SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Lake Nasser

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The Fukushima nuclear accident in Japan resulted in the deposition of radiocesium over forested and rural landscapes northwest of the power plant. Although there have been several investigations into the dynamics of contaminated river sediment, less attention has been paid to the sources of deposited particulate matter in dams and reservoirs. In the Fukushima Prefecture, there are 10 significant dams and over a 1000 reservoirs for both agricultural and surface water management. These reservoirs may have trapped a significant volume of radiocesium-contaminated sediment. Therefore, characterizing the sources of contaminated particulate matter is important for the ongoing management of contamination in the region. Accordingly, the composition of particulate matter deposited in the Mano Dam reservoir, approximately 40km northwest of the power plant, was investigated with the analyses and modelling of carbon and nitrogen stable isotope ratios (δ(13)C and δ(15)N), total organic carbon (TOC) and total nitrogen (TN) concentrations. Four sediment cores, with lengths ranging 29-41cm, were sampled in the Mano Dam. Source samples from 46 forest soils, 28 cultivated soils and 25 subsoils were used to determine the source contributions of particulate matter. Carbon and nitrogen parameters were analyzed on all samples and a concentration-dependent distribution modelling approach was used to apportion source contributions. Three of the four cores sampled in the Mano Dam reservoir had distinct radiocesium peaks representative of the initial post-accident wash-off phase. Cultivated sources were responsible for 48±7% of the deposited fine particulate matter whereas forests were modelled to contribute 27±6% and subsoil sources 25±4%. Ongoing decontamination of cultivated sources in the Fukushima region should result in a decrease of contaminated matter deposition in reservoirs.

Concepts: Agriculture, Drainage basin, Dam, Reservoir, Drought, Lake Nasser, Reservoirs

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This article analyzes the modernization campaigns in Egypt in the 1960s and early 1970s. The regulation of the Nile by the Aswan High Dam and the resulting irrigation projects caused the rate of schistosomiasis infestation in the population to rise. The result was a discourse between experts from the global north and Egyptian elites about modernization, development aid, dam building and health care. The fight against schistosomiasis was like a cipher, which combined different power-laden concepts and arguments. This article will decode the cipher and allow a deeper look into the contemporary dimensions of power bound to this subject. The text is conceived around three thematic axes. The first deals with the discursive interplay of modernization, health and development aid in and for Egypt. The second focuses on far-reaching and long-standing arguments within an international expert discourse about these concepts. Finally, the third presents an exemplary case study of West German health and development aid for fighting schistosomiasis in the Egyptian Fayoum oasis.

Concepts: Egypt, Nile, Cairo, Aswan Dam, Aswan, Lake Nasser, Nubia, Flooding of the Nile

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The monitoring of stable isotopes (δ(18)O and δ(2)H) in water can provide a sensitive indicator of water loss by evaporation. We obtained water samples from surface water and groundwater from both the young and old alluvial plains in the central part of the Nile Valley of Egypt. Groundwater is the only source for irrigation in the old alluvial plains while both surface water (River Nile and irrigation canals) and groundwater are used in the young alluvial plain. Results showed different isotopic compositions between each group of samples and hydrologic connections between shallow groundwater and surface water in the young alluvial plain. The δ(18)O and δ(2)H relationship of the samples collected from the desert areas of the old alluvial plains below agricultural lands define an evaporation line with a slope of 4.5 and low deuterium excess of <-14‰. These values can be attributed to return flow of irrigation water that has been subjected to evaporative processes, further amplified by intense agricultural practices. Average evaporative losses were estimated to be between 31% and 36%.

