Colorado River sediment transport: 2. Systematic bed‐elevation and grain‐size effects of sand supply limitation

Science.gov (United States)

Topping, David J.; Rubin, David M.; Nelson, Jonathan M.; Kinzel, Paul J.; Corson, Ingrid C.

2000-01-01

The Colorado River in Marble and Grand Canyons displays evidence of annual supply limitation with respect to sand both prior to [Topping et al, this issue] and after the closure of Glen Canyon Dam in 1963. Systematic changes in bed elevation and systematic coupled changes in suspended‐sand concentration and grain size result from this supply limitation. During floods, sand supply limitation either causes or modifies a lag between the time of maximum discharge and the time of either maximum or minimum (depending on reach geometry) bed elevation. If, at a cross section where the bed aggrades with increasing flow, the maximum bed elevation is observed to lead the peak or the receding limb of a flood, then this observed response of the bed is due to sand supply limitation. Sand supply limitation also leads to the systematic evolution of sand grain size (both on the bed and in suspension) in the Colorado River. Sand input during a tributary flood travels down the Colorado River as an elongating sediment wave, with the finest sizes (because of their lower settling velocities) traveling the fastest. As the fine front of a sediment wave arrives at a given location, the bed fines and suspended‐sand concentrations increase in response to the enhanced upstream supply of finer sand. Then, as the front of the sediment wave passes that location, the bed is winnowed and suspended‐sand concentrations decrease in response to the depletion of the upstream supply of finer sand. The grain‐size effects of depletion of the upstream sand supply are most obvious during periods of higher dam releases (e.g., the 1996 flood experiment and the 1997 test flow). Because of substantial changes in the grain‐size distribution of the bed, stable relationships between the discharge of water and sand‐transport rates (i.e., stable sand rating curves) are precluded. Sand budgets in a supply‐limited river like the Colorado River can only be constructed through inclusion of the physical

The satellite archaeological survey of Egypt

OpenAIRE

Sparavigna, Amelia Carolina

2011-01-01

A recent announcement of some pyramids, buried under the sand of Egypt and discovered by means of infrared remote sensing, renewed the interest on the archaeological surveys aided by satellites. Here we propose the use of images, obtained from those of Google Maps after some processing to enhance their details, to locate archaeological remains in Egypt.

Short-term impact of deep sand extraction and ecosystem-based landscaping on macrozoobenthos and sediment characteristics.

Science.gov (United States)

de Jong, Maarten F; Baptist, Martin J; Lindeboom, Han J; Hoekstra, Piet

2015-08-15

We studied short-term changes in macrozoobenthos in a 20m deep borrow pit. A boxcorer was used to sample macrobenthic infauna and a bottom sledge was used to sample macrobenthic epifauna. Sediment characteristics were determined from the boxcore samples, bed shear stress and near-bed salinity were estimated with a hydrodynamic model. Two years after the cessation of sand extraction, macrozoobenthic biomass increased fivefold in the deepest areas. Species composition changed significantly and white furrow shell (Abra alba) became abundant. Several sediment characteristics also changed significantly in the deepest parts. Macrozoobenthic species composition and biomass significantly correlated with time after cessation of sand extraction, sediment and hydrographical characteristics. Ecosystem-based landscaped sand bars were found to be effective in influencing sediment characteristics and macrozoobenthic assemblage. Significant changes in epifauna occurred in deepest parts in 2012 which coincided with the highest sedimentation rate. We recommend continuing monitoring to investigate medium and long-term impacts. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geomorphology and sediment transport on a submerged back-reef sand apron: One Tree Reef, Great Barrier Reef

Science.gov (United States)

Harris, Daniel L.; Vila-Concejo, Ana; Webster, Jody M.

2014-10-01

Back-reef sand aprons are conspicuous and dynamic sedimentary features in coral reef systems. The development of these features influences the evolution and defines the maturity of coral reefs. However, the hydrodynamic processes that drive changes on sand aprons are poorly understood with only a few studies directly assessing sediment entrainment and transport. Current and wave conditions on a back-reef sand apron were measured during this study and a digital elevation model was developed through topographic and bathymetric surveying of the sand apron, reef flats and lagoon. The current and wave processes that may entrain and transport sediment were assessed using second order small amplitude (Stokes) wave theory and Shields equations. The morphodynamic interactions between current flow and geomorphology were also examined. The results showed that sediment transport occurs under modal hydrodynamic conditions with waves the main force entraining sediment rather than average currents. A morphodynamic relationship between current flow and geomorphology was also observed with current flow primarily towards the lagoon in shallow areas of the sand apron and deeper channel-like areas directing current off the sand apron towards the lagoon or the reef crest. These results show that the short-term mutual interaction of hydrodynamics and geomorphology in coral reefs can result in morphodynamic equilibrium.

A Laboratory Experiment on the Evolution of a Sand Gravel Reach Under a Lack of Sediment Supply

Science.gov (United States)

Orru, C.; Chavarrias, V.; Ferrara, V.; Blom, A.

2014-12-01

A flume experiment was conducted to examine the evolution of a sand-gravel reach under a lack of sediment supply. The experimental data are used to validate a numerical sand-gravel model. A bed composed of a bi-modal sediment mixture is installed with a uniform slope and an imposed gradual fining pattern. Initially, the sand fraction gradually increases in streamwise direction until the bed is fully composed of sand. The water discharge and downstream water level were constant, and the sediment feed rate was equal to zero. The experiment was dominated by bed load, partial transport, and a subcritical flow regime was imposed. The flow rate was such that only sand was mobile (partial transport), which led to a coarsening over the upstream reach and a gradual reduction of the sediment transport rate during the experiment. New equipment was used to measure the evolution of the grain size distribution of the bed surface during the experiment over the entire flume using image analysis. In the upstream reach we observed a gradual coarsening over time and the formation of an armour layer, which resulted in a more abrupt transition in grain size of the bed surface. Bed degradation increased in streamwise direction. This is due to the initial streamwise increase in the availability of sand in the bed. The different volume fraction content of sand in the bed allowed for the gravel to sink more in the downstream part of the upstream reach. The sand reach suffered from a larger degradation. Finally, we see one reach dominated by sand, small bedforms, and a small bed slope, and a gravel reach dominated by a larger bed slope.

Tidal River Elbe - a sediment budget for the grain size fraction of medium sand

Science.gov (United States)

Winterscheid, Axel

2016-04-01

Human interventions have a historic and ongoing impact on estuarine sediment budgets across many estuaries worldwide. An early inference was the construction of embankments resulting in a constant loss of intertidal flats. Additionally, settlement activities and large scale land use changes in the upstream catchment areas had also an effect on sediment inflow rates. Today, the navigation channels in estuaries have been deepened for larger and more efficient vessels to reach a well-developed infrastructure of harbors and industrial areas often located far inland. In the past few years and just within the North-East Atlantic, the total annual amount of dredged sediments dumped at sea varied from 80 to 130 million tons (OSPAR Commission). In most estuaries across Europe the resulting human impact on the sediment fluxes and morphodynamics is significant. A good understanding of estuarine processes is essential for determining useful and meaningful measures to mitigate negative effects and to improve the current situation. Maintenance dredging and its environmental effects are therefore in the focus of public attention. Against this background, it is the aim of the presentation to identify and therefore to separate the particular effect that maintenance dredging has on sediment fluxes and budgets in the estuarine environment. Case study is the Tidal River Elbe in Germany, and here we set the focus on the grain size fraction of medium sand. In the past, river engineering measures forced the natural dynamics to form a concentrated stream flow along a fixed channel, except at a number of locations where side channels still exist. In addition to that, the main channel was deepened several times. The last deepening was in 1999/2000. The most significant deepening, however, took place from 1957 to 1962. Until then, an erosion-stable layer of marine clay (in German called "Klei") formed a flat bottom along most sections of the main channel. After removal of this layer of

Physiological and biochemical responses of small fish exposed to Athabasca oil sands sediment

International Nuclear Information System (INIS)

Tetrault, G.R.; Environment Canada, Burlington, ON; McMaster, M.E.; Dixon, D.G.; Parrott, J.L.

2002-01-01

A study was conducted to determine the influence of naturally occurring oil sands related compounds on the reproductive function and hepatic responses of fish. Wild fish, both exposed and unexposed to the compounds in question, were collected along with sediments for laboratory testing. The study showed that in vitro gonadal incubation levels of steroid production were lower at the tributary sites within the oil sands deposits. One indicator of exposure to oil sands related compounds (hepatic 7-ethoxyresorufin-O-deethylase activity) was shown to be 5 times higher at the same sites. In addition, slimy sculpin were exposed to sediment samples from the Steepbank River site for 4 to 8 days to evaluate the absorption of the indicator. The indicator in exposed fish was found to be comparable to that measured in fish native to the oil sands area. The study was not capable of predicting an altered ability of gonadal tissue of exposed fish to produce steroid hormones in vitro. It was concluded that future development could compromise the reproductive health of fish in the area

Alexandria's Eastern Harbor, Egypt: Pollen, microscopic charcoal, and the transition from natural to human-modified basin

Science.gov (United States)

Stanley, J.-D.; Bernhardt, C.E.

2010-01-01

Pollen and microscopic charcoal examined in Holocene sediment core samples record major environmental modifications affecting Alexandria's Eastern Harbor through time. We assess whether such changes on Egypt's coastal margin were influenced primarily by natural, or natural plus human, or primarily human factors. We focus on (1) the times when pollen assemblages and microscopic charcoal content changed in the core, (2) how they changed, and (3) why this occurred. The analysis takes into account the core's stratigraphy, regional climate variability, human history, and local archaeological record. Four pollenmicroscopic charcoal zones are identified. The earliest change occurred at ca. 6000 YBP, during Egypt's earlier Predynastic (Neolithic) period, coinciding with a lithologic break from sand to muddy sand. Pollen during this time indicates a transition to a much drier climate rather than effects of human activity. The second change in pollen occurred 3600-2900 YBP, during a period of continued aridity with no lithologic variation in this core interval. Pollen (cereal taxa, agricultural weeds, grape) and a sharp increase in microscopic charcoal indicate that human activity became prevalent at least 700 y before Alexander the Great's arrival in this region, and these results highlight the transition from a largely natural climatecontrolled environment to one influenced by both climate and anthropogenic activity. The third shift up-core in pollen assemblages is dated at ca. 2300 YBP, at the boundary between a sand and mud unit. It coincides with construction by the Ptolemies of the Heptastadion between Alexandria and Pharos Island. From this time onward, harbor sediment in the nearly enclosed catchment basin indicates a near-continuous record of dominant proximal human activity. ?? 2010 Coastal Education and Research Foundation.

Influence of porewater advection on denitrification in carbonate sands: Evidence from repacked sediment column experiments

DEFF Research Database (Denmark)

Santos, Isaac R.; Eyre, Bradley D.; Glud, Ronnie N.

2012-01-01

Porewater flow enhances mineralization rates in organic-poor permeable sands. Here, a series of sediment column experiments were undertaken to assess the potential effect of advective porewater transport on denitrification in permeable carbonate sands collected from Heron Island (Great Barrier Re...

On the influence of suspended sediment transport on the generation of offshore sand waves

NARCIS (Netherlands)

Sterlini-Van der Meer, Fenneke; Hulscher, Suzanne J.M.H.; van den Berg, J.; Geurts, Bernardus J.; Clercx, H.J.H.; Uijttewaal, Wim

2007-01-01

Sand waves are bed-forms occurring in shallow seas. Although their characteristics are mainly affected by bed load transport, during rough weather suspended sediment transport can influence their characteristics. As a first step to model these influences, we added suspended sediment transport to a

Evaluate of head loss, sediment value and copper removal in sand media (rapid sand filter

Directory of Open Access Journals (Sweden)

Daneshi Navab

2014-06-01

Full Text Available Along with the technology development and increasing consumption of water resources, we are experiencing low qualities in the mentioned resources. Copper brings about serious environment al pollution, threatening human health and ecosystem. This metal found variously in water resources and industrial activities. Therefore, it needs to treat the water resources from these excessive amounts. Different methods have used for this reason but the most used method during recent years has been the absorption by economic absorbers such as sand. Rapid sand filters usually used in water and wastewater treatment plants for water clarification. In this research, a single layer gravity rapid sand filter has used to reduce different concentrations of copper. sediment value and head loss arising in filter media is simulated by using combination of Carman-Kozeny, Rose and Gregory models in different discharges of rapid sand filter. Results have shown that with increasing in discharge and decreasing in input copper concentration, arriving time to given head loss, is increasing. In addition, results demonstrated that with increasing in copper concentration in influent, removal efficiency is decreasing somewhat. Results of this research can applied in an appropriate design of rapid sand filter to copper removal, a prediction of rapid sand filter ability to copper removal and an estimation of arising head loss during filter work thus evaluating of time interval backwash. DOI: http://dx.doi.org/10.3126/ije.v3i2.10641 International Journal of the Environment Vol.3(2 2014: 276-286

A Visual Basic program to classify sediments based on gravel-sand-silt-clay ratios

Science.gov (United States)

Poppe, L.J.; Eliason, A.H.; Hastings, M.E.

2003-01-01

Nomenclature describing size distributions is important to geologists because grain size is the most basic attribute of sediments. Traditionally, geologists have divided sediments into four size fractions that include gravel, sand, silt, and clay, and classified these sediments based on ratios of the various proportions of the fractions. Definitions of these fractions have long been standardized to the grade scale described by Wentworth (1922), and two main classification schemes have been adopted to describe the approximate relationship between the size fractions.Specifically, according to the Wentworth grade scale gravel-sized particles have a nominal diameter of ⩾2.0 mm; sand-sized particles have nominal diameters from <2.0 mm to ⩾62.5 μm; silt-sized particles have nominal diameters from <62.5 to ⩾4.0 μm; and clay is <4.0 μm. As for sediment classification, most sedimentologists use one of the systems described either by Shepard (1954) or Folk (1954, 1974). The original scheme devised by Shepard (1954) utilized a single ternary diagram with sand, silt, and clay in the corners to graphically show the relative proportions among these three grades within a sample. This scheme, however, does not allow for sediments with significant amounts of gravel. Therefore, Shepard's classification scheme (Fig. 1) was subsequently modified by the addition of a second ternary diagram to account for the gravel fraction (Schlee, 1973). The system devised by Folk (1954, 1974) is also based on two triangular diagrams (Fig. 2), but it has 23 major categories, and uses the term mud (defined as silt plus clay). The patterns within the triangles of both systems differ, as does the emphasis placed on gravel. For example, in the system described by Shepard, gravelly sediments have more than 10% gravel; in Folk's system, slightly gravelly sediments have as little as 0.01% gravel. Folk's classification scheme stresses gravel because its concentration is a function of

Environmental assessment of rosetta area,mediterranean sea coast - egypt

International Nuclear Information System (INIS)

Aly, A.M.A.

2013-01-01

This study is titled (Environmental Assessment of Rosetta Area,Mediterranean Sea Coast, Egypt). The environmental assessment can be defined here as the process of assessing the potential impacts (positive or negative) of the presence of certain influential on a particular ecosystem. Samples were collected from Abu Khashaba beach area, Rosetta on the Mediterranean Sea coast. Samples of the beach sediments, sea-water and the scattered shells in this coastal region were collected. Sediments in this region are characterized by its large content of heavy metals, which added to these sediments its black color. It is known that these black sands occurred along the Mediterranean Sea coast from Alexandria to Rafah. The advantage of these black sand deposits is their contents from multiple economic metals which have important industrial uses, such as magnetite, ilmenite, rutile, monazite, zircon, garnet and other important minerals. Ten sampling profiles spaced in-between by about 600 m distance, and extending into the land from the shoreline for about 50 m or less. Along each profile, three sediment samples were collected; the first sample from the surface at the beach line, the second sample from the end of the foreshore area at a depth of about 50 cm and the third sample was taken from the backshore area at a depth of about 1 m. Extending from each profile into the sea, marine-water samples were taken at a distance of about 3 m from the beach line, and from a depth of about 1 m below the sea surface. The shells samples were collected from the scattered shells on the beach. By examination of these samples a 15 different shells types were defined.

Relationship between sediment morphology and oil pollution along the Suez Canal beaches, Egypt

International Nuclear Information System (INIS)

Barakat, M.A.K.; Shimy, T.M.; Mostafa, Y.M.

1996-01-01

In this study, marine surface sediments are collected from nine locations along the Suez Canal in order to investigate the relationship between the morphology of sands in the studied beaches and pollution by oil. Basically, the studied samples were analyzed by three techniques: grains-size analysis, microscopic examination, and gas chromatographic (GC) analysis. This study concluded that medium sand is the major class represented in the studied marine sediments. Pollution in these sand grains increases in the irregular grains more so than in the more rounded grains. Also, deep surface points, pitting, and fissures are considered to be good sites to precipitate oil contamination. Also, the presence of iron oxides may be taken as evidence for tanker ballast washings. The heavy fraction (zircon) shows more contamination than the light fraction (quartz) in these samples. Finally, GC profiles have shown two types of samples: one typical of weathered or highly weathered crude oil patterns and the other for samples with very highly weathered profiles. The relationship obtained between morphology studies and both oil content and GC chromatogram profiles indicates that all of the studied locations are suffering from pollution of oil that is spilled while shipping petroleum through the Suez Canal

Radiological Study Investigation of the Black Sand Region of the North-East of the Nile Delta

International Nuclear Information System (INIS)

Moafy, W.A.; El-Tahawy, M.S.

2009-01-01

Within a comprehensive radiological investigation of the Mediterranean cost of Egypt an environmental radiation survey of the black sand region of the North-East of Nile Delta was carried out. The activity concentration of the natural 226 Ra , 238 U, 232 Th and 40 K for 18 soil samples, 25 shore sediment samples and 6 bottom sediment samples were determined using gamma spectrometers based on HpGe detector and were found to reach 193 Bq/kg for 226 Ra and 267 Bq/kg of 232 Th for some shore sediment samples. Ten sea water samples were analyzed using laser fluorimetry technique after applying a radiochemical separation procedure and the determined total uranium concentration in these samples was found to be in the range (5.2-21.8) mBq/lt.

Stratigraphic framework of sediment-starved sand ridges on a mixed siliciclastic/carbonate inner shelf; west-central Florida

Science.gov (United States)

Edwards, J.H.; Harrison, S.E.; Locker, S.D.; Hine, A.C.; Twichell, D.C.

2003-01-01

Seismic reflection profiles and vibracores have revealed that an inner shelf, sand-ridge field has developed over the past few thousand years situated on an elevated, broad bedrock terrace. This terrace extends seaward of a major headland associated with the modern barrier-island coastline of west-central Florida. The overall geologic setting is a low-energy, sediment-starved, mixed siliciclastic/carbonate inner continental shelf supporting a thin sedimentary veneer. This veneer is arranged in a series of subparallel, shore-oblique, and to a minor extent, shore-parallel sand ridges. Seven major facies are present beneath the ridges, including a basal Neogene limestone gravel facies and a blue-green clay facies indicative of dominantly authigenic sedimentation. A major sequence boundary separates these older units from Holocene age, organic-rich mud facies (marsh), which grades upward into a muddy sand facies (lagoon or shallow open shelf/seagrass meadows). Cores reveal that the muddy shelf facies is either in sharp contact or grades upward into a shelly sand facies (ravinement or sudden termination of seagrass meadows). The shelly sand facies grades upward to a mixed siliciclastic/carbonate facies, which forms the sand ridges themselves. This mixed siliciclastic/carbonate facies differs from the sediment on the beach and shoreface, suggesting insignificant sediment exchange between the offshore ridges and the modern coastline. Additionally, the lack of early Holocene, pre-ridge facies in the troughs between the ridges suggests that the ridges themselves do not migrate laterally extensively. Radiocarbon dating has indicated that these sand ridges can form relatively quickly (???1.3 ka) on relatively low-energy inner shelves once open-marine conditions are available, and that frequent, high-energy, storm-dominated conditions are not necessarily required. We suggest that the two inner shelf depositional models presented (open-shelf vs. migrating barrier-island) may

Correlation between radionuclides associated with zircon and monazite in beach sand of Rosetta, Egypt

International Nuclear Information System (INIS)

Nada, A.; Abd El-Maksoud, T.M.; Abu Zeid, H.; Abd El-Azeem, S.A.; Mostafa, S.M.I.

2012-01-01

The study aims to evaluate the activity concentrations of 238 U, 232 Th, 40 K and 137 Cs along Rosetta beach, Egypt. Non-destructive assay techniques were carried out using HP-Ge spectrometer and binocular microscope. The results of this study serve as a database for radioactivity levels of the mineral sand deposits of Rosetta area. The activity concentrations of 238 U, 232 Th and 40 K ranged from 5.39 to 134.2, 6.6 to 160.8 and 57.6 to 492 Bq kg -1 respectively. The range of activity concentrations of 137 Cs is between 0.05 and 0.91 Bq kg -1 . The total gamma absorbed dose rates varied from 11.59 to 160.01 nGyh -1 with a mean value of 50.53 nGyh -1 . These values correspond to an annual effective dose equivalent of 0.01-0.2 mSvy -1 with a mean of 0.07 mSvy -1 , which is in agreement with the worldwide average. Also, a correlation between the calculated zircon and monazite radioactive mineral contents with the measured radioactive isotopes was carried out to determine the contribution of each mineral for radioactivity. These correlations predicted that both zircon and monazite minerals are the main contributors for radioactivity in the Egyptian beach black sands. Also the present study ensured that area under investigation is to be safe for public. (author)

Assessment of natural radioactivity levels and identification of minerals in Brahmaputra (Jamuna) river sand and sediment, Bangladesh

International Nuclear Information System (INIS)

Khalil, Md. Ibrahim; Majumder, Ratan Kumar; Kabir, Md. Zafrul; Deeba, Farah; Khan, Md. Nazrul Islam; Ali, Md. Idris; Paul, Debasish; Haydar, Md. Abu; Islam, Syed Mohammad Azharul

2016-01-01

Distribution of the natural radionuclides ( 238 U, 232 Th, and 40 K) and their specific activities in sands and sediments of the Brahmaputra (Jamuna) river of Bangladesh together with mineral characteristics has been studied to assess the radiation levels as well as to develop a baseline database for comparison in the future in case of any change in the area under study due to anthropogenic activities. The radiological parameters of natural radioactivity were assessed calculating the radium equivalent activity, hazard index, the absorbed dose rate, and annual effective dose. The average activity concentrations of 226 Ra ( 238 U), 232 Th, and 40 K in sand and sediment were found to be 59 ± 2 and 60 ± 2 Bq/kg, 113 ± 5 and 135 ± 5 Bq/kg, and 983 ± 42 and 1002 ± 43 Bq/kg, respectively. The calculated average absorbed dose rate and annual effective dose were found to be 150 nGy/h and 0.18 mSv/year respectively. These high values are associated with mineral content of the sediment. X-ray diffraction peaks of sand and sediment samples identify quartz, feldspar, rutile, zircon, monazite, uranium fluoride, hematite, kyanite, and uranium arsenide minerals to be present in the samples. (author)

Acoustic characteristics of sand sediment with circular cylindrical pores

International Nuclear Information System (INIS)

Roh, Heui-Seol; Lee, Kang-Il; Yoon, Suk-Wang

2004-01-01

The acoustic pressure transmission coefficient and the phase velocity are experimentally measured as functions of the frequency and the porosity in sand sediment slabs with circular cylindrical pores filled with water and air. They are also theoretically estimated with the modified Biot-Attenborough (MBA) model, which uses a separate treatment of the viscous and the thermal effects in a non-rigid porous medium with water- and air-filled cylindrical pores. In this study, the fast (first kind) wave and the slow (second kind) wave are not separated in the transmitted signals through a sediment slab without the circular cylindrical pores, but they are separated in the transmitted signals through a sediment slab with pores. Both the phase velocities and the transmission coefficients of the fast wave and the slow wave in the sediment slabs with water- and air-filled cylindrical pores are sensitive to the air and the water porosities. It is proposed that the fast and the slow waves have opposite behaviors for several acoustic characteristics. The generalized tortuosity factor and the dynamic shape factor are introduced from the acoustic characteristics of the fast wave. The experimental results show reasonable agreement with the theoretical results estimated with the MBA model. These results suggest the possibility of predicting the acoustic characteristics of a sediment as functions of arbitrary water and air porosities. This study may also be applicable to understanding acoustic wave propagations in a bubbly liquid sediment for underwater applications and in cancellous bone for the diagnosis of osteoporosis.

Next-Generation Sequencing Assessment of Eukaryotic Diversity in Oil Sands Tailings Ponds Sediments and Surface Water.

Science.gov (United States)

Aguilar, Maria; Richardson, Elisabeth; Tan, BoonFei; Walker, Giselle; Dunfield, Peter F; Bass, David; Nesbø, Camilla; Foght, Julia; Dacks, Joel B

2016-11-01

Tailings ponds in the Athabasca oil sands (Canada) contain fluid wastes, generated by the extraction of bitumen from oil sands ores. Although the autochthonous prokaryotic communities have been relatively well characterized, almost nothing is known about microbial eukaryotes living in the anoxic soft sediments of tailings ponds or in the thin oxic layer of water that covers them. We carried out the first next-generation sequencing study of microbial eukaryotic diversity in oil sands tailings ponds. In metagenomes prepared from tailings sediment and surface water, we detected very low numbers of sequences encoding eukaryotic small subunit ribosomal RNA representing seven major taxonomic groups of protists. We also produced and analysed three amplicon-based 18S rRNA libraries prepared from sediment samples. These revealed a more diverse set of taxa, 169 different OTUs encompassing up to eleven higher order groups of eukaryotes, according to detailed classification using homology searching and phylogenetic methods. The 10 most abundant OTUs accounted for > 90% of the total of reads, vs. large numbers of rare OTUs (< 1% abundance). Despite the anoxic and hydrocarbon-enriched nature of the environment, the tailings ponds harbour complex communities of microbial eukaryotes indicating that these organisms should be taken into account when studying the microbiology of the oil sands. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

Local enhancement of the natural radionuclides in beach sand in Al-ar ish, Egypt

International Nuclear Information System (INIS)

Seddek, M.K.; Ragab, H.S.; Sharshar, T.; Mahmoud, K.R.; Badran, H.M.; Elnimr, T.

2005-01-01

Radionuclidic concentrations in Al-Arish city area, north Sinai, Egypt, were measured. The activities of the 232 Th and 238 U series in soil samples from two locations in harbor area and a location ∼ 3 km east the harbor were higher than those from other sites, with activities of 81.610.7, 50.6 ± 0.5, and 24.8 ± 0.4 Bq/kg 228 ,for ' Rn and 98.9 ± 1.3, 67.2±1.1, and 52.2±0.8 Bq/kg for 8 Ac. The average contents for the other sites were 8. 7.2 and 7.5 ± 6.7 Bq/kg for 222 Rn and 228 Ac, respectively. No significant difference in the 40 K activity was found between these two groups. The measured depth profiles in the site with the highest activity are studied. Samples with the smallest grain size (<0.2 mrr) were found to contain the highest level of activities, due to its high content of black sand

Gravel-Sand-Clay Mixture Model for Predictions of Permeability and Velocity of Unconsolidated Sediments

Science.gov (United States)

Konishi, C.

2014-12-01

Gravel-sand-clay mixture model is proposed particularly for unconsolidated sediments to predict permeability and velocity from volume fractions of the three components (i.e. gravel, sand, and clay). A well-known sand-clay mixture model or bimodal mixture model treats clay contents as volume fraction of the small particle and the rest of the volume is considered as that of the large particle. This simple approach has been commonly accepted and has validated by many studies before. However, a collection of laboratory measurements of permeability and grain size distribution for unconsolidated samples show an impact of presence of another large particle; i.e. only a few percent of gravel particles increases the permeability of the sample significantly. This observation cannot be explained by the bimodal mixture model and it suggests the necessity of considering the gravel-sand-clay mixture model. In the proposed model, I consider the three volume fractions of each component instead of using only the clay contents. Sand becomes either larger or smaller particles in the three component mixture model, whereas it is always the large particle in the bimodal mixture model. The total porosity of the two cases, one is the case that the sand is smaller particle and the other is the case that the sand is larger particle, can be modeled independently from sand volume fraction by the same fashion in the bimodal model. However, the two cases can co-exist in one sample; thus, the total porosity of the mixed sample is calculated by weighted average of the two cases by the volume fractions of gravel and clay. The effective porosity is distinguished from the total porosity assuming that the porosity associated with clay is zero effective porosity. In addition, effective grain size can be computed from the volume fractions and representative grain sizes for each component. Using the effective porosity and the effective grain size, the permeability is predicted by Kozeny-Carman equation

SEDIMENT ANALYSIS NETWORK FOR DECISION SUPPORT (SANDS) LANDSAT GEOLOGICAL SURVEY OF AL (GSA) ANALYSIS V1

Data.gov (United States)

National Aeronautics and Space Administration — The Sediment Analysis Network for Decision Support (SANDS) Landsat Geological Survey of AL (GSA) Analysis dataset analyzed changes in the coastal shoreline and...

Geochemical distribution of polycyclic aromatic hydrocarbons in soils and sediments of El-Tabbin, Egypt.

Science.gov (United States)

Havelcová, Martina; Melegy, Ahmed; Rapant, Stanislav

2014-01-01

Polycyclic aromatic hydrocarbons (PAHs) were extracted from 30 samples (24 soils and 6 stream sediments) collected in El-Tabbin area in the southern part of Greater Cairo, Egypt. Isopleth maps of PAHs clarified the regional variability and identified the most affected regions in the area suffering from high pollution. The total PAH concentrations were 53.4-5558.0 ng g(-1) in the sample extracts. The highest values were found in a soil sample near a coke factory, with the highest concentration of single PAHs, which were 1064.8 ng g(-1) of fluoranthene and 1286.4 ng g(-1) of phenanthrene. The calculated ratios and indexes allowed to elucidate origin of the organic compounds and to identify emission sources. The overall molecular patterns are signatures of pyrolysis of fossil fuels and biomass. Petrogenic contamination was recognised in the sediment samples due to petroleum products deliveries from ships. Also perylene was prominent especially in samples of the River Nile sediments as a diagenetic product of fungi. Other detailed information on petrogenic sources was provided by analysis of alkanes and calculation of alkane ratios. Copyright © 2013 Elsevier Ltd. All rights reserved.

A laboratory experiment on the evolution of a sand gravel reach under a lack of sediment supply

NARCIS (Netherlands)

Orru, C.; Chavarrias Borras, V.; Ferrara, V.; Stecca, G.; Blom, A.

2015-01-01

A flume experiment was conducted to examine the evolution of a sand-gravel reach under a lack of sediment supply. A bed composed of a bimodal sediment mixture was installed with a uniform slope and an gradual fining pattern. At the upstream end of the flume the initial bed consisted of 100% gravel,

Development of a bioassay to assess the toxicity of oil sands sediments to pike (Esox lucius)

Energy Technology Data Exchange (ETDEWEB)

Turcotte, D.; Yuan, H.; Tumber, V.; Parrott, J. [Environment Canada, Ottawa, ON (Canada); Raine, J. [Saskatchewan Univ., Saskatoon, SK (Canada)

2010-07-01

Pike (Esox lucius) are a commercially sought fish species that inhabit the Athabasca River, which flows through the Athabasca oil sands. The fish are exposed to natural sources of bitumen from the McMurray formation. This study was conducted to design and implement a daily-renewal bioassay to assess the toxicity of oil sands to this fish species and to obtain information regarding the development of pike exposed to bitumen. Eggs were collected and fertilized with milt from spawning wild pike captured from Lake Diefenbaker in Saskatchewan. The fertilized eggs were exposed to different concentrations of sediments or culture water only (negative controls) until complete yolk absorption of control fish, approximately 15 days post-hatch. For the rest of the experiment, brine shrimp were fed to the walleye embryos every day after hatching. The developing fish were examined for morphological deformities, survival, hatching success, and changes in weight and length. The research findings indicated that pike is less sensitive than walleye and fathead minnow to the toxicity of oil sands sediments.

Radioactivity levels of salt for natural sediments in the northwestern desert and local markets in Egypt

International Nuclear Information System (INIS)

El-Bahi, S.M.

2003-01-01

Thirteen samples of salt collected from different locations of old sediments in the western desert at El-Harra and Ain Giffara, Sitra lake and local markets in Egypt have been investigated. Natural radionuclide contents have been measured by γ-ray spectrometry employing a shielded HPGe detector. The activities of 238 U, 232 Th and 40 K have been determined in Bq/kg dry weight. The absorbed dose rate of gamma radiation was estimated to be 1.46-16.13 nGy/h. The thorium-to-uranium concentration ratios were also estimated for the samples

Correlation of aeolian sediment transport measured by sand traps and fluorescent tracers

Science.gov (United States)

Cabrera, Laura L.; Alonso, Ignacio

2010-03-01

Two different methods, fluorescent tracers and vertical sand traps, were simultaneously used to carry out an aeolian sediment transport study designed to test the goodness of fluorescent tracers in aeolian environments. Field experiments were performed in a nebkha field close to Famara beach at Lanzarote Island (Canary Islands, Spain) in a sector where the dunes were between 0.5 and 0.8 m height and 1-2 m wide and the vegetal cover was approximately 22%. In this dune field the sediment supply comes from Famara beach and is blown by trade winds toward the south, where the vegetation acts as natural sediment traps. Wind data were obtained by means of four Aanderaa wind speed sensors and one Aanderaa vane, all them distributed in a vertical array from 0.1 to 4 m height for 27 h. The average velocity at 1 m height during the experiment was 5.26 m s - 1 with the wind direction from the north. The tracer was under wind influence for 90 min at midday. During this period two series of sand traps (T1 and T2) N, S, E and W oriented were used. Resultant transport rates were 0.0131 and 0.0184 kg m - 1 min - 1 respectively. Tracer collection was performed with a sticky tape to sample only surface sediments. Tagged grains were visually counted under UV light. The transport rate was computed from the centroid displacement, that moved 0.875 m southwards, and the depth of the active layer considered was the size of one single grain. Taking into account these data the transport rate was 0.0072 kg m - 1 min - 1 . The discrepancy in results between both methods is related to several factors, such as the thickness of the active layer and the grain size difference between the tagged and the native material.

Sediment monitoring and benthic faunal sampling adjacent to the Sand Island ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900088)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna and sediment in the vicinity of the Sand Island ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size and...

Comparisons of Unconsolidated Sediments Analyzed by APXS (MSL-Curiosity) within Gale Crater, Mars: Soils, Sands of the Barchan and Linear Dunes of the Active Bagnold Dune Field, and Ripple-field Sands.

Science.gov (United States)

Thompson, L. M.; O'Connell-Cooper, C.; Spray, J. G.; Gellert, R.; Boyd, N. I.; Desouza, E.

2017-12-01

The MSL-APXS has analyzed a variety of unconsolidated sediments within the Gale impact crater, including soils, sands from barchan [High, Namib dunes], and linear dunes [Nathan Bridges, Mount Desert dunes], within the active Bagnold dune field, and sands from two smaller ripple fields ("mega-ripples"). The Gale "soils" (unsorted, unconsolidated sediments, ranging from fine-grained particles (including dust) to coarser "pebbly" material [>2 mm]), are, to a large degree, similar to Martian basaltic soils quantified by APXS, at Gusev crater (MER-A_Spirit) and Meridiani Planum (MER-B_Opportunity). Some local contributions are indicated by, for example, the enriched K levels (relative to a martian average basaltic soil [ABS]) within coarser Gale soil samples, and a Cr, Mn, Fe enrichment within finer-grained samples. Sands (grain size 62 µm to 2 mm) of the Bagnold dunes, generally, exhibit elevated Mg and Ni, indicating enrichment from olivine and pyroxene, but depleted S, Cl and Zn, indicating high activity levels and low dust. Compositional differences, related both to position within a dune (i.e., crest versus off-crest sand), and type of dune (linear versus barchan), are identified. Off-crest sands have Na, Al, Si, K, P contents similar to (or slightly depleted, relative to) the ABS, enrichment in Mg, and low dust content, whilst crest sands contain very high Mg and Ni (relative to the ABS), low felsic elemental concentrations and very low dust content. Cr is significantly enriched (and, to a lesser degree, Mn, Fe, Ti) in the off-crest sands of the linear dunes. In contrast, barchan dunes off-crest sands have Cr, Mn, Fe, and Ti abundances similar to those in the Gale soils. Additionally, Ni concentrations in barchan dunes off-crest sands are enriched relative to the linear dunes. Analyses from a small, isolated "mega-ripple" reveal a composition similar to that of the Gale soils, including a high dust content. The second mega-ripple, within a larger ripple field, is

Provenance of Coastal dune sands along Red Sea, Egypt

Indian Academy of Sciences (India)

26

accumulation of sands behind vegetation or any other obstacles. ... The study areas Safaga (SF) and Quseir (QS) field dunes (Fig. 1) ..... coastal dune sands were deposited in a passive margin of a synrift .... Sed Petrol 63(6), 1110-1117.

Solar Energy for Rural Egypt

Science.gov (United States)

Abdelsalam, Tarek I.; Darwish, Ziad; Hatem, Tarek M.

Egypt is currently experiencing the symptoms of an energy crisis, such as electricity outage and high deficit, due to increasing rates of fossil fuels consumption. Conversely, Egypt has a high solar availability of more than 18.5 MJ daily. Additionally, Egypt has large uninhabited deserts on both sides of the Nile valley and Sinai Peninsula, which both represent more than 96.5 % of the nation's total land area. Therefore, solar energy is one of the promising solutions for the energy shortage in Egypt. Furthermore, these vast lands are advantageous for commissioning large-scaled solar power projects, not only in terms of space availability, but also of availability of high quality silicon (sand) required for manufacturing silicon wafers used in photovoltaic (PV) modules. Also, rural Egypt is considered market a gap for investors, due to low local competition, and numerous remote areas that are not connected to the national electricity grid. Nevertheless, there are some obstacles that hinder the progress of solar energy in Egypt; for instance, the lack of local manufacturing capabilities, security, and turbulent market in addition to other challenges. This paper exhibits an experience of the authors designing and installing decentralized PV solar systems, with a total rated power of about 11 kW, installed at two rural villages in at the suburbs of Fayoum city, in addition to a conceptual design of a utility scale, 2 MW, PV power plant to be installed in Kuraymat. The outcomes of this experience asserted that solar PV systems can be a more technically and economically feasible solution for the energy problem in rural villages.

Purification and measurement of acid leachable europium in sands as an aid in the study of sediment transport

International Nuclear Information System (INIS)

Ditchburn, R.G.; McCabe, W.J.

1982-05-01

The use of europium labelled sand as an aid in the study of sediment transport has been suggested. A method for the purification of acid leachable europium is described. The final measurement is made by flame emission spectrometry using a nitrous oxide-acetylene flame. The usefulness of the method is limited by the natural levels of europium which, in the sand studied, was around 0.3 ppm

Monitoring radioactive contamination in food, water sediments and other environmental samples in Egypt. Final report for the period 1 October 1992 - 31 July 1996

International Nuclear Information System (INIS)

Farouk, M.

1996-09-01

A detailed survey for radioactivity content was carried out in the following materials: 1) Raw (from quarries) and finished (e.g., bricks, cement, ceramic tiles) building materials originating in central Egypt; 2) soils and plants (particularly cattle fodder) in upper Egypt, including soil to plant transfer factors; 3) water, bottom sediments and shore sediments from Lake Nasser and its immediate surroundings; 4) water, fish, bottom and shore sediments from the Lake Quaran region; 5) soil, plant, drinking water, bottom and shore sediments from the Sinai Peninsula. The concentrations of the following radionuclides were measured: K-40, Cs-137, Ra-226, Th-232 and U-238. Samples were sealed in Marinelli beakers for 4 weeks to allow complete ingrowth of Rn-222 and daughters. High resolution gamma-ray spectrometry was used to measure K-40 and Cs-137 directly and Ra-226, Th-232 and U-238 indirectly by means of daughter radioactivities. In addition, uranium measurements were also made after chemical decomposition of selected samples by laser fluorimetry and by alpha spectrometry techniques. The results were used for establishing a database of baseline radioactivity levels, for evaluating average doses to the population, for comparison with similar materials from other countries and for determining soil to plant transfer factors which can be used to estimate internal doses to the population. (author). Refs, figs, tabs

Environmental hazards and distribution of radioactive black sand along the Rosetta coastal zone in Egypt using airborne spectrometric and remote sensing data.

