Radiological and mineralogical investigation of accretion and erosion coastal sediments in Nile Delta Region, Egypt

Textural characterization and heavy mineral studies of beach sediments in Ibeno and Eastern Obolo Local Government Areas of Akwa Ibom State were carried out in the present study. The main aim was to infer their provenance, transport history and environment of deposition. Sediment samples were collected at the water–sediment contact along the shoreline at an interval of about 3m. Ten samples were collected from study location 1 (Ibeno Beach) and twelve samples were collected from study location 2 (Eastern Obolo Beach). A total of twenty–two samples were collected from the field and brought to the laboratory for textural and compositional analyses. The results showed that the value of graphic mean size ranged from 1.70Ф to 2.83Ф, sorting values ranged from 0.39Ф – 0.60Ф, skewness values ranged from -0.02 to 0.10 while kurtosis values ranged from 1.02 to 2.46, indicating medium to fine grained and well sorted sediments. This suggested that the sediments have been transported far from their source. Longshore current and onshore–offshore movements of sediment are primarily responsible in sorting of the heavy minerals. The histogram charts for the different samples and standard deviation versus skewness indicated a beach environment of deposition. This implies that the sediments are dominated by one class of grain size; a phenomenon characteristic of beach environments. The heavy mineral assemblages identified in this research work were rutile, zircon, tourmaline, hornblende, apatite, diopside, glauconite, pumpellyite, cassiterite, epidote, garnet, augite, enstatite, andalusite and opaque minerals. The zircon-tourmaline-rutile (ZTR) index ranged from 47.30% to 87.00% with most of the samples showing a ZTR index greater than 50%. These indicated that the sediments were mineralogically sub-mature and have been transported far from their source. The heavy minerals identified are indicative of being products of reworked sediments of both metamorphic (high rank) and igneous (both mafic and sialic) origin probably derived from the basement rocks of the Oban Massif as well as reworked sediments of the Benue Trough. Therefore, findings from the present study indicated that erosion, accretion, and stability of beaches are controlled by strong hydrodynamic and hydraulic processes.

The most extensive coverage of surficial sediment samples collected to date on Egypt’s Nile Delta coast and shelf is needed to better define sediment dispersal patterns across this setting’s rapidly eroding margin. Changes in time are now induced by River Nile sediment cutoff by dams, sea level rise, marked shelf subsidence, and regional climate changes, which have altered the amounts and components of sediments; these require replacement, along with the implementation of more effective coastal protection measures. Multiple computer-generated offshore maps depict the distributions and proportions of sand, silt, and mud; the mean grain size and standard deviation (sorting); heavy mineral concentrations; and carbonate content. Heavy mineral lobes at the coast and offshore identify former Nile branch sites. Channel lobes extending seaward resulted from their progradational phase and from the delta’s altered sedimentation from the early to late Holocene. The progressive deposition and erosion of these fossil fluvial lobes, and of two active Nile channels, selectively removed their quartz and less dense minerals, thus concentrating heavy minerals on the coast and inner shelf. The prolonged dispersal of original sediment effluence from relict and recent Nile tributaries induced variable depositional patterns on the present shelf. These coastal depocenters, along with extensive sand, silt, and mud from shelf sediments, were reworked further seaward and dispersed by bottom currents, thus masking most previous onshore-to-offshore transport patterns. The major surficial features document long-term responses to the diverse dispersal that influenced the shoreline to the outer shelf deposits from the Pleistocene to the present.

Depuis 2004, plus de 1,7 million d’Egyptiens ont proteste sur leur lieu de travail en recourant a la greve, au sit-in ou a d’autres formes de protestation. L’une des particularites de ces mobilisations qui constituent le plus important mouvement de contestation depuis 1952 est d’emaner de secteurs tres varies de l’economie. Cet article etudie d’une part l’impact du contexte politique et economique a l’echelle locale. Par ailleurs, a travers une etude ethnographique realisee dans deux usines textiles situees dans la region du Delta – Misr li-lghazl wa al-nasij a Mahalla al-Kubra et Indorama a Shibin al-Kawm – je propose de presenter le mode d’organisation a l’echelle locale en mettant en evidence les reseaux sociaux, les structures permettant de promouvoir les revendications des grevistes ainsi que les trajectoires des organisateurs.