Concepts: Water, Irrigation, Sudan, Desert, Nile, Cairo, Aswan, Lake Nasser

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Contamination of reservoirs with radiocesium is one of the main concerns in Fukushima Prefecture, Japan. We performed simulations using the three-dimensional finite volume code FLESCOT to understand sediment and radiocesium transport in generic models of reservoirs with parameters similar to those in Fukushima Prefecture. The simulations model turbulent water flows, transport of sediments with different grain sizes, and radiocesium migration both in dissolved and particulate forms. To demonstrate the validity of the modeling approach for the Fukushima environment, we performed a test simulation of the Ogaki Dam reservoir over Typhoon Man-yi in September 2013 and compared the results with field measurements. We simulated a set of generic model reservoirs systematically varying features such as flood intensity, reservoir volume and the radiocesium distribution coefficient. The results ascertain how these features affect the amount of sediment or (137)Cs discharge downstream from the reservoirs, and the forms in which (137)Cs is discharged. Silt carries the majority of the radiocesium in the larger flood events, while the clay-sorbed followed by dissolved forms are dominant in smaller events. The results can be used to derive indicative values of discharges from Fukushima reservoirs under arbitrary flood events. For example the generic model simulations indicate that about 30% of radiocesium that entered the Ogaki Dam reservoir over the flood in September 2015 caused by Typhoon Etau discharged downstream. Continued monitoring and numerical predictions are necessary to quantify future radiocesium migration in Fukushima Prefecture and evaluate possible countermeasures since reservoirs can be a sink of radiocesium.

Concepts: Simulation, Dam, Canal, Reservoir, Tōhoku region, Aswan Dam, Lake Nasser

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This study investigated heavy metal pollution in sediments of the Rosetta branch of the River Nile of Egypt to quantify the toxic distribution potential of metals into the surrounding environment. Sediment samples were collected at 9 sites during in four seasons. Organic matter and total metal concentrations were determined using loss on ignition and inductively coupled plasma spectrometry, respectively. Principal component analysis has been applied to evaluate the metal sources and the relationships between metals in sediments. Metal concentrations showed the following order: winter > autumn > spring > summer. Mean concentrations of Cu, Zn, Cd, and Pb in sediments were above the average background value of metals in shale. Pb and Cd showed higher enrichment during all seasons at stations N3/N4, Zn at stations N1 to N4, and Cu at stations N6/N8. The variations in heavy metal total concentration and organic matter are due to different input sources, physico-chemical conditions, and adsorption/precipitation/redox conditions in sediments. Mean values of Geo-accumulation index (Igeo) for Fe, Mn, and Cu were below 0 which were classified as unpolluted during spring, summer, and autumn, except Cu increased from unpolluted to moderately polluted during winter. Igeo values for Cd, Pb, and Zn increased from unpolluted-moderately polluted to highly-very highly polluted during autumn and winter. Pollution Load Index was recorded in highest values during winter, especially at Fuwwah/Basioun and in lowest values during summer at after the Edfina Barrage/before Kafer El-Zayat due to industrial/human activities. Both natural and anthropogenic sources contributed to the metal accumulations in sediments, and industrial, agricultural, and municipal sewage effluents discharged from non-point sources may be the main anthropogenic sources for metals in the Rosetta branch.

Concepts: Water pollution, Season, Ancient Egypt, Heavy metal music, Nile, Cairo, Aswan, Lake Nasser

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In Egypt, until yet no records are available regarding possible multiple hormonal activities in the aquatic systems and especially in the river Nile. In this paper, in vitro yeast estrogen screen (YES) and yeast androgen screen (YAS) were used to assess (for the first time) the multiple hormonal activities in surface waters and sediments of the river Nile. This study aimed to determine whether river Nile water can cause changes in gonadal histology of Nile tilapia (Oreochromis niloticus niloticus). All water samples exhibited extremely low levels of estrogenicity. Estrogenicity was nearly not detected in any of the sediment samples. Unlike the estrogenicity, significant androgenic activities were recorded in the water and sediment samples along the course of the river Nile. The present study reports for the first time quantification anti-estrogenic and anti-androgenic activities with high levels in both water and sediment of the river Nile. The greatest anti-estrogenic and anti-androgenic activities were observed in samples from downstream river Nile. These results indicated that the anti-estrogenic and anti-androgenic activities along the Nile course were great and the pollution of the sites at downstream was more serious than the upstream sites due to industrial and anthropogenic activities at these sites. Good correlations were observed among some hormonal activities, suggesting coexistence of these contaminants in the environmental matrices. There were no signs of sexual disruption in any of the gonads analyzed from either male or female Nile tilapia, demonstrating that no hormonal activity present along the Nile course was sufficient to induce adverse effects on reproductive development. Further investigation is necessary to identify the compounds responsible for the hormonal activities in the river Nile and to examine effects of very low levels of hormonally active compounds on gonadal histology, as well as in the development of more sensitive biomarkers.