Science.gov (United States)

Kaiser, M F; Aziz, A M; Ghieth, B M

2014-11-01

High-resolution airborne gamma ray spectrometry, conducted in 2003, was used to estimate radioactive elements spatial abundance along the Rosetta coastal zone area. It was noticed that both Uranium and Thorium are concentrated in the black sand deposits along the beach. In contrary, Potassium was observed in high level abundance at the cultivated Nile Delta lands due to the accumulated usage of fertilizers. Exposure Rate (ER), Absorbed Dose Rate (ADR) and Annual Effective Dose Rate (AEDR) were calculated to evaluate the radiation background influence in human. Results indicated that the human body in the study sites is subjected to radiation hazards exceeds the accepted limit for long duration exposure. In addition, the areas covered by the highest concentration of Uranium and Thorium show the highest level of radiogenic heat production. Detection the environmental hazards of the radioactive black sands in the study site encouraged this research to monitor the spatial and temporal distribution of these sediments. The Landsat Thematic Mapper images acquired in 1990, 2003 and 2013 were analyzed using remote sensing image processing techniques. Image enhancements, classification and changes detection indicated a positive significant relationship between the patterns of coastline changes and distribution of the radioactive black sand in the study sites. The radioactive black sands are usually concentrated in the eroded areas. Therefore, in 1990 high concentration of the radioactive black sands were observed along the eastern and western flanks of the Rosetta promontory. Distribution of these sediments decreased due to the construction of the protective sea walls. Most of the radioactive black sands are transported toward the east in Abu Khashaba bay under the effect of the longshore currents and toward the west in Alexandria and Abu Quir bay under the action of the seasonal reverse currents. Copyright © 2014 Elsevier Ltd. All rights reserved.

Distribution and bioavailability of cadmium in ornithogenic coral-sand sediments of the Xisha archipelago, South China Sea

International Nuclear Information System (INIS)

Liu Xiaodong; Lou Chuangneng; Xu Liqiang; Sun Liguang

2012-01-01

Total cadmium (Cd) concentrations in four ornithogenic coral-sand sedimentary profiles displayed a strong positive correlation with guano-derived phosphorus, but had no correlation with plant-originated organic matter in the top sediments. These results indicate that the total Cd distributions were predominantly controlled by guano input. Bioavailable Cd and zinc (Zn) had a greater input rate in the top sediments with respect to total Cd and total Zn, and a positive correlation with total organic carbon (TOC) derived from plant humus. Multi-regression analysis showed that the total Cd and TOC explained over 80% of the variation of bioavailable Cd, suggesting that both guano and plant inputs could significantly influence the distribution of bioavailable Cd, and that plant biocycling processes contribute more to the recent increase of bioavailable Cd. A pollution assessment indicates that the Yongle archipelago is moderately to strongly polluted with guano-derived Cd. - Guano and plant biocycling processes can exert different influences on the distributions of total Cd and bioavailable Cd in coral-sand ornithogenic sediments.

Stochastic Modeling of Sediment Connectivity for Reconstructing Sand Fluxes and Origins in the Unmonitored Se Kong, Se San, and Sre Pok Tributaries of the Mekong River

Science.gov (United States)

Schmitt, R. J. P.; Bizzi, S.; Castelletti, A. F.; Kondolf, G. M.

2018-01-01

Sediment supply to rivers, subsequent fluvial transport, and the resulting sediment connectivity on network scales are often sparsely monitored and subject to major uncertainty. We propose to approach that uncertainty by adopting a stochastic method for modeling network sediment connectivity, which we present for the Se Kong, Se San, and Sre Pok (3S) tributaries of the Mekong. We quantify how unknown properties of sand sources translate into uncertainty regarding network connectivity by running the CASCADE (CAtchment Sediment Connectivity And DElivery) modeling framework in a Monte Carlo approach for 7,500 random realizations. Only a small ensemble of realizations reproduces downstream observations of sand transport. This ensemble presents an inverse stochastic approximation of the magnitude and variability of transport capacity, sediment flux, and grain size distribution of the sediment transported in the network (i.e., upscaling point observations to the entire network). The approximated magnitude of sand delivered from each tributary to the Mekong is controlled by reaches of low transport capacity ("bottlenecks"). These bottlenecks limit the ability to predict transport in the upper parts of the catchment through inverse stochastic approximation, a limitation that could be addressed by targeted monitoring upstream of identified bottlenecks. Nonetheless, bottlenecks also allow a clear partitioning of natural sand deliveries from the 3S to the Mekong, with the Se Kong delivering less (1.9 Mt/yr) and coarser (median grain size: 0.4 mm) sand than the Se San (5.3 Mt/yr, 0.22 mm) and Sre Pok (11 Mt/yr, 0.19 mm).

Sediment oxygen demand of wetlands in the oil sands region of northeastern Alberta

International Nuclear Information System (INIS)

Slama, C.; Gardner Costa, J.; Ciborowski, J.

2010-01-01

Sediment oxygen demand (SOD) can significantly influence the dissolved oxygen concentrations in shallow water bodies. This study discussed the types of sediments used to reclaim wetlands and their influence on SOD, successional processes, and ecosystem trajectories. The study hypothesized that oil sands process material (OSPM) affected wetlands would support cyanobacterial biofilms as opposed to submergent macrophytes as a result of insufficient phosphorus levels. SOD was assessed by monitoring dissolved oxygen concentrations within domes placed on the sediment surface for a 3-hour period. Gas flux and composition analyses were used to quantify the biological SOD components. Chemical SOD components were then determined by subtraction. Concentrations of phosphorus bioavailable to the macrophytes were estimated using plant root simulator probes. The study showed that OSPM wetlands exhibited higher chemical SOD and SOD than reference wetlands, and supported benthic biofilms as opposed to the submergent macrophyte communities typically found in northeastern Alberta wetlands.

Sediment oxygen demand of wetlands in the oil sands region of northeastern Alberta

Energy Technology Data Exchange (ETDEWEB)

Slama, C.; Gardner Costa, J.; Ciborowski, J. [Windsor Univ., ON (Canada)

2010-07-01

Sediment oxygen demand (SOD) can significantly influence the dissolved oxygen concentrations in shallow water bodies. This study discussed the types of sediments used to reclaim wetlands and their influence on SOD, successional processes, and ecosystem trajectories. The study hypothesized that oil sands process material (OSPM) affected wetlands would support cyanobacterial biofilms as opposed to submergent macrophytes as a result of insufficient phosphorus levels. SOD was assessed by monitoring dissolved oxygen concentrations within domes placed on the sediment surface for a 3-hour period. Gas flux and composition analyses were used to quantify the biological SOD components. Chemical SOD components were then determined by subtraction. Concentrations of phosphorus bioavailable to the macrophytes were estimated using plant root simulator probes. The study showed that OSPM wetlands exhibited higher chemical SOD and SOD than reference wetlands, and supported benthic biofilms as opposed to the submergent macrophyte communities typically found in northeastern Alberta wetlands.

Levels of polycyclic aromatic hydrocarbons and dibenzothiophenes in wetland sediments and aquatic insects in the oil sands area of northeastern Alberta, Canada.

Science.gov (United States)

Wayland, Mark; Headley, John V; Peru, Kerry M; Crosley, Robert; Brownlee, Brian G

2008-01-01

An immense volume of tailings and tailings water is accumulating in tailings ponds located on mine leases in the oil sands area of Alberta, Canada. Oil sands mining companies have proposed to use tailings- and tailings water-amended lakes and wetlands as part of their mine remediation plans. Polycyclic aromatic hydrocarbons (PAHs) are substances of concern in oil sands tailings and tailings water. In this study, we determined concentrations of PAHs in sediments, insect larvae and adult insects collected in or adjacent to three groups of wetlands: experimental wetlands to which tailings or tailings water had been purposely added, oil sands wetlands that were located on the mine leases but which had not been experimentally manipulated and reference wetlands located near the mine leases. Alkylated PAHs dominated the PAH profile in all types of samples in the three categories of wetlands. Median and maximum PAH concentrations, especially alkylated PAH concentrations, tended to be higher in sediments and insect larvae in experimental wetlands than in the other types of wetlands. Such was not the case for adult insects, which contained higher than expected levels of PAHs in the three types of ponds. Overlap in PAH concentrations in larvae among pond types suggests that any increase in PAH levels resulting from the addition of tailings and tailings water to wetlands would be modest. Biota-sediment accumulation factors were higher for alkylated PAHs than for their parent counterparts and were lower in experimental wetlands than in oil sands and reference wetlands. Research is needed to examine factors that affect the bioavailability of PAHs in oil sands tailings- or tailings water-amended wetlands.

Environmental hazards and distribution of radioactive black sand along the Rosetta coastal zone in Egypt using airborne spectrometric and remote sensing data

International Nuclear Information System (INIS)

Kaiser, M.F.; Aziz, A.M.; Ghieth, B.M.

2014-01-01

High-resolution airborne gamma ray spectrometry, conducted in 2003, was used to estimate radioactive elements spatial abundance along the Rosetta coastal zone area. It was noticed that both Uranium and Thorium are concentrated in the black sand deposits along the beach. In contrary, Potassium was observed in high level abundance at the cultivated Nile Delta lands due to the accumulated usage of fertilizers. Exposure Rate (ER), Absorbed Dose Rate (ADR) and Annual Effective Dose Rate (AEDR) were calculated to evaluate the radiation background influence in human. Results indicated that the human body in the study sites is subjected to radiation hazards exceeds the accepted limit for long duration exposure. In addition, the areas covered by the highest concentration of Uranium and Thorium show the highest level of radiogenic heat production. Detection the environmental hazards of the radioactive black sands in the study site encouraged this research to monitor the spatial and temporal distribution of these sediments. The Landsat Thematic Mapper images acquired in 1990, 2003 and 2013 were analyzed using remote sensing image processing techniques. Image enhancements, classification and changes detection indicated a positive significant relationship between the patterns of coastline changes and distribution of the radioactive black sand in the study sites. The radioactive black sands are usually concentrated in the eroded areas. Therefore, in 1990 high concentration of the radioactive black sands were observed along the eastern and western flanks of the Rosetta promontory. Distribution of these sediments decreased due to the construction of the protective sea walls. Most of the radioactive black sands are transported toward the east in Abu Khashaba bay under the effect of the longshore currents and toward the west in Alexandria and Abu Quir bay under the action of the seasonal reverse currents. - Highlights: • Spatial and temporal distributions of the black sand were

Phase behavior of methane hydrate in silica sand

International Nuclear Information System (INIS)

Sun, Shi-Cai; Liu, Chang-Ling; Ye, Yu-Guang; Liu, Yu-Feng

2014-01-01

Highlights: • Hydrate p-T trace in coarse-grained sediment is consistent with that in bulk water. • Fine-grained sediment affects hydrate equilibrium for the depressed water activity. • Hydrate equilibrium in sediment is related to the pore size distribution. • The application of hydrate equilibrium in sediment depends on the actual condition. -- Abstract: Two kinds of silica sand powder with different particle size were used to investigate the phase behavior of methane hydrate bearing sediment. In coarse-grained silica sand, the measured temperature and pressure range was (281.1 to 284.2) K and (5.9 to 7.8) MPa, respectively. In fine-grained silica sand, the measured temperature and pressure range was (281.5 to 289.5) K and (7.3 to 16.0) MPa, respectively. The results show that the effect of coarse-grained silica sand on methane hydrate phase equilibrium can be ignored; however, the effect of fine-grained silica sand on methane hydrate phase equilibrium is significant, which is attributed to the depression of water activity caused by the hydrophilicity and negatively charged characteristic of silica particle as well as the pore capillary pressure. Besides, the analysis of experimental results using the Gibbs–Thomson equation shows that methane hydrate phase equilibrium is related to the pore size distribution of silica sand. Consequently, for the correct application of phase equilibrium data of hydrate bearing sediment, the geological condition and engineering requirement should be taken into consideration in gas production, resource evaluation, etc

Origin of the Sinai-Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history

Science.gov (United States)

Muhs, Daniel R.; Roskin, Joel; Tsoar, Haim; Skipp, Gary; Budahn, James R.; Sneh, Amihai; Porat, Naomi; Stanley, Jean-Daniel; Katra, Itzhak; Blumberg, Dan G.

2013-01-01

The Sinai–Negev erg occupies an area of 13,000 km2 in the deserts of Egypt and Israel. Aeolian sand of this erg has been proposed to be derived from the Nile Delta, but empirical data supporting this view are lacking. An alternative source sediment is sand from the large Wadi El Arish drainage system in central and northern Sinai. Mineralogy of the Negev and Sinai dunes shows that they are high in quartz, with much smaller amounts of K-feldspar and plagioclase. Both Nile Delta sands and Sinai wadi sands, upstream of the dunes, also have high amounts of quartz relative to K-feldspar and plagioclase. However, Sinai wadi sands have abundant calcite, whereas Nile Delta sands have little or no calcite. Overall, the mineralogical data suggest that the dunes are derived dominantly from the Nile Delta, with Sinai wadi sands being a minor contributor. Geochemical data that proxy for both the light mineral fraction (SiO2/10–Al2O3 + Na2O + K2O–CaO) and heavy mineral fraction (Fe2O3–MgO–TiO2) also indicate a dominant Nile Delta source for the dunes. Thus, we report here the first empirical evidence that the Sinai–Negev dunes are derived dominantly from the Nile Delta. Linkage of the Sinai–Negev erg to the Nile Delta as a source is consistent with the distribution of OSL ages of Negev dunes in recent studies. Stratigraphic studies show that during the Last Glacial period, when dune incursions in the Sinai–Negev erg began, what is now the Nile Delta area was characterized by a broad, sandy, minimally vegetated plain, with seasonally dry anastomosing channels. Such conditions were ideal for providing a ready source of sand for aeolian transport under what were probably much stronger glacial-age winds. With the post-glacial rise in sea level, the Nile River began to aggrade. Post-glacial sedimentation has been dominated by fine-grained silts and clays. Thus, sea level, along with favorable climatic conditions, emerges as a major influence on the timing of dune

Bedform Dimensions and Suspended Sediment Observations in a Mixed Sand-Mud Intertidal Environment

Science.gov (United States)

Lichtman, I. D.; Amoudry, L.; Peter, T.; Jaco, B.

2016-02-01

Small-scale bedforms, such as ripples, can profoundly modify near-bed hydrodynamics, near-bed sediment transport and resuspension, and benthic-pelagic fluxes. Knowledge of their dimensions is important for a number of applications. Fundamentally different processes can occur depending on the dimensions of ripples: for low and long ripples, the bed remains dynamically flat and diffusive processes dominate sediment entrainment; for steep ripples, flow separation occurs above the ripples creating vortices, which are far more efficient at entraining sediment into the water column. Recent laboratory experiments for mixtures of sand and mud have shown that bedform dimensions decrease with increasing sediment mud content. However, these same experiments also showed that mud is selectively taken into suspension when bedforms are created and migrate on the bed, leaving sandy bedforms. This entrainment process, selectively suspending fine sediment, is referred to as winnowing. To improve our understanding of bedform and entrainment dynamics of mixed sediments, in situ observations were made on intertidal flats in the Dee Estuary, United Kingdom. A suite of instruments were deployed collecting co-located measurements of the near-bed hydrodynamics, waves, small-scale bed morphology and suspended sediment. Three sites were occupied consecutively, over a Spring-Neap cycle, collecting data for different bed compositions, tide levels and wind conditions. Bed samples were taken when the flats became exposed at low water and a sediment trap collected suspended load when inundated. This study will combine these measurements to investigate the interactions between small-scale bed morphology, near-bed hydrodynamics and sediment entrainment. We will examine bedform development in the complex hydrodynamic and wave climate of tidal flats, in relation to standard ripple predictors. We will also relate the variability in small-scale bedforms to variation in hydrodynamic and wave conditions

Phase transition behavior of sediment transport at the sand-mud interface, across scales from flumes to the large rivers

Science.gov (United States)

Ma, H.; Nittrouer, J. A.; Wu, B.; Zhang, Y.; Mohrig, D. C.; Lamb, M. P.; Wang, Y.; Fu, X.; Moodie, A. J.; Naito, K.; Parker, G.

2017-12-01

Sediment dispersal and deposition creates deltaic landscapes, establishes coastlines, and produces fertile floodplains, all of which serve as critical landforms inhabited by a large proportion of humankind. If poorly managed, sediment loads in these environments can elevate and clog channels, thereby enhancing hazards such as severe flooding. Predictive descriptions of sediment loads, however, are not well constrained, especially for fine-grained (silt and very-fine sand) dispersal systems, which often include river deltas and coastlines. Here, we show efforts to collect and analyze an extensive sediment load database for fine-grained channels, spanning from small flume experiments to large rivers, in order to evaluate the nature of sediment flux. Our analyses determined that sediment transport exhibits two distinct transport phases, separated by a discontinuous transition, whereby sediment flux differs by one to two orders of magnitude. It is determined that the transition responds to the bed material grain size, and we propose a phase diagram based on this metric alone. These findings help elucidate why previous theories of sediment transport at the sand-silt interface, which are typically continuous, are not able to give satisfactory predictions across different scales and environments. Our work serves to help evaluate anthropic influences on rivers, deltas, and coastlines, and can be applied to better constrain sediment flux of paleo-fluvial systems found on Earth and Mars. For example, in situ measurements of sediment flux for the silty-sandy bed of the lower Yellow River, China, validate the aforementioned phase transition behavior, and illustrate that the channel resides near the transition of high to low efficiency transport modes. Recent dam construction and resulting downstream coarsening of the bed via armoring, however, might lead to the unintended consequence of enhancing flood risk by driving the system to a low efficiency transport mode with high

The provenance of Taklamakan desert sand

Science.gov (United States)

Rittner, Martin; Vermeesch, Pieter; Carter, Andrew; Bird, Anna; Stevens, Thomas; Garzanti, Eduardo; Andò, Sergio; Vezzoli, Giovanni; Dutt, Ripul; Xu, Zhiwei; Lu, Huayu

2016-03-01

Sand migration in the vast Taklamakan desert within the Tarim Basin (Xinjiang Uyghur Autonomous region, PR China) is governed by two competing transport agents: wind and water, which work in diametrically opposed directions. Net aeolian transport is from northeast to south, while fluvial transport occurs from the south to the north and then west to east at the northern rim, due to a gradual northward slope of the underlying topography. We here present the first comprehensive provenance study of Taklamakan desert sand with the aim to characterise the interplay of these two transport mechanisms and their roles in the formation of the sand sea, and to consider the potential of the Tarim Basin as a contributing source to the Chinese Loess Plateau (CLP). Our dataset comprises 39 aeolian and fluvial samples, which were characterised by detrital-zircon U-Pb geochronology, heavy-mineral, and bulk-petrography analyses. Although the inter-sample differences of all three datasets are subtle, a multivariate statistical analysis using multidimensional scaling (MDS) clearly shows that Tarim desert sand is most similar in composition to rivers draining the Kunlun Shan (south) and the Pamirs (west), and is distinctly different from sediment sources in the Tian Shan (north). A small set of samples from the Junggar Basin (north of the Tian Shan) yields different detrital compositions and age spectra than anywhere in the Tarim Basin, indicating that aeolian sediment exchange between the two basins is minimal. Although river transport dominates delivery of sand into the Tarim Basin, wind remobilises and reworks the sediment in the central sand sea. Characteristic signatures of main rivers can be traced from entrance into the basin to the terminus of the Tarim River, and those crossing the desert from the south to north can seasonally bypass sediment through the sand sea. Smaller ephemeral rivers from the Kunlun Shan end in the desert and discharge their sediment there. Both river run

Bacterial Diversity and Bioremediation Potential of the Highly Contaminated Marine Sediments at El-Max District (Egypt, Mediterranean Sea)

KAUST Repository

Amer, Ranya A.

2015-02-01

Coastal environments worldwide are threatened by the effects of pollution, a risk particularly high in semienclosed basins like the Mediterranean Sea that is poorly studied from bioremediation potential perspective especially in the Southern coast. Here, we investigated the physical, chemical, and microbiological features of hydrocarbon and heavy metals contaminated sediments collected at El-Max bay (Egypt). Molecular and statistical approaches assessing the structure of the sediment-dwelling bacterial communities showed correlations between the composition of bacterial assemblages and the associated environmental parameters. Fifty strains were isolated on mineral media supplemented by 1% crude oil and identified as a diverse range of hydrocarbon-degrading bacteria involved in different successional stages of biodegradation. We screened the collection for biotechnological potential studying biosurfactant production, biofilm formation, and the capability to utilize different hydrocarbons. Some strains were able to grow on multiple hydrocarbons as unique carbon source and presented biosurfactant-like activities and/or capacity to form biofilm and owned genes involved in different detoxification/degradation processes. El-Max sediments represent a promising reservoir of novel bacterial strains adapted to high hydrocarbon contamination loads. The potential of the strains for exploitation for in situ intervention to combat pollution in coastal areas is discussed.

Heavy metals seasonal variability and distribution in Lake Qaroun sediments, El-Fayoum, Egypt

Science.gov (United States)

Redwan, Mostafa; Elhaddad, Engy

2017-10-01

This study was carried out to investigate the seasonal variability and distribution of heavy metals ;HMs; (Fe, Mn, Co, Cr, Cu, Ni, Pb, Zn and V) in the bottom sediments of Lake Qaroun, in Egypt. The samples were collected from 10 sites in summer and winter seasons in 2015. Total metals concentrations were measured using inductively coupled plasma spectrometer. Multivariate techniques were applied to analyse the distribution and potential source of heavy metals. The mean seasonal concentrations follow a descending order of Fe > Mn > V > Zn > Cr > Ni > Cu > Co > Pb. The mean concentrations of HMs in sediments during summer were higher than the concentrations during winter and above the average world shale values, except for Pb, suggesting potential adverse toxicity to aquatic organisms. All metals showed enrichment during summer and winter at sites S3 and S5 in the southeastern parts of the lake due to the heavy discharge of contaminants from El-Bats and El-Wadi drains. Principal component analysis results suggested two principal components controlling HMs variability in sediments, which accounted for 63.9% (factor 1: Co, Cr, Cu, Ni, Zn, Pb and V), 15.9% (factor 2: Mn and Fe) during summer, and 76.7% (factor 1: Fe, Co, Cr, Cu, Ni, Zn, Pb and V), 13.8% (factor 2: Mn) during winter of the total variance. Geo-accumulation index (Igeo) showed some pollution risk at the southeastern and southern parts (sites S3 and S5). Dilution during winter, concentration during summer, impact of non-point sources from different agricultural, industrial, municipal sewage and fish farms in the southern part of Lake Qaroun, adsorption and salt dissolution reactions and lithogenic sources are the main controlling factors for HMs in the study area. Monitoring of contaminant discharge at Lake Qaroun should be introduced for future remediation and management strategies.

Total and methyl mercury concentrations in sediment and water of a constructed wetland in the Athabasca Oil Sands Region

International Nuclear Information System (INIS)

Oswald, Claire J.; Carey, Sean K.

2016-01-01

In the Athabasca Oil Sands Region in northeastern Alberta, Canada, oil sands operators are testing the feasibility of peatland construction on the post-mining landscape. In 2009, Syncrude Canada Ltd. began construction of the 52 ha Sandhill Fen pilot watershed, including a 15 ha, hydrologically managed fen peatland built on sand-capped soft oil sands tailings. An integral component of fen reclamation is post-construction monitoring of water quality, including salinity, fluvial carbon, and priority pollutant elements. In this study, the effects of fen reclamation and elevated sulfate levels on mercury (Hg) fate and transport in the constructed system were assessed. Total mercury (THg) and methylmercury (MeHg) concentrations in the fen sediment were lower than in two nearby natural fens, which may be due to the higher mineral content of the Sandhill Fen peat mix and/or a loss of Hg through evasion during the peat harvesting, stockpiling and placement processes. Porewater MeHg concentrations in the Sandhill Fen typically did not exceed 1.0 ng L −1 . The low MeHg concentrations may be a result of elevated porewater sulfate concentrations (mean 346 mg L −1 ) and an increase in sulphide concentrations with depth in the peat, which are known to suppress MeHg production. Total Hg and MeHg concentrations increased during a controlled mid-summer flooding event where the water table rose above the ground surface in most of the fen. The Hg dynamics during this event showed that hydrologic fluctuations in this system exacerbate the release of THg and MeHg downstream. In addition, the elevated SO 4 2− concentrations in the peat porewaters may become a problem with respect to downstream MeHg production once the fen is hydrologically connected to a larger wetland network that is currently being constructed. - Highlights: • A constructed fen peatland in the Athabasca Oil Sands Region was studied. • Total and methyl mercury concentrations in fen sediment and waters

Genesis and continuity of quaternary sand and gravel in glacigenic sediment at a proposed low-level radioactive waste disposal site in east-central Illinois

Science.gov (United States)

Troost, K.G.; Curry, B. Brandon

1991-01-01

The Illinois Department of Nuclear Safety has characterized the Martinsville Alternative Site (MAS) for a proposed low-level radioactive waste disposal facility. The MAS is located in east-central Illinois approximately 1.6 km (1 mi) north of the city of Martinsville. Geologic investigation of the 5.5-km2 (1380-acre) site revealed a sequence of chiefly Illinoian glacigenic sediments from 6 to 60 m (20-200 ft) thick overlying two major bedrock valleys carved in Pennsylvanian strata. Relatively permeable buried units include basal, preglacial alluvium; a complex of intraglacial and subglacial sediment; englacial deposits; and supraglacial fluvial deposits. Postglacial alluvium underlies stream valleys on and adjacent to the site. In most areas, the buried sand units are confined by low-permeability till, lacustrine sediment, colluvium, and loess. The distribution and thickness of the most extensive and continuous buried sand units have been modified considerably by subglacial erosion, and their distributions have been influenced by the buried bedrock valleys. The most continuous of the various sand units were deposited as preglacial and postglacial alluvium and are the uppermost and lowermost stratigraphic units at the alternative site. Sand units that were deposited in englacial or ice-marginal environments are less continuous. Aquifer pumping tests, potentiometric head data, and groundwater geochemistry analyses indicate minimal interaction of groundwater across localized interconnections of the permeable units. ?? 1991 Springer-Verlag New York Inc.

Bacterial Diversity and Bioremediation Potential of the Highly Contaminated Marine Sediments at El-Max District (Egypt, Mediterranean Sea

Directory of Open Access Journals (Sweden)

Ranya A. Amer

2015-01-01

Full Text Available Coastal environments worldwide are threatened by the effects of pollution, a risk particularly high in semienclosed basins like the Mediterranean Sea that is poorly studied from bioremediation potential perspective especially in the Southern coast. Here, we investigated the physical, chemical, and microbiological features of hydrocarbon and heavy metals contaminated sediments collected at El-Max bay (Egypt. Molecular and statistical approaches assessing the structure of the sediment-dwelling bacterial communities showed correlations between the composition of bacterial assemblages and the associated environmental parameters. Fifty strains were isolated on mineral media supplemented by 1% crude oil and identified as a diverse range of hydrocarbon-degrading bacteria involved in different successional stages of biodegradation. We screened the collection for biotechnological potential studying biosurfactant production, biofilm formation, and the capability to utilize different hydrocarbons. Some strains were able to grow on multiple hydrocarbons as unique carbon source and presented biosurfactant-like activities and/or capacity to form biofilm and owned genes involved in different detoxification/degradation processes. El-Max sediments represent a promising reservoir of novel bacterial strains adapted to high hydrocarbon contamination loads. The potential of the strains for exploitation for in situ intervention to combat pollution in coastal areas is discussed.

Bacterial Diversity and Bioremediation Potential of the Highly Contaminated Marine Sediments at El-Max District (Egypt, Mediterranean Sea)

Science.gov (United States)

Amer, Ranya A.; El Gendi, Hamada M.; Goda, Doaa A.; Corsini, Anna; Cavalca, Lucia; Fusi, Marco; Daffonchio, Daniele; Abdel-Fattah, Yasser R.

2015-01-01

Coastal environments worldwide are threatened by the effects of pollution, a risk particularly high in semienclosed basins like the Mediterranean Sea that is poorly studied from bioremediation potential perspective especially in the Southern coast. Here, we investigated the physical, chemical, and microbiological features of hydrocarbon and heavy metals contaminated sediments collected at El-Max bay (Egypt). Molecular and statistical approaches assessing the structure of the sediment-dwelling bacterial communities showed correlations between the composition of bacterial assemblages and the associated environmental parameters. Fifty strains were isolated on mineral media supplemented by 1% crude oil and identified as a diverse range of hydrocarbon-degrading bacteria involved in different successional stages of biodegradation. We screened the collection for biotechnological potential studying biosurfactant production, biofilm formation, and the capability to utilize different hydrocarbons. Some strains were able to grow on multiple hydrocarbons as unique carbon source and presented biosurfactant-like activities and/or capacity to form biofilm and owned genes involved in different detoxification/degradation processes. El-Max sediments represent a promising reservoir of novel bacterial strains adapted to high hydrocarbon contamination loads. The potential of the strains for exploitation for in situ intervention to combat pollution in coastal areas is discussed. PMID:26273661

Scour at Vertical Piles in Sand-Clay Mixtures under Waves

DEFF Research Database (Denmark)

Dey, Subhasish; Helkjær, Anders; Sumer, B. Mutlu

2011-01-01

Marine sediments often contain sand-clay mixtures in widely varying proportions. This study presents the results of equilibrium scour and time variation of scour depths at circular piles embedded vertically in clay alone and sand-clay mixed beds under waves. Experiments were conducted in a wave...... flume with different proportions of sand-clay mixtures as bed sediments. Test results for the cases of steady current and sand alone under waves are used as references. The equilibrium scour depth reduces with an increase in clay proportion n (by weight) in a sand-clay mixture. Interestingly, the scour...

Use of pre-industrial floodplain lake sediments to establish baseline river metal concentrations downstream of Alberta oil sands: a new approach for detecting pollution of rivers

International Nuclear Information System (INIS)

Wiklund, Johan A; Hall, Roland I; Farwell, Andrea J; George Dixon, D; Wolfe, Brent B; Edwards, Thomas WD

2014-01-01

In the Alberta oil sands region, insufficient knowledge of pre-disturbance reference conditions has undermined the ability of the Regional Aquatics Monitoring Program (RAMP) to detect pollution of the Athabasca River, because sampling began three decades after the industry started and the river naturally erodes oil-bearing strata. Here, we apply a novel approach to characterize pre-industrial reference metal concentrations in river sediment downstream of Alberta oil sands development by analyzing metal concentrations in sediments deposited in floodplain lakes of the Athabasca Delta during 1700–1916, when they were strongly influenced by Athabasca River floodwaters. We compared results to metal concentrations in surficial bottom sediments sampled by RAMP (2010–2013) at downstream sites of the Athabasca River and distributaries. When normalized to lithium content, concentrations of vanadium (a metal of concern in the oil sands region) and other priority pollutants (Be, Cd, Cr, Cu, Pb, Ni, Zn) in nearly all of the RAMP river sediment samples lie below the upper 95% prediction interval linearly extrapolated from the river-derived lake sediments. Assuming the RAMP protocols obtained recently deposited sediment, this indicates that the metal concentrations in downstream Athabasca River sediment have not increased above pre-disturbance levels. Reference conditions derived from the lake sediment data were used to develop profiles of metal residual concentrations versus time for the RAMP river sediment data, which provides an excellent tool for decision-makers to identify and quantify levels of metal pollution for any given sample, and to monitor for future trends. We recommend that the approach be applied to resurrect the utility of RAMP data at other river sampling locations closer to the development, and for ongoing risk assessment. The approach is also readily transferable to other rivers where insufficient pre-disturbance reference data impairs an ability to

Heavy metal contamination in sand and sediments near to disposal site of reject brine from desalination plant, Arabian Gulf: Assessment of environmental pollution.

Science.gov (United States)

Alshahri, Fatimh

2017-01-01

Accumulation of heavy metals in environment may cause series potential risk in the living system. This study was carried out to investigate heavy metal contamination in sand samples and sediments along the beach near to disposal site of reject brine from Alkhobar desalination plant, which is one of the oldest and largest reverse osmosis desalination plants in eastern Saudi Arabia, Arabian Gulf. Fourteen heavy metals (U, Ca, Fe, Al, Ti, Sr, Rb, Ni, Pb, Cd, Cr, Cu, As, and Zr) were measured using gamma-ray spectrometry, atomic absorption spectrometer (AAS) and energy dispersive X-ray fluorescence spectrometer (EDX). The obtained data revealed that the concentrations of these metals were higher than the values in sediment and soil for other studies in Arabian Gulf. Furthermore, the mean values of Fe, Mn, Cr, Cu, As, Sr, and Zr concentrations in sand and sediments were higher than the geochemical background values in shale. The contamination factor (CF), modified degree of contamination (mC d ) and pollution load index (PLI) were assessed. According to contamination factors (CF > 1), the results showed elevated levels of Cu, Cr, Mn, Zr, and As in all samples. The highest value of contamination factor was found for As. Based on PLI (PLI > 1), the values of all sampling sites indicate a localized pollution in the study area. Current study could be useful as baseline data for heavy metals in sand and sediments nearby a desalination plant.

Sediment sorting along tidal sand waves: A comparison between field observations and theoretical predictions

Science.gov (United States)

Van Oyen, Tomas; Blondeaux, Paolo; Van den Eynde, Dries

2013-07-01

A site-by-site comparison between field observations and theoretical predictions of sediment sorting patterns along tidal sand waves is performed for ten locations in the North Sea. At each site, the observed grain size distribution along the bottom topography and the geometry of the bed forms is described in detail and the procedure used to obtain the model parameters is summarized. The model appears to accurately describe the wavelength of the observed sand waves for the majority of the locations; still providing a reliable estimate for the other sites. In addition, it is found that for seven out of the ten locations, the qualitative sorting process provided by the model agrees with the observed grain size distribution. A discussion of the site-by-site comparison is provided which, taking into account uncertainties in the field data, indicates that the model grasps the major part of the key processes controlling the phenomenon.

Southeast Florida Sediment Assessment and Needs Determination (SAND) Study

Science.gov (United States)

2014-09-01

sand with some shell beds, sandstone , and limestone *Miami Limestone 0 to 80 ft Oolitic limestone, quartz sand, and sandstone Anastasia 0 to 100 ft...Sand, shell beds, marl, calcareous sandstone (coquina/calcarenite) Fort Thompson 0 to 80 ft Silty limestone, silty sand, clayey marl, shell marl...highly- to moderately- weathered quartzose sandstone , and highly-weathered (saprolitic) to moderately-weathered hard limestone. North-south and

Natural equilibria and anthropic effects on sediment transport in big river systems: The Nile case

Science.gov (United States)

Garzanti, Eduardo; Andò, Sergio; Padoan, Marta; Vezzoli, Giovanni; Villa, Igor

2014-05-01

The Nile River flows for ~ 6700 km, from Burundi and Rwanda highlands south of the Equator to the Mediterranean Sea at northern subtropical latitudes. It is thus the longest natural laboratory on Earth, a unique setting in which we are carrying out a continuing research project to investigate changes in sediment composition associated with a variety of chemical and physical processes, including weathering in equatorial climate and hydraulic sorting during transport and deposition. Petrographic, mineralogical, chemical, and isotopic fingerprints of sand and mud have been monitored along all Nile branches, from the Kagera and White Nile draining Archean, Paleoproterozoic and Mesoproterozoic basements uplifted along the western branch of the East African rift, to the Blue Nile and Atbara Rivers sourced in Ethiopian volcanic highlands made of Oligocene basalt. Downstream of the Atbara confluence, the Nile receives no significant tributary water and hardly any rainfall across the Sahara. After construction of the Aswan High Dam in 1964, the Nile ceased to be an active conveyor-belt in Egypt, where the mighty river has been tamed to a water canal; transported sediments are thus chiefly reworked from older bed and levee deposits, with minor contributions from widyan sourced in the Red Sea Hills and wind-blown desert sand and dust. Extensive dam construction has determined a dramatic sediment deficit at the mouth, where deltaic cusps are undergoing ravaging erosion. Nile delta sediments are thus recycled under the effect of dominant waves from the northwest, the longest Mediterranean fetch direction. Nile sands, progressively enriched in more stable minerals such as quartz and amphiboles relative to volcanic rock fragments and pyroxene, thus undergo multistep transport by E- and NE-directed longshore currents all along the coast of Egypt and Palestine, and are carried as far as Akko Bay in northern Israel. Nile mud reaches the Iskenderun Gulf in southern Turkey. A full

External costs of sand mining in rivers: evidence from South Africa.

CSIR Research Space (South Africa)

De Lange, Willem J

2009-05-01

Full Text Available river sand load content and excluding the impacts of dams and sand mining). Accounting for the impacts of dams on sediment yield decreased the estimate by at least 33 percent (Theron et al., 2008). An aerial survey identified thirty-one active sand... mining operations, extracting approximately 400 000 cubic meters of sand per year (a conservative estimate) in the eThekwini area (Theron et al., 2008). The estimated remaining sediment yield from rivers after accounting for the impacts of dams...

Development of a bioassay using walleye (Sander vitreus) to assess the toxicity of oil sands sediments

Energy Technology Data Exchange (ETDEWEB)

Turcotte, D.; Yuan, H.; Tumber, V.; Parrott, J. [Environment Canada, Ottawa, ON (Canada); Raine, J. [Saskatchewan Univ., Saskatoon, SK (Canada)

2010-07-01

This study examined the effects of sediments from the Athabasca oil sands area on fish development and survival. Walleye (Sander vitreus) which inhabit the Athabasca River are exposed to natural sources of bitumen eroding from the McMurray formation. This study described the design and implementation of a daily-renewal bioassay to evaluate the potential effects of toxicants on walleye development. Eggs were collected and fertilized with milt from spawning wild walleye captured from Lake Diefenbaker in Saskatchewan. The fertilized eggs were exposed to different concentrations of sediments or culture water only (negative controls) until complete yolk absorption of control fish. The walleye embryos were fed brine shrimp daily after hatching and the developing fish were examined for morphological deformities, survival, hatching success, and changes in weight and length between treatments. Organics concentrations in fish tissues and water were measured when possible. Fathead minnows and northern pikes will also be exposed to the same sediments in order to compare the relative sensitivity of the three species.