Nile delta: extreme case of sediment entrapment on a delta plain and consequent coastal land loss

Thirty-two heavy-mineral separates, each comprising approximately 2000 grains, were analyzed using the Automatic Geological Scanning Electron Microscope (AutoGeoSEM). This analysis was undertaken to study the influence of depositional environment on the distribution of heavy minerals throughout a regressive Pliocene coastal sequence. The majority of these heavy minerals were separated from the Loxton-Parilla sands, the host of the Bondi Main heavy-mineral beach placer deposit in the Murray Basin of southeastern Australia. The remaining heavy minerals were separated from a number of other Neogene units encountered at the deposit. The heavy-mineral suite is dominated by stable to ultrastable minerals such as zircon, rutile, and tourmaline, along with ilmenite, various intermediate titanates, and anatase. Sillimanite, andalusite, topaz, chrome spinel/chromite, monazite, and muscovite also occur. These heavy minerals are heterogeneously distributed throughout both the Loxton-Parilla sands and the remaining Neogene units. The main process controlling the heterogeneous distribution of these heavy minerals throughout the Loxton-Parilla sands appears to have been the hydraulic conditions, which are intimately linked with the environment of deposition. Consequently, the dense heavy minerals (density > ~ 3.5 g/cm3) are concentrated in relatively high-energy environments such as the breaker zone and swash zone. The less dense heavy minerals (density < ~ 3.5 g/cm3) are concentrated in the shoaling zone and shelf environments. The erratic distribution of the various heavy minerals in some of the other Neogene units is also apparently due to varying depositional conditions. Postdepositional weathering has altered the heavy-mineral assemblages in all units. Accordingly, some primary minerals, such as ilmenite, appear to have altered to secondary minerals, such as pseudorutile and anatase.

Sediments of two Gondwana glaciations in Ethiopia: Provenance of the Enticho Sandstone and the Edaga Arbi Glacials

Quartz grain surface textures and depositional interpretations, Nile Delta region, Egypt

The current study concentrates on heavy mineral separation using the bromoform technique. The main structural element is the distribution of several heavy minerals in coastal areas along a stretch of India's southeast coast in Tamil Nadu. The observed variations in the distribution of heavy minerals in the area are connected to differences in sediment supply, sorting, and oceanographic processes, all of which cause the sediments to be sorted in a specific way. The main factors affecting how heavy minerals are distributed in the depositional basin are mineral stability, density, particle size, wave velocity, and dynamics of beach morphologies. The heavy mineral assemblage of the study region is determined by the distribution of various types of minerals, and each mineral was identified using microscope techniques in the main study area. The assemblage is dominated by a select few minerals, including garnet (colourless), garnet (pink), zircon, rutile, chlorite, etc. Numerous igneous rocks, high-grade metamorphic rocks, Precambrian gneissic, granitic, and basic rocks were present in the heterogeneous provenance that gave rise to the ubiquitous zircon, monazite, and sillimanite that can be found in both seashore and inland red teri sands. This provenance almost probably originated from a coastal region

Twenty-six species of aquatic hyphomycetes were isolated from woody sources (unidentified wood segments, leaf skeletons and neck of leaves and bark) in the North River Nile (Delta region). Alatospora acuminata, Anguillospora crassa, Flagellaspora penicillioides, Lunulospra curvula, Tetracladium marchalianum and Triscelophorus monosporus were the most common species. Temperature was the highest physico-chemical parameter affecting the aquatic hyphomycetes occurrence. Twelve species of hyphomycetes, isolated from woody substrates, were screened for their ability to produce extracellular lignocellulolytic enzymes on solid media. The enzymes tested included: endoglucanase, endoxylanase, beta-glucosidase, laccase, peroxidase, polyphenoloxidase, tyrosinase and beta-xylosidase. Three species, A. acuminata, F. penicillioides, T. monosporus, were positive for all tested enzymes. Also, A. longissima was positive for all enzymes except lignin-peroxidase. The ability to produce cellulase was 100% for all species while only, four species were positive for lignin-peroxidase. The ability of the species to produce other lignocellulotic enzyme ranged from 50% to 83%. Freshwater hyphomycetes have been shown to produce a rich array of enzymes able to degrade the polysaccharides of plant debris.