Concepts: Cichlid, Oreochromis, Oreochromis niloticus, Egypt, Nile, Cairo, Aswan, Lake Nasser

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The present study was carried out as part of an ongoing general survey for myxosporean parasites infecting tilapias in the River Nile, Egypt. In the present study, 77 Nile tilapia (Oreochromis niloticus) were collected from boat landing sites at Beni-Suef governorate, Egypt and examined for the myxosporean infection. The infection was encountered as a huge number of free spores in the kidney and the spleen. The infection showed a prevalence of 51.9% (40/77) for Myxobolus brachysporus while it was 25.9% (20/77) for Myxobolus israelensis. Mature spores of M. brachysporus were ellipsoidal and measured 8.6 × 13.2 μm. The polar capsules were subcircular with 5-6 filament turns and measured 4.7 × 3.6 μm. Spores of M. israelensis were ellipsoidal in the frontal view and fusiform in the lateral view. Spore measurements were 13.4 μm long and 8.7 μm wide. The polar capsules were elongated with 6-7 filament coils and measured 8.6 × 3.1 μm. The findings presented here proved that tilapia fishes in the Nile River are still suffering from infections with Myxobolus species. Therefore, further studies should be carried out to survey the Myxobolus infection among tilapias under culture conditions to clarify the pathological impacts of this parasite in tilapias aquaculture.

Concepts: Nile, Cairo, Aswan, Lake Nasser, Egyptian Public Works

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Two Myxobolus spp. are described from the kidney of the Nile tilapia (Oreochromis niloticus) collected from the River Nile, Egypt. The prevalence of infection was 61 % (47/77), with the infected fish in each case parasitized by the two Myxobolus species simultaneously. The infection was exhibited as free spores in Bowman capsules and renal glomeruli, which makes their original structures difficult to discern. In some cases, the infection appeared as a fibrous plasmodia-like structure containing degenerated developmental stages and spores in the interstitium. The paper identifies each species based on the morphological characteristics of its spores and identifies the histological impacts of Myxobolus infection in this species of fish.

Concepts: Kidney, Cichlid, Oreochromis niloticus, Egypt, Nile, Cairo, Aswan, Lake Nasser

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Stroke is a major health problem in developing countries. In a previous survey, the prevalence rate of stroke in the Nile Valley governorate of Assiut was significantly higher than other Arabic countries. In view of this, we carried out a follow-up study in a second Nile Valley governorate (Qena).

Concepts: Stroke, Egypt, Sudan, Nile, Cairo, Aswan, Lake Nasser, Governorates of Egypt

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Some organs of the reproductive system of the protogynous monogenean skin parasite Macrogyrodactylus congolensis (Prudhoe, 1957) Yamaguti, 1963 have been studied using transmission electron microscopy. The vesicula seminalis is enclosed by a prominent layer of circular muscle fibres and has inner syncytial protrusions. The penis bulb is a highly muscular organ with prominent radial and circular muscle fibres, a gutter-shaped large spine and 16 small spines. Two syncytial male accessory glands, and a single reservoir for male accessory secretion were identified. The secretory bodies in the male accessory glands and male accessory reservoir have a unique structure. A large oocyte is situated in a chamber, previously referred to as the “ootype” or “egg-cell-forming region” (ECFR), which also contains one or two small undifferentiated cells and vacuolated tissue. Mature spermatozoa were abundant in the receptaculum seminis and dispersed in the vacuolated tissue in the ECFR and appeared to be attached to the membrane of the large oocyte. Mature spermatozoa were also seen in the parenchymal tissue near the chamber containing embryos and even in the tissues of the embryo.

Concepts: Cell, Reproduction, Secretion, Heart, Organ, Tissues, Nile, Lake Nasser