Provenance of the heavy metals in sand sediments of the Oman Sea (Sistan and Baluchestan district

Directory of Open Access Journals (Sweden)

Maryam Soleimani

2015-04-01

Full Text Available Introduction Mineral composition of source rock is one of the most important factors for concentration and distribution of heavy metals in sediments. Therefore, study on distribution of these elements and the related minerals in sediments provides information about natural origin of elements. Moreover, the interpretation of origin and distribution of sandy sediments is considerably enhanced by mineralogical and geochemical studies of these sediments. The main objective of this research is to evaluate distribution of Zn, Cu, Sr, Cd, Fe and Mn in sand sediments of the Oman Sea, their relationship with mineral composition of the sediments and also determining their provenance. Materials and Methods Sampling of surface sediments of the Oman Sea was performed in 16 sampling stations. Heavy minerals and rock fragments of the sediments in fine and coarse sand sizes respectively were qualitatively and quantitatively studied by polarizing microscope (Folk, 1974; Pettijohn et al., 1981; Tucker, 1988. Concentration of the heavy metals were also analyzed by AAS method (Mico et al., 2008. Result Mineralogical composition of the studied sediments contain quartz, feldspars and heavy minerals in their order of abundances. The rock fragments consist of sedimentary, igneous and metamorphic in their order of frequencies as well. The concentrations of the studied heavy metals (in ppm in the sediments are Cd (1.42, Cu (9.99, Zn (36.72, Sr (181.18, Mn (377.33 and Fe (20247.55 in their order of abundances. Distribution of the Zn concentration generally shows decreasing trend from west of the study area to the Guatr Bay. The concentrations of Zn and Cu show close relationship with the frequencies of biotite and muscovite. The Cu concentration also shows positive correlation with the Zn and Fe concentrations. Distribution of the Sr and Cd concentrations is similar to variation of the calcium carbonate content. The Cd and Sr concentrations also show positive correlation

Provenance of coastal dune sands along Red Sea, Egypt

Indian Academy of Sciences (India)

Samir M Zaid

2017-06-07

Jun 7, 2017 ... been mainly formed by the accumulation of sands ... the upstream of the catchment areas of rain- fall, where ... deposited at the margin of the developing Red Sea ...... average upper continental crust (UCC) normalized ...... Petrol. 34 625–632. Egyptian Meteorological Authority, Ministry of Transporta-.

Improving the geotechnical behavior of sand through cohesive admixtures

Directory of Open Access Journals (Sweden)

Mohie eldin Mohamed Afify Elmashad

2018-04-01

Full Text Available Irrigation projects in Egypt have been facing tremendous challenges, mostly is the scarcity of irrigation water. The current research presents the effect of different cohesive admixture on the conductivity of siliceous sand in general and its other geotechnical properties. Two different types of conventional swelling clay from (Toshka, 6th of October as well as bentonite were used to construct the irrigation canals and embankment. The results indicated that increase in the plasticity properties of the treated soil also decrease the permeability and infiltration. Moreover, the dry density of 2.08 t/m3 was obtained from sand and 20% 6th of October mixture, also the CBR of 31.20% were obtained from sand and 8% 6th of October mixture. Increasing the bentonite ratio increases the cohesion and decreasing the permeability. The swelling ratios of sand 6th of October Clay mixture is equal to 0.28%, and the fictitious stress at which the swelling ratio is nil, is equal to 16 kPa. Keywords: Sand, Swelling clay, Bentonite, Compaction test, Consolidation test, Triaxial test

Characterization of sand lenses embedded in tills

DEFF Research Database (Denmark)

Kessler, Timo Christian; Klint, K.E.S.; Nilsson, B.

2012-01-01

Tills dominate large parts of the superficial sediments on the Northern hemisphere. These glacial diamictons are extremely heterogeneous and riddled with fractures and lenses of sand or gravel. The frequency and geometry of sand lenses within tills are strongly linked to glaciodynamic processes...

Evaluating process origins of sand-dominated fluvial stratigraphy

Science.gov (United States)

Chamberlin, E.; Hajek, E. A.

2015-12-01

Sand-dominated fluvial stratigraphy is often interpreted as indicating times of relatively slow subsidence because of the assumption that fine sediment (silt and clay) is reworked or bypassed during periods of low accommodation. However, sand-dominated successions may instead represent proximal, coarse-grained reaches of paleo-river basins and/or fluvial systems with a sandy sediment supply. Differentiating between these cases is critical for accurately interpreting mass-extraction profiles, basin-subsidence rates, and paleo-river avulsion and migration behavior from ancient fluvial deposits. We explore the degree to which sand-rich accumulations reflect supply-driven progradation or accommodation-limited reworking, by re-evaluating the Castlegate Sandstone (Utah, USA) and the upper Williams Fork Formation (Colorado, USA) - two Upper Cretaceous sandy fluvial deposits previously interpreted as having formed during periods of relatively low accommodation. Both units comprise amalgamated channel and bar deposits with minor intra-channel and overbank mudstones. To constrain relative reworking, we quantify the preservation of bar deposits in each unit using detailed facies and channel-deposit mapping, and compare bar-deposit preservation to expected preservation statistics generated with object-based models spanning a range of boundary conditions. To estimate the grain-size distribution of paleo-sediment input, we leverage results of experimental work that shows both bed-material deposits and accumulations on the downstream side of bars ("interbar fines") sample suspended and wash loads of active flows. We measure grain-size distributions of bar deposits and interbar fines to reconstruct the relative sandiness of paleo-sediment supplies for both systems. By using these novel approaches to test whether sand-rich fluvial deposits reflect river systems with accommodation-limited reworking and/or particularly sand-rich sediment loads, we can gain insight into large

Turbulence and sediment transport over sand dunes and ripples

Science.gov (United States)

Bennis, A.; Le Bot, S.; lafite, R.; Bonneton, P.; Ardhuin, F.

2013-12-01

Several bedforms are present near to the surfzone of natural beaches. Dunes and ripples are frequently observed. Understanding the turbulence over these forms is essential for the sediment transport. The turbulent flow and the suspended sand particles interact with each other. At the moment, the modelling strategy for turbulence is still a challenge. According to the spatial scales, some different methods to model the turbulence are employed, in particular the RANS (Reynolds Averaged Navier-Stokes) and the LES (Large Eddy Simulation). A hybrid method combining both RANS and LES is set up here. We have adapted this method, initially developed for atmospheric flow, to the oceanic flow. This new method is implemented inside the 3D hydrodynamic model, MARS 3D, which is forced by waves. LES is currently the best way to simulate turbulent flow but its higher cost prevents it from being used for large scale applications. So, here we use RANS near the bottom while LES is set elsewhere. It allows us minimize the computational cost and ensure a better accuracy of the results than with a fully RANS model. In the case of megaripples, the validation step was performed with two sets of field data (Sandy Duck'97 and Forsoms'13) but also with the data from Dune2D model which uses only RANS for turbulence. The main findings are: a) the vertical profiles of the velocity are similar throughout the data b) the turbulent kinetic energy, which was underestimated by Dune2D, is in line with the observations c) the concentration of the suspended sediment is simulated with a better accuracy than with Dune2D but this remains lower than the observations.

Controls on the abruptness of gravel-sand transitions

Science.gov (United States)

Venditti, J. G.; Church, M. A.; Lamb, M. P.; Domarad, N.; Rennie, C. D.

2014-12-01

As gravel-bedded rivers fine downstream, they characteristically exhibit an abrupt transition from gravel- to sand-bed. This is the only abrupt transition in grain-size that occurs in the fluvial system and has attracted considerable attention. A number of competing theories have been proposed to account for the abruptness of the transition, including base-level control, attrition of ~10mm gravel to produce sand, and sediment sorting processes. The prevailing theory for the emergence of abrupt transitions is size selective sorting of bimodal sediment wherein gravel deposits due to downstream declining shear stress, fining the bedload until a sand-bed emerges. We explored this hypothesis by examining grain-size, shear stress, gravel mobility and sand suspension thresholds through the gravel-sand transition (GST) of the Fraser River, British Columbia. The Fraser GST is an arrested gravel wedge with patches of gravel downstream of the wedge forming a diffuse extension. There is an abrupt change in bed slope through the transition that leads to an abrupt change in shear stress. The GST, bed-slope change and backwater caused by the ocean are all coincident spatially, which enhances the sharpness of the GST. Interestingly, the bimodal reach of the river occurs downstream of the GST and exhibits no downstream gradients in shear stress, suspended sediment flux, gravel mobility or sand suspension thresholds. This calls into question the prevailing theory for the emergence of an abrupt GST by size selective sorting. We provide evidence, both empirical and theoretical, that suggests the emergence of an abrupt GST is caused by rapid deposition of sand when fine gravel deposits. We argue that the emergence of gravel-sand transitions is a consequence of gravel-bedded rivers adopting a steeper slope than sand-bedded rivers. The abruptness arises because the bed slope required to convey the gravel load fixes the distal location of a terminal gravel wedge, and once the river has

Egypt.

Science.gov (United States)

1987-12-01

Attention in this discussion of Egypt is directed to the following: geography; the people; history; government and political conditions; the economy; defense; foreign relations; and relations between Egypt and the US. The population totaled 50.5 million in 1986 with an annual growth rate of 2.8%. The infant mortality rate is 102/1000 (1986), and life expectancy is 58.3 years. Located in the northeastern corner of Africa, Egypt has a land area of about 1 million square kilometers and is bounded by the Mediterranean Sea, Libya, Sudan, the Red Sea, the Gulf of Aqaba, and Israel. Egypt is the most populous country in the Arab world. Egyptians are a fairly homogenous people of Hamitic origin. Mediterranean and Arab influences appear in the north, and there is some mixing in the south with the Nubians of northern Sudan. Egypt has been a unified state for over 5000 years, and archeological evidence indicates that a developed Egyptian society has existed for considerably longer. The constitution of Egypt provides for a strong executive with authority vested in an elected president who can appoint 1 or more vice presidents, a prime minister, and a cabinet. Egypt's legislative body has 458 members -- 448 popularly elected and 10 appointed by the president. Power is concentrated in the hands of the president and the National Democratic Party's majority in the People's Assembly, but opposition parties organize, publish their views, and represent their followers at various levels in the political system. The process of gradual political liberalization begun by Sadat has continued under Mubarak. In fiscal year 1987 the gross domestic product (GDP) reached about US$30 billion. Agriculture and services each contribute about 1/3 of GDP; the remainder comes from industry, petroleum, mining, electricity, and construction. At this time, the Egyptian economy faces several challenges. In 1986 the government of Egypt initiated a major review of economic policy and initiated an economic

Seasonal changing sand waves and the effect of surface waves

NARCIS (Netherlands)

Sterlini, Fenneke; van Dijk, Thaiënne A.G.P.; IJzer, Steven; Hulscher, Suzanne; Schüttrumpf, Holger; Tomasicchio, Guiseppe Roberto

2012-01-01

Sand waves are wavelike subaqueous sediment structures that exist in large areas in shelf seas. Due to their characteristics sand waves can severely affect human offshore activities, such as navigation. This makes it important to understand the physical processes that shape and change sand waves. In

Transport processes in intertidal sand flats

Science.gov (United States)

Wu, Christy

2010-05-01

Methane rich sulfate depleted seeps are observed along the low water line of the intertidal sand flat Janssand in the Wadden Sea. It is unclear where in the flat the methane is formed, and how it is transported to the edge of the sand flat where the sulfidic water seeps out. Methane and sulfate distributions in pore water were determined along transects from low water line toward the central area of the sand flat. The resulting profiles showed a zone of methane-rich and sulfate-depleted pore water below 2 m sediment depth. Methane production and sulfate reduction are monitored over time for surface sediments collected from the upper flat and seeping area. Both activities were at 22 C twice as high as at 15 C. The rates in sediments from the central area were higher than in sediments from the methane seeps. Methanogenesis occurred in the presence of sulfate, and was not significantly accelerated when sulfate was depleted. The observations show a rapid anaerobic degradation of organic matter in the Janssand. The methane rich pore water is obviously transported with a unidirectional flow from the central area of the intertidal sand flat toward the low water line. This pore water flow is driven by the pressure head caused by elevation of the pore water relative to the sea surface at low tide (Billerbeck et al. 2006a). The high methane concentration at the low water line accumulates due to a continuous outflow of pore water at the seepage site that prevents penetration of electron acceptors such as oxygen and sulfate to reoxidize the reduced products of anaerobic degradation (de Beer et al. 2006). It is, however, not clear why no methane accumulates or sulfate is depleted in the upper 2 m of the flats.

Intermontane eolian sand sheet development, Upper Tulum Valley, central-western Argentina

Directory of Open Access Journals (Sweden)

Patrick Francisco Fuhr Dal' Bó

Full Text Available ABSTRACTThe intermontane Upper Tulum eolian sand sheet covers an area of ca. 125 km² at north of the San Juan Province, central-western Argentina. The sand sheet is currently an aggrading system where vegetation cover, surface cementation and periodic flooding withhold the development of dunes with slipfaces. The sand sheet surface is divided into three parts according to the distribution of sedimentary features, which reflects the variation in sediment budget, water table level and periodic flooding. The central sand sheet part is the main area of eolian deposition and is largely stabilized by vegetation. The sedimentary succession is 4 m thick and records the vertical interbedding of eolian and subaqueous deposits, which have been deposited for at least 3.6 ky with sedimentation rates of 86.1 cm/ky. The construction of the sand sheet is associated with deflation of the sand-graded debris sourced by San Juan alluvial fan, which is available mainly in drier fall-winter months where water table is lower and wind speeds are periodically above the threshold velocity for sand transport. The accumulation of sedimentary bodies occurs in a stabilized eolian system where vegetation cover, thin mud veneers and surface cementation are the main agents in promoting accumulation. The preservation of the sand sheet accumulations is enabled by the progressive creation of the accommodation space in a tectonically active basin and the continuous burial of geological bodies favored by high rates of sedimentation.

Sand waves on an epicontinental shelf: Northern Bering Sea

Science.gov (United States)

Field, M.E.; Nelson, C.H.; Cacchione, D.A.; Drake, D.E.

1981-01-01

Sand waves and current ripples occupy the crests and flanks of a series of large linear sand ridges (20 km ?? 5 km ?? 10 m high) lying in an open-marine setting in the northern Bering Sea. The sand wave area, which lies west of Seward Peninsula and southeast of Bering Strait, is exposed to the strong continuous flow of coastal water northward toward Bering Strait. A hierarchy of three sizes of superimposed bedforms, all facing northward, was observed in successive cruises in 1976 and 1977. Large sand waves (height 2 m; spacing 200 m) have smaller sand waves (height 1 m; spacing 20 m) lying at a small oblique angle on their stoss slopes. The smaller sand waves in turn have linguoid ripples on their stoss slopes. Repeated studies of the sand wave fields were made both years with high-resolution seismic-reflection profiles, side-scan sonographs, underwater photographs, current-meter stations, vibracores, and suspended-sediment samplers. Comparison of seismic and side-scan data collected along profile lines run both years showed changes in sand wave shape that indicate significant bedload transport within the year. Gouge marks made in sediment by keels of floating ice also showed significantly different patterns each year, further documenting modification to the bottom by sediment transport. During calm sea conditions in 1977, underwater video and camera observations showed formation and active migration of linguoid and straight-crested current ripples. Current speeds 1 m above the bottom were between 20 and 30 cm/s. Maximum current velocities and sand wave migration apparently occur when strong southwesterly winds enhance the steady northerly flow of coastal water. Many cross-stratified sand bodies in the geologic record are interpreted as having formed in a tidal- or storm-dominated setting. This study provides an example of formation and migration of large bedforms by the interaction of storms with strong uniform coastal currents in an open-marine setting. ?? 1981.

Long-term sand supply to Coachella Valley Fringe-toed Lizard Habitat in the Northern Coachella Valley, California

Science.gov (United States)

Griffiths, Peter G.; Webb, Robert H.; Lancaster, Nicholas; Kaehler, Charles A.; Lundstrom, Scott C.

2002-01-01

The Coachella Valley fringe-toed lizard (Uma inornata) is a federally listed threatened species that inhabits active sand dunes in the vicinity of Palm Springs, California. The Whitewater Floodplain and Willow Hole Reserves provide some of the primary remaining habitat for this species. The sediment-delivery system that creates these active sand dunes consists of fluvial depositional areas fed episodically by ephemeral streams. Finer fluvial sediments (typically sand size and finer) are mobilized in a largely unidirectional wind field associated with strong westerly winds through San Gorgonio Pass. The fluvial depositional areas are primarily associated with floodplains of the Whitewater?San Gorgonio Rivers and Mission Creek?Morongo Wash; other small drainages also contribute fluvial sediment to the eolian system. The eolian dunes are transitory as a result of unidirectional sand movement from the depositional areas, which are recharged with fine-grained sediment only during episodic floods that typically occur during El Ni?o years. Eolian sand moves primarily from west to east through the study area; the period of maximum eolian activity is April through June. Wind speed varies diurnally, with maximum velocities typically occurring during the afternoon. Development of alluvial fans, alteration of stream channels by channelization, in-stream gravel mining, and construction of infiltration galleries were thought to reduce the amount of fluvial sediment reaching the depositional areas upwind of Uma habitat. Also, the presence of roadways, railroads, and housing developments was thought to disrupt or redirect eolian sand movement. Most of the sediment yield to the fluvial system is generated in higher elevation areas with little or no development, and sediment yield is affected primarily by climatic fluctuations and rural land use, particularly livestock grazing and wildfire. Channelization benefits sediment delivery to the depositional plains upwind of the reserves

Sediment Budget in the Taiwan Strait with High Fluvial Sediment Inputs from Mountainous Rivers: New Observations and Synthesis

Directory of Open Access Journals (Sweden)

Shuh-Ji Kao

2008-01-01

Full Text Available The shallow Taiwan Strait at the southern opening of the East China Sea (ECS receives abundant sediments from turbid mountainous rivers in Taiwan. The volume of sediment is among the highest sediment yields on the global surface. This large amount of sediment discharged from modern Taiwan (range: 175 - 380 Mt y-1 based on 50-yr data is comparable to that discharged from Changjaing (500 Mt y-1-decreasing in recent decades, underscoring the importance of sediment budget in the Taiwan Strait and sediment flux from Taiwan into the ECS.We documented fluvial mud and sand concentrations during flash flooding with our observations indicating that fluvial materials in Taiwan¡¦s rivers are chiefly composed of mud (> 70 and up to 98 . By contrast, sand fraction dominates (> 85 for most stations surface sediments in the Taiwan Strait. Super typhoon Herb alone delivered 130 Mt of sediments from Choshui, the largest river in Taiwan, yet only insignificant amounts of mud were found at the river mouth six months later. The actions of waves, tides, and currents apparently prevent the deposition of fine grained sediments. Assuming sand occupied 30 (the maximum of the 60 Mt y-1 total sediment input from major western Taiwanese rivers, our annual budget estimate shows that the amount of sand input (18 5 Mt y-1 is comparable to the burial output of sand (12 10 Mt y-1. However, mud burial (6 5 Mt y-1 in the strait is far below the estimated mud input (42 11 Mt y-1, resulting in a significant shortfall. Hydrodynamic conditions were synthesized to explain the distribution pattern of limited mud patches in the strait and to reveal potential pathways by which fine-grain sediment transportation takes place in the seas surrounding Taiwan. A significant shortfall in the mud budget in the Taiwan Strait suggests that ~85 of the fluvial mud left the strait. Alternatively, the 50-year modern sediment flux data used in this study reflects exacerbated sediment flux due to human

Multi scenario seismic hazard assessment for Egypt

Science.gov (United States)

Mostafa, Shaimaa Ismail; Abd el-aal, Abd el-aziz Khairy; El-Eraki, Mohamed Ahmed

2018-05-01

Egypt is located in the northeastern corner of Africa within a sensitive seismotectonic location. Earthquakes are concentrated along the active tectonic boundaries of African, Eurasian, and Arabian plates. The study area is characterized by northward increasing sediment thickness leading to more damage to structures in the north due to multiple reflections of seismic waves. Unfortunately, man-made constructions in Egypt were not designed to resist earthquake ground motions. So, it is important to evaluate the seismic hazard to reduce social and economic losses and preserve lives. The probabilistic seismic hazard assessment is used to evaluate the hazard using alternative seismotectonic models within a logic tree framework. Alternate seismotectonic models, magnitude-frequency relations, and various indigenous attenuation relationships were amended within a logic tree formulation to compute and develop the regional exposure on a set of hazard maps. Hazard contour maps are constructed for peak ground acceleration as well as 0.1-, 0.2-, 0.5-, 1-, and 2-s spectral periods for 100 and 475 years return periods for ground motion on rock. The results illustrate that Egypt is characterized by very low to high seismic activity grading from the west to the eastern part of the country. The uniform hazard spectra are estimated at some important cities distributed allover Egypt. The deaggregation of seismic hazard is estimated at some cities to identify the scenario events that contribute to a selected seismic hazard level. The results of this study can be used in seismic microzonation, risk mitigation, and earthquake engineering purposes.

Count rate balance method of measuring sediment transport of sand beds by radioactive tracers

International Nuclear Information System (INIS)

Sauzay, G.

1968-01-01

Radioactive tracers are applied to the direct measurement of the sediment transport rate of sand beds. The theoretical measurement formula is derived: the variation of the count rate balance is inverse of that of the transport thickness. Simultaneously the representativeness of the tracer is critically studied. The minimum quantity of tracer which has to be injected in order to obtain a correct statistical definition of count rate given by a low number of grains 'seen' by the detector is then studied. A field experiment was made and has let to study the technological conditions for applying this method: only the treatment of results is new, the experiment itself is carried out with conventional techniques applied with great care. (author) [fr

Flow and suspended-sand behavior in large rivers after dredging.

Science.gov (United States)

Yuill, B. T.; Wang, Y.; Allison, M. A.; Meselhe, E. A.

2017-12-01

Dredging is commonly used in large rivers to promote navigation and provide sediment for engineering projects. Channel bars typically have thicker, coarser sediment deposits than elsewhere on the channel bed and are often the focus of dredging projects. Bar dredging may create deep pits ("borrow pits") that significantly alter flow and sediment transport. Locally, the pit acts as a large bedform, contracting and expanding the flow field and enhancing turbulence. At the reach scale, the pit acts as a new sediment sink and disrupts the sediment budget which may have consequences for channel stability and aquatic ecosystem health. In this study, we focus on the local impact of the borrow pit and how it, similar to dunes, creates a turbulent wake within the downstream flow column. We hypothesize that this wake may have implications for the overlapping suspended-sediment transport fields. Efficient dredging operations requires the ability to predict channel infilling/recovery timescales and in large, sandy rivers, a substantial fraction of the sediment infilling results from the settling of suspended sediment. However, if the turbulent wake significantly alters pathways of sediment settling within the borrow pit, typical models of sediment deposition that do not account for the wake effects may not apply. To explore this problem, we use numerical modelling to predict sand behavior with and without resolving the effects of wake turbulence. Wake turbulence is resolved using detached-eddy simulation and sand settling is simulated using Lagrangian particle tracking. Our study area is a >1 km2 channel bar in the lower Mississippi River, which was dredged in October 2016. We used vessel-based measurements (MBES, ADCP) to characterize the post-dredge hydrodynamic environment. Study results indicate that the turbulent wake significantly impacted suspended-sand behavior as it entered the borrow pit and large eddies increased the vertical grain velocities, mean grain settling was

Sedimentology and preservation of aeolian sediments on steep terrains: Incipient sand ramps on the Atacama coast (northern Chile)

Science.gov (United States)

Ventra, Dario; Rodríguez-López, Juan Pedro; de Boer, Poppe L.

2017-05-01

The origin of topographically controlled aeolian landforms in high-relief settings is difficult to synthesize under general models, given the dependence of such accumulations on local morphology. Quaternary sand ramps have been linked to palaeoclimate, regional geomorphology and wind patterns; however, controls on the early development and preservation of such landforms are poorly known. This study describes the morphology and sedimentology of complex sedimentary aprons along steep coastal slopes in the Atacama Desert (Chile). Direct slope accessibility and continuous stratigraphic exposures enable comparisons between active processes and stratigraphic signatures. Stratigraphic facies distribution and its links with patterns of aeolian deposition show that the preservation of wind-laid sediments depends on the morphology and processes of specific slope sectors. The spatial organization of runoff depends on bedrock configuration and directly controls the permanence or erosion of aeolian sediment. The occurrence of either water or mass flows depends on the role of aeolian fines in the rheology of flash floods. In turn, the establishment of a rugged surface topography controlled by patterns of mass-flow deposition creates local accommodation for aeolian fines, sustaining the initial aggradation of a colluvial-aeolian system. By contrast, slopes subject to runoff develop a thin, extensive aeolian mantle whose featureless surface is subject mostly to sediment bypass down- and across-slope; the corresponding stratigraphic record comprises almost exclusively thin debris-flow and sheetflood deposits. Slope morphology and processes are fundamental in promoting or inhibiting aeolian aggradation in mountain settings. Long-term sand-ramp construction depends on climate and regional topography, but the initial development is probably controlled by local geomorphic factors. The observed interactions between wind and topography in the study area may also represent a process

Experimental study on compressive strength of sediment brick masonry

Science.gov (United States)

Woen, Ean Lee; Malek, Marlinda Abdul; Mohammed, Bashar S.; Chao-Wei, Tang; Tamunif, Muhammad Thaqif

2018-02-01

The effects of pre-wetted unit bricks, mortar type and slenderness ratio of prisms on the compressive strength and failure mode of newly developed sediment brick have been evaluated and compared to clay brick and cement-sand bricks. The results show that pre-wetted sediment brick masonry exhibits higher compressive strength of up to 20% compared to the dry sediment masonry. Using cement-lime mortar leads to lower compressive strength compared to cement mortar. However, the sediment brick masonry with the cement lime mortar exhibit higher compressive strength in comparison with cement mortar masonry. More of diagonal shear cracks have been observed in the failure mode of the sediment bricks masonry compared to clay and cement-sand bricks masonry that show mostly vertical cracks and crushing. The sediment unit bricks display compressive strength in between clay and cement-sand bricks.

Visual accumulation tube for size analysis of sands

Science.gov (United States)

Colby, B.C.; Christensen, R.P.

1956-01-01

The visual-accumulation-tube method was developed primarily for making size analyses of the sand fractions of suspended-sediment and bed-material samples. Because the fundamental property governing the motion of a sediment particle in a fluid is believed to be its fall velocity. the analysis is designed to determine the fall-velocity-frequency distribution of the individual particles of the sample. The analysis is based on a stratified sedimentation system in which the sample is introduced at the top of a transparent settling tube containing distilled water. The procedure involves the direct visual tracing of the height of sediment accumulation in a contracted section at the bottom of the tube. A pen records the height on a moving chart. The method is simple and fast, provides a continuous and permanent record, gives highly reproducible results, and accurately determines the fall-velocity characteristics of the sample. The apparatus, procedure, results, and accuracy of the visual-accumulation-tube method for determining the sedimentation-size distribution of sands are presented in this paper.

Sand transportation and reverse patterns over leeward face of sand dune

Science.gov (United States)

Jiang, Hong; Dun, Hongchao; Tong, Ding; Huang, Ning

2017-04-01

Sand saltation has complex interactions with turbulent flow and dune form. Most models of wind-blown sand consider ideal circumstances such as steady wind velocity and a flat surface, and the bulk of data on wind flow and sand transport over an individual dune has focused mostly on the influence of dune shape or inter-dune space on the wind flow, neglecting the effect of morphology on sand saltation, particularly airflow and sand transportation over the leeward slope. Wind flow structures over the leeward slope of sand dunes have a fundamental influence on the organization of sand dunes. In order to understand sand dune dynamics, lee face airflow and sediment transportation should be paid more attention. Previous field observations could not measure turbulent flow structure well because of the limited observation points and the influence of experiment structure on wind field. In addition, the reverse sand particles over leeward face could not be collected by sand trap in field. Numerous field observations could not measure turbulent flow structure because of the limited observation points and the influence of experimental structures on the wind field. In addition, the reverse transport of sand particles over leeward face could not be collected by sand traps in field. Therefore, this paper aims to investigate the turbulent flow structure and sand transport pattern over the leeward slope. A numerical model of sand saltation over slope terrain is constructed, which also considers the coupling effects between air flow and sand particles. The large eddy simulation method is used to model turbulent flow. Sand transport is simulated by tracking the trajectory of each sand particle. The results show that terrain significantly alters the turbulent air flow structure and wind-blown sand movement, especially over the leeward slope. Here, mass flux increases initially and then decreases with height in the reversed flow region in the direction of wind flow, and the mass flux

The presence of radioactive materials in soil, sand and sediment samples of Potenga sea beach area, Chittagong, Bangladesh: Geological characteristics and environmental implication

Science.gov (United States)

Yasmin, Sabina; Barua, Bijoy Sonker; Uddin Khandaker, Mayeen; Kamal, Masud; Abdur Rashid, Md.; Abdul Sani, S. F.; Ahmed, H.; Nikouravan, Bijan; Bradley, D. A.

2018-03-01

Accurate quantification of naturally occurring radioactive materials in soil provides information on geological characteristics, possibility of petroleum and mineral exploration, radiation hazards to the dwelling populace etc. Of practical significance, the earth surface media (soil, sand and sediment) collected from the densely populated coastal area of Chittagong city, Bangladesh were analysed using a high purity germanium γ-ray spectrometer with low background radiation environment. The mean activities of 226Ra (238U), 232Th and 40K in the studied materials show higher values than the respective world average of 33, 36 and 474 Bq/kg reported by the UNSCEAR (2000). The deduced mass concentrations of the primordial radionuclides 238U, 232Th and 40K in the investigated samples are corresponding to the granite rocks, crustal minerals and typical rocks respectively. The estimated mean value of 232Th/238U for soil (3.98) and sediment (3.94) are in-line with the continental crustal average concentration of 3.82 for typical rock range reported by the National Council on Radiation Protection and Measurements (NCRP). But the tonalites and more silicic rocks elevate the mean value of 232Th/238U for sand samples amounting to 4.69. This indicates a significant fractionation during weathering or associated with the metasomatic activity in the investigated area of sand collection.

Benthic foraminiferal assemblages as bio-indicators of metals contamination in sediments, Qarun Lake as a case study, Egypt

Science.gov (United States)

Abd El Naby, Ahmed; Al Menoufy, Safia; Gad, Ahmed

2018-03-01

Qarun Lake, in the Fayoum Depression of the Western Desert of Egypt, lies within the deepest area in the River Nile flood plain. The drainage water in the Qarun Lake is derived from the discharge of the natural and artificial drainage systems in the Fayoum. Mixed domestic and agricultural pollutants, including heavy metals, nitrates, phosphates, sulfates and pesticides, are discharged into Qarun Lake. Forty-six samples, collected from the undisturbed layer of sediments were used for benthic foraminiferal analysis. Concentrations of some selected trace metal elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V, and Zn) were also determined. Statistical analysis of the abiotic variables (Texture distribution of sediments, Physico-chemical parameters, and metals concentrations) and of the biotic variables (distribution of benthic foraminiferal species) were also performed. The Q-mode cluster analysis of benthic foraminiferal distribution has provided evidence that the Qarun Lake can be subdivided into two cluster groups (A and B), reflecting environmental changes in the lake ecosystem. Cluster B can also be subdivided into two sub-clusters (B1 and B2). The presence of only pollution tolerant taxa with higher faunal density and lower diversity and the absence of the other foraminiferal assemblages in cluster A were attributed to the high concentration of trace metal elements and the strong environmental stress at the eastern and central parts of the Qarun Lake.

Radiological responses of different types of Egyptian Mediterranean coastal sediments

Science.gov (United States)

El-Gamal, A.; Rashad, M.; Ghatass, Z.

2010-08-01

The aim of this study was to identify gamma self-absorption correction factors for different types of Egyptian Mediterranean coastal sediments. Self-absorption corrections based on direct transmission through different thicknesses of the most dominant sediment species have been tested against point sources with gamma-ray energies of 241Am, 137Cs and 60Co with 2% uncertainties. Black sand samples from the Rashid branch of the Nile River quantitatively absorbed the low energy of 241Am through a thickness of 5 cm. In decreasing order of gamma energy self-absorption of 241Am, the samples under investigation ranked black sand, Matrouh sand, Sidi Gaber sand, shells, Salloum sand, and clay. Empirical self-absorption correction formulas were also deduced. Chemical analyses such as pH, CaCO 3, total dissolved solids, Ca 2+, Mg 2+, CO 32-, HCO 3- and total Fe 2+ have been carried out for the sediments. The relationships between self absorption corrections and the other chemical parameters of the sediments were also examined.

Effects of Aging Quartz Sand and Hanford Site Sediment with Sodium Hydroxide on Radionuclide Sorption Coefficients and Sediment Physical and Hydrologic Properties: Final Report for Subtask 2a

Energy Technology Data Exchange (ETDEWEB)

DI Kaplan; JC Ritter; KE Parker

1998-12-04

Column and batch experiments were conducted in fiscal year 1998 at Pacific Northwest National Laboratory to evaluate the effect of varying concentrations of NaOH on the sorptive, physical, and hydraulic properties of two media, a quartz sand and a composite subsurface sediment from the 200-East Area of the Hanford Site. The NaOH solutions were used as a simplified effluent from a low-activity glass waste form. These experiments were conducted over a limited (O-to 10-month) contact time, with respect to the 10,000-to 100,000-year scenarios described in the Immobilized Low-Activity Waste- Performance Assessment (ILAW-PA). Wheq these two solids were put in contact with the NaOH solutions, dissolution was evident by a substantial increase in dissolved Si concentrations in the leachates. Incremental increases in NaOH con- centrations, resulted in corresponding increases in Si concentrations. A number of physical and hydraulic properties also changed as the NaOH concentrations were changed. It was observed that quartz sand was less reactive than the composite sediment. Further, moisture- retention measurements were made on the quartz sand and composite sedimen$ which showed that the NaOH-treated solids retained more water than the non-NaOH-treated solids. Because the other chemical, physical, and hydraulic measurements did not change dramatically after the high-NaOH treatments, the greater moisture retention of the high-NaOH treatments was attributed to a "salt effect" and not to the formation of small particles during the dissolution (weathering). The distribution coefficients (IQ) for Cs and Sr were measured on the NaOH-treated sediments, with decreases from -3,000 to 1,000 and 1,300 to 300 mL/g noted, respectively, at the 0.01-to 1.O-M NaOH levels. There was no apparent trend for the Sr & values with contact time. The lack of such a trend sug- gests that dissolution of sediment particles is not controlling the drop in IQ rather, it is the competition of the added Na

Interpreting Hydraulic Conditions from Morphology, Sedimentology, and Grain Size of Sand Bars in the Colorado River in Grand Canyon

Science.gov (United States)

Rubin, D. M.; Topping, D. J.; Schmidt, J. C.; Grams, P. E.; Buscombe, D.; East, A. E.; Wright, S. A.

2015-12-01

During three decades of research on sand bars and sediment transport in the Colorado River in Grand Canyon, we have collected unprecedented quantities of data on bar morphology, sedimentary structures, grain size of sand on the riverbed (~40,000 measurements), grain size of sand in flood deposits (dozens of vertical grain-size profiles), and time series of suspended sediment concentration and grain size (more than 3 million measurements using acoustic and laser-diffraction instruments sampling every 15 minutes at several locations). These data, which include measurements of flow and suspended sediment as well as sediment within the deposits, show that grain size within flood deposits generally coarsens or fines proportionally to the grain size of sediment that was in suspension when the beds were deposited. The inverse problem of calculating changing flow conditions from a vertical profile of grain size within a deposit is difficult because at least two processes can cause similar changes. For example, upward coarsening in a deposit can result from either an increase in discharge of the flow (causing coarser sand to be transported to the depositional site), or from winnowing of the upstream supply of sand (causing suspended sand to coarsen because a greater proportion of the bed that is supplying sediment is covered with coarse grains). These two processes can be easy to distinguish where suspended-sediment observations are available: flow-regulated changes cause concentration and grain size of sand in suspension to be positively correlated, whereas changes in supply can cause concentration and grain size of sand in suspension to be negatively correlated. The latter case (supply regulation) is more typical of flood deposits in Grand Canyon.

Laboratory Investigation of Complex Conductivity and Magnetic Susceptibility on Natural Iron Oxide Coated Sand

Science.gov (United States)

Wang, C.; Slater, L. D.; Day-Lewis, F. D.; Briggs, M. A.

2017-12-01

Redox reactions occurring at the oxic/anoxic interface where groundwater discharges to surface water commonly result in iron oxide deposition that coats sediment grains. With relatively large total surface area, these iron oxide coated sediments serve as a sink for sorption of dissolved contaminants, although this sink may be temporary if redox conditions fluctuate with varied flow conditions. Characterization of the distribution of iron oxides in streambed sediments could provide valuable understanding of biogeochemical reactions and the ability of a natural system to sorb contaminants. Towards developing a field methodology, we conducted laboratory spectral induced polarization (SIP) and magnetic susceptibility (MS) measurements on natural iron oxide coated sand (Fe-sand) with grain sizes ranging from 0.3 to 2.0 mm in order to assess the sensitivity of these measurements to iron oxides in sediments. The Fe-sand was also sorted by sieving into various grain sizes to study the impact of grain size on the polarization mechanisms. The unsorted Fe-sand saturated with 0.01 S/m NaCl solution exhibited a distinct phase response ( > 4 mrad) in the frequency range from 0.001 to 100 Hz whereas regular silica sand was characterized by a phase response less than 1 mrad under the same conditions. The presence of iron oxide substantially increased MS (3.08×10-3 SI) over that of regular sand ( Laboratory results demonstrated that SIP and MS may be well suited to mapping the distribution of iron oxides in streambed sediments associated with anoxic groundwater discharge.

Sediment Characterization in St. Alban's Bay, VT

Science.gov (United States)

Nethercutt, S.; Manley, T.; Manley, P.

2017-12-01

St. Alban's Bay within Lake Champlain is plagued with harmful algal blooms. With future intensification due to climate change, a multidisciplinary program (BREE-Basin Resilience to Extreme Events) was initiated in 2016. In order to assess the mobilization of harmful nutrients from sediment resuspension events and riverine input, 74 sediment samples were collected in a grid fashion throughout St. Alban's Bay. Sediments were deflocculated and analyzed using a LA920 Horiba laser scattering particle size distribution analyzer to define the frequency of sediment sizes from clay to sand. Gridded surfaces of mean sortable silt percentage, silt percentage, sand percentage, and clay percentage were used to represent the sediment distribution of the region. A plot of diameter versus frequency showed the bimodal nature of some of the sediments, with one peak at about 10 microns diameter (silt) and the second at about 525 microns diameter (sand). The data showed an extremely low percentage of clay relative to that of sand and silt. The highest frequencies of sortable silt, which represents the most easily mobilized particle size, are found in the deepest areas of the bay, suggesting that these regions are where dominant bottom flow occurs. The high occurrence of sortable silt in the St. Alban's Bay does suggest that sediment mobilization, and therefore nutrient mobilization has the potential to occur. These data combined with high-resolution multibeam and hydrodynamic data will allow for future models of water flow and remobilization studies in the future.

Distribution and origin of sediments on the northern Sunda Shelf, South China Sea

Science.gov (United States)

Wu, Shi-Guo; Wong, H. K.; Luo, You-Lang; Liang, Zhi-Rong

1999-03-01

Seventy-seven surface sediment samples and core samples from the outer Sunda Shelf were analyzed and a number of seismic profiles of the shelf were interpreted. The bottom sediments could be divided into six types: terrigenous sand, biogenic sand, silt-sand, clay-silt-sand, clayey silt and coral reef detritus. Our seismic data showed a thick, prograding Pleistocene deltaic sequence near the shelf-break and a thin Holocene sedimentary layer on the outer shelf. Eleven thermoluminescence (TL) ages were determined. The oldest relict sediments were derived from Late Pleistocene deposits. Based on sediment types, ages, and origins, five sedimentary areas were identified: area of modern Mekong sediments; insular shelf area receiving modern sediments from small Borneo rivers; shelf area near the Natuna-Anambas islands in the southeastern Gulf of Thailand Basin off the Malay Peninsula; area of relict sediments on the outer shelf north of the Natuna Islands, and typical coral reefs and detritus sediments.