The current Egyptian situation is framed by land and water scarcity, which are under severe pressure. The Nile Delta is one of the most densely populated deltas in the world. Soil and water resources are at the center of sustainable development and are critical for socio-economic development. Nile Delta branches gain water from the aquifer in some reaches and lose water to the aquifer in other reaches. The flow directions between groundwater and surface water can change seasonally with variations of the water table level with respect to the level in nearby waterways. Available data on the evolution of the salinity of groundwater in the Delta indicate that the construction of the High Aswan dam resulted in a shift of salinity isolines towards the seashore, and that current pumping rates have not yet critically affected this balance. Possible localized over-pumping, however, results in “up-coning” of salinity from deeper layers. Contamination of groundwater by agriculture and more prominently by seepage from domestic and industrial effluents had already attained worrying levels. This may jeopardize the quality of the Nile Delta aquifer in the end. The increasing use of groundwater for irrigation poses a serious threat to food security and could lead to unaffordable prices of staple foods. Therefore, groundwater overuse rising could hit food prices. Aquifer depletion can induce significant environmental degradation, such as land subsidence and seawater intrusion. The amount of non-renewable groundwater used for irrigation was doubled in Nile Valley and Delta. The annual groundwater abstraction in the Nile aquifer system and fringes is about 4.6 billion m3. Another 0.5 billion m3 is abstracted from the desert aquifers and the coastal areas. Groundwater abstraction is expected to increase to 11.4 billion m3. Model output revealed that groundwater recharge has not changed significantly over time, while pumping has. Because of these trends, groundwater was estimated to be in a deficit of approximately 24 billion m3 (±15%) in year 2011, compared to year 1957. Most of the Nile Delta soils are recent alluvial soils. The soils generally have a light to heavy clay texture. The clay content varies from 40% in the south to nearly 70% in the north. The soils located near the north coast and lakes are of marine and alluvial deposits. Close to the desert fringe on both sides of the Delta occurs the desert sandy plains, which are flat to undulating topography. The soils of the coastal plains and beaches are sandy with some low to medium longitudinal sand dunes. The salinity problem becomes more severe in the Delta as we approach the seacoast and lakes, due to the effect of the shallow, saline groundwater and the brackish water intrusion from the sea and lake. The old and young terraces of both western and eastern sides of the Nile Delta are of alluvial origin and non-uniform in nature. Most of the soils are originated from the ancient Nile sediments, which are mostly derived from igneous and metamorphic rocks of the Abyssinian Plateau. The soils are alluvial deposits of the Nile Delta (Qatabeya) and valley (Qena), swamps and fluviomarine-lacustrine deposits (El-Manzala), beach sands (Edku). The old alluvial soil is more developed than other soils.

This paper examines how environmental migration, justice, and governance intersect in the context of climate change. The study focuses on Egypt’s Nile Delta as case. The Nile Delta, which is one of the most vulnerable regions in the World in terms of climate, has the risk from sea level rise and consequently land loss. The main argument of this research is that due to these factors, people are forced to migrate from Nile Delta region both just because of social and political inequalities but also due to environmental pressures. There is the lack of resources, unequal resource access, exclusion of society from decision-making process and fragmented governance. From a justice-oriented perspective, this study assesses the top-down adaptation strategies of the government which focuses on the infrastructure over the needs of populations. Under this claim, this study first discussed the theoretical framework which is environmental justice and environmental migration. Then, the sea level rise and migration risk in the Nile Delta are examined as a case. After that, the governance, participation and climate justice in the Nile Delta are considered. Before the conclusion, the discussion on environmental migration, transnational justice and regional governance are conducted from the case of the Nile Delta.

Heavy and clay mineral analysis is a significant tool to interpret the provenance and paleoclimate of sandstone in proterozoic intracratonic Kaladgi-Badami basin, southern India. The distributions of heavy minerals are more in lower conglomerate; at the depth of 162.35m, zircon is 9.01%, magnetite is 74.18% and ilmenite is 24.61%. The ZTR index is 97.02%. The lower part of the upper unit of core quartz arenite, at the depth of 70.55m shows the following distribution of heavy minerals; zircon 2.94%, magnetite 50.84% and ilmenite 35.71%. The ZTR index of the quartz arenite is 65.52%; moderately abundant heavy minerals are tourmaline, rutile, and garnet; less abundant mineral is zircon in the core. The clay deposits in the basal arenite unit starts from 187 to 171.45m. The X-ray diffraction patterns shows 75% of Illite at the depth of 187m and 181.4m, 40% of chlorite at the depth of 181.7m, 36.36% of monmorillonite and 25% of kaolinite at the depth of 183m but 36.36% at the depth of 177.1m. kaolinite peaks are identified only in two samples. The study reveals that intense weathering in humid climate was responsible for alteration of granitic source rocks in the formation of kaolinitic clays in an acidic environment. The ZTR index reflects that the Badami sediments have attained moderate to high mineralogical maturity. The inference made out of the assemblage of heavy minerals point out that the Badami sediments have been sourced mainly from granitic and metamorphic terrain with a broad drainage basin. In most sandstone and conglomerate, the average ZTR index is moderate but varies widely among samples; apparently local lithologic source area variations largely control these relatively unmodified heavy mineral assemblages.

