguished by its pale sandy coloration, fawn-colored markings, and namesake long, slender horns. Gazella leptoceros is a dune specialist that inhabits the hyperarid northern Sahara Desert between Algeria and Egypt. It feeds on shrubs and low desert plants and ranges over large distances in small groups of 1–5 animals. Because of its very small, isolated populations, G. leptoceros is classified as "Endangered" (EN) on the International Union for Conservation of Nature Red List of Threatened Species and is on Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. [ABSTRACT FROM AUTHOR]

First scientifically documented by the British explorer and soldier Ralph Alger Bagnold, the Selima Sand Sheet is an extensive low-relief area located within the modern hyperarid core of the Eastern Sahara. Field survey and trenching reveal a surface mantle of near 'pinstripe" laminated aeolian sands that comprise active chevron (or zibar) bedforms, which are apparent on satellite datasets. These active sands cover Quaternary paleosols with morphostratigraphic characteristics that reflect differing degrees of soil development over time as a function of in situ weathering of quartz parent materials, addition of silts and clays via illuviation and eluviation processes, the precipitation of carbonates, rubification, and bioturbation by plants and insects. A relative chronostratigraphy is inferred from the associated archaeological (Neolithic) and historical materials (Late Historic to World War II), and absolute ages for these deposits are provided by optical dates using single aliquot regeneration techniques (SAR). Constraining the timing of aeolian sedimentation provides a basis for reconstructing paleoenvironmental changes and pedogenesis over Late Quaternary timescales in this region of northeast Africa. Accretion of the sand sheet was episodic and occurred during time periods of enhanced aeolian activity at ∼20–14 and ∼5–3 ka years ago. Late Pleistocene deposition of the sand sheet was out-of-phase with the widely recognized period of rainwater-fed "pluvial" playa lake formation and wadi river drainage alluviation documented in the Sahara, which resulted from enhanced monsoonal rains associated with the orbitally-forced precessional insolation maximum in the Northern Hemisphere. Enhanced bioturbation processes associated with wet phases during the Holocene have completely obliterated most primary sedimentary structures in the Pleistocene-aged sand sheet, resulting in the development of a cohesive, coarse sand and granule-dominated deposit exhibiting incipient prismatic soil structural development. The younger sand sheets dating to the Late Holocene (∼4–3 ka years ago) preserve primary sedimentary structures (e.g. planar laminations), and increasing amounts of cohesion and structure with age. Reconstructing the maximum estimated accumulation rates, and assuming approximately uniform rates of sedimentation across the Selima Sand Sheet area, sediment storage within the sand sheet may be on the order of ∼7 km3/1000 years during the time period that has elapsed since the mid-Holocene onset of arid conditions. [ABSTRACT FROM AUTHOR]

The present study represents an integrated study using the potential field maps and well geochemical data of the West Dakhla area in the western central area of the Western Desert area, Egypt. The potential field data are represented by the airborne gravity and total magnetic maps acquired by the Nuclear Material Authority (NMA), Egypt, on behalf of Dana Petroleum Company. The geochemical data consist of geochemical analysis in Ammonite-1 well that were done for source rock evaluation. Different processing techniques on the gravity and magnetic maps are carried out for separating the regional and residual separation and filtering. Modelling and Euler deconvolution tools are utilized for proposing the depth to basement and constructing basement-depth maps to infer the basin configuration of the study area. Before acquiring the present geophysical data, the study area wasn’t subjected to any exploration investigations. Therefore, these data and this study are considered as the first efforts carried out and submitted for publication in this area. In addition, a comparison of the present basin is done with matched basins in southern Libya, where this basin is expected to have similar geological features. The study indicates that the studied basin may be a part of a wider basin extending in Egypt and Libya. This basin is expected to have the thickness and features that are favourable for hydrocarbon habitat. The geochemical analysis shows TOC values ranging from poor to very good source rock potentiality. [ABSTRACT FROM AUTHOR]

Abstract: The isotopic composition of modern precipitation collected monthly from the International Atomic Energy Agency (IAEA) stations over North Africa is enriched (average δD: Morocco: -25.8‰; Algeria: -21.3‰; Tunisia: -20.6‰; Libya: -17.7‰; Egypt: -11.7‰) compared to fossil groundwater across North Africa, which shows progressive west-to-east depletion; this indicates that precipitation from paleowind regimes was different from those prevailing in the present day (late Holocene). However, a few monthly records (March 1982, December 1987, December 1991, March 2002, and April 2002) collected from IAEA stations (Sidi Barrani, Cairo, Rafah, and El-Arish) showed isotopic depletions (δD=–56‰ to –43.7‰) approaching those of the fossil groundwater in Egypt. For each of the five events, we investigated the direction of cloud propagation in relation to the isotopic composition of precipitation as it travels over the African continent and surroundings. Cloud propagation directions and air parcel flow paths were extracted from temporal (every 30min) Meteosat image products: (1) Infra-red EUMETSAT, (2) Cloud Motion Winds (CMW), and (3) Back Trajectory Models (BTM). The inferred wind regimes for each of these events were then compared to those for the remaining Egyptian records (160) that produced precipitation with enriched to intermediate isotopic compositions (δD: –39.7‰ to +34.6‰). The extracted cloud propagation directions and the observed spatial variation in the isotopic compositions of the precipitating rain support a model that attributes previous wet climatic periods over North Africa to the intensification of palaeowesterlies during glacial periods. [Copyright &y& Elsevier]

Several natural ventilation techniques are employed in traditional desert architecture across the hot- dry region. These techniques vary depending on the socio-climatic requirements of the communities. This article presents the results of a field study investigating the natural ventilation techniques used in a traditional Sahara desert village called El-Qasr located in El-Dakhla Oasis in Egypt. The study investigates the drivers of the natural ventilation systems used. It was found that the main drivers of natural ventilation in El-Oasr are: street canyon design: Street and building wind orientation; building form and spatial planning; and opening design. [ABSTRACT FROM AUTHOR]

The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5–6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe. [Copyright &y& Elsevier]