Changes in active eolian sand at northern Coachella Valley, California

Science.gov (United States)

Katra, Itzhak; Scheidt, Stephen; Lancaster, Nicholas

2009-04-01

Climate variability and rapid urbanization have influenced the sand environments in the northern Coachella Valley throughout the late 20th century. This paper addresses changes in the spatial relationships among different sand deposits at northern Coachella Valley between two recent time periods by using satellite data acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). The approach employed here, involving multispectral thermal infrared (TIR) data and spectral mixture analysis, has shown that the major sand deposits can be spatially modeled at northern Coachella Valley. The "coarse-grained (quartz-rich) sand" deposit is associated with active eolian sand, and the "mixed sandy soil" and "fine-grained (quartz-rich) sand" deposits are associated with inactive eolian sand. The fractional abundance images showed a significant decrease between 2000 and 2006 in the percentage of active sand in the major depositional area for fluvial sediment, the Whitewater River, but also in two downwind areas: the Whitewater and Willow Hole Reserves. The pattern of the active sand appears to be related to variations in annual precipitation (wet and dry years) and river discharge in the northern Coachella Valley. We suggest here that recent human modifications to the major watercourses that supply sand affect the capability of fluvial deposition areas to restore sediments over time and consequently the responses of the sand transport system to climate change, becoming more sensitive to dry years where areas of active sand may shrink, degrade, and/or stabilize faster. The approach utilized in this study can be advantageous for future monitoring of sand in the northern Coachella Valley for management of these and similar environments.

Comparison. US P-61 and Delft sediment samplers

Science.gov (United States)

Beverage, Joseph P.; Williams, David T.

1990-01-01

The Delft Bottle (DB) is a flow-through device designed by the Delft Hydraulic Laboratory (DHL), The Netherlands, to sample sand-sized sediment suspended in streams. The US P-61 sampler was designed by the Federal Interagency Sedimentation Project (FISP) at the St. Anthony Falls Hydraulic Laboratory, Minneapolis, Minnesota, to collect suspended sediment from deep, swift rivers. The results of two point-sampling tests in the United States, the Mississippi River near Vicksburg, Mississippi, in 1983 and the Colorado River near Blythe, California, in 1984, are provided in this report. These studies compare sand-transport rates, rather than total sediment-transport rates, because fine material washes through the DB sampler. In the United States, the commonly used limits for sand-sized material are 0.062 mm to 2.00 mm (Vanoni 1975).

Sediment transport processes in the Pearl River Estuary as revealed by grain-size end-member modeling and sediment trend analysis

Science.gov (United States)

Li, Tao; Li, Tuan-Jie

2018-04-01

The analysis of grain-size distribution enables us to decipher sediment transport processes and understand the causal relations between dynamic processes and grain-size distributions. In the present study, grain sizes were measured from surface sediments collected in the Pearl River Estuary and its adjacent coastal areas. End-member modeling analysis attempts to unmix the grain sizes into geologically meaningful populations. Six grain-size end-members were identified. Their dominant modes are 0 Φ, 1.5 Φ, 2.75 Φ, 4.5 Φ, 7 Φ, and 8 Φ, corresponding to coarse sand, medium sand, fine sand, very coarse silt, silt, and clay, respectively. The spatial distributions of the six end-members are influenced by sediment transport and depositional processes. The two coarsest end-members (coarse sand and medium sand) may reflect relict sediments deposited during the last glacial period. The fine sand end-member would be difficult to transport under fair weather conditions, and likely indicates storm deposits. The three remaining fine-grained end-members (very coarse silt, silt, and clay) are recognized as suspended particles transported by saltwater intrusion via the flood tidal current, the Guangdong Coastal Current, and riverine outflow. The grain-size trend analysis shows distinct transport patterns for the three fine-grained end-members. The landward transport of the very coarse silt end-member occurs in the eastern part of the estuary, the seaward transport of the silt end-member occurs in the western part, and the east-west transport of the clay end-member occurs in the coastal areas. The results show that grain-size end-member modeling analysis in combination with sediment trend analysis help to better understand sediment transport patterns and the associated transport mechanisms.

Sand Waves in Environmental Flows: Insights gained by LES

Science.gov (United States)

Sotiropoulos, Fotis

2014-11-01

In fluvial and coastal environments, sediment transport processes induced by near-bed coherent structures in the turbulent boundary layer developing over a mobile sediment bed result in the formation of dynamically rich sand waves, or bed forms, which grow and migrate continuously. Bed form migration alters streambed roughness and provides the primary mechanism for transporting large amounts of sediment through riverine systems impacting the morphology, streambank stability, and ecology of waterways. I will present recent computational advances, which have enabled coupled, hydro-morphodynamic large-eddy simulation (LES) of turbulent flow in mobile-bed open channels. Numerical simulations: 1) elucidate the role of near-bed sweeps in the turbulent boundary layer as the mechanism for initiating the instability of the initially flat sand bed; 2) show how near-bed processes give rise to aperiodic eruptions of suspended sediment at the free surface; and 3) clarify the mechanism via which sand waves migrate. Furthermore, in agreement with recent experimental observations, the computed spectra of the resolved velocity fluctuations above the bed exhibit a distinct spectral gap whose width increases with distance from the bed. The spectral gap delineates the spectrum of turbulence from that of slowly evolving coherent structures associated with sand wave migration. The talk will also present computational results demonstrating the feasibility of carrying out coupled, hydro-morphodynamic LES of large dunes migrating in meandering streams and rivers with embedded hydraulic structures and discuss future challenges and opportunities. This work was supported by NSF Grants EAR-0120914 and EAR-0738726, and National Cooperative Highway Research Program Grant NCHRP-HR 24-33.

The influence of groundwater depth on coastal dune development at sand flats close to inlets

Science.gov (United States)

Silva, Filipe Galiforni; Wijnberg, Kathelijne M.; de Groot, Alma V.; Hulscher, Suzanne J. M. H.

2018-05-01

A cellular automata model is used to analyze the effects of groundwater levels and sediment supply on aeolian dune development occurring on sand flats close to inlets. The model considers, in a schematized and probabilistic way, aeolian transport processes, groundwater influence, vegetation development, and combined effects of waves and tides that can both erode and accrete the sand flat. Next to three idealized cases, a sand flat adjoining the barrier island of Texel, the Netherlands, was chosen as a case study. Elevation data from 18 annual LIDAR surveys was used to characterize sand flat and dune development. Additionally, a field survey was carried out to map the spatial variation in capillary fringe depth across the sand flat. Results show that for high groundwater situations, sediment supply became limited inducing formation of Coppice-like dunes, even though aeolian losses were regularly replenished by marine import during sand flat flooding. Long dune rows developed for high sediment supply scenarios which occurred for deep groundwater levels. Furthermore, a threshold depth appears to exist at which the groundwater level starts to affect dune development on the inlet sand flat. The threshold can vary spatially depending on external conditions such as topography. On sand flats close to inlets, groundwater is capable of introducing spatial variability in dune growth, which is consistent with dune development patterns found on the Texel sand flat.

The timing of sediment transport down Monterey Submarine Canyon, offshore California

Science.gov (United States)

Stevens, Thomas; Paull, Charles K.; Ussler, William III; McGann, Mary; Buylaert, Jan-Pieter; Lundsten, Eve M.

2013-01-01

While submarine canyons are the major conduits through which sediments are transported from the continents out into the deep sea, the time it takes for sediment to pass down through a submarine canyon system is poorly constrained. Here we report on the first study to couple optically stimulated luminescence (OSL) ages of quartz sand deposits and accelerator mass spectrometry 14C ages measured on benthic foraminifera to examine the timing of sediment transport through the axial channel of Monterey Submarine Canyon and Fan, offshore California. The OSL ages date the timing of sediment entry into the canyon head while the 14C ages of benthic foraminifera record the deposition of hemipelagic sediments that bound the sand horizons. We use both single-grain and small (∼2 mm area) single-aliquot regeneration approaches on vibracore samples from fining-upward sequences at various water depths to demonstrate relatively rapid, decadal-scale sand transport to at least 1.1 km depth and more variable decadal- to millennial-scale transport to a least 3.5 km depth on the fan. Significant differences between the time sand was last exposed at the canyon head (OSL age) and the timing of deposition of the sand (from 14C ages of benthic foraminifera in bracketing hemipelagic sediments) are interpreted as indicating that the sand does not pass through the entire canyon instantly in large individual events, but rather moves multiple times before emerging onto the fan. The increased spread in single-grain OSL dates with water depth provides evidence of mixing and temporary storage of sediment as it moves through the canyon system. The ages also indicate that the frequency of sediment transport events decreases with distance down the canyon channel system. The amalgamated sands near the canyon head yield OSL ages that are consistent with a sub-decadal recurrence frequency while the fining-upward sand sequences on the fan indicate that the channel is still experiencing events with a 150�

Using high-resolution suspended-sediment measurements to infer changes in the topographic distribution and grain size of bed sediment in the Colorado River downstream from Glen Canyon Dam

Science.gov (United States)

Topping, D. J.; Rubin, D. M.; Melis, T. S.; Wright, S. A.

2004-12-01

Eddy sandbars and other sandy deposits in and along the Colorado River in Grand Canyon National Park (GCNP) were an integral part of the pre-dam riverscape, and are still important for habitat, protection of archeological sites, and recreation. Recent work has shown that eddy bars are dynamic landforms and represent the bulk of the ecosystem's sand reserves. These deposits began eroding following the 1963 closure of Glen Canyon Dam that reduced the supply of sand at the upstream boundary of GCNP by about 94% and are still eroding today. Sand transport in the post-dam river is limited by episodic resupply from tributaries, and is equally regulated by the discharge of water and short-term changes in the grain size of sand available for transport (Rubin and Topping, WRR, 2001). During tributary floods, sand on the bed of the Colorado River fines; this causes the suspended sand to fine and the suspended-sand concentration to increase even when the discharge of water remains constant. Subsequently, the bed is winnowed of finer sand, the suspended sand coarsens, and the suspended-sand concentration decreases independently of discharge. This prohibits the computation of sand-transport rates in the Colorado River using stable relations between water discharge and sand transport (i.e., sediment rating curves) and requires a more continuous method for measuring sand transport. To monitor suspended sediment at higher (i.e., 15-minute) resolutions, we began testing a laser-acoustic system at four locations along the Colorado River in Grand Canyon in August 2002. Because they are much easier to acquire, the high-resolution suspended-sediment datasets collected using the laser-acoustic systems greatly outnumber (by >5 orders of magnitude) direct grain-size measurements of the upstream bed sediment. Furthermore, suspension processes effectively provide an average "sample" of the bed sediment on the perimeter of the upstream channel and the underwater portions of the banks and

Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand-Gravel Riverbeds

Science.gov (United States)

Buscombe, D.; Grams, P. E.; Kaplinski, M. A.

2017-10-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

Compositional signatures in acoustic backscatter over vegetated and unvegetated mixed sand-gravel riverbeds

Science.gov (United States)

Buscombe, Daniel; Grams, Paul E.; Kaplinski, Matt A.

2017-01-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

Observations on sediment sources in the Lower Athabasca River basin: implications of natural hydrocarbons inputs from oil sands deposits

International Nuclear Information System (INIS)

Conly, F.M.

1999-01-01

Government, industry and public concern exists over the environmental consequences of the development of the oil sand deposits in the McMurray Formation in the lower Athabasca River basin, Alberta. The impact of this development is unclear and is undergoing investigation. Investigations to date have focussed on the nature of the effluent produced by the extraction industry and its effect on biotic systems, and on the spatial distribution of hydrocarbon contaminants associated with deposited fluvial sediments. Natural hydrocarbon outcrops may be responsible for observed biomarker responses in areas not exposed to industrial effluent. Given this source of hydrocarbons and doubt concerning its environmental impact, it is difficult to ascertain the impact of oil extraction activities within a fluvial system. A study was conducted to determine the nature and extent of natural hydrocarbon releases within the context of the sediment regime of the lower Athabasca River basin. A description is included of observations from the field and a context is set up for assessing sediment-bound hydrocarbon contaminants in the lower Athabasca River basin. Abstract only included

Image analysis to measure sorting and stratification applied to sand-gravel experiments

OpenAIRE

Orrú, C.

2016-01-01

The main objective of this project is to develop new measuring techniques for providing detailed data on sediment sorting suitable for sand-gravel laboratory experiments. Such data will be of aid in obtaining new insights on sorting mechanisms and improving prediction capabilities of morphodynamic models. Two measuring techniques have been developed. The first technique is aimed at measuring the size stratification of a sand-gravel deposit through combining image analysis and a sediment remov...

Natural Radioactivity Levels in Environmental Samples in North Western Desert of Egypt

International Nuclear Information System (INIS)

El-Daly, A.; Hussein, A.S.

2009-01-01

Soil and sediment samples were collected from North western desert of Egypt. Gamma spectroscopy was used to determine the concentration of naturally occurring radionuclides 238 U, 232 Th and 40 K. The hazard index due to these radionuclides has been calculated. The measurement results obtained from this study indicate that the region has background radioactivity levels within natural limits

Radiological responses of different types of Egyptian Mediterranean coastal sediments

Energy Technology Data Exchange (ETDEWEB)

El-Gamal, A., E-mail: ayman_elgamal@yahoo.co [Department of Oceanography, Coastal Research Institute, National Water Research Center, 15 Elpharaana St., Elshallalat, Postal code 21514, Alexandria (Egypt); Rashad, M. [Land and Water Technologies Department, Arid Land Cultivation and Development Research Institute, Mubarak City for Scientific Research, Burg El-Arab, Alexandria (Egypt); Ghatass, Z. [Department of Environmental Studies, Institute of Graduate Studies and Research, Alexandria University, Alexandria (Egypt)

2010-08-15

The aim of this study was to identify gamma self-absorption correction factors for different types of Egyptian Mediterranean coastal sediments. Self-absorption corrections based on direct transmission through different thicknesses of the most dominant sediment species have been tested against point sources with gamma-ray energies of {sup 241}Am, {sup 137}Cs and {sup 60}Co with 2% uncertainties. Black sand samples from the Rashid branch of the Nile River quantitatively absorbed the low energy of {sup 241}Am through a thickness of 5 cm. In decreasing order of gamma energy self-absorption of {sup 241}Am, the samples under investigation ranked black sand, Matrouh sand, Sidi Gaber sand, shells, Salloum sand, and clay. Empirical self-absorption correction formulas were also deduced. Chemical analyses such as pH, CaCO{sub 3}, total dissolved solids, Ca{sup 2+}, Mg{sup 2+}, CO{sub 3}{sup 2-}, HCO{sub 3}{sup -} and total Fe{sup 2+} have been carried out for the sediments. The relationships between self absorption corrections and the other chemical parameters of the sediments were also examined.

Mercury Removal from Natural Gas in Egypt

International Nuclear Information System (INIS)

Korkor, H.; AI-Alf, A.; EI-Behairy, S.

2004-01-01

Worldwide natural gas is forecasted to be the fastest growing primary energy source. In Egypt, natural gas is recently playing a key role as one of the major energy sources. This is supported by adequate gas reserves, booming gas industry, and unique geographical location. Egypt's current proven gas reserves accounted for about 62 TCF, in addition to about 100 TCF as probable gas reserves. As a result, it was decided to enter the gas exporting market, where gas is transported through pipelines as in the Arab Gas pipelines project and as a liquid through the liquefied natural gas (LNG) projects in Damietta, and ld ku. With the start up of these currently implemented LNG projects that are dealing with the very low temperatures (down to -162 degree c), the gas has to be subjected to a regular analysis in order to check the compliance with the required specifications. Mercury is a trace component of all fossil fuels including natural gas, condensates, crude oil, coal, tar sands, and other bitumens. The use of fossil hydrocarbons as fuels provides the main opportunity for emissions of mercury they contain to the atmospheric environment: while other traces exist in production, transportation and processing systems

Mercury Removal from Natural Gas in Egypt

Energy Technology Data Exchange (ETDEWEB)

Korkor, H; AI-Alf, A; EI-Behairy, S [EGAS, Cairo (Egypt)

2004-07-01

Worldwide natural gas is forecasted to be the fastest growing primary energy source. In Egypt, natural gas is recently playing a key role as one of the major energy sources. This is supported by adequate gas reserves, booming gas industry, and unique geographical location. Egypt's current proven gas reserves accounted for about 62 TCF, in addition to about 100 TCF as probable gas reserves. As a result, it was decided to enter the gas exporting market, where gas is transported through pipelines as in the Arab Gas pipelines project and as a liquid through the liquefied natural gas (LNG) projects in Damietta, and ld ku. With the start up of these currently implemented LNG projects that are dealing with the very low temperatures (down to -162 degree c), the gas has to be subjected to a regular analysis in order to check the compliance with the required specifications. Mercury is a trace component of all fossil fuels including natural gas, condensates, crude oil, coal, tar sands, and other bitumens. The use of fossil hydrocarbons as fuels provides the main opportunity for emissions of mercury they contain to the atmospheric environment: while other traces exist in production, transportation and processing systems.

Biodegradation of crude oil in different types of marine sediment

International Nuclear Information System (INIS)

Hii, Y.S.; Law, A.T.

1999-01-01

An active oil-oxidizing bacterium, named Nap C was isolated from the sediment sample of Port Dickson coastal area for this study. Nap C is a gram negative, rod shape marine bacterium. It forms spore when the condition is not favorable. Three different types of treated marine sediment; sand, silt and clay were used in this study. The degradation of Malaysian Tapis A crude oil in the different types of marine sediment were assessed. Silt type of marine sediment was found to sustain highest biodegradation compared to clay type and sand type. 8.6.67% of the Malaysian Tapis A crude oil was degraded in silt type of marine sediment within 10 days of incubation. Where as there were only 60% and 73% of the Malaysian Tapis A crude oil was degraded in sand and clay type of marine sediment respectively. Microbial biomass estimation in the sediment was estimated by indirect phospholipid enumeration technique. (author)

Psammomys obesus Cretzschmar, 1828 and zoonotic cutaneous leishmaniasis in Sinai Peninsula, Egypt.

Science.gov (United States)

Morsy, T A; Sabry, A H; Rifaat, M M; Wahba, M M

1996-08-01

In the Middle East, the fat sand rat Psammomys obesus is the most important reservoir host of zoonotic cutaneous leishmamiasis (ZCL). It is the most incriminated host in outbreaks. Two P. obesus caught in Wadi El Gedeiret (Al Arish, North Sinai) were found naturally infected with Leishmania major as indicated by enzyme electrophoresis. In Egypt, the already known reservoir hosts are Gerbillus pyramidum I. Geoffroy St. Hilaire, 1825; Meriones crassus Sundevall, 1984 and Meriones sacramenti Thomas, 1922. The hostal role of P. obesus was discussed.

Can we predict the response of large sand bed rivers to changes in flow and sediment supply? The case of the Missouri River.

Science.gov (United States)

Viparelli, E.; Blum, M. D.

2015-12-01

In the past century engineering projects and changes in land use significantly modified the hydrology and the sediment supply of large sand bed rivers all over the world. Field studies documented the river responses to the imposed changes, which can be summarized as adjustments in channel geometry, slope, and/or characteristics of the bed material. Further, one-, two- and three-dimensional river morphodynamic models were used to predict the fluvial system response to the imposed changes at time scales ranging from few months up to several decades. Notwithstading this previous research effort, the spatial and temporal scales of river adjustment, as well as quantitative predictions of the river responses, are still a matter of debate due to the difficulties associated with the interpretation of limited field datasets and with the large scale sediment transport modeling. Here we present the preliminary results of a study of the Missouri River response to the construction of dams, i.e. reduction in flood flow and sediment supply. In particular, we first compare the numerical results of a one-dimensional model of river morphodynamics for large, low slope sand bed rivers with field data to validate the model. The validated model is then used to constrain the spatial and temporal scales of the river adjustment, i.e. bed degradation in the Missouri River case. In other words, our numerical work focuses on how the magnitude and speed of the wave of channel bed degradation changes in time and space for the Missouri River case and how these scales change for different values of the ratio between pre- and pos-dam flow rates, and pre- and post-dam sediment loads.

Scaling of Sediment Dynamics in a Reach-Scale Laboratory Model of a Sand-Bed Stream with Riparian Vegetation

Science.gov (United States)

Gorrick, S.; Rodriguez, J. F.

2011-12-01

A movable bed physical model was designed in a laboratory flume to simulate both bed and suspended load transport in a mildly sinuous sand-bed stream. Model simulations investigated the impact of different vegetation arrangements along the outer bank to evaluate rehabilitation options. Preserving similitude in the 1:16 laboratory model was very important. In this presentation the scaling approach, as well as the successes and challenges of the strategy are outlined. Firstly a near-bankfull flow event was chosen for laboratory simulation. In nature, bankfull events at the field site deposit new in-channel features but cause only small amounts of bank erosion. Thus the fixed banks in the model were not a drastic simplification. Next, and as in other studies, the flow velocity and turbulence measurements were collected in separate fixed bed experiments. The scaling of flow in these experiments was simply maintained by matching the Froude number and roughness levels. The subsequent movable bed experiments were then conducted under similar hydrodynamic conditions. In nature, the sand-bed stream is fairly typical; in high flows most sediment transport occurs in suspension and migrating dunes cover the bed. To achieve similar dynamics in the model equivalent values of the dimensionless bed shear stress and the particle Reynolds number were important. Close values of the two dimensionless numbers were achieved with lightweight sediments (R=0.3) including coal and apricot pips with a particle size distribution similar to that of the field site. Overall the moveable bed experiments were able to replicate the dominant sediment dynamics present in the stream during a bankfull flow and yielded relevant information for the analysis of the effects of riparian vegetation. There was a potential conflict in the strategy, in that grain roughness was exaggerated with respect to nature. The advantage of this strategy is that although grain roughness is exaggerated, the similarity of

Wind Atlas for Egypt

DEFF Research Database (Denmark)

The results of a comprehensive, 8-year wind resource assessment programme in Egypt are presented. The objective has been to provide reliable and accurate wind atlas data sets for evaluating the potential wind power output from large electricityproducing wind turbine installations. The regional wind...... climates of Egypt have been determined by two independent methods: a traditional wind atlas based on observations from more than 30 stations all over Egypt, and a numerical wind atlas based on long-term reanalysis data and a mesoscale model (KAMM). The mean absolute error comparing the two methods is about...... 10% for two large-scale KAMM domains covering all of Egypt, and typically about 5% for several smaller-scale regional domains. The numerical wind atlas covers all of Egypt, whereas the meteorological stations are concentrated in six regions. The Wind Atlas for Egypt represents a significant step...

Wind Atlas for Egypt

DEFF Research Database (Denmark)

Mortensen, Niels Gylling; Said Said, Usama; Badger, Jake

2006-01-01

The results of a comprehensive, 8-year wind resource assessment programme in Egypt are presented. The objective has been to provide reliable and accurate wind atlas data sets for evaluating the potential wind power output from large electricityproducing wind turbine installations. The regional wind...... climates of Egypt have been determined by two independent methods: a traditional wind atlas based on observations from more than 30 stations all over Egypt, and a numerical wind atlas based on long-term reanalysis data and a mesoscale model (KAMM). The mean absolute error comparing the two methods is about...... 10% for two large-scale KAMM domains covering all of Egypt, and typically about 5% for several smaller-scale regional domains. The numerical wind atlas covers all of Egypt, whereas the meteorological stations are concentrated in six regions. The Wind Atlas for Egypt represents a significant step...

Modelling offshore sand wave evolution

NARCIS (Netherlands)

Nemeth, Attila; Hulscher, Suzanne J.M.H.; van Damme, Rudolf M.J.

2007-01-01

We present a two-dimensional vertical (2DV) flow and morphological numerical model describing the behaviour of offshore sand waves. The model contains the 2DV shallow water equations, with a free water surface and a general bed load formula. The water movement is coupled to the sediment transport

Magnetic Characterization of Sand and Boulder Samples from Citarum River and Their Origin

Directory of Open Access Journals (Sweden)

Sudarningsih

2017-09-01

Full Text Available The Citarum River is a nationally strategic river located near Bandung, the capital city of West Java Province. The feasibility of using magnetic methods for monitoring pollution level is currently being tested in the river. Due to its location in a volcanic area, the sediments from the river are expected to be highly magnetic. In this study, sand and boulder samples from Balekambang, a relatively pristine upstream area of the river, were subjected to magnetic and geochemical characterizations to establish the baseline for unpolluted sediments. Such baseline is important for future magnetic monitoring of sediments in the river. The mass-specific magnetic susceptibility of boulder samples was found to be varied from 819.2 to 2340.5 × 10-8m3 kg-1 while that of sand samples varied from 2293.9 to 3845.3 × 10-8m3 kg-1. These high magnetic susceptibility values infer that river sediments are highly magnetic even before being contaminated by industrial and household wastes. The predominant magnetic mineral in sand samples was multi-domain magnetite while that in boulder samples was single to pseudo-single domain magnetite. These differences were supported by the results from petrographic and XRF analyses, implying that the sand and boulder samples originated from different geological formations.

Sand ramps as palaeoenvironmental archives: Integrating general principles and regional contexts through reanalysis of the Klipkraal Sands, South Africa

Science.gov (United States)

Rowell, Alexandra L. K.; Thomas, David S. G.; Bailey, Richard M.; Holmes, Peter J.

2018-06-01

Sand ramps occur on a continuum of topographically-controlled landforms, ranging from purely aeolian features (climbing/falling dunes) to talus cones and alluvial fans. Sand ramps have been identified as potentially important palaeoenvironmental archives in dryland regions that possess relatively few Quaternary proxy records. Their utility however requires not only good age control of depositional phases but clear identification of process regimes, determined through morphological and sedimentological analyses, with several recent studies indicating the complexities of palaeoenvironmental interpretations and the controls of ramp development (Bateman et al., 2012; Rowell et al., 2018). Klipkraal Sands is a sand ramp on the north-eastern margin of the semi-arid Karoo that has been important for inferences of the extent of southern African Late Quaternary aeolian activity (Thomas et al., 2002). We reanalyse this feature, in the light of both its significance and other recent studies that have inferred extensive southern African LGM aeolian activity (Telfer et al., 2012, 2014). New sedimentological data and twelve OSL dates indicate the Klipkraal Sands formed episodically between 100-0.14 ka, rather than accumulating rapidly, while sedimentological data question the aeolian affinities of the bulk of the feature. Therefore, Klipkraal is reinterpreted as showing no particular affinity to the LGM, with sediments locally sourced with a significant colluvial component. Only the upper historical sediments can be clearly interpreted as aeolian deposits. A complex interplay of processes is suggested, for which a meaningful palaeoenvironmental interpretation cannot be easily defined. This implies that the local geomorphic processes and controls operating on sand ramps need to be established before they can be fully utilised as palaeoenvironmental archives, with implications for their interpretation worldwide.

U.S. Geological Survey ArcMap Sediment Classification tool

Science.gov (United States)

O'Malley, John

2007-01-01

The U.S. Geological Survey (USGS) ArcMap Sediment Classification tool is a custom toolbar that extends the Environmental Systems Research Institute, Inc. (ESRI) ArcGIS 9.2 Desktop application to aid in the analysis of seabed sediment classification. The tool uses as input either a point data layer with field attributes containing percentage of gravel, sand, silt, and clay or four raster data layers representing a percentage of sediment (0-100%) for the various sediment grain size analysis: sand, gravel, silt and clay. This tool is designed to analyze the percent of sediment at a given location and classify the sediments according to either the Folk (1954, 1974) or Shepard (1954) as modified by Schlee(1973) classification schemes. The sediment analysis tool is based upon the USGS SEDCLASS program (Poppe, et al. 2004).

Fusion of arkosic sand by intrusive andesite

Science.gov (United States)

Bailey, Roy A.

1954-01-01

An andesite dike in the Valles Mountains of northern New Mexico has intruded and partly fused arkosic sediments for a distance of 50 feet from its contacts. The dike is semi-circular in form, has a maximum width of about 100 feet, and is about 500 feet long. Small associated arcuate dikes are arranged in spiral fashion around the main dike, suggesting that they were intruded along shear fractures similar to those described by Burbank (1941). The fused rocks surrounding the andesite dike are of three general types: 1) partly fused arkosic sand, 2) fused clay, and 3) hybrid rocks. The fused arkosic sand consists of relict detrital grains of quartz, orthoclose, and plagioclase, imbedded in colorless glass containing microlites of tridymite, cordierite, and magnetite. The relict quartz grains are corroded and embayed by glass; the orthoclase is sanidinized and partly fused; and the plagioclase is inverted to the high temperature form and is partly fused. The fused clay, which was originally a mixture of montmorillonite and hydromica, consists primarily of cordierite but also contains needle-like crystals of sillimanite (?) or mullite (?). The hybrid rocks originated in part by intermixing of fused arkosic sediments and andesitic liquid and in part by diffusion of mafic constituents through the fused sediments. They are rich in cordierite and magnetite and also contain hypersthene, augite, and plagioclase. The composition of pigeonite in the andesite indicates that the temperature of the andesite at the time of intrusion probably did not exceed 1200?C. Samples of arkosic sand were fused in the presence of water in a Morey bomb at 1050?C. Stability relations of certain minerals in the fused sand suggest that fusion may have taken place at a lower temperature, however, and the fluxing action of volatiles from the andesite are thought to have made this possible.

Synthesis of Goethite-Coated Sand and Analysis of its Interactions with Uranium

International Nuclear Information System (INIS)

Vijay A. Loganathan; Sushil R. Kanel; Mark O. Barnett; T. Prabhakar Clement

2007-01-01

Iron(III) oxide coating on soils/sediments is reported to be the most important factor for controlling the sorption of radioactive metals in groundwater systems. Various forms of Fe(III) oxides occur in nature; they exist in both crystalline and amorphous forms. Our review indicated that goethite (α-FeOOH) is one of the most common iron oxides present in subsurface sediments. Therefore, it is important to understand the reactive chemistry of U(VI) with goethite-coated sand (GCS). Our overall objective is to develop scalable reaction models to predict uranium fate and transport in subsurface environment. In this paper, we focus on U(VI) interactions with well-characterized, synthetic goethite-coated sand. The objectives of the present work are to: (1) To identify a standard protocol to synthesize pure goethite-coated sand; (2) To characterize the goethite-coated sand synthesized using various methods; (3) To analyze the interaction of U(VI) with the goethite-coated sand; and (4) To predict the adsorption characteristics using surface complexation models

Identification of discontinuous sand pulses on the bed of the Colorado River in Grand Canyon

Science.gov (United States)

Mueller, E. R.; Grams, P. E.; Buscombe, D.; Topping, D. J.

2017-12-01

Decades of research on alluvial sandbars and sand transport on the Colorado River in Grand Canyon has contributed to in-depth understanding of the sand budget and lead to management actions designed to rebuild eroded sandbars. However, some basic, but difficult to address, questions about the processes and rates of sand movement through the system still limit our ability to predict geomorphic responses. The coarse fraction of the bed is heterogeneous and varies among boulders, cobble, gravel, and bedrock. Sand covers these substrates in patches of variable size and thickness, fills interstices to varying degrees, and forms mixed sand/coarse bed configurations such as linear stripes. Understanding the locations of sand accumulation, the quantities of sand contained in those locations, and the processes by which sand is exchanged among depositional locations is needed to predict the morphological response of sandbars to management actions, such as the controlled flood releases, and to predict whether sandbars are likely to increase or decrease in size over long (i.e. decadal) time periods. Here, we present evidence for the downstream translation of the sand component of tributary sediment inputs as discontinuous sand pulses. The silt and clay (mud) fraction of sediment introduced episodically by seasonal floods from tributary streams is transported entirely in suspension and moves through the 400 km series of canyons in a few days. The sand fraction of this sediment, which is transported on the bed and in suspension, moves downstream in sand pulses that we estimate range in length from a few km to tens of km. Owing to the complex geomorphic organization, the sand pulses are not detectable as coherent bed features; each individual sand pulse is comprised of many isolated storage locations, separated by rapids and riffles where sand cover is sparse. The presence of the sand pulses is inferred by the existence of alternating segments of sand accumulation and depletion

Improvement of Low-Grade Silica Sand Deposits in Um Bogma Area-West Central Sinai, Egypt

International Nuclear Information System (INIS)

Abdel-Rahman, I.F.; El Shennawy, A.A.

2012-01-01

There are several silica sand deposits in Sinai, but they require upgrading to provide a raw materials acceptable for the glass manufacture. This study records beneficiation of low-grade silica sand deposits near Um Bogma at west central Sinai. The improvement techniques of ore dressing involving wet sieving, attrition scrubbing, decantation, gravimetric and magnetic separations have been applied depending on the physical properties of the constituents.

A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change

Science.gov (United States)

Grams, Paul E.

2013-01-01

Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input into the Colorado River is crucial to protecting endangered native fish, animals, and plants and cultural and recreational resources along the river in Glen Canyon National Recreation Area and Grand Canyon National Park.

Deep River Velocity and Sediment Profiles and the Suspended Sand Load,

Science.gov (United States)

1963-02-01

5.03 x IO~~ ATCHAFALAVA RIVER WIDTH : 1587 FT D 5, : 6.75 w 0 ~ FT SIMM ESPORT u : 6.66 FPS WATER TEMP. : 70 F d : 46.3 FT FINE SAND PORTION OP BED...1.34 * 10 3FT SIMM ESPORT ~ : 5.85 FPS WATCR TEMP. :69 ’F d : 47.7 FT FiNE SAND PORTION OP BED MATERIAL : 39.$ ~~ FIG. 16...DEC. 14,196 1 Q : 218,000 CF’S S : 336 *io ’~ ATCHAFALAVA RIVERWIDTH ?~ FPS WATER TEMP : løOx I0~~ FT SIMM ESPORT d : 4 1 .7 FT FINE SAND PORTION OF B

Investigating Deep-Marine Sediment Waves in the Northern Gulf of Mexico Using 3D Seismic Data

Science.gov (United States)

Wang, Z.; Gani, M. R.

2016-12-01

Deep-water depositional elements have been studied for decades using outcrop, flume tank, sidescan sonar, and seismic data. Even though they have been well recognized by researchers, the improvements in the quality of 3D seismic data with increasingly larger dimension allow detailed analysis of deep-water depositional elements with new insights. This study focuses on the deep-marine sediment waves in the northern Gulf of Mexico. By interpreting a 3D seismic dataset covering 635 km2 at Mississippi Canyon and Viosca Knoll areas, large sediment waves, generated by sediment gravity flows, were mapped and analyzed with various seismic attributes. A succession of sediment waves, approximately 100 m in thickness, is observed on the marine slope that tapers out at the toe of the slope. The individual sediment wave exhibits up to 500 m in wavelength and up to 20 m in height. The wave crests oriented northeast-southwest are broadly aligned parallel to the regional slope-strike, indicating their sediment gravity flow origin. The crestlines are straight or slightly sinuous, with sinuosity increasing downslope. Their anti-dune patterns likely imply the presence of supercritical flows. The sediment waves have a retrogradational stacking pattern. Seismic amplitude maps of each sediment wave revealed that after depositing the majority of sheet-like sands on the upper slope, sediment gravity flows started to form large sediment waves on the lower slope. The steep and narrow upcurrent flanks of the sediment waves always display higher amplitudes than the gentle and wide downcurrent flanks, indicating that the sands were likely preferentially trapped along the upcurrent flanks, whereas the muds spread along the downcurrent flanks. The formation of sediment waves likely requires a moderate sand-mud ratio, as suggested by these observations: (1) absence of sediment waves on the upper slope where the sands were mainly deposited as unconfined sheets with a high sand-mud ratio; (2

Provenance and recycling of Arabian desert sand

Science.gov (United States)

Garzanti, Eduardo; Vermeesch, Pieter; Andò, Sergio; Vezzoli, Giovanni; Valagussa, Manuel; Allen, Kate; Kadi, Khalid A.; Al-Juboury, Ali I. A.

2013-05-01

This study seeks to determine the ultimate origin of aeolian sand in Arabian deserts by high-resolution petrographic and heavy-mineral techniques combined with zircon U-Pb geochronology. Point-counting is used here as the sole method by which unbiased volume percentages of heavy minerals can be obtained. A comprehensive analysis of river and wadi sands from the Red Sea to the Bitlis-Zagros orogen allowed us to characterize all potential sediment sources, and thus to quantitatively constrain provenance of Arabian dune fields. Two main types of aeolian sand can be distinguished. Quartzose sands with very poor heavy-mineral suites including zircon occupy most of the region comprising the Great Nafud and Rub' al-Khali Sand Seas, and are largely recycled from thick Lower Palaeozoic quartzarenites with very minor first-cycle contributions from Precambrian basement, Mesozoic carbonate rocks, or Neogene basalts. Instead, carbonaticlastic sands with richer lithic and heavy-mineral populations characterize coastal dunes bordering the Arabian Gulf from the Jafurah Sand Sea of Saudi Arabia to the United Arab Emirates. The similarity with detritus carried by the axial Tigris-Euphrates system and by transverse rivers draining carbonate rocks of the Zagros indicates that Arabian coastal dunes largely consist of far-travelled sand, deposited on the exposed floor of the Gulf during Pleistocene lowstands and blown inland by dominant Shamal northerly winds. A dataset of detrital zircon U-Pb ages measured on twelve dune samples and two Lower Palaeozoic sandstones yielded fourteen identical age spectra. The age distributions all show a major Neoproterozoic peak corresponding to the Pan-African magmatic and tectonic events by which the Arabian Shield was assembled, with minor late Palaeoproterozoic and Neoarchean peaks. A similar U-Pb signature characterizes also Jafurah dune sands, suggesting that zircons are dominantly derived from interior Arabia, possibly deflated from the Wadi al

Marine pollution: Let us not forget beach sand

OpenAIRE

Galgani, Francois; Ellerbrake, Katrin; Fries, Elke; Goreux, Chantal

2011-01-01

Background: Assessing the chemical or bacterial contamination in marine waters and sediments is a very common approach to evaluate marine pollution and associated risks. However, toxicity and organic pollution of beach sands have not yet been considered, except in adjacent waters. In the present study, the toxicity and the chemical contamination of natural beach sands collected 20 m from the shoreline at two sites located on the Mediterranean Sea (Marseille and La Marana, Corsica) were studie...

Uptake study of some radionuclides by Suez Canal bottom sediment

International Nuclear Information System (INIS)

El-Shinawy, R.M.K.; Abdel Fattah, A.T.; Essa, M.W.A.

1986-01-01

Chemical and physical analyses of Suez Canal bottom sediment at its south entrance (Port Taweffek) were carried out. The sediment was separated into its particle size fractions (clay, silt and sand). The different sediment fractions can be arranged with respect to their sorption capacity as follows: clay, natural sediment, sit and sand. The increase of pH results in small increase in the uptake reaching in some cases a maximum value of pH 6 or 8. More significant increase of uptake is observed when the carrier concentration is increased from 10 -6 to 10 -2 M/L

A SEDIMENT TOXICITY METHOD USING LEMNA MINOR, DUCKWEED

Science.gov (United States)

We developed a Lemna minor sediment toxicity test method to assess sediment contaminants which may affect plants. This 96-hour test used 15 ml of sediment and 2 ml of overlying water which was renewed after 48 hours. Sand was used as the control sediment and also to dilute test ...

A semi-automated approach for mapping geomorphology of El Bardawil Lake, Northern Sinai, Egypt, using integrated remote sensing and GIS techniques

Directory of Open Access Journals (Sweden)

Nabil Sayed Embabi

2014-06-01

Full Text Available Among the other coastal lakes of the Mediterranean northern coast of Egypt, Bardawil Lake is a unique lagoon, as it is fed only by seawater. The lagoon is composed of two main basins, and several other internal small basins interconnected to one another. Although the general geomorphologic characteristics are treated in some regional studies, we used a semi-automated approach based on a wide variety of digital image processing for mapping the major geomorphological landforms of the lake on a medium scale of 1:250,000. The approach is based primarily on data fusion of Landsat ETM+ image, and validated by other ancillary spatial data (e.g. topographic maps, Google images and GPS in situ data. Interpretations of high resolution space images by Google Earth and the large-scale topographic maps (1:25,000, in specific, revealed new microforms and some detailed geomorphologic aspects with the aid of GPS measurements. Small sand barriers, submerged sand dunes, tidal channels, fans and flats, and micro-lagoons are the recurrent forms in the lake. The approach used in this study could be widely applied to study the low-lying coastal lands along the Nile Delta. However, it is concluded from geological data and geomorphologic aspects that Bardawil Lake is of a tectonic origin; it was much deeper than it is currently, and has been filled with sediments mostly since the Flandrian transgression (∼8–6 ka bp.