The Chavara coast of south-west India is well known for its rich beach placer deposits which are being commercially mined by two public sector firms. The erosion of the beach and innershelf and the depletion of heavy mineral content of this coast have attracted a lot of attention of late, and an investigation of the mechanisms that drive these changes was taken up recently. The results of the investigation are presented in three parts. This paper, which is the last in the series, presents a study of the morphological changes of the beach and innershelf and integrates the results from the other two papers with an analysis of multi-dated shoreline and bathymetry data. The analysis of the multi-dated data showed an overall retreat of the shoreline and a relative deepening of the innershelf. The shoreline retreat has been quite alarming at the mining sites with one of the mining sites showing a retreat of nearly 400 m. The sediment deposition adjacent to the breakwater (built during 2000–2007) at the northern inlet has defused to some extent the high erosion observed earlier in the northernmost sector, and the presence of well-maintained seawalls has nearly maintained the shoreline south of the mining site. The erosion of the beach is accompanied by a deepening of the innershelf which is more pronounced in the shallower portions up to 10 m depth. The observed changes in the beach–innershelf morphology are analysed with respect to the nearshore sediment transport regime and heavy mineral distribution of the coast. It is observed that the combined intake of sediments by the two firms during the past one and a half decade is much above the sustainable mining level. Another contributing factor is the 2004 tsunami which drained off a sizable quantity of innershelf sediments rich in heavy minerals to the hinterland regions. The breakwaters at the two inlets bordering this coast have virtually compartmentalized this coast from the rest of the south-west coast making it a sediment sub-cell. In addition, the breakwaters act as groins causing imbalances in the erosion/accretion pattern. The recent spate in construction of shore protection structures like groins and seawalls is another contributing factor to the morphological changes. The study points to the urgent need for regulating the mining volumes to the sustainable levels as well as controlling the introduction of hard structures without proper impact analysis.

Grain size and heavy mineral analyses of 6 cliff, 12 beach, and 44 marine sediment and rock samples from Bolmas Bay and its surrounding drainage area were done as part of a long term study of sediment transport on the continental shelf off Central California Sediments in the bay are predominately very fine sands Some samples, particularly adjacent to Duxbury Reef on the west, have a coarse sand to pebble component The primary mode of the marine samples is in the range 088 to 125 mm, whereas, the primary mode for beach material is from 175 to 25 mm The range of median diameters of the marine samples is from 07 to 14 mm The median diameters show a trend of decreasing grain size seaward parallel to the depth contours except opposite the entrance to Bolmas Lagoon where a tongue of relatively coarser material cuts across the depth contours The range of other statistical parameters are (1) sorting coefficient 1 10 to 1 41, (2) skewness 0 83 to 1 18, and (3) kurtosis 0 15 to 0 32 Our sediment studies indicate (1) The heavy mineral assemblage is predominantly green hornblende with secondary amounts of hypersthene and augite Glaucophane and jadeite occur in locally high concentrations near shore (2) The pattern of distribution of the heavy minerals shows (a) a tongue of high concentrations of minerals with a granitic source extending northwest from the San Francisco Bar, (b) flanked on the north and northeast by increasing landward concentrations of Franciscan metamorphic minerals (3) The major source of heavy minerals is the San Francisco Bar Secondary contributions come from Bolmas Lagoon and the adjacent cliffs (4) The circulation in the Bay is primarily counterclockwise, produced by a combination of wave refraction around Duxbury Reef and the tidal Coast Eddy Current The tidal influence, however, of Bolmas Lagoon is restricted to about one mile from the lagoon mouth.

This paper has a three-fold aim. Firstly, it demonstrates the practicability of a mechanical method alternative to panning for the preliminary concentration, prior to final bromoform separation, of arenaceous materials carrying only very small percentages of heavy mineral residues. This method utilizes the laboratory Aafley concentrating-table and the Haultain superpanner, with crushed calcite stained green by basic cupric nitrate for visual control to ensure reasonable recovery. Secondly, it serves to present some fresh ideas for the computation of comparative indices and for the illustrative graphical representation of statistical data. Empirical colour ratios and roundness ratios are calculated, in addition to volume frequency ratios of tourmaline, rutile, and zircon, for each grade size of concentrate obtained, and corresponding coefficients are derived for each sample over a common range of grade sizes. Thirdly, it records the results obtained in conjunction with an optical examination of the heavy minerals separated from various quartzites occurring in certain areas of Malaya. The diagnostic feature of the data determined by this preliminary investigation indicate the possibilities of utilizing heavy mineral characteristics, as analternative to fossil evidence, for the differentiation or correlation of these quartzites.