Estimation of suspended sediment concentration by acoustic ...

African Journals Online (AJOL)

concentration of sediments such as glass spheres or sand. However, the acoustic properties of natural sediments vary and depend on many parameters such as particle size, shape, mineralogy and distribution of those parameters in sample. Therefore, this study was conducted to determine the possibility of soil sediment ...

Time-independent compaction behavior of quartz sands

NARCIS (Netherlands)

Brzesowsky, R. H.; Spiers, C. J.|info:eu-repo/dai/nl/304829323; Peach, C. J.|info:eu-repo/dai/nl/082101906; Hangx, Suzanne|info:eu-repo/dai/nl/30483579X

Mechanisms such as grain rearrangement, coupled with elastic deformation and grain breakage, are believed to play an important role in the time-independent compaction of sands, controlling porosity and permeability reduction during burial of clastic sediments and during depletion of highly porous

IDRC in Egypt

International Development Research Centre (IDRC) Digital Library (Canada)

IDRC began to support research in. Egypt. Five years ... Cutting red tape for business. In Egypt ... 85% of jobs in the private sector, and. 40% of all ... sector to drive economic growth over the next ... and reducing poverty in the Middle East and.

Total and methyl mercury concentrations in sediment and water of a constructed wetland in the Athabasca Oil Sands Region.

Science.gov (United States)

Oswald, Claire J; Carey, Sean K

2016-06-01

In the Athabasca Oil Sands Region in northeastern Alberta, Canada, oil sands operators are testing the feasibility of peatland construction on the post-mining landscape. In 2009, Syncrude Canada Ltd. began construction of the 52 ha Sandhill Fen pilot watershed, including a 15 ha, hydrologically managed fen peatland built on sand-capped soft oil sands tailings. An integral component of fen reclamation is post-construction monitoring of water quality, including salinity, fluvial carbon, and priority pollutant elements. In this study, the effects of fen reclamation and elevated sulfate levels on mercury (Hg) fate and transport in the constructed system were assessed. Total mercury (THg) and methylmercury (MeHg) concentrations in the fen sediment were lower than in two nearby natural fens, which may be due to the higher mineral content of the Sandhill Fen peat mix and/or a loss of Hg through evasion during the peat harvesting, stockpiling and placement processes. Porewater MeHg concentrations in the Sandhill Fen typically did not exceed 1.0 ng L(-1). The low MeHg concentrations may be a result of elevated porewater sulfate concentrations (mean 346 mg L(-1)) and an increase in sulphide concentrations with depth in the peat, which are known to suppress MeHg production. Total Hg and MeHg concentrations increased during a controlled mid-summer flooding event where the water table rose above the ground surface in most of the fen. The Hg dynamics during this event showed that hydrologic fluctuations in this system exacerbate the release of THg and MeHg downstream. In addition, the elevated SO4(2-) concentrations in the peat porewaters may become a problem with respect to downstream MeHg production once the fen is hydrologically connected to a larger wetland network that is currently being constructed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Size distribution and carbonate content of the sediments of the western shelf of India

Digital Repository Service at National Institute of Oceanography (India)

Nair, R.R.; Pylee, A.

%). (2) The outer shelf (approximately 20 to 70 fms) is a zone of relict sediments, having relatively low rates of sedimentation and composed of fine to medium sands. Occasional patches of coarse iron stained sands and pebbles are also present...

Dendrogeomorphology - a new tool to study drift-sand dynamics Netherlands Journal of Geosciences

NARCIS (Netherlands)

Ouden, den J.; Sass-Klaassen, U.; Copini, P.

2007-01-01

dendrogeomorphological approach is presented, using wood characteristics of native oak (Quercus robur L.) to infer dynamics of aeolian sediment transport in drift-sand areas. Wood samples, taken from oaks in two drift-sand areas, were analysed to study changes in tree-ring pattern and wood anatomy

Sediment transport in an active erodible channel bend

Indian Academy of Sciences (India)

Local variation of sediment transport is primarily controlled by active bank erosion, land spur and sand bar formation. Vertical distribution of suspended sediment concentration follows a power function with normalized depth. Average bed-material concentration at the reach level is computed from observed sediment profiles, ...

Sedimentary controls on modern sand grain coat formation

Science.gov (United States)

Dowey, Patrick J.; Worden, Richard H.; Utley, James; Hodgson, David M.

2017-05-01

Coated sand grains can influence reservoir quality evolution during sandstone diagenesis. Porosity can be reduced and fluid flow restricted where grain coats encroach into pore space. Conversely pore-lining grain coats can restrict the growth of pore-filling quartz cement in deeply buried sandstones, and thus can result in unusually high porosity in deeply buried sandstones. Being able to predict the distribution of coated sand grains within petroleum reservoirs is thus important to help find good reservoir quality. Here we report a modern analogue study of 12 sediment cores from the Anllóns Estuary, Galicia, NW Spain, collected from a range of sub-environments, to help develop an understanding of the occurrence and distribution of coated grains. The cores were described for grain size, bioturbation and sedimentary structures, and then sub-sampled for electron and light microscopy, laser granulometry, and X-ray diffraction analysis. The Anllóns Estuary is sand-dominated with intertidal sand flats and saltmarsh environments at the margins; there is a shallowing/fining-upwards trend in the estuary-fill succession. Grain coats are present in nearly every sample analysed; they are between 1 μm and 100 μm thick and typically lack internal organisation. The extent of grain coat coverage can exceed 25% in some samples with coverage highest in the top 20 cm of cores. Samples from muddy intertidal flat and the muddy saltmarsh environments, close to the margins of the estuary, have the highest coat coverage (mean coat coverage of 20.2% and 21.3%, respectively). The lowest mean coat coverage occurs in the sandy saltmarsh (10.4%), beyond the upper tidal limit and sandy intertidal flat environments (8.4%), close to the main estuary channel. Mean coat coverage correlates with the concentration of clay fraction. The primary controls on the distribution of fine-grained sediment, and therefore grain coat distribution, are primary sediment transport and deposition processes that

The Middle Jurassic microflora from El Maghara N° 4 borehole, Northern Sinai, Egypt

Science.gov (United States)

Mohsen, Sayed Abdel

The coal bearing formation in El Maghara area, northern Sinai, yielded abundant, diverse and generally well preserved spores, pollen and marine microflora. The palynological analysis of the fine clastic sediments in this formation yielded (71) species related to (44) genera. Three different palynological assemblage zones can be distinguished. The sediments which contain lower and the upper assemblage zones bearing the coal seems, were deposited in non-marine (swamp) environment. In the middle assemblage zone few marine microflora can be identified, indicating a coastal near shore marine environment. Compared with other palynologic data obtained from Egypt and other countries, the three described assemblage zones belong to Middle Jurassic (Bathonian) age.

A multiscale approach to mapping seabed sediments.

Directory of Open Access Journals (Sweden)

Benjamin Misiuk

Full Text Available Benthic habitat maps, including maps of seabed sediments, have become critical spatial-decision support tools for marine ecological management and conservation. Despite the increasing recognition that environmental variables should be considered at multiple spatial scales, variables used in habitat mapping are often implemented at a single scale. The objective of this study was to evaluate the potential for using environmental variables at multiple scales for modelling and mapping seabed sediments. Sixteen environmental variables were derived from multibeam echosounder data collected near Qikiqtarjuaq, Nunavut, Canada at eight spatial scales ranging from 5 to 275 m, and were tested as predictor variables for modelling seabed sediment distributions. Using grain size data obtained from grab samples, we tested which scales of each predictor variable contributed most to sediment models. Results showed that the default scale was often not the best. Out of 129 potential scale-dependent variables, 11 were selected to model the additive log-ratio of mud and sand at five different scales, and 15 were selected to model the additive log-ratio of gravel and sand, also at five different scales. Boosted Regression Tree models that explained between 46.4 and 56.3% of statistical deviance produced multiscale predictions of mud, sand, and gravel that were correlated with cross-validated test data (Spearman's ρmud = 0.77, ρsand = 0.71, ρgravel = 0.58. Predictions of individual size fractions were classified to produce a map of seabed sediments that is useful for marine spatial planning. Based on the scale-dependence of variables in this study, we concluded that spatial scale consideration is at least as important as variable selection in seabed mapping.

PERENCANAAN SAND POCKET SEBAGAI BANGUNAN PENGENDALI ALIRAN SEDIMEN DI KALI OPAK YOGYAKARTA

Directory of Open Access Journals (Sweden)

Yeri Sutopo

2016-07-01

Full Text Available This research conducted in Opak River, in Yogyakarta. This river has broad (river flow area 27,04 km2, and 20,11 km in length. The research objective is to make a planning about effective rainfall in 50 years and found the Opak Sand Pocket design. This research used methods with direct-survey in location, and collected secondary data from related agencies. From the data, it was obtained the value of precipitation the design, discharge flood design, dimensions of building hydrolic design (Main Dam, Sub Dam, Apron, and analysis the effectiveness of sand pocket in reducing the sediment that has happened. Based on the results of the research, discharge maximum ( Q50 that occurs in the river of 202,77 m3/s. So it can be calculated that sand pocket designed will have wide of apron 54,04 m, with total high of Main Dam 6 m, total high of Sub Dam 6 m, length of apron 10 m, thick of apron 0,96 m. Based on the ability of sand pocket in reducing the rate of the sediment that is happened, the building has effectiveness until 90,20 % in reducing bed load based on the calculation. Therefore, it can be argued that the building has been effective to reduce the speed of sediment occurring in Opak River.

Characterization of sand lenses and their role for subsurface transport in low-permeability clay tills

DEFF Research Database (Denmark)

Kessler, Timo Christian; Klint, K. E.; Nilsson, B.

2011-01-01

Glacial sediments dominate large parts of the geological topology in Denmark. They predominantly consist of lowpermeability tills, but fractures and sand-lenses constitute zones of enhanced permeability facilitating preferential flow. This study focuses on characterization of sand deposits with r...... the sand lenses in hydro-geological models to successfully characterize subsurface flow and transport, e.g. for remediation activities....

Modern sedimentation processes in a wave-dominated coastal embayment: Espírito Santo Bay, southeast Brazil

Science.gov (United States)

Bastos, Alex Cardoso; Costa Moscon, Daphnne Moraes; Carmo, Dannilo; Neto, José Antonio Baptista; da Silva Quaresma, Valéria

2015-02-01

Sediment dynamics in wave-dominated coastal embayments are generally controlled by seasonal meteorological conditions, storms having a particularly strong influence. In the present study, such hydrodynamic processes and associated deposits have been investigated in a coastal embayment located along the southeast coast of Brazil, i.e. Espírito Santo Bay, in the winter (June/July) of 2008. The bay has undergone a series of human interventions that have altered the local hydrodynamic processes and, consequently, the sediment transport patterns. Facies distribution and sediment dynamics were examined by acoustic seabed mapping, sediment and core sampling, hydrodynamic measurements and sand transport modelling. The results show that sediment distribution can be described in terms of nearshore and offshore zones. The offshore bay sector is predominantly composed of "palimpsest" lithoclastic medium-coarse sands deposited in the course of the early Holocene transgression that peaked about 5,000 years ago. In the inner bay or nearshore zone (up to depths of 4-8 m), these older transgressive deposits are today overlain by a thin (up to 30-cm-thick) and partly patchy blanket of younger regressive fine sand/muddy fine sands. Both coarse- and fine-grained facies are being reworked during high-energy events (Hs>1.5 m) when fine sediment is resuspended, weak tide-induced drift currents causing the sand patches to be displaced. The coarser sediment, by contrast, is mobilized as bedload to produce wave ripples with spacings of up to 1.2 m. These processes lead to a sharp spatial delimitation between a fine sand/mud facies and a rippled coarse sand facies. The fine sand patches have a relief of about 20-30 cm and reveal a typical internal tempestite depositional sequence. Fair-weather wave-induced sediment transport (Hs<1 m), supported by weak tidal currents, seems to only affect the fine sediment facies. Sediment dynamics in Espírito Santo Bay is thus essentially controlled by

Napoleon in Egypt.

Science.gov (United States)

Fagan, Brian

1989-01-01

Recounts the 1798 Egyptian campaign of Napoleon Bonaparte, whose Scientific and Artistic Commission documented and described the glories of ancient Egypt. The expedition was a disaster by military standards, but the cultural legacies included the Rosetta Stone, and a chronicle entitled "Description de L'Egypte," which did much to…

Assessment of Suspended Sand Availability under Different Flow Conditions of the Lowermost Mississippi River at Tarbert Landing during 1973–2013

Directory of Open Access Journals (Sweden)

Sanjeev Joshi

2015-12-01

Full Text Available Rapid land loss in the Mississippi River Delta Plain has led to intensive efforts by state and federal agencies for finding solutions in coastal land restoration in the past decade. One of the proposed solutions includes diversion of the Mississippi River water into drowning wetland areas. Although a few recent studies have investigated flow-sediment relationships in the Lowermost Mississippi River (LmMR, defined as the 500 km reach from the Old River Control Structure to the river’s Gulf outlet, it is unclear how individual sediment fractions behave under varying flow conditions of the river. The information can be especially pertinent because the quantity of coarse sands plays a critical role for the Mississippi-Atchafalaya River deltaic development. In this study, we utilized long-term (1973–2013 records on discharge and sediments at Tarbert Landing of the LmMR to assess sand behavior and availability under different river flow regimes, and extreme sand transport events and their recurrence. We found an average annual sand load (SL of 27.2 megatonnes (MT during 1973 and 2013, varying largely from 3.37 to 52.30 MT. For the entire 41-year study period, a total of approximately 1115 MT sand were discharged at Tarbert Landing, half of which occurred during the peak 20% flow events. A combination of intermediate, high and peak flow stages (i.e., river discharge was ≥18,000 cubic meter per second produced about 71% of the total annual SL within approximately 120 days of a year. Based on the long-term sediment assessment, we predict that the LmMR has a high likelihood to transport 4 to 446 thousand tonnes of sand every day over the next 40 years, during which annual sand loads could reach a maximum of 51.68 MT. Currently, no effective plan is in place to utilize this considerably high sand quantity and we suggest that river engineering and sediment management in the LmMR consider practices of hydrograph-based approach for maximally capturing

Using Nd-Sr isotopes and rare earth elements to study sediment provenance of the modern radial sand ridges in the southwestern Yellow Sea

International Nuclear Information System (INIS)

Rao, Wenbo; Mao, Changping; Wang, Yigang; Huang, Huiming; Ji, Junfeng

2017-01-01

The radial sand ridges (RSRs) in the southwestern Yellow Sea off the Jiangsu Coast, East China have been intensively studied at least since 1975. Despite decades of studies, the provenance of the RSR sediments remains uncertain. In this study, the Nd-Sr isotopic and REE geochemical compositions of residual sediments (i.e., the acid-insoluble fractions) were investigated to determine the provenance of the RSR sediments. The Nd isotopic composition, PAAS-normalized REE patterns and characteristic parameters (e.g., Sm/Nd, (La/Sm)_N, (Gd/Yb)_N) were merely associated with source rocks but not with particle sorting while the Sr isotopic composition and REE contents of residual sediments were affected by particle sorting in addition to source rocks. The onshore RSR sediments originated mainly from mixing of the fine-grained sediments from various parts of the offshore RSR in terms of REE geochemical and isotopic analyses. Isotopic and REE geochemical comparison further reveals that the RSRs off the Jiangsu Coast were fed chiefly by the dispersal of surface sediments from the Yangtze River Mouth. Surface sediments from the Yangtze River Mouth were directly dispersed to the RSRs along the Jiangsu Coast and significantly affected the seaward part of the offshore RSR and the old Yellow River Delta area by a northward branch of the Changjiang Diluted Freshwater Plume. Only minor quantities of surface sediments from the modern Yellow River Mouth were introduced into the RSRs by the Jiangsu Coastal Current and mainly contaminated the landward part of the offshore RSR area. Our findings highlighted the potential of the Nd isotopes with REE geochemistry to trace the provenance of coastal sediments. - Highlights: • Nd isotopic and REE geochemical compositions of coastal and estuary sediments are mainly associated with source rocks. • Onshore RSR sediments originate from mixing of fine-grained sediments from various parts of the offshore RSR. • The RSRs off the Jiangsu Coast

Sediment supply to beaches

DEFF Research Database (Denmark)

Aagaard, Troels

2014-01-01

Many beaches have been built by an onshore supply of sand from the shoreface, and future long-term coastal evolution critically depends on cross-shore sediment exchange between the upper and the lower shorefaces. Even so, cross-shore sediment supply remains poorly known in quantitative terms...... and this reduces confidence in predictions of long-term shoreline change. In this paper, field measurements of suspended sediment load and cross-shore transport on the lower shoreface are used to derive a model for sediment supply from the lower to the upper shoreface at large spatial and temporal scales. Data...

Quality-Assurance Plan for the Analysis of Fluvial Sediment by the U. S. Geological Survey Kentucky Water Science Center Sediment Laboratory

National Research Council Canada - National Science Library

Shreve, Elizabeth A; Downs, Aimee C

2005-01-01

This report describes laboratory procedures used by the U. S. Geological Survey Kentucky Water Science Center Sediment Laboratory for the processing and analysis of fluvial sediment samples for concentration of sand and finer material...

Transformation and fate of microphytobenthos carbon in subtropical shallow subtidal sands: A

NARCIS (Netherlands)

Oakes, J.M.; Eyre, B.D.; Middelburg, J.J.

2012-01-01

Microphytobenthos (MPB) in photic sediments are highly productive but the fate of this production remains uncertain. Over 33 d, tracing of C-13 from added bicarbonate in subtropical shallow subtidal sand showed rapid transfer of MPB-derived carbon to deeper sediment; below 2 cm (31% within 60 h) and

Regional distribution of released earthquake energy in northern Egypt along with Inahass area

International Nuclear Information System (INIS)

El-hemamy, S.T.; Adel, A.A. Othman

1999-01-01

A review of the seismic history of Egypt indicates sone areas of high activity concentrated along Oligocene-Miocene faults. These areas support the idea of recent activation of the Oligocene-Miocene stress cycle. There are similarities in the special distribution of recent and historical epicenters. Form the tectonic map of Egypt, distribution of Intensity and magnitude show strong activity along Nile Delta. This due to the presence of a thick layers of recent alluvial sediments. The released energy of the earthquakes are effective on the structures. The present study deals with the computed released energies of the reported earthquakes in Egypt and around Inshas area . Its effect on the urban and nuclear facilities inside Inshas site is considered. Special consideration will be given to old and new waste repository sites. The application of the determined released energy reveals that Inshas site is affected by seismic activity from five seismo-tectonic source zones, namely the Red Sea, Nile Delta, El-Faiyum, the Mediterranean Sea and the Gulf of Aqaba seismo-tectonic zones. El-Faiyum seismo-tectonic source zone has the maximum effect on the site and gave a high released energy reaching to 5.4E +2 1 erg

Remote Sensing and Shallow Geophysical Investigations on Moghra Lake in Northeastern Qattarra Depression, Western Desert, Egypt

Science.gov (United States)

Khan, S. D.; Fathy, M. S.; Azeem, M. A.

2012-12-01

covered by about 2 m of lacustrine sediments of post-Miocene age in the east side and by recent eolian dunes in the west. These sediments are characterized by shallowing upward, horizontal to cross-bedded with an unconformity in between. The eastern end of the paleochannel surveyed by GPR is covered by recent sand dunes followed by an ephemeral stream that feeds the current lake. Field observations suggest that the movement of sand dunes in the northeast direction may have blocked the paleo-channel. A two meters deep trench was dug to confirm the GPR findings. Regional gravity mapping of this area also shows major gravity anomalies. More work is planned to carry out additional high resolution potential field surveys in conjunction with remote sensing and GPR studies to understand the paleo-drainage of this area. Identifying the exact track of the paleo-channels will help reconstructing of paleo drainage of this region and may help in mapping groundwater, this will be very important for the development of this rapidly expanding desert area.

Mud-farming of fine oil sands tailings

Energy Technology Data Exchange (ETDEWEB)

Yao, Y.; Tol van, F.; Paassen van, L.; Everts, B.; Mulder, A. [Delft Univ. of Technology, Delft (Netherlands). Dept. of Geotechnology

2010-07-01

This PowerPoint presentation discussed an experimental mud-farming technique for fine oil sands tailings. The technique was based on a sub-areal drying technique for dredging sludge developed in the Netherlands for Rotterdam harbour sediments. Between 1960 and 1985, the sludge was deposited in confined disposal sites on land. The sludge was converted to usable clay between 1970 and 1980. The polluted portion of the sludge is stored in a man-made disposal site. The sludge was deposited in thin layers. Stagnant water was then removed. The mud was then dewatered and reused. The sludge was furrowed with amphirol and disc wheels in order to accelerate the ripening process. The dredged material was re-used in a clay factory. The technique was applied to oil sands tailings in order to understand the suction behaviour, sedimentation behaviour, and precipitation deficit of the tailings. State changes of the sludge were monitored. No clear sedimentation phase was identified prior to consolidation. A comparison of material properties showed that the total amount of water to be extracted was more than the Rotterdam sludge, but the suction behaviour was similar. The precipitation deficit from mid-April until September will require a customized deposition strategy. Details and photographs of the experimental studies were included. tabs., figs.

Geology of wadi atalla - el missikat area, eastern desert, egypt.

OpenAIRE

El Kassas, I. A. [ابراهيم علي القصاص; Bakhit, F. S.

1989-01-01

Wadi Atalla-El Missikat area covers about 2,000 Km2 in the central Eastern Desert of Egypt, between latitudes 26° 10' and 26° 40' N, and longitudes 33° 15' and 33° 40' E. The area is mainly formed of basement complex except its extreme south-western corner where it is covered by foreland sediments of Nubian sandstone. The area is structurally complicated where it has been subjected to various stages of successive tectonic movements since the Precambrian times. The basement complex in the stud...

Biomphalaria alexandrina in Egypt

Indian Academy of Sciences (India)

2013-06-04

Jun 4, 2013 ... species within Egypt. The National Schistosoma Control Program has made great strides with respect to the .... barley and flax (Caminos 1997). Egyptian ..... Duke L 2008 Schistosomiasis in Ancient Egypt: The 'AAA' De- bate.

Distribution of surficial sediment in Long Island Sound and adjacent waters: Texture and total organic carbon

Science.gov (United States)

Poppe, L.J.; Knebel, H.J.; Mlodzinska, Z.J.; Hastings, M.E.; Seekins, B.A.

2000-01-01

The surficial sediment distribution within Long Island Sound has been mapped and described using bottom samples, photography, and sidescan sonar, combined with information from the geologic literature. The distributions of sediment type and total organic carbon (TOC) reveal several broad trends that are largely related to the sea-floor geology, the bathymetry, and the effects of modern tidal- and wind-driven currents. Sediment types are most heterogeneous in bathymetrically complex and shallow nearshore areas; the heterogeneity diminishes and the texture fines with decreasing bottom-current energy. Lag deposits of gravel and gravelly sand dominate the surficial sediment texture in areas where bottom currents are the strongest (such as where tidal flow is constricted) and where glacial till crops out at the sea floor. Sand is the dominant sediment type in areas characterized by active sediment transport and in shallow areas affected by fine-grained winnowing. Silty sand and sand-silt-clay mark transitions within the basin from higher- to lower-energy environments, suggesting a diminished hydraulic ability to sort and transport sediment. Clayey silt and silty clay are the dominant sediment types accumulating in the central and western basins and in other areas characterized by long-term depositional environments. The amount of TOC in the sediments of Long Island Sound varies inversely with sediment grain size. Concentrations average more than 1.9% (dry weight) in clayey silt, but are less than 0.4% in sand. Generally, values for TOC increase both toward the west in the Sound and from the shallow margins to the deeper parts of the basin floor. Our data also suggest that TOC concentrations can vary seasonally.

Surficial sediments of the continental shelf off Karnataka

Digital Repository Service at National Institute of Oceanography (India)

Hashimi, N.H.; Nair, R.R.

sediments occur betweenthe water depths of 15 to 50m corresponding to a distance of about 40 km from the coast. Beyond 50 m to the shelf edge are calcareous sands. Non-carbonate components of these deep water sands are essentially quartz, many of which...

Modeling fine-scale geological heterogeneity-examples of sand lenses in tills

DEFF Research Database (Denmark)

Kessler, Timo Christian; Comunian, Alessandro; Oriani, Fabio

2013-01-01

that hamper subsequent simulation. Transition probability (TP) and multiple-point statistics (MPS) were employed to simulate sand lens heterogeneity. We used one cross-section to parameterize the spatial correlation and a second, parallel section as a reference: it allowed testing the quality......Sand lenses at various spatial scales are recognized to add heterogeneity to glacial sediments. They have high hydraulic conductivities relative to the surrounding till matrix and may affect the advective transport of water and contaminants in clayey till settings. Sand lenses were investigated...... on till outcrops producing binary images of geological cross-sections capturing the size, shape and distribution of individual features. Sand lenses occur as elongated, anisotropic geobodies that vary in size and extent. Besides, sand lenses show strong non-stationary patterns on section images...

Experimental Evidence that Abrasion of Carbonate Sand is a Significant Source of Carbonate Mud

Science.gov (United States)

Trower, L.; Kivrak, L.; Lamb, M. P.; Fischer, W. W.

2017-12-01

Carbonate mud is a major sedimentary component of modern and ancient tropical carbonate environments, yet its enigmatic origin remains debated. Early views on the origin of carbonate mud considered the abrasion of carbonate sand during sediment transport as a possible mechanism. In recent decades, however, prevailing thought has generally settled on a binary explanation: 1) precipitation of aragonite needles within the water column, and 2) post-mortem dispersal of biological aragonite, in particular from algae, and perhaps aided by fish. To test these different hypotheses, we designed a model and a set of laboratory experiments to quantify the rates of mud production associated with sediment transport. We adapted a recent model of ooid abrasion rate to predict the rate of mud production by abrasion of carbonate sand as a function of grain size and sediment transport mode. This model predicts large mud production rates, ranging from 103 to 104 g CaCO3/m2/yr for typical grain sizes and transport conditions. These rate estimates are at least one order of magnitude more rapid than the 102 g CaCO3/m2/yr estimates for other mechanisms like algal biomineralization, indicating that abrasion could produce much larger mud fluxes per area as other mechanisms. We tested these estimates using wet abrasion mill experiments; these experiments generated mud through mechanical abrasion of both ooid and skeletal carbonate sand for grain sizes ranging from 250 µm to >1000 µm over a range of sediment transport modes. Experiments were run in artificial seawater, including a series of controls demonstrating that no mud was produced via homogenous nucleation and precipitation in the absence of sand. Our experimental rates match the model predictions well, although we observed small systematic differences in rates between abrasion ooid sand and skeletal carbonate sand that likely stems from innate differences in grain angularity. Electron microscopy of the experimental products revealed

Natural radioactivity in sand used in thermal therapy at the Red Sea Coast

International Nuclear Information System (INIS)

El-Arabi, A.M.

2005-01-01

The development of climatotherapy in Safaga opens the field of medical tourism in Egypt, in order to detect any harmful radiation that would affect the patients during treatment and is becoming important economic resource. Studies and survey of natural radiation and radioactivity in upper Egypt conducted since 1990, included monitoring of the concentration of natural radionuclides in environmental samples. The results of the study reveals that, for all sand samples, the mean activity concentration of 40 K (618 ± 122-548 ± 82 Bq kg -1 ) are much higher than that of both 226 Ra (25.3 ± 14-20.6 ± 10 Bq kg -1 ) and 232 Th (21.4 ± 10-22.4 ± 10 Bq kg -1 ). Different radiation hazard indices were calculated, the radiation dose to which workers are subjected is not negligible (26.5-50.9 nGy h -1 ), although depending on the inhalation of dust

Sediment distribution in the offshore regions of Goa

Digital Repository Service at National Institute of Oceanography (India)

Veerayya, M.; Murty, C.S.; Varadachari, V.V.R.

Sediment samples collected from the offshore areas of some of the beaches (Calangute, Baina and Colva) along the coast of Goa, have been studied for their particle size and areal distributions. These areas are dominated by sediments in the sand size...

Solar Energy Perspectives In Egypt

International Nuclear Information System (INIS)

Comsan, M.N.H.

2010-01-01

Egypt belongs to the global sun-belt. The country is in advantageous position with solar energy. In 1991 solar atlas for Egypt was issued indicating that the country enjoys 2900-3200 hours of sunshine annually with annual direct normal energy density 1970-3200 kWh/m2 and technical solar-thermal electricity generating potential of 73.6 Peta watt hour (PWh). Egypt was among the first countries to utilize solar energy. In 1910, a practical industrial scale solar system engine was built at Maadi south to Cairo using solar thermal parabolic collectors. The engine was used to produce steam which drove a series of large water pumps for irrigation. Nowadays utilization of solar energy includes use of photovoltaic cells, solar water heating and solar thermal power. Use of solar thermal technology may include both electricity generation and water desalination, which is advantageous for Egypt taking in consideration its shortage in water supply. The article discusses perspectives of solar energy in Egypt and developmental trends till 2050

The timing of sediment transport down Monterey Submarine Canyon, offshore California

DEFF Research Database (Denmark)

Stevens, Thomas; Paull, C.K.; Ussler, W., III

2014-01-01

luminescence (OSL) ages of quartz sand deposits and accelerator mass spectrometry 14C ages measured on benthic foraminifera to examine the timing of sediment transport through the axial channel of Monterey Submarine Canyon and Fan, offshore California. The OSL ages date the timing of sediment entry...... dates with water depth provides evidence of mixing and temporary storage of sediment as it moves through the canyon system. The ages also indicate that the frequency of sediment transport events decreases with distance down the canyon channel system. The amalgamated sands near the canyon head yield OSL......While submarine canyons are the major conduits through which sediments are transported from the continents out into the deep sea, the time it takes for sediment to pass down through a submarine canyon system is poorly constrained. Here we report on the first study to couple optically stimulated...

Assessment of Mud-Capped Dredge Pit Evolution Offshore Louisiana: Implications to Sand Excavation and Coastal Restoration

Science.gov (United States)

Xu, K.; Miner, M. D.; Bentley, S. J.; Li, C.; Obelcz, J.; O'Connor, M. C.

2016-02-01

The shelf offshore Louisiana is characterized by a dominantly muddy seafloor with a paucity of restoration-quality sand proximal to shore. Discrete sand deposits associated with ancient rivers that incised the shelf during lower sea-level positions occur close to shore. These shelf channel sands have been targeted for coastal restoration projects resulting in significant cost savings over more distal deposits. Several recent projects targeted shelf paleo-fluvial deposits comprising relatively deep (10 m) channel sands underlying a muddy overburden. Because of contrasting characteristics of cohesive mud vs. non-cohesive sand and potential modern fluvial mud supply from the Mississippi and Atchafalaya Rivers, long term pit evolution is poorly understood relative to their more common sand-only counterparts. Alterations to seafloor topography from dredging shelf sediment resources can potentially affect oil and gas infrastructure or other resources of concern (i.e. historic shipwrecks) located proximal to dredge pits. Site-specific data required to make accurate predictions and empirical measurements to test and validate predictive models were only available for Peveto Channel offshore Holly Beach, Louisiana. Here we present new geophysical and geological data (bathymetry, sidescan, subbottom, and radionuclide of sediment cores) and physical oceanographic observations (hydrodynamics and sediment dynamics) collected at Raccoon Island (dredged in 2013) dredge pit in Louisiana. These field data collections along with pre-existing data provide a time-series to capture evolution at Raccoon Island post-excavation. Conceptual morphological models will be developed for dredge pit evolution and testing effectiveness of setback buffers protecting pipelines, habitats, and cultural resources. Our results will increase decision making ability regarding safety and protecting environmental and cultural resources, and better management of valuable sand resources.

The eye and its diseases in Ancient Egypt

DEFF Research Database (Denmark)

Andersen, S. Ry

1997-01-01

Ophthalmology, History of ophthalmology, eyes in the Ancient Egypt, eye disease in Ancient Egypt, porotic hyperostosis, mummification......Ophthalmology, History of ophthalmology, eyes in the Ancient Egypt, eye disease in Ancient Egypt, porotic hyperostosis, mummification...

Elemental Analysis and Radionuclides Monitoring of Beach Black Sand at North of Nile Delta, Egypt

Science.gov (United States)

Ali, Abdallah; Fayez-Hassan, M.; Mansour, N. A.; Mubarak, Fawzia; Ahmed, Talaat Salah; Hassanin, W. F.

2017-12-01

A study was carried out on the concentrations of elements presented in beach black sand samples collected from North of Nile Delta along Mediterranean Coast using instrumental neutron activation analysis (INAA) as an effective analysis technique, especially for monitoring elements. The Egyptian Research Reactor-2 (ETRR-2) as a facility was used for the samples irradiation in the thermal mode of a neutron flux 3 × 1011 n/cm2 s. Natural radioactive elements, rare element and heavy elements as U, Th, La, Lu, Sm, Ce, Nd, Eu, Gd, Sc, Tb, Yb, As, Br, Na, Sb, Ba, Co, Cr, Fe, Hg, Hf, Sr, Ta, Zn and Zr were determined with concentrations average values 16.3, 78.8, 195.4, 3.3, 31.3, 445.1, 223, 7.2, 8.5, 97.1, 3.6, 31.1, 6.1, 24.5, 27,236.8, 1.42, 1327.7, 81.1, 1814.3, 263,735, 0.1, 237.3, 878.7, 20.8, 671.1 and 6225.9 (mg/kg), respectively. The experimental data results were analyzed to evidence any correlations of these elements as well as to know the geological formation in the study area. The elements concentrations in the black sand samples were found higher than the world average crustal soil values except for As and Sb. Results were compared with similar beach black sand in previous studies. The enrichment factor (EF) and geoaccumulation index (I geo) for heavy elements were presented to evaluate the contamination rate. We can summarize that exposure for natural radionuclides (U and Th) in this area were still within the acceptable limits due to little time of exposure. Therefore, the black sands from North of Nile Delta are not recommended for use in building constructions due to high radioactive doses.

A new depositional model for sand-rich loess on the Buckley Flats outwash plain, northwestern Lower Michigan

Science.gov (United States)

Nyland, Kelsey E.; Schaetzl, Randall J.; Ignatov, Anthony; Miller, Bradley A.

2018-04-01

Loess was first studied in Michigan on the Buckley Flats, where outwash, overlain by ≈70 cm of loamy sediment, was originally interpreted as loess mixed with underlying sands. This paper re-evaluates this landscape through a spatial analysis of data from auger samples and soil pits. To better estimate the loamy sediment's initial textures, we utilized "filtered" laser diffraction data, which remove much of the coarser sand data. Textures of filtered silt data for the loamy sediment are similar to loess. The siltiest soils are found in the low-relief, central part of the Flats. Spatial analyses revealed that many silt fractions are nearly uniformly distributed, suggesting that the loess was not derived from a single source. The previous depositional model for the loamy mantle relied on loessfall followed by pedoturbation, but does not explain (1) the variation in sand contents across the Flats, or (2) the abrupt contact below the loamy mantle. This contact suggests that the outwash was frozen when the sediments above were deposited. Deep gullies at the western margins of the Flats were likely cut as permafrost facilitated runoff. Our new model for the origin of the loamy mantle suggests that the sands on the uplands were generated from eroding gullies and saltated onto the uplands along with loess that fell more widely. Sands saltating to the west of the Flats may have entrained some silts, facilitating loessfall downwind. At most sites, the loamy mantle gets increasingly silty near the surface, suggesting that saltation ended before loess deposition.

Uranium concentration in building materials used in the central region of Egypt

International Nuclear Information System (INIS)

Higgy, R.H.; El-Tahawy, M.S.; Ghods, A.

1997-01-01

Within a radiological survey of the building materials used in the urban dwellings in the central region of Egypt, the uranium concentration in 80 representative samples of raw and fabricated building materials are determined using laser fluorimetry technique. For 40 samples from the studied raw building materials of sand, gravel, gypsum, lime-stone, granite and marble the determined uranium concentration values range between 0.3 and 3.6 ppm for all these samples except for one type of granite having the corresponding value of 7.8 ppm. For 37 samples from studied fabricated building materials of normal cement, clay brick, sand brick, tiles and ceramic plates the determined uranium concentration values range from 0.5 to 3.4 ppm. The corresponding values for three types of iron cement are 3.1, 6.1 and 9.3 ppm. The radium-226 content (of the uranium-238 series) in the same samples was determined using high resolution gamma-ray spectrometers based on HP Ge-detectors. The data obtained by the two techniques are in good agreement for the majority of the studied samples. (author)

A new GIS-based model for automated extraction of Sand Dune encroachment case study: Dakhla Oases, western desert of Egypt

Directory of Open Access Journals (Sweden)

M. Ghadiry

2012-06-01

Full Text Available The movements of the sand dunes are considered as a threat for roads, irrigation networks, water resources, urban areas, agriculture and infrastructures. The main objectives of this study are to develop a new GIS-based model for automated extraction of sand dune encroachment using remote sensing data and to assess the rate of sand dune movement. To monitor and assess the movements of sand dunes in Dakhla oases area, multi-temporal satellite images and a GIS-developed model, using Python script in Arc GIS, were used. The satellite images (SPOT images, 1995 and 2007 were geo-rectified using Erdas Imagine. Image subtraction was performed using spatial analyst in Arc GIS, the result of image subtraction obtains the sand dune movement between the two dates. The raster and vector shape of sand dune migration was automatically extracted using spatial analyst tools. The frontiers of individual dunes were measured at different dates and movement rates were analyzed in GIS. The ModelBuilder in Arc GIS was used in order to create a user friendly tool. The custom built model window is easy to handle by any user who wishes to adapt the model in his work. It was found that the rate of sand dune movement ranged between 3 and 9 m per year. The majority of sand dunes have a rate movement between 0 and 6 m and very few dunes had a movement rate between 6 and 9 m. Integrating remote sensing and GIS provided the necessary information for determining the minimum, maximum, mean, rate and area of sand dune migration.

Numerical modelling of the erosion and deposition of sand inside a filter layer

DEFF Research Database (Denmark)

Jacobsen, Niels Gjøl; van Gent, Marcel R. A.; Fredsøe, Jørgen

2017-01-01

This paper treats the numerical modelling of the behaviour of a sand core covered by rocks and exposed to waves. The associated displacement of the rock is also studied. A design that allows for erosion and deposition of the sand core beneath a rock layer in a coastal structure requires an accurate...... prediction method to assure that the amount of erosion remains within acceptable limits. This work presents a numerical model that is capable of describing the erosion and deposition patterns inside of an open filter of rock on top of sand. The hydraulic loading is that of incident irregular waves...... and the open filters are surface piercing. Due to the few experimental data sets on sediment transport inside of rock layers, a sediment transport formulation has been proposed based on a matching between the numerical model and experimental data on the profile deformation inside an open filter. The rock layer...

Political history of modern Egypt

Directory of Open Access Journals (Sweden)

MA. Islam Islami

2016-07-01

Gamal Abdel Nasser was the one who established the Republic of Egypt and ended the monarchy rule in Egypt following the Egyptian revolution in 1952. Egypt was ruled autocratically by three presidents over the following six decades, by Nasser from 1954 until his death in 1970, by Anwar Sadat from 1971 until his assassination 1981, and by Hosni Mubarak from 1981 until his resignation in the face of the 2011 Egyptian revolution.

Effect of water flux and sediment discharge of the Yangtze River on PAHs sedimentation in the estuary.

Science.gov (United States)

Li, Rufeng; Feng, Chenghong; Wang, Dongxin; He, Maozhi; Hu, Lijuan; Shen, Zhenyao

2016-12-01

Historical distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) and their carriers (i.e., organic matter and mineral particles) in the sediment cores of the Yangtze Estuary were investigated, with emphasis laid on the role of the Yangtze River. Grain size component of sediments (clay, silt, and sand) and organic carbon (black carbon and total organic carbon) in the sediment cores were markedly affected by water flux and sediment discharge of the Yangtze River. Qualitative and quantitative analysis results showed that sands and black carbon acted as the main carriers of PAHs. The sedimentation of two-ring to three-ring PAHs in the estuary had significant correlations with water flux and sediment discharge of the Yangtze River. The relative lower level of the four-ring and five-ring to six-ring PAHs concentrations appeared around the year 2003 and remained for the following several years. This time period accorded well with the water impoundment time of the Three Gorges Reservoir. The decreased level of two-ring to three-ring PAHs occurred in the year 1994, and the peak points around the year 2009 indicated that PAHs sedimentation in the estuary also had close relationship to severe drought and flood in the catchments. The findings presented in this paper could provide references for assessing the impacts of water flux and sediment discharge on the historical deposition of PAHs and their carriers in the Yangtze Estuary.

General characteristics of current in front of Port Said, Egypt

Directory of Open Access Journals (Sweden)

Mohamed S. Elsharkawy

2017-06-01

Full Text Available This paper is a preliminary investigation of the general characteristics of the current in front of the coastal Mediterranean city: Port Said, Egypt. The study of the current regime in front of Port Said helps environmental engineers to tackle problems as marine port sedimentation and shoreline changes. Surface and bottom current recordings at a single offshore station of depth 104 m located at 31° 34.90′ N, 32° 30.01′ E have been subject to statistical analysis. The measurements showed unexpectedly that bottom currents were relatively stronger than surface currents during May-99.

Coastal geology and recent origins for Sand Point, Lake Superior

Science.gov (United States)

Fisher, Timothy G.; Krantz, David E.; Castaneda, Mario R.; Loope, Walter L.; Jol, Harry M.; Goble, Ronald J.; Higley, Melinda C.; DeWald, Samantha; Hansen, Paul

2014-01-01

Sand Point is a small cuspate foreland located along the southeastern shore of Lake Superior within Pictured Rocks National Lakeshore near Munising, Michigan. Park managers’ concerns for the integrity of historic buildings at the northern periphery of the point during the rising lake levels in the mid-1980s greatly elevated the priority of research into the geomorphic history and age of Sand Point. To pursue this priority, we recovered sediment cores from four ponds on Sand Point, assessed subsurface stratigraphy onshore and offshore using geophysical techniques, and interpreted the chronology of events using radiocarbon and luminescence dating. Sand Point formed at the southwest edge of a subaqueous platform whose base is probably constructed of glacial diamicton and outwash. During the post-glacial Nipissing Transgression, the base was mantled with sand derived from erosion of adjacent sandstone cliffs. An aerial photograph time sequence, 1939–present, shows that the periphery of the platform has evolved considerably during historical time, infl uenced by transport of sediment into adjacent South Bay. Shallow seismic refl ections suggest slump blocks along the leading edge of the platform. Light detection and ranging (LiDAR) and shallow seismic refl ections to the northwest of the platform reveal large sand waves within a deep (12 m) channel produced by currents fl owing episodically to the northeast into Lake Superior. Ground-penetrating radar profi les show transport and deposition of sand across the upper surface of the platform. Basal radiocarbon dates from ponds between subaerial beach ridges range in age from 540 to 910 cal yr B.P., suggesting that Sand Point became emergent during the last ~1000 years, upon the separation of Lake Superior from Lakes Huron and Michigan. However, optically stimulated luminescence (OSL) ages from the beach ridges were two to three times as old as the radiocarbon ages, implying that emergence of Sand Point may have begun

Studies on the shelf sediments off the Madras coast

Digital Repository Service at National Institute of Oceanography (India)

Rao, Ch.M.; Murty, P.S.N.

content. Grain size study has shown that the sediments off Madras are mainly sandy in nature and vary from fine to very fine sands in the nearshore and outer shelf regions to medium to coarse sands in the midshelf region. Off Karaikal they vary from coarse...

Mineral Resource Assessment of Marine Sand Resources in Cape- and Ridge-Associated Marine Sand Deposits in Three Tracts, New York and New Jersey, United States Atlantic Continental Shelf

Science.gov (United States)

Bliss, James D.; Williams, S. Jeffress; Arsenault, Matthew A.

2009-01-01

Demand is growing in the United States and worldwide for information about the geology of offshore continental shelf regions, the character of the seafloor, and sediments comprising the seafloor and subbottom. Interest in locating sand bodies or high quality deposits that have potential as sources for beach nourishment and ecosystem restoration is especially great in some regions of the country. The Atlantic coast, particularly New York and New Jersey, has been the focus of these studies for the past 40 years with widely varying results. This study is the first attempt at applying probability statistics to modeling Holocene-age cape-and ridge-associated sand deposits and thus focuses on distinct sand body morphology. This modeling technique may have application for other continental shelf regions that have similar geologic character and late Quaternary sea-level transgression history. An estimated volume of 3.9 billion m3 of marine sand resources is predicted in the cape-and ridge-associated marine sand deposits in three representative regions or tracts on the continental shelf offshore of New York and New Jersey. These estimates are taken from probabilistic distributions of sand resources and are produced using deposit models and Monte Carlo Simulation (MCS) techniques. The estimated sand resources presented here are for only three tracts as described below and for Holocene age sand resources contained in cape-and ridge-associated marine sand deposit types within this area. Other areas may qualify as tracts for this deposit type and other deposit types and geologic ages (for example, paleo-stream channels, blanket and outwash deposits, ebb-tide shoals, and lower sea level-stand deltas), which are present on the New Jersey and New York continental shelf area but are not delineated and modeled in this initial evaluation. Admittedly, only a portion of these probable sand resources will ultimately be available and suitable for production, dependent largely on

Benthic faunal sampling adjacent to the Sand Island ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900088)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna in the vicinity of the Sand Island ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size and sediment...

Underwater Sediment Sampling Research

Science.gov (United States)

2017-01-01

impacted sediments was found to be directly related to the concentration of crude oil detected in the sediment pore waters . Applying this mathematical...Kurt.A.Hansen@uscg.mil. 16. Abstract (MAXIMUM 200 WORDS ) The USCG R&D Center sought to develop a bench top system to determine the amount of total...scattered. The approach here is to sample the interstitial water between the grains of sand and attempt to determine the amount of oil in and on

Relationships between sand and water quality at recreational beaches.

Science.gov (United States)

Phillips, Matthew C; Solo-Gabriele, Helena M; Piggot, Alan M; Klaus, James S; Zhang, Yifan

2011-12-15

Enterococci are used to assess the risk of negative human health impacts from recreational waters. Studies have shown sustained populations of enterococci within sediments of beaches but comprehensive surveys of multiple tidal zones on beaches in a regional area and their relationship to beach management decisions are limited. We sampled three tidal zones on eight South Florida beaches in Miami-Dade and Broward counties and found that enterococci were ubiquitous within South Florida beach sands although their levels varied greatly both among the beaches and between the supratidal, intertidal and subtidal zones. The supratidal sands consistently had significantly higher (p sand) than the other two zones. Levels of enterococci within the subtidal sand correlated with the average level of enterococci in the water (CFU/100mL) for the season during which samples were collected (r(s) = 0.73). The average sand enterococci content over all the zones on each beach correlated with the average water enterococci levels of the year prior to sand samplings (r(s) = 0.64) as well as the average water enterococci levels for the month after sand samplings (r(s) = 0.54). Results indicate a connection between levels of enterococci in beach water and sands throughout South Florida's beaches and suggest that the sands are one of the predominant reservoirs of enterococci impacting beach water quality. As a result, beaches with lower levels of enterococci in the sand had fewer exceedences relative to beaches with higher levels of sand enterococci. More research should focus on evaluating beach sand quality as a means to predict and regulate marine recreational water quality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Development of a two-phase SPH model for sediment laden flows

Science.gov (United States)

Shi, Huabin; Yu, Xiping; Dalrymple, Robert A.

2017-12-01

A SPH model based on a general formulation for solid-fluid two-phase flows is proposed for suspended sediment motion in free surface flows. The water and the sediment are treated as two miscible fluids, and the multi-fluid system is discretized by a single set of SPH particles, which move with the water velocity and carry properties of the two phases. Large eddy simulation (LES) is introduced to deal with the turbulence effect, and the widely used Smagorinsky model is modified to take into account the influence of sediment particles on the turbulence. The drag force is accurately formulated by including the hindered settling effect. In the model, the water is assumed to be weakly compressible while the sediment is incompressible, and a new equation of state is proposed for the pressure in the sediment-water mixture. Dynamic boundary condition is employed to treat wall boundaries, and a new strategy of Shepard filtering is adopted to damp the pressure oscillation. The developed two-phase SPH model is validated by comparing the numerical results with analytical solutions for idealized cases of still water containing both neutrally buoyant and naturally settling sand and for plane Poiseuille flows carrying neutrally buoyant particles, and is then applied to sand dumping from a line source into a water tank, where the sand cloud settles with a response of the free water surface. It is shown that the numerical results are in good agreement with the experimental data as well as the empirical formulas. The characteristics of the settling sand cloud, the pressure field, and the flow vortices are studied. The motion of the free water surface is also discussed. The proposed two-phase SPH model is proven to be effective for numerical simulation of sand dumping into waters.

Responses of macroinvertebrates and local environment to short-term commercial sand dredging practices in a flood-plain lake.

Science.gov (United States)

Meng, Xingliang; Jiang, Xiaoming; Li, Zhengfei; Wang, Jun; Cooper, Keith M; Xie, Zhicai

2018-08-01

In parts of the developing world, the expansion of industrial sand mining activities has led to serious environmental concerns. However, current understanding of the effects of this activity on an inland water ecosystem remains limited. Herein, we choose the "most affected" lake in China (Dongting Lake), to assess short-term (1year) effects of sand dredging on key environmental parameters and on the structure of the macroinvertebrate assemblage. Within the dredged area we observed increases in water depth (on average 2.17m), turbidity and changes in sediment composition (e.g., increase in % medium sand, and a decrease in % clay). In addition, dredging was associated with a 50 % reduction in taxa richness, Simpson and Shannon-Wiener indices, and a 72 and 99 % reduction in abundance and biomass, respectively. Indirect effects were also observed in the zone surrounding the extraction sites (ca. 500m), most likely as a result of the dredging processes (e.g., sediment screening and overspill) and water flow. No such effects were observed at a nearby reference site. The direct removal of sediment and indirect alteration of physical conditions (e.g., water depth, turbidity and sediment composition) appear to be the most likely cause of variations in the benthic community. Implications of our findings for the planning, management and monitoring of sand dredging in inland waters are discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Contemporary sand wedge development in seasonally frozen ground and paleoenvironmental implications

Science.gov (United States)

Wolfe, Stephen A.; Morse, Peter D.; Neudorf, Christina M.; Kokelj, Steven V.; Lian, Olav B.; O'Neill, H. Brendan

2018-05-01

Contemporary sand wedges and sand veins are active in seasonally frozen ground within the extensive discontinuous permafrost zone in Northwest Territories, Canada. The region has a subarctic continental climate with 291 mm a-1 precipitation, -4.1 °C mean annual air temperature, warm summers (July mean 17.0 °C), and cold winters (January mean -26.6 °C). Five years of continuous observations indicate that interannual variation of the ground thermal regime is dominantly controlled by winter air temperature and snow cover conditions. At sandy sites, thin snow cover and high thermal conductivity promote rapid freezing, high rates of ground cooling, and low near-surface ground temperatures (-15 to -25 °C), resulting in thermal contraction cracking to depths of 1.2 m. Cracking potentials are high in sandy soils when air temperatures are air temperatures are ≤-17 °C, and snow cover is conditions in peatlands maintain permafrost, but thermal contraction cracking does not occur because thicker snow cover and the thermal properties of peat prolong freezeback and maintain higher winter ground temperatures. A combination of radiocarbon dating, optical dating, and stratigraphic observations were used to differentiate sand wedge types and formation histories. Thermal contraction cracks that develop in the sandy terrain are filled by surface (allochthonous) and/or host (autochthonous) material during the thaw season. Epigenetic sand wedges infilled with allochthonous sand develop within former beach sediments beneath an active eolian sand sheet. Narrower and deeper syngenetic wedges developed within aggrading eolian sand sheets, whereas wider and shallower antisyngenetic wedges developed in areas of active erosion. Thermal contraction cracking beneath vegetation-stabilized surfaces leads to crack infilling by autochthonous host and overlying organic material, with resultant downturning and subsidence of adjacent strata. Sand wedge development in seasonally frozen ground

Dwarfs in ancient Egypt.

Science.gov (United States)

Kozma, Chahira

2006-02-15

Ancient Egypt was one of the most advanced and productive civilizations in antiquity, spanning 3000 years before the "Christian" era. Ancient Egyptians built colossal temples and magnificent tombs to honor their gods and religious leaders. Their hieroglyphic language, system of organization, and recording of events give contemporary researchers insights into their daily activities. Based on the record left by their art, the ancient Egyptians documented the presence of dwarfs in almost every facet of life. Due to the hot dry climate and natural and artificial mummification, Egypt is a major source of information on achondroplasia in the old world. The remains of dwarfs are abundant and include complete and partial skeletons. Dwarfs were employed as personal attendants, animal tenders, jewelers, and entertainers. Several high-ranking dwarfs especially from the Old Kingdom (2700-2190 BCE) achieved important status and had lavish burial places close to the pyramids. Their costly tombs in the royal cemeteries and the inscriptions on their statutes indicate their high-ranking position in Egyptian society and their close relation to the king. Some of them were Seneb, Pereniankh, Khnumhotpe, and Djeder. There were at least two dwarf gods, Ptah and Bes. The god Ptah was associated with regeneration and rejuvenation. The god Bes was a protector of sexuality, childbirth, women, and children. He was a favored deity particularly during the Greco-Roman period. His temple was recently excavated in the Baharia oasis in the middle of Egypt. The burial sites and artistic sources provide glimpses of the positions of dwarfs in daily life in ancient Egypt. Dwarfs were accepted in ancient Egypt; their recorded daily activities suggest assimilation into daily life, and their disorder was not shown as a physical handicap. Wisdom writings and moral teachings in ancient Egypt commanded respect for dwarfs and other individuals with disabilities. Copyright (c) 2005 Wiley-Liss, Inc.

Concentration of 60Co by marine organisms through sediments

International Nuclear Information System (INIS)

Nakahara, Motokazu; Koyanagi, Taku; Saiki, Masamichi

1976-01-01

Uptake of 60 Co absorbed on sea sands by benthic marine organisms was observed in laboratory experiments, since the radioactive cobalt released from nuclear power plants or other establishments into coastal seawater trends to be absorbed on sea sediments and also various kinds of marine organisms live in bottom sediments. Few kinds of flatfishes (Limanda spp.) and shrimp (Trachypenaeus curvirostris) were reared in aquariums contained seawater and sea sands which were highly contaminated with 60 Co previously, and whole body retention and distribution of radioactivity were measured on the organisms taken up from the aquariums occasionally by a scintillation counter. Uptake of 60 Co from ingested sea sands was also observed on the flatfishes administrating the contaminated sands orally. Concentration of 60 Co by the flatfishes reared in the sands was not significant while the shrimp showed high retention of the radioactivity. The food habit of shrimp which usually feeds on organic detritus with other small benthic organisms is different from that of flatfishes, one of the carnivorous, and considered to bring the difference on the pathway of radionuclides concentration. Assimilation of 60 Co via the digestive tract of flatfishes through the sands was estimated as about 10 per cent of the administrated radioactivity. (auth.)

Monsoonal effects on beach and offshore sediments from kalbadevi bay, Ratnagiri, Maharashtra state, India.

Digital Repository Service at National Institute of Oceanography (India)

Valsangkar, A.B.; Farnnades, D.

environment. The beach sediment samples were obtained by push core method using 50 cm long different diameter acrylic core liners. The sampling was performed at dune, berm, hide tide (HT), mid tide (MT) and low tide (LT) areas of the beach in three seasons... are compared and the seasonal variations are discussed below. A) Beach sediments The major constituent of the beach sediment is sand followed by the silt and clay. Compared to HT, MT, and LT environment, variations in the sand content in dune and berm...

Quantifying Sediment Characteristics and Infilling Rate within a Ship Shoal Dredge Borrow Area, Offshore Louisiana

Science.gov (United States)

Xue, Z.; Wilson, C.; Bentley, S. J.; Xu, K.; Liu, H.; Li, C.; Miner, M. D.

2017-12-01

Barrier islands provide protection to interior wetlands and maintain estuarine gradients. Mississippi River delta plain barrier islands are undergoing rapid disintegration due to high rates of subsidence and a deficit in the coastal sand supply. To mitigate for barrier island land loss, Louisiana has implemented a restoration program that intends to supplement coastal sand deficits by introducing sand from outside of the active coastal system. Inner-shelf shoals offshore Louisiana are one of the only sand resource options containing large volumes of restoration quality sand. Ship Shoal is one of these inner-shelf shoals that was produced by marine reworking of former Mississippi River Delta barrier island sediments during late Holocene time. Though indirect effects to protected areas or infrastructure adjacent to excavations have been considered, there is a paucity of observational data on their evolution. Caminada borrow area, dredged in 2013-2016 for the Caminada Headland Restoration Project, provides a valuable opportunity to validate and improve predictive models for how borrow areas evolve. In July 2017, a subbottom and bathymetric geophysical survey was conducted and sediment cores were collected to test the hypothesis that sedimentation within the excavation is affected by lateral bedload transport after initial rapid infill as slopes equilibrate. Preliminary results show the sediment within the excavation is predominantly very fine sand with isolated mud drapes. These sediments overlay older delta complex muddy strata. This contrasts strongly with other dredge pits outside of shoal areas and closer to shore, which have been infilled largely by advection of fine suspended sediments of fluvial origin. Laboratory work on cores will include laser grain size, x-ray analyses of sedimentary structures, and radiochemistry analyses for rates and age of deposition. With the knowledge of stratigraphy and sediment dynamics surrounding the dredge pit, we can quantify

Long-term continuous acoustical suspended-sediment measurements in rivers - Theory, application, bias, and error

Science.gov (United States)

Topping, David J.; Wright, Scott A.

2016-05-04

It is commonly recognized that suspended-sediment concentrations in rivers can change rapidly in time and independently of water discharge during important sediment‑transporting events (for example, during floods); thus, suspended-sediment measurements at closely spaced time intervals are necessary to characterize suspended‑sediment loads. Because the manual collection of sufficient numbers of suspended-sediment samples required to characterize this variability is often time and cost prohibitive, several “surrogate” techniques have been developed for in situ measurements of properties related to suspended-sediment characteristics (for example, turbidity, laser-diffraction, acoustics). Herein, we present a new physically based method for the simultaneous measurement of suspended-silt-and-clay concentration, suspended-sand concentration, and suspended‑sand median grain size in rivers, using multi‑frequency arrays of single-frequency side‑looking acoustic-Doppler profilers. The method is strongly grounded in the extensive scientific literature on the incoherent scattering of sound by random suspensions of small particles. In particular, the method takes advantage of theory that relates acoustic frequency, acoustic attenuation, acoustic backscatter, suspended-sediment concentration, and suspended-sediment grain-size distribution. We develop the theory and methods, and demonstrate the application of the method at six study sites on the Colorado River and Rio Grande, where large numbers of suspended-sediment samples have been collected concurrently with acoustic attenuation and backscatter measurements over many years. The method produces acoustical measurements of suspended-silt-and-clay and suspended-sand concentration (in units of mg/L), and acoustical measurements of suspended-sand median grain size (in units of mm) that are generally in good to excellent agreement with concurrent physical measurements of these quantities in the river cross sections at

Sediment distribution and composition on the shallow water ...

African Journals Online (AJOL)

Sediments of the shallow water carbonate basin in Zanzibar channel were investigated for composition and grain size distribution. The surface sediment composition was dominated by carbonate sands (with CaCO3 > 30%), except in the area adjacent to mainland coastline and a thin lobe which projects from Ruvu River to ...

Quarternary Sediment Characteristics of Floodplain area: Study Case at Kampar River, Rumbio Area and Surroundings, Riau Province

Directory of Open Access Journals (Sweden)

Yuniarti Yuskar

2018-03-01

Full Text Available The study area is located in some floodplains of meandering river environment along the Kampar River, Rumbio. Typical morphology of meandering river that found in this area can be classified as stream channel, floodplain, abandoned channel, and sand bars deposit. Meandering river system carries sediment supply by suspended and bed - load (mixed load in conjunction with low energy into a particular characteristic on sediment deposition. This study aims to determine the characteristics of the sediments, changes in vertical and lateral spread of sediment deposition on the floodplain environment. This study conducted by field survey using a hand auger of 1.5m - 4m depth and trenching which is a layer that has been exposed of 1-2 meters depth. Further analysis had been carried out using granulometri method and core data analysis to determine the characteristics and depositional facies. Sediment deposit that formed along the Kampar River is the result of the main channel migration of Kampar River. The characteristic of quaternary sediment facies is coarse to gravelly sand on the bottom followed by fine to very fine sand with pattern fining upwards and silt to clay and abundant terrestrial organic matter at the uppermost layer. Depositional facies are determined based on the characteristics of sediment facies which can be grouped into a stream channel, oblique accretion deposits, sand bars and overbank deposits.

Metal pollution assessment in the surface sediment of Lake Nasser, Egypt

Directory of Open Access Journals (Sweden)

Mohamed E. Goher

2014-01-01

Full Text Available Eight heavy metals were measured seasonally in the sediment of Lake Nasser during 2013. 27 sites were chosen through 9 sectors across the main channel of the lake from Abu-Simbel to Aswan High Dam to assess the levels of the selected metals. The abundance of these metals was in the order of Fe > Mn > Zn > Cr > Ni > Cu > Pb > Cd, with mean concentrations of 12.41 mg/g, 279.56, 35.38, 30.79, 27.56, 21.78, 11.21 and 0.183 μg/g, respectively. Heavy metals are positively correlated with fine particles (mud fractions and organic matter accumulation. The results showed perspicuous spatial high significant differences (P < 0.01 for all the measured metals. Fe, Cr, Ni, Pb and Cd exhibited temporally high significant differences (P < 0.01 before and after the flood period. Four Pollution Indices were used for the environmental assessment of Lake Nasser sediment. The indices included three single indices, Enrichment Factor (EF, Index of Geo-accumulation (Igeo and Contamination Factor (CF. While the fourth, Pollution Load Index (PLI was an integrated index. The pollution indexes confirmed that the Lake Nasser sediment was not contaminated with these elements. Sediments of Lake Nasser may be represented as a reference for the pre-industrial background of River Nile Sediments downstream Aswan High Dam.

Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 1. Electromagnetic properties

Science.gov (United States)

Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

2010-01-01

The marked decrease in bulk electrical conductivity of sediments in the presence of gas hydrates has been used to interpret borehole electrical resistivity logs and, to a lesser extent, the results of controlled source electromagnetic surveys to constrain the spatial distribution and predicted concentration of gas hydrate in natural settings. Until now, an exhaustive laboratory data set that could be used to assess the impact of gas hydrate on the electromagnetic properties of different soils (sand, silt, and clay) at different effective stress and with different saturations of hydrate has been lacking. The laboratory results reported here are obtained using a standard geotechnical cell and the hydrate-formed tetrahydrofuran (THF), a liquid that is fully miscible in water and able to produce closely controlled saturations of hydrate from dissolved phase. Both permittivity and electrical conductivity are good indicators of the volume fraction of free water in the sediment, which is in turn dependent on hydrate saturation. Permittivity in the microwave frequency range is particularly predictive of free water content since it is barely affected by ionic concentration, pore structure, and surface conduction. Electrical conductivity (or resistivity) is less reliable for constraining water content or hydrate saturation: In addition to fluid-filled porosity, other factors, such as the ionic concentration of the pore fluid and possibly other conduction effects (e.g., surface conduction in high specific surface soils having low conductivity pore fluid), also influence electrical conductivity.

Validating Experimental Bedform Dynamics on Cohesive Sand-Mud Beds in the Dee Estuary

Science.gov (United States)

Baas, Jaco H.; Baker, Megan; Hope, Julie; Malarkey, Jonathan; Rocha, Renata

2014-05-01

Recent laboratory experiments and field measurements have shown that small quantities of cohesive clay, and in particular 'sticky' biological polymers, within a sandy substrate dramatically reduce the development rate of sedimentary bedforms, with major implications for sediment transport rate calculations and process interpretations from the sedimentary record. FURTHER INFORMATION Flow and sediment transport predictions from sedimentary structures found in modern estuaries and within estuarine geological systems are impeded by an almost complete lack of process-based knowledge of the behaviour of natural sediments that consist of mixtures of cohesionless sand and biologically-active cohesive mud. Indeed, existing predictive models are largely based on non-organic cohesionless sands, despite the fact that mud, in pure form or mixed with sand, is the most common sediment on Earth and also the most biologically active interface across a range of Earth-surface environments, including rivers and shallow seas. The multidisciplinary COHBED project uses state-of-the-art laboratory and field technologies to measure the erosional properties of mixed cohesive sediment beds and the formation and stability of sedimentary bedforms on these beds, integrating the key physical and biological processes that govern bed evolution. The development of current ripples on cohesive mixed sediment beds was investigated as a function of physical control on bed cohesion versus biological control on bed cohesion. These investigations included laboratory flume experiments in the Hydrodynamics Laboratory (Bangor University) and field experiments in the Dee estuary (at West Kirby near Liverpool). The flume experiments showed that winnowing of fine-grained cohesive sediment, including biological stabilisers, is an important process affecting the development rate, size and shape of the cohesive bedforms. The ripples developed progressively slower as the kaolin clay fraction in the sandy substrate

Hydroacoustic signatures of Colorado Riverbed sediments in Marble and Grand Canyons using multibeam sonar

Science.gov (United States)

Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matthew; Tusso, Robert B.; Rubin, David M.

2015-01-01

Grand Canyon National Park have been studied for several decades (e.g. Howard and Dolan, 1981; Rubin et al., 2002). Particular focus has been given to sandbars in large eddies downstream of tributary debris fans (Schmidt, 1990) because they are considered valuable resources by stakeholders and managers. Due to the severe limitations in sand supply imposed by Glen Canyon Dam (Howard and Dolan, 1981; Topping et al., 2000; Hazel et al., 2006), understanding the effectiveness of sandbar management practices, such as controlled floods (Rubin et al. 2002; Topping et al., 2006; Hazel et al., 2010), and the long-term fate of sand in Grand Canyon over decadal timescales, requires construction of accurate sand budgets, which involves detailed monitoring of influx, efflux and changes in sand storage (Topping et al., 2000; Topping et al., 2010; Grams et al., 2013) and assessments of uncertainties in sand-budget calculations (Grams et al., 2013). In order to estimate the sand budget, it is necessary to estimate what component of observed morphological changes is sand and what component is coarser. Grams et al. (2013) classified sand and coarse substrates using topographic roughness derived from digital elevation models, but the classification skill was estimated to be only 60-70%. In addition, sand bedforms had to be delineated manually, and validation was based on grain-size observations with positional uncertainties up to tens of meters. Because the morphology of the Colorado riverbed in Grand Canyon is mapped - to a large extent - using MBES (Kaplinski et al., 2009), the primary motivation for the present study is to examine how uncertainties in sand budgets can be constrained by producing maps of surface sediment types using the completely automated methods of Buscombe et al (2014b, 2014c) based on statistical analysis of MBES acoustic backscatter.

Sediment transport in the lower Snake and Clearwater River Basins, Idaho and Washington, 2008–11

Science.gov (United States)

Clark, Gregory M.; Fosness, Ryan L.; Wood, Molly S.

2013-01-01

/L), and the Middle Fork Clearwater River at Kooskia, Idaho (15 mg/L). The largest measured concentrations of suspended sediment (3,300 and 1,400 mg/L) during a rain-on-snow event in January 2011 were from samples collected at the Potlatch River near Spalding, Idaho, and the Palouse River at Hooper, Washington, respectively. Generally, samples collected from agricultural watersheds had a high percentage of silt and clay-sized suspended sediment, whereas samples collected from forested watersheds had a high percentage of sand. During water years 2009–11, Lower Granite Reservoir received about 10 million tons of suspended sediment from the combined loads of the Snake and Clearwater Rivers. The Snake River accounted for about 2.97 million tons per year (about 89 percent) of the total suspended sediment, 1.48 million tons per year (about 90 percent) of the suspended sand, and about 1.52 million tons per year (87 percent) of the suspended silt and clay. Of the suspended sediment transported to Lower Granite Reservoir, the Salmon River accounted for about 51 percent of the total suspended sediment, about 56 percent of the suspended sand, and about 44 percent of the suspended silt and clay. About 6.2 million tons (62 percent) of the sediment contributed to Lower Granite Reservoir during 2009–11 entered during water year 2011, which was characterized by an above average winter snowpack and sustained spring runoff. A comparison of historical data collected from the Snake River near Anatone with data collected during this study indicates that concentrations of total suspended sediment and suspended sand in the Snake River were significantly smaller during water years 1972–79 than during 2008–11. Most of the increased sediment content in the Snake River is attributable to an increase of sand-size material. During 1972–79, sand accounted for an average of 28 percent of the suspended-sediment load; during 2008–11, sand accounted for an average of 48 percent. Historical data

Contribution To The Geology Of Basement Rocks In The South Western Desert Of Egypt

International Nuclear Information System (INIS)

Sadek, M.F.; Khyamy, A.A.

2003-01-01

Three major Precambrian basement inliers are exposed in the South Western Desert of Egypt between Long. 29 degree E and the River Nile within the Uweinat-Bir Safsaf-Aswan E-W uplift system. These are Bir Safsaf, Gabal EI-Asr and Gabal Umm Shaghir areas. Smaller outcrops include Gabal EI-Gara El-Hamra and Gabal El-Gara EI-Soda, Gabal Siri, GabaI EI-Fantas and Aswan-Kalabsha area as well as the scattered outcrops around Darb El-Arbain road. Band ratios 5/7, 5/1, 4 of Landsat TM images were applied to delineate the borders, the lithologic units and structural features of low relief basement outcrops within the surrounding flat lying sedimentary rocks and sand plains. These basement rocks comprise ortho gneisses (assumed by many authors as related to old continent pre Pan-African rocks), G 1 tonalite-granodiorite, and G2 monzogranite-alkali feldspar granite intruded by variable dykes. The boundaries between the basement exposures and the sedimentary rocks are marked by nonconformity surfaces or sets of faults. Both basement and sedimentary rocks are intruded by Mesozoic syenite-G3 granites, rhyolite, trachytic plugs and Upper Cretaceous to Tertiary basalts. The basement exposures are structurally controlled by major E- W fault systems. Their vertical uplifting is overprinted by folding the overlying sedimentary rocks. This study revealed that, the different basement exposures in the SE of the Western Desert of Egypt are similar in appearance and field relations to the Pan-African basement rocks extending towards the east of the River Nile and exposed everywhere in the Eastern Desert of Egypt

Laboratory observations of artificial sand and oil agglomerates

Science.gov (United States)

Jenkins, Robert L.; Dalyander, P. Soupy; Penko, Allison; Long, Joseph W.

2018-04-27

Sand and oil agglomerates (SOAs) form when weathered oil reaches the surf zone and combines with suspended sediments. The presence of large SOAs in the form of thick mats (up to 10 centimeters [cm] in height and up to 10 square meters [m2] in area) and smaller SOAs, sometimes referred to as surface residual balls (SRBs), may lead to the re-oiling of beaches previously affected by an oil spill. A limited number of numerical modeling and field studies exist on the transport and dynamics of centimeter-scale SOAs and their interaction with the sea floor. Numerical models used to study SOAs have relied on shear-stress formulations to predict incipient motion. However, uncertainty exists as to the accuracy of applying these formulations, originally developed for sand grains in a uniformly sorted sediment bed, to larger, nonspherical SOAs. In the current effort, artificial sand and oil agglomerates (aSOAs) created with the size, density, and shape characteristics of SOAs were studied in a small-oscillatory flow tunnel. These experiments expanded the available data on SOA motion and interaction with the sea floor and were used to examine the applicability of shear-stress formulations to predict SOA mobility. Data collected during these two sets of experiments, including photographs, video, and flow velocity, are presented in this report, along with an analysis of shear-stress-based formulations for incipient motion. The results showed that shear-stress thresholds for typical quartz sand predicted the incipient motion of aSOAs with 0.5–1.0-cm diameters, but were inaccurate for aSOAs with larger diameters (>2.5 cm). This finding implies that modified parameterizations of incipient motion may be necessary under certain combinations of aSOA characteristics and environmental conditions.

Mass Transfer Behavior of Perfluorinated Chemicals in Saturated Clay-rich Sands: A Laboratory-based Study on Fate and Transport in Groundwater and Sediments

Science.gov (United States)

Greenberg, R. R.; Tick, G. R.; Abbott, J. B., III; Carroll, K. C.

2017-12-01

Perfluoroalkyl substances (PFAS) are a class of emerging contaminants that pose a threat to the human health and the quality of groundwater, surface water, and drinking water supplies. This study aims to elucidate the primary physicochemical factors controlling the fate and transport of the PFAS contaminants, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), in groundwater. Physicochemical processes of intercalation, adsorption, and desorption were investigated for the retention of PFAS at different initial aqueous-phase concentrations in modified-natural sediments composed of sand (40/50 accusand; foc = 0.04% unmodified) with low, medium, and high organic carbon contents (foc = 10, 20, and 50%) and various pre-conditioned clay-fractions. Diffusional mass-transfer limitations were evaluated based on initial PFAS concentration, specific clay structure, and resulting contaminant intercalation (d-spacing changes). A series of short- (48 hr), medium- (7 day) and long-term (30 day) batch and column experiments were conducted to determine physicochemical processes as a function of compound chemistry, sediment geochemistry, sorbent crystalline structure, and contaminant/sediment contact-time. Physicochemical parameters, PFAS concentrations, and sediment characterization were conducted using high performance liquid chromatography (HPLC), X-ray diffraction (XRD), and furnace combustion analytical techniques. The results of PFAS contaminant transport, under the different conditions tested, provide a scientific contribution with application to the development of improved risk assessments, predictions of fate and transport, and more effective remediation strategies for emerging perfluorinated contaminants in soil and groundwater.

Vertical distribution of radioactive particles in Ottawa River sediment near the Chalk River Laboratories

International Nuclear Information System (INIS)

Lee, D.R.; Hartwig, D.S.

2011-01-01

Previously, we described an area of above-background levels of radioactivity in the bed of the Ottawa River near the Chalk River Laboratories. The area was about 200 m wide by 400 m long and in water 8 to 30 m deep. The source of the radioactivity was associated with the location of cooling-water discharge. Particles of radioactive material were later recovered from the upper 10-15 cm of sediment and were determined to be sand-sized grains of nuclear fuel and corrosion products. This report provides an examination of the vertical distribution of radioactive particles in the riverbed. Twenty-three dredge samples (representing 1.2 m 2 of riverbed) were collected near the Process Outfall. Each dredge sample was dissected in horizontal intervals 1-cm-thick. Each interval provided a 524 cm 3 sample of sediment that was carefully examined for particulate radioactivity. Approximately 80% of the radioactivity appeared to be associated with discrete particles. Although the natural sediment in the general area is cohesive, silty clay and contains less than 10% sand, the sediment near the Outfall was found to be rich in natural sand, presumably from sources such as winter sanding of roads at the laboratories. The radioactive particles were almost entirely contained in the top-most 10 cm of the river bed. The majority of the particles were found several centimetres beneath the sediment surface and the numbers of particles and the radioactivity of the particles peaked 3 to 7 cm below the sediment surface. Based on the sediment profile, there appeared to have been a marked decrease in the deposition of particulate radioactivity in recent decades. The vertical distribution of radioactive particles indicated that sedimentation is resulting in burial and that the deposition of most of the particulate radioactivity coincided with the operation of Chalk River's NRX reactor from 1947 to 1992. (author)

The influence of pore-water advection, benthic photosynthesis, and respiration on calcium carbonate dynamics in reef sands

NARCIS (Netherlands)

Rao, A.M.F.; Polerecky, L.; Ionescu, D.; Meysman, F.J.R.; de-Beer, D.

2012-01-01

To investigate diel calcium carbonate (CaCO₃) dynamics in permeable coral reef sands, we measured pore-water profiles and fluxes of oxygen (O₂), nutrients, pH, calcium (Ca²⁺), and alkalinity (TA) across the sediment-water interface in sands of different permeability

Field testing, comparison, and discussion of five aeolian sand transport measuring devices operating on different measuring principles

NARCIS (Netherlands)

Goossens, Dirk; Nolet, Corjan; Etyemezian, Vicken; Duarte-campos, Leonardo; Bakker, Gerben; Riksen, Michel

2018-01-01

Five types of sediment samplers designed to measure aeolian sand transport were tested during a wind erosion event on the Sand Motor, an area on the west coast of the Netherlands prone to severe wind erosion. Each of the samplers operates on a different principle. The MWAC (Modified Wilson And

Field testing, comparison, and discussion of five aeolian sand transport measuring devices operation on different measuring priciples

NARCIS (Netherlands)

Goossens, Dirk; Nolet, C.; Etyemezian, Vicken; Duarte-Campos, Leonardo; Bakker, G.; Riksen, M.J.P.M.

2018-01-01

Five types of sediment samplers designed to measure aeolian sand transport were tested during a wind erosion event on the Sand Motor, an area on the west coast of the Netherlands prone to severe wind erosion. Each of the samplers operates on a different principle. The MWAC (Modified Wilson And

Dose rates of beach sands along the Enshu-nada coast

International Nuclear Information System (INIS)

Minato, Susumu; Shimo, Michikuni

2014-01-01

In order to understand the mechanism of beach-to-beach variations in dose rates, measurements at 35 sand beaches were carried out along the Enshu-nada coast (a total of 140km). The sand samples were collected at 10 beaches to obtain the concentrations of potassium, uranium and thorium by means of Ge(Li) spectroscopy. Factors affecting the variation in dose rates were discussed, incorporating these data with data of coastal sea-bottom sediments taken by the Geological Survey of Japan. Two-dimensional measurements were performed at 50 locations each in two beaches near the Tenryu river mouth to know within-beach variations in detail. Contour maps of the data revealed a considerable regularity. It was found from simple analyses of the data collected in this work that the dose rate levels at beaches are affected by the distance from the river mouth, erosion or sedimentation of beach, and depth distribution of seawater. (author)

Desorption of Sr 89, Co 60 and Cs 134 from Suez Canal bottom sediments (Port Tawfeek Area)

International Nuclear Information System (INIS)

El-Assy, N.B.; Abdel-Fattah, A.T.; El-Shinawy, R.M.K.; Essa, M.W.A.

1986-01-01

Chemical and physical properties of Suez Canal Bottom Sediments (S.C.B.S) and seawater at Port Tawfeek, the south entrance of Suez Canal, were studied. The (S.C.B.S) was separated into its size fractions (natural sediment, sand, silt and clay). These different sediment fractions were allowed to be in equilibrium with Strontium 89, Cobalt 60 and Cesium 134 solutions. Desorption studies were carried out on these contaminated sediments. The release of Strontium 89 and Cesium 134 was found to be identical and the sequence of this release was as follows : sand> silt> natural sediment> clay. The effect of seawater is 6-8 times that of bidistilled water. In case of Cobalt 60 the above sequence was disturbed and the salinity effect was only 2 times that of bidistilled water. It was also found that Strontium and Cobalt were more easily desorbed from the sand fraction a behaviour which can be explained by their loose attachment to the crystal surface

The exceptional sediment load of fine-grained dispersal systems: Example of the Yellow River, China.

Science.gov (United States)

Ma, Hongbo; Nittrouer, Jeffrey A; Naito, Kensuke; Fu, Xudong; Zhang, Yuanfeng; Moodie, Andrew J; Wang, Yuanjian; Wu, Baosheng; Parker, Gary

2017-05-01

Sedimentary dispersal systems with fine-grained beds are common, yet the physics of sediment movement within them remains poorly constrained. We analyze sediment transport data for the best-documented, fine-grained river worldwide, the Huanghe (Yellow River) of China, where sediment flux is underpredicted by an order of magnitude according to well-accepted sediment transport relations. Our theoretical framework, bolstered by field observations, demonstrates that the Huanghe tends toward upper-stage plane bed, yielding minimal form drag, thus markedly enhancing sediment transport efficiency. We present a sediment transport formulation applicable to all river systems with silt to coarse-sand beds. This formulation demonstrates a remarkably sensitive dependence on grain size within a certain narrow range and therefore has special relevance to silt-sand fluvial systems, particularly those affected by dams.

The exceptional sediment load of fine-grained dispersal systems: Example of the Yellow River, China

Science.gov (United States)

Ma, Hongbo; Nittrouer, Jeffrey A.; Naito, Kensuke; Fu, Xudong; Zhang, Yuanfeng; Moodie, Andrew J.; Wang, Yuanjian; Wu, Baosheng; Parker, Gary

2017-01-01

Sedimentary dispersal systems with fine-grained beds are common, yet the physics of sediment movement within them remains poorly constrained. We analyze sediment transport data for the best-documented, fine-grained river worldwide, the Huanghe (Yellow River) of China, where sediment flux is underpredicted by an order of magnitude according to well-accepted sediment transport relations. Our theoretical framework, bolstered by field observations, demonstrates that the Huanghe tends toward upper-stage plane bed, yielding minimal form drag, thus markedly enhancing sediment transport efficiency. We present a sediment transport formulation applicable to all river systems with silt to coarse-sand beds. This formulation demonstrates a remarkably sensitive dependence on grain size within a certain narrow range and therefore has special relevance to silt-sand fluvial systems, particularly those affected by dams. PMID:28508078

Gravel Mobility in a High Sand Content Riverbed

Science.gov (United States)

Haschenburger, J. K.

2017-12-01

In sand-gravel channels, sand may modify gravel transport by changing conditions of entrainment and promoting longer displacements or gravel may inhibit sand transport if concentrated into distinct deposits, which restrict sand supply with consequences for migrating bedform size or form. This study reports on gravel mobility in the lower San Antonio River, Texas, where gravel content in the bed material ranges from about 1% to more than 20%. Sediment transport observations were collected at three U.S. Geological Survey gauging stations by deploying a Helley-Smith sampler with a 0.2 mm mesh bag from which transport rates and mobile grain sizes were determined. The flow rates sampled translate into an annual exceedance expectation from 0.2% to 98%. Gravel transport rates are generally two orders of magnitude smaller than the rates of sand transport. However, the finest gravels are transported at rates on the same order of magnitude as the coarsest sands. At all sites, the 2 and 2.8 mm fractions are transported at the lowest flow rate sampled, suggesting mobility for at least 38% to as much as 98% of the year. Fractions as large as 8 mm are mobilized at flow rates that are expected between 25% and 53% of the year. The largest fractions captured in the sampling (16 to 32 mm) require flows closer to bankfull conditions that occur no more than 0.8% of the year. Results document that some gravel sizes can be frequently transported in low gradient riverbeds with high sand content.

Shallow stratigraphy of the Skagit River Delta, Washington, derived from sediment cores

Science.gov (United States)

Grossman, Eric E.; George, Douglas A.; Lam, Angela

2011-01-01

Sedimentologic analyses of 21 sediment cores, ranging from 0.4 to 9.6 m in length, reveal that the shallow geologic framework of the Skagit River Delta, western Washington, United States, has changed significantly since 1850. The cores collected from elevations of 3.94 to -2.41 m (relative to mean lower low water) along four cross-shore transects between the emergent marsh and delta front show relatively similar environmental changes across an area spanning ~75 km2. Offshore of the present North Fork Skagit River and South Fork Skagit River mouths where river discharge is focused by diked channels through the delta, the entire 5–7-km-wide tidal flats are covered with 1–2 m of cross-bedded medium-to-coarse sands. The bottoms of cores, collected in these areas are composed of mud. A sharp transition from mud to a cross-bedded sand unit indicates that the tidal flats changed abruptly from a calm environment to an energetic one. This is in stark contrast to the Martha's Bay tidal flats north of the Skagit Bay jetty that was completed in the 1940s to protect the newly constructed Swinomish Channel from flooding and sedimentation. North of the jetty, mud ranging from 1 to 2 m thick drapes a previously silt- and sand-rich tidal flat. The silty sand is a sediment facies that would be expected there where North Fork Skagit River sedimentation occurred prior to jetty emplacement. This report describes the compositional and textural properties of the sediment cores by using geophysical, photographic, x-radiography, and standard sediment grain-size and carbon-analytical methods. The findings help to characterize benthic habitat structure and sediment transport processes and the environmental changes that have occurred across the nearshore of the Skagit River Delta. The findings will be useful for quantifying changes to nearshore marine resources, including impacts resulting from diking, river-delta channelization, shoreline development, and natural variations in fluvial-sediment

Effect of Suez Canal Marine Sediment on Sorption of Cesium

International Nuclear Information System (INIS)

Hassan, H.B.

2016-01-01

Suez Canal is surrounded by navigation, industrial, agricultural activities and suffers from high rate of population growth that discharging waste into Suez Canal. The Suez Canal coastal waters are influenced by a complex variety of physical, geochemical and biological processes, which influence the behavior, transport and fate of containments released into the marine environment. Sorption of releasing containment such as cesium in Suez Canal water is investigated because of its toxic effect on the marine environment. The object of present study is to determine the effects some of physical and chemical characteristics of collected sediment samples from the three important locations on Suez Canal (Suez Bay, Bitter Lakes and El- Temsah Lake beaches) on sorption behavior of cesium by using batch experiment. Batch experiment was used to study the sorption of the cesium ion. The sorption process is dependent on mineral constituents of Suez Canal sediment and their characteristics. Analytical methods which included particle size and X-ray diffraction (XRD) analyses found that particle size of Suez Canal sediment samples is characterized by sand to fine sand and quartz is the main mineralogical species. Distribution coefficient (K d ) which represent geochemical processes and particle size of these sediment samples effect on the degree of cesium sorption to the sediment. Also (K d ) increase with increase cation exchangeable capacity (CEC). The Suez Canal sediment samples have low (K d ) values which effected by their physical and chemical properties. Sample (2) has highest distribution coefficient (K d ) between measured samples due to containing ratio 30% of fine sand and high ratio of organic matter.

Transformation and fate of microphytobenthos carbon in subtropical shallow subtidal sands: A 13C-labeling study

NARCIS (Netherlands)

Oakes, J.M.; Eyre, B.D.; Middelburg, J.J.

2012-01-01

Microphytobenthos (MPB) in photic sediments are highly productive but the fate of this production remains uncertain. Over 33 d, tracing of 13C from added bicarbonate in subtropical shallow subtidal sand showed rapid transfer of MPB-derived carbon to deeper sediment; below 2 cm (31% within 60 h)

Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: issues of scale, geomorphic setting, and sampling design

Science.gov (United States)

Grams, Paul E.; Topping, David J.; Schmidt, John C.; Hazel, Joseph E.; Kaplinski, Matt

2013-01-01

Measurements of morphologic change are often used to infer sediment mass balance. Such measurements may, however, result in gross errors when morphologic changes over short reaches are extrapolated to predict changes in sediment mass balance for long river segments. This issue is investigated by examination of morphologic change and sediment influx and efflux for a 100 km segment of the Colorado River in Grand Canyon, Arizona. For each of four monitoring intervals within a 7 year study period, the direction of sand-storage response within short morphologic monitoring reaches was consistent with the flux-based sand mass balance. Both budgeting methods indicate that sand storage was stable or increased during the 7 year period. Extrapolation of the morphologic measurements outside the monitoring reaches does not, however, provide a reasonable estimate of the magnitude of sand-storage change for the 100 km study area. Extrapolation results in large errors, because there is large local variation in site behavior driven by interactions between the flow and local bed topography. During the same flow regime and reach-average sediment supply, some locations accumulate sand while others evacuate sand. The interaction of local hydraulics with local channel geometry exerts more control on local morphodynamic response than sand supply over an encompassing river segment. Changes in the upstream supply of sand modify bed responses but typically do not completely offset the effect of local hydraulics. Thus, accurate sediment budgets for long river segments inferred from reach-scale morphologic measurements must incorporate the effect of local hydraulics in a sampling design or avoid extrapolation altogether.

Laboratory observations of sediment transport using combined particle image and tracking velocimetry (Conference Presentation)

Science.gov (United States)

Frank, Donya; Calantoni, Joseph

2017-05-01

Improved understanding of coastal hydrodynamics and morphology will lead to more effective mitigation measures that reduce fatalities and property damage caused by natural disasters such as hurricanes. We investigated sediment transport under oscillatory flow over flat and rippled beds with phase-separated stereoscopic Particle Image Velocimetry (PIV). Standard PIV techniques severely limit measurements at the fluid-sediment interface and do not allow for the observation of separate phases in multi-phase flow (e.g. sand grains in water). We have implemented phase-separated Particle Image Velocimetry by adding fluorescent tracer particles to the fluid in order to observe fluid flow and sediment transport simultaneously. While sand grains scatter 532 nm wavelength laser light, the fluorescent particles absorb 532 nm laser light and re-emit light at a wavelength of 584 nm. Optical long-pass filters with a cut-on wavelength of 550 nm were installed on two cameras configured to perform stereoscopic PIV to capture only the light emitted by the fluorescent tracer particles. A third high-speed camera was used to capture the light scattered by the sand grains allowing for sediment particle tracking via particle tracking velocimetry (PTV). Together, these overlapping, simultaneously recorded images provided sediment particle and fluid velocities at high temporal and spatial resolution (100 Hz sampling with 0.8 mm vector spacing for the 2D-3C fluid velocity field). Measurements were made under a wide range of oscillatory flows over flat and rippled sand beds. The set of observations allow for the investigation of the relative importance of pressure gradients and shear stresses on sediment transport.

Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

Science.gov (United States)

Remo, Jonathan; Heine, Ruben A.; Ickes, Brian

2016-01-01

In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

A new turbulence-based model for sand transport

Science.gov (United States)

Mayaud, Jerome; Wiggs, Giles; Bailey, Richard

2016-04-01

Knowledge of the changing rate of sediment flux in space and time is essential for quantifying surface erosion and deposition in desert landscapes. While many aeolian studies have relied on time-averaged parameters such as wind velocity (U) and wind shear velocity (u*) to determine sediment flux, there is increasing evidence that high-frequency turbulence is an important driving force behind the entrainment and transport of sand. However, turbulence has yet to be incorporated into a functional sand transport model that can be used for predictive purposes. In this study we present a new transport model (the 'turbulence model') that accounts for high-frequency variations in the horizontal (u) and vertical (w) components of wind flow. The turbulence model is fitted to wind velocity and sediment transport data from a field experiment undertaken in Namibia's Skeleton Coast National Park, and its performance at three temporal resolutions (10 Hz, 1 Hz, 1 min) is compared to two existing models that rely on time-averaged wind velocity data (Radok, 1977; Dong et al., 2003). The validity of the three models is analysed under a variety of saltation conditions, using a 2-hour (1 Hz measurement resolution) dataset from the Skeleton Coast and a 5-hour (1 min measurement resolution) dataset from the southwestern Kalahari Desert. The turbulence model is shown to outperform the Radok and Dong models when predicting total saltation count over the three experimental periods. For all temporal resolutions presented in this study (10 Hz-10 min), the turbulence model predicted total saltation count to within at least 0.34%, whereas the Radok and Dong models over- or underestimated total count by up to 5.50% and 20.53% respectively. The strong performance of the turbulence model can be attributed to a lag in mass flux response built into its formulation, which can be adapted depending on the temporal resolution of investigation. This accounts for the inherent lag within the physical

137Cs in northern Adriatic sediments

International Nuclear Information System (INIS)

Barisic, D.; Lulic, S.; Vdovic, N.; Vertacnik, A.; Juracic, M.

1996-01-01

The activity of 137 Cs in shallow northern Adriatic sediments was obtained on the basis of measurement results from 25 sediment box cores, sampled during the Adriatic Scientific COoperation Program (ASCOP) 16 cruise in the summer 1990. 137 Cs was determined in surface sediments (0-3 cm) and 12-15 cm-deep sediment. It was found that the lowest caesium concentrations correspond to sands, which are spread along the Croatian coast. Parallel to the Italian coast, 137 Cs concentrations in pelites are the highest. It seems that the influence of Po River is significant for 137 Cs activities in recent marine sediments along Italian coast south of Po River delta. Significantly higher 137 Cs activities in 0-3 cm sediment layer can be attributed to the deposition caused by Chernobyl accident. (author)

Influence green sand system by core sand additions

Directory of Open Access Journals (Sweden)

N. Špirutová

2012-01-01

Full Text Available Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this contribution is: “How the green sand systems are influenced by core sands?”This effect is considered by determination of selected technological properties and degree of green sand system re-bonding. From the studies, which have been published yet, there is not consistent opinion on influence of core sand dilution on green sand system properties. In order to simulation of the effect of core sands on the technological properties of green sands, there were applied the most common used technologies of cores production, which are based on bonding with phenolic resin. Core sand concentration added to green sand system, was up to 50 %. Influence of core sand dilution on basic properties of green sand systems was determined by evaluation of basic industrial properties: moisture, green compression strength and splitting strength, wet tensile strength, mixture stability against staling and physical-chemistry properties (pH, conductivity, and loss of ignition. Ratio of active betonite by Methylene blue test was also determined.

Historical overview of infantile visceral leishmaniasis in El Agamy, Alexandria, Egypt.

Science.gov (United States)

Kassem, Hala A; Beier, John C; El Sawaf, Bahira M

2017-12-01

Infantile visceral leishmaniasis (IVL) is considered a rare and neglected disease in Egypt. An outbreak of the disease in El Agamy, Alexandria occurred in 1982 although the disease was previously reported 80 years before. Epidemiological and entomological studies were conducted ever since the 1982 outbreak to identify human cases, the parasite, reservoir host and the sand fly vector. Leishmania infantum MON-98, a new and unique zymodeme, was responsible of the disease. Stray dogs acted as the reservoir host and Phlebotomus langeroni was the proven vector. The parasite isolates from human cases were identical to the parasite isolates from the reservoir host and the sand fly vector. The El Agamy focus in 1982 was basically a rural Bedouin setting of recently built cement houses surrounded by lime stone fences. The numbers of human cases of IVL in this area have been declining, with the last reported case in 2005. This coincides with the completion of irregular urbanization of El Agamy which resulted in the disappearance of P. langeroni. In this review, we characterize the old focus of IVL in El Agamy based on published literature to identify factors underlying the appearance and disappearance of the disease. Copyright © 2017 Elsevier B.V. All rights reserved.

lower and Middle Miocene Foraminiferal Paleoecology of Southwest Sinai Area, Egypt

International Nuclear Information System (INIS)

El Ashwah, A.A.E.; Mandur, M.M.; Obeid, F.L.

2005-01-01

The planktonic and benthonic foraminifera content of the lower and middle miocene successions exposed at southwest Sinai in Egypt have been studied. One hundred and thirty three foraminifera species were identified (30 planktonic species and 103 benthonic species). This study aims to contribute in the understanding of the paleoecology, paleobathymetry and tectonic history of these sedimentary sequences. These sediments are subdivided into four rock units, from base to top, as follow: Nukhul, Rudeis, Kareem and Balayim formations. According to the foraminifera content the studied successions are subdivided into five eco zones. The environment of each ec ozone is deduced. These environments point to outer neritic for the Nukhul formation, middle to inner neritic for the Rudeis formation, inner to littoral neritic for the Kareem formation and littoral neritic for the Belayim formation. A proposed paleobathymetric curve is presented. The interpretation of this curve helped to deduce the tectonic history of the lower and Middle Miocene sediments in the studied area

Sediment Sources and Transport Pathway Identification Based on Grain-Size Distributions on the SW Coast of Portugal

Directory of Open Access Journals (Sweden)

Xiaoqin Du

2015-01-01

Full Text Available Espichel-Sines is an embayed coast in SW Portugal, consisting of two capes at both extremities, a tidal inlet and associated ebb tidal delta, a barrier spit, sandy beaches, sea cliffs, and a submarine canyon. Beach berm, backshore, near shore and inner shelf sediment samples were taken. Samples were analyzed for their grain-size compositions. This study ranks the hypothetical sediment sources influences on the sediment distributions in the study area using the multivariate Empirical Orthogonal Function (EOF techniques. Transport pathways in this study were independently identified using the grain size trend analysis (GSTA technique to verify the EOF findings. The results show that the cliff-erosion sediment is composed of pebbles and sand and is the most important sediment source for the entire embayment. The sediment at the inlet mouth is a mixture of pebbles, sand, silt, and clay, which is a minor sediment source that only has local influence. The overall grain-size distributions on the shelf are dominated by the sand except for the high mud content around the tidal delta front in the northern embayment. Sediment transport patterns on the inner shelf at the landward and north sides of the canyon head are landward and northward along the barrier spit, respectively. On the south side of the canyon head, the prevailing sediment transport is seaward. Sediment transport occurs in both directions along the shore.

Research on the cavitation characteristic of Kaplan turbine under sediment flow condition

International Nuclear Information System (INIS)

Weili, L; Jinling, L; Xingqi, L; Yuan, L

2010-01-01

The sediment concentration in many rivers in our world is very high, and the Kaplan turbine running in these rivers are usually seriously abraded. Since the existence of sand, the probability of cavitation is greatly enhanced. Under the joint action and mutual promotion of cavitation and sand erosion, serious abrasion could be made, the hydraulic performance of the Kaplan turbine may be descended, and the safety and stability of turbine are greatly threatened. Therefore, it is very important and significant to investigate the cavitation characteristic of Kaplan turbine under sediment flow condition. In this paper, numerical simulation of cavitation characteristic in pure water and solid-liquid two-phase flow in Kaplan turbine was performed. The solid-liquid two-fluid model were adopted in the numerical simulation, and the pressure, velocity and particle concentration distributive regularity on turbine blade surface under different diameter and concentration was revealed. Particle trajectory model was used to investigate the region and degree of runner blade abrasion in different conditions. The results showed that serious sand abrasion could be found near the blade head and outlet in large flow rate working condition. Relatively slight abrasion may be found near blade flange in small flow rate working condition. The more the sediment concentration and the large the sand diameter, the serious the runner is abraded, and the greater the efficiency is decreased. further analysis of the combined effects of wear and abrasion was performed. The result shows that the cavitation in silt flow is more serious than in pure water. The runner cavitation performance become worse under high sand concentration and large particle diameter, and the efficiency decrease greatly with the increase of sediment concentration.

Research on the cavitation characteristic of Kaplan turbine under sediment flow condition

Energy Technology Data Exchange (ETDEWEB)

Weili, L; Jinling, L; Xingqi, L; Yuan, L, E-mail: liaoweili2004@163.co [Institute of Water Resources and Hydro-Electric Engineering, Xi' an University of Technology No.5 South Jinhua Road, Xi' an, Shaanxi, 710048 (China)

2010-08-15

The sediment concentration in many rivers in our world is very high, and the Kaplan turbine running in these rivers are usually seriously abraded. Since the existence of sand, the probability of cavitation is greatly enhanced. Under the joint action and mutual promotion of cavitation and sand erosion, serious abrasion could be made, the hydraulic performance of the Kaplan turbine may be descended, and the safety and stability of turbine are greatly threatened. Therefore, it is very important and significant to investigate the cavitation characteristic of Kaplan turbine under sediment flow condition. In this paper, numerical simulation of cavitation characteristic in pure water and solid-liquid two-phase flow in Kaplan turbine was performed. The solid-liquid two-fluid model were adopted in the numerical simulation, and the pressure, velocity and particle concentration distributive regularity on turbine blade surface under different diameter and concentration was revealed. Particle trajectory model was used to investigate the region and degree of runner blade abrasion in different conditions. The results showed that serious sand abrasion could be found near the blade head and outlet in large flow rate working condition. Relatively slight abrasion may be found near blade flange in small flow rate working condition. The more the sediment concentration and the large the sand diameter, the serious the runner is abraded, and the greater the efficiency is decreased. further analysis of the combined effects of wear and abrasion was performed. The result shows that the cavitation in silt flow is more serious than in pure water. The runner cavitation performance become worse under high sand concentration and large particle diameter, and the efficiency decrease greatly with the increase of sediment concentration.

Research on the cavitation characteristic of Kaplan turbine under sediment flow condition

Science.gov (United States)

Weili, L.; Jinling, L.; Xingqi, L.; Yuan, L.

2010-08-01

The sediment concentration in many rivers in our world is very high, and the Kaplan turbine running in these rivers are usually seriously abraded. Since the existence of sand, the probability of cavitation is greatly enhanced. Under the joint action and mutual promotion of cavitation and sand erosion, serious abrasion could be made, the hydraulic performance of the Kaplan turbine may be descended, and the safety and stability of turbine are greatly threatened. Therefore, it is very important and significant to investigate the cavitation characteristic of Kaplan turbine under sediment flow condition. In this paper, numerical simulation of cavitation characteristic in pure water and solid-liquid two-phase flow in Kaplan turbine was performed. The solid-liquid two-fluid model were adopted in the numerical simulation, and the pressure, velocity and particle concentration distributive regularity on turbine blade surface under different diameter and concentration was revealed. Particle trajectory model was used to investigate the region and degree of runner blade abrasion in different conditions. The results showed that serious sand abrasion could be found near the blade head and outlet in large flow rate working condition. Relatively slight abrasion may be found near blade flange in small flow rate working condition. The more the sediment concentration and the large the sand diameter, the serious the runner is abraded, and the greater the efficiency is decreased. further analysis of the combined effects of wear and abrasion was performed. The result shows that the cavitation in silt flow is more serious than in pure water. The runner cavitation performance become worse under high sand concentration and large particle diameter, and the efficiency decrease greatly with the increase of sediment concentration.

Sand transport in the lower Mississippi River does not yield to dams: Applications for building deltaic land in Louisiana

Science.gov (United States)

Nittrouer, J. A.; Viparelli, E.

2013-12-01

The Mississippi Delta is presently undergoing a catastrophic drowning, whereby 5000 km2 of low-lying wetlands have converted to open water. This land loss is primarily the result of: a) relative sea-level rise, occurring due to the combined effect of rapid subsidence associated with subsurface fluids extraction and eustatic rise; b) leveeing and damming of the river and its tributaries, which restricts sediment delivery to and dispersal within the delta; and c) severe excavation of the delta for navigation channels. It has been argued that continued net land loss of the Mississippi Delta is inevitable due to declining measured total (sand and mud) suspended sediment loads over the past 6 decades. However, recent research has documented that the key to delta growth is deposition of sand, which accounts for ~50-70% of modern and ancient (up to 9 m.a.) Mississippi Delta deposits, but comprises only ~20% of the sampled portion of the total load. Here we present new analysis of existing data to show that sand transport has not diminished since dam construction. Furthermore, we produce a numerical model based on the mass balance of bed material loads over the lower 1600 km of the Mississippi River to show that mining of sand from the channel bed continues to replenish downstream sand loads. For example, our model results indicate that it requires approximately 240 years for a reduced sand load to reach the delta apex. Furthermore, our calculations indicate that sand load at the delta apex is reduced by a noticeable amount (17%) only after about 600 years. We also show how channel bed elevations are predicted to change over the lower 1600 km of the river channel due to channel mining. Channel-bed degradation is greatest at the upstream end of the study reach and decreases downstream. After 300 years the wave of significant degradation has just passed ~800 km downstream, or roughly half of our model domain. These results are in contrast to the measurements which concern

Characterizing riverbed sediment using high-frequency acoustics 2: scattering signatures of Colorado River bed sediment in Marble and Grand Canyons

Science.gov (United States)

Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matt A.

2014-01-01

In this, the second of a pair of papers on the statistical signatures of riverbed sediment in high-frequency acoustic backscatter, spatially explicit maps of the stochastic geometries (length- and amplitude-scales) of backscatter are related to patches of riverbed surfaces composed of known sediment types, as determined by geo-referenced underwater video observations. Statistics of backscatter magnitudes alone are found to be poor discriminators between sediment types. However, the variance of the power spectrum, and the intercept and slope from a power-law spectral form (termed the spectral strength and exponent, respectively) successfully discriminate between sediment types. A decision-tree approach was able to classify spatially heterogeneous patches of homogeneous sands, gravels (and sand-gravel mixtures), and cobbles/boulders with 95, 88, and 91% accuracy, respectively. Application to sites outside the calibration, and surveys made at calibration sites at different times, were plausible based on observations from underwater video. Analysis of decision trees built with different training data sets suggested that the spectral exponent was consistently the most important variable in the classification. In the absence of theory concerning how spatially variable sediment surfaces scatter high-frequency sound, the primary advantage of this data-driven approach to classify bed sediment over alternatives is that spectral methods have well understood properties and make no assumptions about the distributional form of the fluctuating component of backscatter over small spatial scales.

Analysis of Sedimentation Rates in the Densu River Channel: The ...

African Journals Online (AJOL)

Sediment is important in determining the morphology of river systems. The Densu basin has come under intense anthropogenic activities such as farming, sand winning, bushfires, among others, which are impacting on the fluvial processes, forms and channel morphology of the river. The study investigated sedimentation of ...

Direct sampling during multiple sediment density flows reveals dynamic sediment transport and depositional environment in Monterey submarine canyon

Science.gov (United States)

Maier, K. L.; Gales, J. A.; Paull, C. K.; Gwiazda, R.; Rosenberger, K. J.; McGann, M.; Lundsten, E. M.; Anderson, K.; Talling, P.; Xu, J.; Parsons, D. R.; Barry, J.; Simmons, S.; Clare, M. A.; Carvajal, C.; Wolfson-Schwehr, M.; Sumner, E.; Cartigny, M.

2017-12-01

Sediment density flows were directly sampled with a coupled sediment trap-ADCP-instrument mooring array to evaluate the character and frequency of turbidity current events through Monterey Canyon, offshore California. This novel experiment aimed to provide links between globally significant sediment density flow processes and their resulting deposits. Eight to ten Anderson sediment traps were repeatedly deployed at 10 to 300 meters above the seafloor on six moorings anchored at 290 to 1850 meters water depth in the Monterey Canyon axial channel during 6-month deployments (October 2015 - April 2017). Anderson sediment traps include a funnel and intervalometer (discs released at set time intervals) above a meter-long tube, which preserves fine-scale stratigraphy and chronology. Photographs, multi-sensor logs, CT scans, and grain size analyses reveal layers from multiple sediment density flow events that carried sediment ranging from fine sand to granules. More sediment accumulation from sediment density flows, and from between flows, occurred in the upper canyon ( 300 - 800 m water depth) compared to the lower canyon ( 1300 - 1850 m water depth). Sediment accumulated in the traps during sediment density flows is sandy and becomes finer down-canyon. In the lower canyon where sediment directly sampled from density flows are clearly distinguished within the trap tubes, sands have sharp basal contacts, normal grading, and muddy tops that exhibit late-stage pulses. In at least two of the sediment density flows, the simultaneous low velocity and high backscatter measured by the ADCPs suggest that the trap only captured the collapsing end of a sediment density flow event. In the upper canyon, accumulation between sediment density flow events is twice as fast compared to the lower canyon; it is characterized by sub-cm-scale layers in muddy sediment that appear to have accumulated with daily to sub-daily frequency, likely related to known internal tidal dynamics also measured

Quantifying the effects of European beach grass on aeolian sand transport over the last century: Bodega Marine Reserve, California

Science.gov (United States)

Cesmat, R.; Werner, S.; Smith, M. E.; Riedel, T.; Best, R.; Olyarnik, S.

2012-12-01

Introduction of European beach grass (Ammophila arenaria) to coastal dune systems of western North America induced significant changes to the transport and storage of sediment, and consequently the nesting habitat of the western snowy plover (Charadrius alexandrinus nivosus). At the Bodega Marine Reserve and Sonoma Coast State Park, Ammophila was introduced within the ~0.5 km2 dune area in the 1920's to limit the flux of sand through Bodega Harbor and agricultural land. To assess the potential impact of restoration efforts (Ammophila removal) on aeolian sediment flux, we measured sediment flux as a function of wind speeds and ground cover, and used these measurements to parameterize a spatial model for historical sand deposition Fine- to coarse-grained lithic to sub-lithic sand is delivered to the Bodega dune system from Salmon Creek beach, the down-shore terminus of a littoral system fed by the 3846 km2 Russian River catchment, several small (Gaffney ridge) at the edge of the planted region. An average accumulation rate of ~4,000 m3/yr is indicated within the study swath by the preserved sediment volumes. Within the modern dune system, unvegetated areas exhibit 2-3 meter wavelength, ~1/2 meter amplitude mega-ripples, and the uppermost 2-10 cm consists of coarse-sand to granule-sized armor layer. In contrast, grain-sizes in vegetated areas are largely vertically homogenous. Open areas are typically 2-8 meters lower than adjacent vegetated areas, and show evidence for net lowering of the land surface (i.e., exposed fence posts, roots). Conversely, vegetated areas appear prone to sediment accumulation, particularly downwind of unvegetated areas. We measured sand transport using 0.5 m high traps deployed at 18 sites throughout the dune field, and used a linear mixed effects model to predict transport rate as a function of wind and ground cover class, taking into account random effects of sampling date and repeated measurements at each site. The analysis indicates up

Numerical simulation of mechanical compaction of deepwater shallow sediments

Science.gov (United States)

Sun, Jin; Wu, Shiguo; Deng, Jingen; Lin, Hai; Zhang, Hanyu; Wang, Jiliang; Gao, Jinwei

2018-02-01

To study the compaction law and overpressure evolution in deepwater shallow sediments, a large-strain compaction model that considers material nonlinearity and moving boundary is formulated. The model considers the dependence of permeability and material properties on void ratio. The modified Cam-Clay model is selected as the constitutive relations of the sediments, and the deactivation/reactivation method is used to capture the moving top surface during the deposition process. A one-dimensional model is used to study the compaction law of the shallow sediments. Results show that the settlement of the shallow sediments is large under their own weight during compaction. The void ratio decreases strictly with burial depth and decreases more quickly near the seafloor than in the deeper layers. The generation of abnormal pressure in the shallow flow sands is closely related to the compaction law of shallow sediments. The two main factors that affect the generation of overpressure in the sands are deposition rate and permeability of overlying clay sediments. Overpressure increases with an increase in deposition rate and a decrease in the permeability of the overlying clay sediment. Moreover, an upper limit for the overpressure exists. A two-dimensional model is used to study the differential compaction of the shallow sediments. The pore pressure will still increase due to the inflow of the pore fluid from the neighboring clay sediment even though the deposition process is interrupted.

The sediment accumulation rates measured in Lake Poyang using 210Pb dating method

International Nuclear Information System (INIS)

Wang Xiuyu; Zeng Erkang; Wan Yusong; Liu Xiaosong

1987-01-01

The sediment accumulation rates were estimated from the vertical distribution of excess 210 Pb measured in sediment cores collected from Lake Poyang, Jiangxi Provence of China. These rates were various with the differences in hydrology. The sedimentation rates are the lowest in the middle region of the lake, in which the rates could not be determined from the two samples and the other one is 0.14 cm/a. The sedimentation rates are lower in the northeast basin section, averaging to 0.19 cm/a. The sediment rates in the diffusion area of the lake from which 5 rivers enter sand deposion is more than the rates in other areas of the lake (0.08 cm/a to 0.28 cm/a) and the hydrology factors are various. Because of the sand from the Yangzhi River the sedimentation rates are the highest in the water-way section of the lake, averaging from 0.23 to 0.62 cm/a

The preglacial sediment record of Lake Ladoga, NW Russia - first results from a multi-proxy study on a 23 m sediment record

Science.gov (United States)

Gromig, R.; Melles, M.; Wagner, B.; Krastel, S.; Andreev, A.; Fedorov, G.; Just, J.; Wennrich, V.; Savelieva, L.; Subetto, D.; Shumilovskikh, L.

2016-12-01

The joint German-Russian project 'PLOT - Paleolimnological Transect' aims to recover lake sediment sequences along a more than 6000 km long longitudinal transect across the Eurasian Arctic in order to study the Late Quaternary climatic and environmental history. The eastern end of the PLOT transect is formed by the well-studied record from Lake El'gygytgyn (NE Siberia). Lake Ladoga (N 60°50' E 31°30') is Europe's largest lake, both by size and volume and forms the westernmost end of the transect. Whereas modern sedimentation as well as the Holocene and Late Glacial history of Lake Ladoga have intensely been studied, the preglacial history of the lake is poorly studied to date by sediment cores drilled in the 1930's. A seismic survey of Lake Ladoga in summer 2013 revealed unconformities in the western lake basin, which may separate preglacial sediments in isolated depressions from Late Glacial and Holocene sediment successions above. A 23 m long sediment core (Co1309) was retrieved from one of these depressions. Core Co1309 was investigated by XRF-scanning, magnetic susceptibility measurements, as well as pollen, grain-size, and bio-geochemical analyses. An age-depth model combining radiocarbon, OSL, and paleomagnetic dates is in progress. Both, the pollen results and the OSL ages from the base of the record indicate a deposition during MIS 5e (Eemian). The well sorted reddish sands from this interval contain dinoflagellates suggesting at least brackish conditions, likely due to the existence of a gateway connecting a precursor of the Baltic Sea with the White Sea via Lake Ladoga. The Late Glacial sequence consists of greyish varved clays of decreasing thickness upwards with sporadically intercalated sand layers. The Holocene sequence is composed of brownish diatomaceous silty clay with minor proportions of sand.

Impact of erosion and accretion on the distribution of enterococci in beach sands.

Science.gov (United States)

Gast, Rebecca J; Gorrell, Levi; Raubenheimer, Britt; Elgar, Steve

2011-09-15

Bacterial pathogens in coastal sediments may pose a health risk to users of beaches. Although recent work shows that beach sands harbor both indicator bacteria and potential pathogens, it is not known how deep within beach sands the organisms may persist nor if they may be exposed during natural physical processes. In this study, sand cores of approximately 1 m depth were collected at three sites across the beach face in Kitty Hawk, North Carolina before, during and after large waves from an offshore hurricane. The presence of DNA from the fecal indicator bacterium Enterococci was detected in subsamples at different depths within the cores by PCR amplification. Erosion and accretion of beach sand at the three sites also was determined for each sampling day. The results indicate that ocean beach sands with persisting enterococci signals could be exposed and redistributed when wind, waves, and currents cause beach erosion or accretion.

Highstand shelf fans: The role of buoyancy reversal in the deposition of a new type of shelf sand body

Science.gov (United States)

Steel, Elisabeth; Simms, Alexander R.; Warrick, Jonathan; Yokoyama, Yusuke

2016-01-01

Although sea-level highstands are typically associated with sediment-starved continental shelves, high sea level does not hinder major river floods. Turbidity currents generated by plunging of sediment-laden rivers at the fluvial-marine interface, known as hyperpycnal flows, allow for cross-shelf transport of suspended sand beyond the coastline. Hyperpycnal flows in southern California have deposited six subaqueous fans on the shelf of the northern Santa Barbara Channel in the Holocene. Using eight cores and nine grab samples, we describe the deposits, age, and stratigraphic architecture of two fans in the Santa Barbara Channel. Fan lobes have up to 3 m of relief and are composed of multiple hyperpycnite beds ∼5 cm to 40 cm thick. Deposit architecture and geometry suggest the hyperpycnal flows became positively buoyant and lifted off the seabed, resulting in well-sorted, structureless, elongate sand lobes. Contrary to conventional sequence stratigraphic models, the presence of these features on the continental shelf suggests that active-margin shelves may locally develop high-quality reservoir sand bodies during sea-level highstands, and that such shelves need not be solely the site of sediment bypass. These deposits may provide a Quaternary analogue to many well-sorted sand bodies in the rock record that are interpreted as turbidites but lack typical Bouma-type features.

Evaluation of methods to sample fecal indicator bacteria in foreshore sand and pore water at freshwater beaches.

Science.gov (United States)

Vogel, Laura J; Edge, Thomas A; O'Carroll, Denis M; Solo-Gabriele, Helena M; Kushnir, Caitlin S E; Robinson, Clare E

2017-09-15

Fecal indicator bacteria (FIB) are known to accumulate in foreshore beach sand and pore water (referred to as foreshore reservoir) where they act as a non-point source for contaminating adjacent surface waters. While guidelines exist for sampling surface waters at recreational beaches, there is no widely-accepted method to collect sand/sediment or pore water samples for FIB enumeration. The effect of different sampling strategies in quantifying the abundance of FIB in the foreshore reservoir is unclear. Sampling was conducted at six freshwater beaches with different sand types to evaluate sampling methods for characterizing the abundance of E. coli in the foreshore reservoir as well as the partitioning of E. coli between different components in the foreshore reservoir (pore water, saturated sand, unsaturated sand). Methods were evaluated for collection of pore water (drive point, shovel, and careful excavation), unsaturated sand (top 1 cm, top 5 cm), and saturated sand (sediment core, shovel, and careful excavation). Ankle-depth surface water samples were also collected for comparison. Pore water sampled with a shovel resulted in the highest observed E. coli concentrations (only statistically significant at fine sand beaches) and lowest variability compared to other sampling methods. Collection of the top 1 cm of unsaturated sand resulted in higher and more variable concentrations than the top 5 cm of sand. There were no statistical differences in E. coli concentrations when using different methods to sample the saturated sand. Overall, the unsaturated sand had the highest amount of E. coli when compared to saturated sand and pore water (considered on a bulk volumetric basis). The findings presented will help determine the appropriate sampling strategy for characterizing FIB abundance in the foreshore reservoir as a means of predicting its potential impact on nearshore surface water quality and public health risk. Copyright © 2017 Elsevier Ltd. All rights

Large submarine sand waves and gravel lag substrates on Georges Bank off Atlantic Canada

Science.gov (United States)

Todd, B.J.; Valentine, Page C.; Harris, Peter T; Baker, E.K.

2012-01-01

Georges Bank is a large, shallow, continental shelf feature offshore of New England and Atlantic Canada. The bank is mantled with a veneer of glacial debris transported during the late Pleistocene from continental areas lying to the north. These sediments were reworked by marine processes during postglacial sea-level transgression and continue to be modified by the modern oceanic regime. The surficial geology of the Canadian portion of the bank is a widespread gravel lag overlain in places by well sorted sand occurring as bedforms. The most widespread bedforms are large, mobile, asymmetrical sand waves up to 19 m in height formed through sediment transport by strong tidal-driven and possibly storm-driven currents. Well-defined curvilinear bedform crests up to 15 km long form a complex bifurcating pattern having an overall southwest–northeast strike, which is normal to the direction of the major axis of the semidiurnal tidal current ellipse. Minor fields of immobile, symmetrical sand waves are situated in bathymetric lows. Rare mobile, asymmetrical barchan dunes are lying on the gravel lag in areas of low sand supply. On Georges Bank, the management of resources and habitats requires an understanding of the distribution of substrate types, their surface dynamics and susceptibility to movement, and their associated fauna.

Tracing cohesive sediment transportation at river mouths around Tokyo, Japan by Cesium originated from Fukushima Daiichi Power Plant

Science.gov (United States)

koibuchi, Y.

2012-12-01

Sediment transport at river mouths, which consists of suspended-load and bed-load, has not been fully understood, since bed-load transport of cohesive sand is difficult to observe. Especially, the impact of sediment transport on the total amount of fine-grained cohesive sediment has not been elucidated. Cesium-134 and cesium-137 were spread from the Fukushima Daiichi Nuclear Power Plant (FDNPP) after the earthquake of March 11 of 2011, and attached to the fine-grained sand on the land. The contaminated sand flowed into the river mouths through the rivers possibly due to the complex physical processes in estuarine areas. To evaluate the fine-grained sediment transport around Tokyo and Tokyo Bay, field observations were carried out utilizing radionuclide originated from FDNPP as an effective tracer. The cohesive sediment transport at three different river mouths around Tokyo was successfully quantified. The cohesive sediment transport deposited in the estuary was found to be greatly dependent on the land use, geometry, river discharge and salinity. In addition,the transport driven by the rainfall was minute, and its behavior was quite different from suspended solids. Although further field observations of radionuclide are necessary, it is clear that fine-grained sediment in the bay from rivers already settled on the river mouth by aggregation. The settled sand will not move even in rainfall events. Consequently, the transport of radionuclide to the Pacific Ocean may not occur.; Cesium distribution around Tokyo Bay ; Cesium Concentration in Edogawa river

A new macrofaunal limit in the deep biosphere revealed by extreme burrow depths in ancient sediments.

Science.gov (United States)

Cobain, S L; Hodgson, D M; Peakall, J; Wignall, P B; Cobain, M R D

2018-01-10

Macrofauna is known to inhabit the top few 10s cm of marine sediments, with rare burrows up to two metres below the seabed. Here, we provide evidence from deep-water Permian strata for a previously unrecognised habitat up to at least 8 metres below the sediment-water interface. Infaunal organisms exploited networks of forcibly injected sand below the seabed, forming living traces and reworking sediment. This is the first record that shows sediment injections are responsible for hosting macrofaunal life metres below the contemporaneous seabed. In addition, given the widespread occurrence of thick sandy successions that accumulate in deep-water settings, macrofauna living in the deep biosphere are likely much more prevalent than considered previously. These findings should influence future sampling strategies to better constrain the depth range of infaunal animals living in modern deep-sea sands. One Sentence Summary: The living depth of infaunal macrofauna is shown to reach at least 8 metres in new habitats associated with sand injections.

Barriers on the brink? The complex intertwined roles of geologic framework, sediment availability and sea-level rise in island evolution

Science.gov (United States)

Moore, Laura; List, Jeffrey H.; Williams, S. Jeffress; Patsch, Kiki; Rosati, Julie D.; Wang, Ping; Roberts, Tiffany M.

2011-01-01

Sensitivity experiments in the North Carolina Outer Banks (OBX) have previously revealed that substrate sand proportion, followed by substrate slope, sea-level rise rate and sediment-loss rate are the most important factors in determining how barrier islands respond to sea-level rise. High sediment-loss rates and low substrate sand proportions cause barriers to be smaller and more deeply incised. Thus, as sea level rise rates increase, more deeply incised barriers do not need to migrate as far landward as larger, less-incised barriers to liberate sand from the shoreface. However, if the combination of sand losses and substrate sand proportions requires a barrier to migrate landward faster than the shoreface can erode to replenish losses, a barrier will change state and begin to disintegrate. Because the substrate of the OBXis sand-rich, these barriers are likely to persist in the near-term. In contrast, model simulations for the Chandeleur Islands, Louisiana suggest sediment loss rates are too high and/or substrate sand proportions are too low to be matched by liberation of shoreface sand. These simulations further suggest that a state change, from a landward-migrating barrier system to a subaqueous shoal complex, is either already underway or imminent.

Sand Resources, Regional Geology, and Coastal Processes of the Chandeleur Islands Coastal System: an Evaluation of the Breton National Wildlife Refuge

Science.gov (United States)

Lavoie, Dawn

2009-01-01

Breton National Wildlife Refuge, the Chandeleur Islands chain in Louisiana, provides habitat and nesting areas for wildlife and is an initial barrier protecting New Orleans from storms. The U.S. Geological Survey (USGS) in partnership with the University of New Orleans Pontchartrain Institute for Environmental Sciences undertook an intensive study that included (1) an analysis of island change based on historical maps and remotely sensed shoreline and topographic data; (2) a series of lidar surveys at 3- to 4-month intervals after Hurricane Katrina to determine barrier island recovery potential; (3) a discussion of sea level rise and effects on the islands; (4) an analysis of sea floor evolution and sediment dynamics in the refuge over the past 150 years; (5) an assessment of the local sediment transport and sediment resource availability based on the bathymetric and subbottom data; (6) a carefully selected core collection effort to groundtruth the geophysical data and more fully characterize the sediments composing the islands and surrounds; (7) an additional survey of the St. Bernard Shoals to assess their potential as a sand resource; and (8) a modeling study to numerically simulate the potential response of the islands to the low-intensity, intermediate, and extreme events likely to affect the refuge over the next 50 years. Results indicate that the islands have become fragmented and greatly diminished in subaerial extent over time: the southern islands retreating landward as they reorganize into subaerial features, the northern islands remaining in place. Breton Island, because maintenance of the Mississippi River-Gulf Outlet (MRGO) outer bar channel requires dredging, is deprived of sand sufficient to sustain itself. Regional sediment transport trends indicate that large storms are extremely effective in transporting sand and controlling the shoreline development and barrier island geometry. Sand is transported north and south from a divergent zone near

Increased sediment load during a large-scale dam removal changes nearshore subtidal communities.

Directory of Open Access Journals (Sweden)

Stephen P Rubin

Full Text Available The coastal marine ecosystem near the Elwha River was altered by a massive sediment influx-over 10 million tonnes-during the staged three-year removal of two hydropower dams. We used time series of bathymetry, substrate grain size, remotely sensed turbidity, scuba dive surveys, and towed video observations collected before and during dam removal to assess responses of the nearshore subtidal community (3 m to 17 m depth. Biological changes were primarily driven by sediment deposition and elevated suspended sediment concentrations. Macroalgae, predominantly kelp and foliose red algae, were abundant before dam removal with combined cover levels greater than 50%. Where persistent sediment deposits formed, macroalgae decreased greatly or were eliminated. In areas lacking deposition, macroalgae cover decreased inversely to suspended sediment concentration, suggesting impacts from light reduction or scour. Densities of most invertebrate and fish taxa decreased in areas with persistent sediment deposition; however, bivalve densities increased where mud deposited over sand, and flatfish and Pacific sand lance densities increased where sand deposited over gravel. In areas without sediment deposition, most invertebrate and fish taxa were unaffected by increased suspended sediment or the loss of algae cover associated with it; however, densities of tubeworms and flatfish, and primary cover of sessile invertebrates increased suggesting benefits of increased particulate matter or relaxed competition with macroalgae for space. As dam removal neared completion, we saw evidence of macroalgal recovery that likely owed to water column clearing, indicating that long-term recovery from dam removal effects may be starting. Our results are relevant to future dam removal projects in coastal areas and more generally to understanding effects of increased sedimentation on nearshore subtidal benthic communities.

Increased sediment load during a large-scale dam removal changes nearshore subtidal communities

Science.gov (United States)

Rubin, Stephen P.; Miller, Ian M.; Foley, Melissa M.; Berry, Helen D.; Duda, Jeffrey J.; Hudson, Benjamin; Elder, Nancy E.; Beirne, Matthew M.; Warrick, Jonathan; McHenry, Michael L.; Stevens, Andrew; Eidam, Emily; Ogston, Andrea; Gelfenbaum, Guy R.; Pedersen, Rob

2017-01-01

The coastal marine ecosystem near the Elwha River was altered by a massive sediment influx—over 10 million tonnes—during the staged three-year removal of two hydropower dams. We used time series of bathymetry, substrate grain size, remotely sensed turbidity, scuba dive surveys, and towed video observations collected before and during dam removal to assess responses of the nearshore subtidal community (3 m to 17 m depth). Biological changes were primarily driven by sediment deposition and elevated suspended sediment concentrations. Macroalgae, predominantly kelp and foliose red algae, were abundant before dam removal with combined cover levels greater than 50%. Where persistent sediment deposits formed, macroalgae decreased greatly or were eliminated. In areas lacking deposition, macroalgae cover decreased inversely to suspended sediment concentration, suggesting impacts from light reduction or scour. Densities of most invertebrate and fish taxa decreased in areas with persistent sediment deposition; however, bivalve densities increased where mud deposited over sand, and flatfish and Pacific sand lance densities increased where sand deposited over gravel. In areas without sediment deposition, most invertebrate and fish taxa were unaffected by increased suspended sediment or the loss of algae cover associated with it; however, densities of tubeworms and flatfish, and primary cover of sessile invertebrates increased suggesting benefits of increased particulate matter or relaxed competition with macroalgae for space. As dam removal neared completion, we saw evidence of macroalgal recovery that likely owed to water column clearing, indicating that long-term recovery from dam removal effects may be starting. Our results are relevant to future dam removal projects in coastal areas and more generally to understanding effects of increased sedimentation on nearshore subtidal benthic communities.

Evolution of a sediment wave in an experimental channel

Science.gov (United States)

Thomas E. Lisle; James E. Pizzuto; Hiroshi Ikeda; Fujiko Iseya; Yoshinori Kodama

1997-01-01

Abstract - The routing of bed material through channels is poorly understood. We approach the problem by observing and modeling the fate of a low-amplitude sediment wave of poorly sorted sand that we introduced into an experimental channel transporting sediment identical to that of the introduced wave. The wave essentially dispersed upstream and downstream without...

Three-dimensional simulation of flow, salinity, sediment, and radionuclide movements in the Hudson River estuary

International Nuclear Information System (INIS)

Onishi, Y.; Trent, D.S.

1985-04-01

The three-dimensional, finite difference model, FLESCOT simulates time-varying movements of flow, turbulent kinetic energy, salinity, water temperature, sediment, and contaminants in estuarine, coastal, and ocean waters. The model was applied to a 106-km (66-mi) reach of the Hudson River estuary in New York between Chelsea and the mouth of the river. It predicted the time-varying, three-dimensional distributions of tidal flow, salinity, three separate groups of sediments (i.e., sand, silt, and clay), and a radionuclide ( 137 Cs) in both dissolved and particulate (those sorbed by sediments) forms for over 40 days. The model also calculated riverbed elevation changes caused by sediment deposition and bed erosion, bed sediment size distribution and armoring, and distributions of the particulate 137 Cs sorbed by sand, silt, and clay in the bed

Turbulent flow structures and aeolian sediment transport over a barchan sand dune

Science.gov (United States)

Wiggs, G. F. S.; Weaver, C. M.

2012-03-01

The turbulent structure of airflow over a barchan sand dune is determined using quadrant analysis of wind velocity data derived from sonic anemometers. Results indicate an increased frequency of ejection and sweep events in the toe region of the dune, characteristic of the turbulent bursting process. In contrast, at the crest there was a significant increase in the occurrence of outward interactions. Combined with high frequency saltation data our analyses show that turbulent structures characterised by a positive streamwise fluctuating velocity (+u‧ sweeps at the toe and outward interactions at the crest) have a dominant influence on sand transport on the dune, together accounting for up to 83% and 95% of transporting events at the toe and crest respectively.

Gas industry development in Egypt

International Nuclear Information System (INIS)

Roze, J.; Longueville, P.

2000-01-01

Egypt is a country with major gas potential and its gas industry has grown rapidly over the last ten years. Proven natural gas reserves total an estimated 1,050 billion m 3 . According to the re-evaluation of reserves made in January 2000, probable reserves stand at 3,400 billion m 3 , placing Egypt in ninth position as a potential world producer. These reserves are contained in 120 fields located mainly in the Nile Delta and Mediterranean regions and, to a lesser extent, in the Western Desert and the Gulf of Suez. Over the last two years, 54 new gas field have been discovered and registered. Consumption of oil, Egypt's main primary energy source, has declined steadily since the early 1980's in favour of natural gas, which has enjoyed steady growth. The penetration of natural gas is due to the growth of industries consuming large quantities of gas (chemical, fertilizers, etc), the development of new gas fields and the use of gas as a substitute for oil and coal, especially in the power industry which accounts for a major share of energy consumption, i.e., two-thirds of production in 1997. However, as Egypt is currently neither an importer or exporter of natural gas, the growth in consumption has naturally followed that of production, and the lack of infrastructure explains the limited penetration of gas in the residential sector (less than 2 % in 1997). According to the gas development plan drawn up by the Egyptian authorities, internal consumption should increase from 13.5 billion m 3 per year in 1998 to around 45.5 billion m 3 per year in 2017. This consumption increase will be accelerated to respond to domestic needs and, in particular, to favour the implementation of the national redevelopment plan (distribution of the population over 25% of the country by 2020, compared to 4% day). The energy vector of this urban policy is gas. Moreover, this policy should offset the drop in income resulting from declining oil production. The Egyptian authorities, via a range

Characteristics and Dynamics of a Large Sub-Tidal Sand Wave Field—Habitat for Pacific Sand Lance (Ammodytes personatus, Salish Sea, Washington, USA

Directory of Open Access Journals (Sweden)

H. Gary Greene

2017-10-01

Full Text Available Deep-water sand wave fields in the San Juan Archipelago of the Salish Sea and Pacific Northwest Washington, USA, have been found to harbor Pacific sand lance (PSL, Ammodytes personatus, a critical forage fish of the region. Little is known of the dynamics of these sand waves and the stability of the PSL sub-tidal habitats. Therefore, we have undertaken an initial investigation to determine the dynamic conditions of a well-known PSL habitat in the San Juan Channel within the Archipelago using bottom sediment sampling, an acoustical doppler current profiling (ADCP system, and multi-beam echo sounder (MBES bathymetry. Our study indicates that the San Juan Channel sand wave field maintained its shape and bedforms geometry throughout the years it has been studied. Based on bed phase diagrams for channelized bedforms, the sand waves appear to be in a dynamic equilibrium condition. Sea level rise may change the current regime within the Archipelago and may alter some of the deep-water or sub-tidal PSL habitats mapped there. Our findings have global significance in that these dynamic bedforms that harbor PSL and sand-eels elsewhere along the west coast of North America and in the North Sea may also be in a marginally dynamic equilibrium condition and may be prone to alteration by sea level rise, indicating an urgency in locating and investigating these habitats in order to sustain the forage fish.

Adsorption - desorption equilibria of some radionuclides in sediment - sea water system

International Nuclear Information System (INIS)

El-Assy, N.B.; Fattah, A.T.A.; El-Shinawy, R.M.K.; Essa, M.W.A.

1991-01-01

Chemical and physical properties of Suez Canal bottom sediments (SCBS) and sea water at port Tawfeek area, the south entrance of Suez canal, have been studied. The SCBS was separated into its size fractions (natural sediment, sand, silt and clay). These different sediment fractions were allowed to be in equilibrium with 89 Sr, 60 Co and 134 Cs solutions. Desorption studies were carried out on these contaminated sediments. (author) 16 refs.; 1 fig.; 1 tab

New application of the radioactive tracer method for sediment movement measurements in the surf zone

International Nuclear Information System (INIS)

Owczarczyk, A.; Strzelecki, M.; Szpilowski, S.; Wierzchnicki, R.; Basinski, T.

1989-01-01

The investigations of sediment movement with the use of radiotracers have been carried out in a surf zone of Lubiatowo. Inception of sand motion and sediment transport velocity were the objective of the experiment. The spider type construction was located at the depth of 0.7 m. An artificial sand made of iridium glass (γ = 2.660 kg/m 3 ) containing 0.25 weight per cent of 192 Ir was used as a tracer. The fraction of 0.15 to 0.20 mm has been chosen as the representative diameter of sand grains existing at the investigated bottom region. The inception of sand movement versus current velocity and wave conditions as well as displacement velocity of tracer mass were determined. An improved construction was designed and tested. (author)

Microbially-accelerated consolidation of oil sands tailings. Pathway I: changes in porewater chemistry.

Science.gov (United States)

Siddique, Tariq; Kuznetsov, Petr; Kuznetsova, Alsu; Arkell, Nicholas; Young, Rozlyn; Li, Carmen; Guigard, Selma; Underwood, Eleisha; Foght, Julia M

2014-01-01

Dispersed clay particles in mine tailings and soft sediments remain suspended for decades, hindering consolidation and challenging effective management of these aqueous slurries. Current geotechnical engineering models of self-weight consolidation of tailings do not consider microbial contribution to sediment behavior, however, here we show that microorganisms indigenous to oil sands tailings change the porewater chemistry and accelerate consolidation of oil sands tailings. A companion paper describes the role of microbes in alteration of clay chemistry in tailings. Microbial metabolism in mature fine tailings (MFT) amended with an organic substrate (hydrolyzed canola meal) produced methane (CH4) and carbon dioxide (CO2). Dissolution of biogenic CO2 lowered the pH of amended MFT to pH 6.4 vs. unamended MFT (pH 7.7). About 12% more porewater was recovered from amended than unamended MFT during 2 months of active microbial metabolism, concomitant with consolidation of tailings. The lower pH in amended MFT dissolved carbonate minerals, thereby releasing divalent cations including calcium (Ca(2+)) and magnesium (Mg(2+)) and increasing bicarbonate (HCO(-) 3) in porewater. The higher concentrations increased the ionic strength of the porewater, in turn reducing the thickness of the diffuse double layer (DDL) of clay particles by reducing the surface charge potential (repulsive forces) of the clay particles. The combination of these processes accelerated consolidation of oil sands tailings. In addition, ebullition of biogenic gases created transient physical channels for release of porewater. In contrast, saturating the MFT with non-biogenic CO2 had little effect on consolidation. These results have significant implications for management and reclamation of oil sands tailings ponds and broad importance in anaerobic environments such as contaminated harbors and estuaries containing soft sediments rich in clays and organics.

Sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads

Science.gov (United States)

Dean, David; Topping, David; Schmidt, John C.; Griffiths, Ronald; Sabol, Thomas

2016-01-01

The Rio Grande in the Big Bend region of Texas, USA, and Chihuahua and Coahuila, Mexico, undergoes rapid geomorphic changes as a result of its large sediment supply and variable hydrology; thus, it is a useful natural laboratory to investigate the relative importance of flow strength and sediment supply in controlling alluvial channel change. We analyzed a suite of sediment transport and geomorphic data to determine the cumulative influence of different flood types on changing channel form. In this study, physically based analyses suggest that channel change in the Rio Grande is controlled by both changes in flow strength and sediment supply over different spatial and temporal scales. Channel narrowing is primarily caused by substantial deposition of sediment supplied to the Rio Grande during tributary-sourced flash floods. Tributary floods have large suspended-sediment concentrations, occur for short durations, and attenuate rapidly downstream in the Rio Grande, depositing much of their sediment in downstream reaches. Long-duration floods on the mainstem have the capacity to enlarge the Rio Grande, and these floods, released from upstream dams, can either erode or deposit sediment in the Rio Grande depending upon the antecedent in-channel sediment supply and the magnitude and duration of the flood. Geomorphic and sediment transport analyses show that the locations and rates of sand erosion and deposition during long-duration floods are most strongly controlled by spatial changes in flow strength, largely through changes in channel slope. However, spatial differences in the in-channel sediment supply regulate sediment evacuation or accumulation over time in long reaches (greater than a kilometer).

Radioactivity of some alpha, beta and gamma emitting radionuclides in surface marine sediments of different bays in Algeria

International Nuclear Information System (INIS)

Noureddine, A.; Baggoura, B.

1999-01-01

Samples of surface (0-15) cm marine sediments of different grain sizes, namely sand, muddy and fine sand, were collected in the western, central and east coast of Algeria, to measure concentrations of natural and artificial radioactivity. The aim of this study is to detect any radioactive contamination, its origin and also to determine the uptake of radioactivity by marine surface sediments

Investigating the backscatter contrast anomaly in synthetic aperture radar (SAR) imagery of the dunes along the Israel-Egypt border

Science.gov (United States)

Rozenstein, Offer; Siegal, Zehava; Blumberg, Dan G.; Adamowski, Jan

2016-04-01

The dune field intersected by the Israel-Egypt borderline has attracted many remote sensing studies over the years because it exhibits unique optical phenomena in several domains, from the visual to the thermal infrared. These phenomena are the result of land-use policies implemented by the two countries, which have differing effects on the two ecosystems. This study explores the surface properties that affect radar backscatter, namely the surface roughness and dielectric properties, in order to determine the cause for the variation across the border. The backscatter contrast was demonstrated for SIR-C, the first synthetic aperture radar (SAR) sensor to capture this phenomenon, as well as ASAR imagery that coincides with complementary ground observations. These field observations along the border, together with an aerial image from the same year as the SIR-C acquisition were used to analyze differences in vegetation patterns that can affect the surface roughness. The dielectric permittivity of two kinds of topsoil (sand, biocrust) was measured in the field and in the laboratory. The results suggest that the vegetation structure and spatial distribution differ between the two sides of the border in a manner that is consistent with the radar observations. The dielectric permittivity of sand and biocrust was found to be similar, although they are not constant across the radar spectral region (50 MHz-20 GHz). These findings support the hypothesis that changes to the vegetation, as a consequence of the different land-use practices in Israel and Egypt, are the cause for the radar backscatter contrast across the border.

Selection of groundwater sites in Egypt, using geographic information systems, for desalination by solar energy in order to reduce greenhouse gases

Directory of Open Access Journals (Sweden)

Mariam G. Salim

2012-01-01

Full Text Available Although Egypt has already reached the water poverty limit, it possesses a high potential of brackish groundwater available from different aquifers. All Arab countries lie in the best sun-belt region in the world and Egypt has the highest number of sun hours all year round. Solar energy for groundwater desalination is an independent infinite energy resource; it has low running costs and reduces the contribution of greenhouse gases (GHG to global warming. Perfect meteorological conditions and land space are available in remote areas, where solar desalination could supply freshwater for drinking, industry, and for greenhouse agriculture. The present study uses Geographic Information System(s (GIS as a spatial decision support tool to select appropriate sites in Egypt for groundwater solar desalination. Solar radiation, aquifer depth, aquifer salinity, distance from the Delta and the Nile Valley, incidence of flash floods, sand dunes, rock faults, and seawater intrusion in the North Delta, are the criteria that have been taken into consideration in the process of analysis. A specific weight is given to each criterion according to its relative influence on the process of decision making. The results from the application of the presented methodology determine the relative suitability of sites for groundwater solar desalination. These sites are ranked in descending order to help decision-makers in Egypt. The results show that groundwater solar desalination is suitable in remote regions on the North Western Coast, on the North Sinai Coast, and at the Southern Oasis, for reducing greenhouse gases and that it is particularly useful for poor communities suffering from polluted water.

Physical properties and rock physics models of sediment containing natural and laboratory-formed methane gas hydrate

Science.gov (United States)

Winters, W.J.; Pecher, I.A.; Waite, W.F.; Mason, D.H.

2004-01-01

This paper presents results of shear strength and acoustic velocity (p-wave) measurements performed on: (1) samples containing natural gas hydrate from the Mallik 2L-38 well, Mackenzie Delta, Northwest Territories; (2) reconstituted Ottawa sand samples containing methane gas hydrate formed in the laboratory; and (3) ice-bearing sands. These measurements show that hydrate increases shear strength and p-wave velocity in natural and reconstituted samples. The proportion of this increase depends on (1) the amount and distribution of hydrate present, (2) differences, in sediment properties, and (3) differences in test conditions. Stress-strain curves from the Mallik samples suggest that natural gas hydrate does not cement sediment grains. However, stress-strain curves from the Ottawa sand (containing laboratory-formed gas hydrate) do imply cementation is present. Acoustically, rock physics modeling shows that gas hydrate does not cement grains of natural Mackenzie Delta sediment. Natural gas hydrates are best modeled as part of the sediment frame. This finding is in contrast with direct observations and results of Ottawa sand containing laboratory-formed hydrate, which was found to cement grains (Waite et al. 2004). It therefore appears that the microscopic distribution of gas hydrates in sediment, and hence the effect of gas hydrate on sediment physical properties, differs between natural deposits and laboratory-formed samples. This difference may possibly be caused by the location of water molecules that are available to form hydrate. Models that use laboratory-derived properties to predict behavior of natural gas hydrate must account for these differences.

Numerical simulation of flow in centrifugal pump under cavitation and sediment condition

International Nuclear Information System (INIS)

Lu, J L; Guo, P C; Zheng, X B; Zhao, Q; Luo, X Q

2012-01-01

The sediment concentration is very high in many rivers in the world, especially in China. The pumps that designed for the clear water are usually seriously abraded. The probability of pump cavitation is greatly enhanced due to the existence of sand. Under the joint action and mutual promotion of sand erosion and cavitation, serious abrasion could occurred, and the hydraulic performance of the pump may be greatly descended, meanwhile the safety and stability of the whole pump are greatly threatened. Therefore, it is significant to investigate the cavitation characteristic of pump under sediment flow condition. In this paper, the flow in a single stage centrifugal pump under cleat water and sediment flow conditions was numerically simulated. The cavitation performance under clear water was firstly analyzed. Then, The pressure, velocity and solid particle distribution in centrifugal pump under different particle diameter and different particle concentration was investigated by using the two-fluid model; The area and extent of erosion was illustrated by using the particle track model. Finally, the influence of mixed sand on centrifugal pump performance was investigated.

Seismic hazard studies in Egypt

Directory of Open Access Journals (Sweden)

Abuo El-Ela A. Mohamed

2012-12-01

Full Text Available The study of earthquake activity and seismic hazard assessment of Egypt is very important due to the great and rapid spreading of large investments in national projects, especially the nuclear power plant that will be held in the northern part of Egypt. Although Egypt is characterized by low seismicity, it has experienced occurring of damaging earthquake effect through its history. The seismotectonic sitting of Egypt suggests that large earthquakes are possible particularly along the Gulf of Aqaba–Dead Sea transform, the Subduction zone along the Hellenic and Cyprean Arcs, and the Northern Red Sea triple junction point. In addition some inland significant sources at Aswan, Dahshour, and Cairo-Suez District should be considered. The seismic hazard for Egypt is calculated utilizing a probabilistic approach (for a grid of 0.5° × 0.5° within a logic-tree framework. Alternative seismogenic models and ground motion scaling relationships are selected to account for the epistemic uncertainty. Seismic hazard values on rock were calculated to create contour maps for four ground motion spectral periods and for different return periods. In addition, the uniform hazard spectra for rock sites for different 25 periods, and the probabilistic hazard curves for Cairo, and Alexandria cities are graphed. The peak ground acceleration (PGA values were found close to the Gulf of Aqaba and it was about 220 gal for 475 year return period. While the lowest (PGA values were detected in the western part of the western desert and it is less than 25 gal.

Ancient Egypt in our Cultural Heritage?

Directory of Open Access Journals (Sweden)

Vera Vasiljević

2016-02-01

Full Text Available Inspiration derived from ancient Egypt is usually expressed through the Egyptian motifs in arts and popular culture of the 19th and 20th centuries, as well as through the non-scientific interpretations of the culture, very much based upon the Renaissance ones. The number and variety of material and non-material traces of this fascination are most expressed in the countries where, along with the early support for the institutional development of Egyptology, there existed economically potent educated middle classes (Western and Central Europe, USA, but may also be traced elsewhere. The public fascination by ancient Egypt has not ceased by the times of foundation of Egyptology, marked by the decipherment of the hieroglyphic script in 1822. Until the end of the 20th century Egyptologists have rarely dealt with the prelude to their discipline, limiting their interest to the critical approach to ancient sources and to noting the attempts to interpret the hieroglyphic script and the function of pyramids. However, the rising importance of the reception studies in other disciplines raised the interest of Egyptologists for the "fascination of Egypt", thus changing the status of various modes of expressing "Egyptomania" – they have thus become a part of the cultural heritage, registered, documented, preserved and studied. The research of this kind is only beginning in Serbia. The line of inquiry enhances the knowledge of the scope, manifestations and roles of the interest in Egypt, not limited by the national or political borders. On the other hand, the existence of the cultural heritage similar to the wider European view of ancient Egypt – short remarks by Jerotej Račanin, Kandor by Atanasije Stojković, the usage of architectural motifs derived from Egypt, the emergence of small private collections, to mention several early examples – all show that the research into the reception of ancient Egypt may contribute to the knowledge about the history

Image analysis to measure sorting and stratification applied to sand-gravel experiments

NARCIS (Netherlands)

Orrú, C.

2016-01-01

The main objective of this project is to develop new measuring techniques for providing detailed data on sediment sorting suitable for sand-gravel laboratory experiments. Such data will be of aid in obtaining new insights on sorting mechanisms and improving prediction capabilities of morphodynamic

Uranium mineralization rules controlled by sedimentation in Bayanwula region in Erlian basin

International Nuclear Information System (INIS)

Lu Chao

2012-01-01

Uranium mineralization is closely related to sedimentation in Bayanwula region in Erlian Basin. Clarifying the relation of sedimentation and Uranium Mineralization Through detailed analysis of vertical sequences, stratigraphic correlation and the heterogeneity of sand body. Study show that the of development characteristics of sequences of Bayanwula region control the vertical positioning of favorable sand, the skeleton sand bodies of LST in upper Saihan formation is the most favorable reservoir space for uranium. Uranium mineralization is closely related with the heterogeneity of the sand bodies of upper Saihan formation. the heterogeneity of Sand body is mainly reflected in plane and vertical. In plane, with the research of the sand distributed system of upper Saihan formation, the change position of sandstone thickness and sand rate, the position of the variation of shape and trend of sand body, and the change position of sand body character and genesis are most favorable for uranium mineralization. In vertical, the number of layers and thickness of isolated barrier bed not only control the thickness of oxide sandstone. but also they are associated with the distribution of uranium mineralization; The evolution of sedimentary basins created Bayanwula uranium deposits. There is a second order sequence boundary between the upper Saihan formation and the Erlian formation of Late Cretaceous, which is a long-term exposure and erosion unconformity, resulting in the partly erosion of the upper Saihan formation, providing the best conditions of the penetration of the uranium-bearing oxygen water and the development of phreatic oxidation and interlayer oxidation zone. (author)

The Mediterranean Coastal Dunes in Egypt: An Endangered Landscape

Science.gov (United States)

Batanouny, K. H.

1999-08-01

The Mediterranean coast in Egypt extends almost 900 km, the major part of which is bordered by sand dunes of different natures and types. Along the coastline between Alexandria and El-Alamein, a distance of some 100 km, the sand dunes represent a particular landscape with special characteristics and features, and consequently plants with particular attributes. In this area, the belt of sand dunes has developed immediately south of the shore and these dunes may rise up to 10 m in height and extend about 0·5-1·5 km inland from the shore. These dunes are famous as a habitat for the fig (Ficus carica L.) cultivation depending on the irregular rainfall. They also represent a landing station and a cross-road for birds such as quail migrating from Europe in the north. In the past, summer resort areas were confined to limited areas with few people, these same areas support the growth of some important plant species, for example, sand binders, medicinal and range plants. For more than two decades, there has been considerable socio-economic change and an open-door policy in the economy of the country has been adopted. One of the consequences of this change is that a great part of the coastal dune belt west of Alexandria till El-Alamein, has been subjected to destruction, due to the continuous construction of summer resort villages. These were built at a distance of about 100 m of the shoreline, extending 400-600 m inland and a breadth of 400 m or more along the shoreline. The area already covered by the dunes is now almost occupied by new buildings, gardens and other infrastructure. The consequences of these human activities are numerous and include impacts on the soil, water resources, the flora and the fauna, migrating birds, trends of the indigenous people, and the cultural environment. The present paper gives a concise environmental setting of the dune belt before the advent of the new activities, and the socio-economic and political attitudes which threaten the dunes

The chemical and biological evolution of mature fine tailings in oil sands end-pit lakes

International Nuclear Information System (INIS)

Chen, M.; Weisener, C.; Ciborowski, J.

2010-01-01

This presentation described an innovative bench-scale technique to characterize oil sand tailings and their impact on sediment oxygen demand (SOD) for future end-pit lake model behaviour. SOD is a dominant contributor to oxygen depletion in wetlands. The function and sustainability of a wetland ecosystem depends on the biochemical processes occurring at the sediment-water interface. The biochemical reactions associated with natural sediment can change with the addition of oil sands processed material (OSPM), which can affect SOD and ecosystem viability. It is important to establishing the biotic and abiotic controls of SOD. In order to evaluate the effectiveness of current wetland reclamation designs, it is important to establish the biotic and abiotic controls of SOD. The REDOX chemistry of fresh tailings sediment (MFT) was measured in this laboratory microcosm to determine the chemical and biological influences, and to study the role of developing microbial communities as new mature fine tailings (MFT) age. The study evaluated the changes in the main chemical, physical and biological populations of the MFT in both aerobic and anaerobic microcosms. A combination of microelectrode arrays and DNA profiling at the tailings water interface was used in the study.

Uranium exploration in Egypt past, current and future activities

International Nuclear Information System (INIS)

Farag, N.

2014-01-01

The Egyptian Nuclear Materials Authority (NMA), is the government body responsible for exploration of the nuclear raw materials in the country. The early NMA U-exploration activities has included training of exploration teams, conduction of airborne, ground follow up and preliminary geological mapping as well as execution of limited exploration drilling. A number of TC projects and expert missions were mainly executed in collaboration with the IAEA for this purpose. These efforts have resulted in the discovery of seven U-potential prospects. NMA has also exercised limited heap leaching on experimental scale and obtained small amounts of U-concentrates, utilized for R & D purposes. However, the exploration activities remained in the preliminary phases and did not succeed to reach either reliable evaluation of the discovered uranium resources or running productive U-exploitation. By the end of the last decade, Egypt has declared the intention to adopt a peaceful program for electric power generation; this implied NMA to implement a twofold plan as described hereafter. Regarding the conventional U-resources, occurring in the Eastern Desert, NMA focus the exploration activities on the younger granites of Pan African type, and the associated inter-mountain basins. The activities will be restricted to the evaluation of U-reserves in at least three of the most promising uranium prospects that still require extensive exploration drilling programs. NMA is now implementing an international bid announcement seeking for partnership of an experienced international firm, to assess the uranium resources in these sites, in addition to receiving relevant IAEA/TC programs. Regarding non-conventional resources, the black sand project is mainly a resource of a titanium and zirconium minerals; however, NMA is now trying to process monazite to obtain mainly Th and minor U by-products. NMA has successfully completed an exploration study and. the Government of Egypt has recently

Beryllium-10 in continental sediments

International Nuclear Information System (INIS)

Brown, L.; Sacks, I.S.; Tera, F.; Klein, J.; Middleton, R.

1981-01-01

The concentration of 10 Be has been measured in 10 samples taken from a transect of surface sediments beginning in the Atchafalaya River and extending across the Bay 136 km into the Gulf of Mexico. If corrected for a lower retentivity of sand for Be, they have a concentration that is constant within 13%. This concentration is about an order of magnitude smaller than that of deep ocean sediments. For comparison, measurements of 10 Be in rainwater, in a sample of soil and in a deep ocean core were made. (orig.)

A Threshold Continuum for Aeolian Sand Transport

Science.gov (United States)

Swann, C.; Ewing, R. C.; Sherman, D. J.

2015-12-01

The threshold of motion for aeolian sand transport marks the initial entrainment of sand particles by the force of the wind. This is typically defined and modeled as a singular wind speed for a given grain size and is based on field and laboratory experimental data. However, the definition of threshold varies significantly between these empirical models, largely because the definition is based on visual-observations of initial grain movement. For example, in his seminal experiments, Bagnold defined threshold of motion when he observed that 100% of the bed was in motion. Others have used 50% and lesser values. Differences in threshold models, in turn, result is large errors in predicting the fluxes associated with sand and dust transport. Here we use a wind tunnel and novel sediment trap to capture the fractions of sand in creep, reptation and saltation at Earth and Mars pressures and show that the threshold of motion for aeolian sand transport is best defined as a continuum in which grains progress through stages defined by the proportion of grains in creep and saltation. We propose the use of scale dependent thresholds modeled by distinct probability distribution functions that differentiate the threshold based on micro to macro scale applications. For example, a geologic timescale application corresponds to a threshold when 100% of the bed in motion whereas a sub-second application corresponds to a threshold when a single particle is set in motion. We provide quantitative measurements (number and mode of particle movement) corresponding to visual observations, percent of bed in motion and degrees of transport intermittency for Earth and Mars. Understanding transport as a continuum provides a basis for revaluating sand transport thresholds on Earth, Mars and Titan.

Linen in Ancient Egypt

Directory of Open Access Journals (Sweden)

dr.Rehab Mahmoud Ahmed Elsharnouby

2014-01-01

Full Text Available Egypt was famous through the Ancient Near East for both weaving linen cloth and the produced quantities. Cloth was sent as expensive gifts from one king to another and given to a laborer as wages in return for his work. Cloth was regarded as an essential element in everyday life as it could be used for everything: clothing, bedding, trappings for animals, or sails of a ship. It was in fact one of the most widely used item throughout Ancient Egypt. Although other textile fibers were used in Pharaonic Egypt, namely, sheep's wool, goat hair and a form of coir, the majority of textiles were made from the plant Linum usitatissimum, flax. Cloth made from this fiber is defined as linen. The research starts with a brief definition of the flax, and then reviews the scenes representing the sowing and the harvesting of its seeds. It also focuses on the way of removing the seeds heads, the preparing of the flax for spinning: retting, beating and scutching. After that, it deals with transforming flax into orderly lengths, and rolling it into balls or coils. The researcher as well studies the Ancient Egyptian spinning techniques: grasped spindle, support spindle and drop spinning; the different types of weaving: tabby weaves, basket weaves, tapestry weaves and warps-patterned weave and the types of looms that were in use in Egypt, namely, the horizontal and vertical looms.

Sediment concentration and bed form structures of Gulf of Cambay from remote sensing

Digital Repository Service at National Institute of Oceanography (India)

Kunte, P.D.

period, the bottom currents pull sediment (sand) particles supplied by major and minor rivers, rolling along the Gulf bed. These sediments perhaps participate in the formation of bed form structures. The topography of the Gulf bottom comprises of numerous...

Large-eddy simulation of sand dune morphodynamics

Science.gov (United States)

Khosronejad, Ali; Sotiropoulos, Fotis; St. Anthony Falls Laboratory, University of Minnesota Team

2015-11-01

Sand dunes are natural features that form under complex interaction between turbulent flow and bed morphodynamics. We employ a fully-coupled 3D numerical model (Khosronejad and Sotiropoulos, 2014, Journal of Fluid Mechanics, 753:150-216) to perform high-resolution large-eddy simulations of turbulence and bed morphodynamics in a laboratory scale mobile-bed channel to investigate initiation, evolution and quasi-equilibrium of sand dunes (Venditti and Church, 2005, J. Geophysical Research, 110:F01009). We employ a curvilinear immersed boundary method along with convection-diffusion and bed-morphodynamics modules to simulate the suspended sediment and the bed-load transports respectively. The coupled simulation were carried out on a grid with more than 100 million grid nodes and simulated about 3 hours of physical time of dune evolution. The simulations provide the first complete description of sand dune formation and long-term evolution. The geometric characteristics of the simulated dunes are shown to be in excellent agreement with observed data obtained across a broad range of scales. This work was supported by NSF Grants EAR-0120914 (as part of the National Center for Earth-Surface Dynamics). Computational resources were provided by the University of Minnesota Supercomputing Institute.

Integrated Human Futures Modeling in Egypt

Energy Technology Data Exchange (ETDEWEB)

Passell, Howard D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aamir, Munaf Syed [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bernard, Michael Lewis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Beyeler, Walter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fellner, Karen Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hayden, Nancy Kay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jeffers, Robert Fredric [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Keller, Elizabeth James Kistin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Malczynski, Leonard A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silver, Emily [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tidwell, Vincent C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Villa, Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vugrin, Eric D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Engelke, Peter [Atlantic Council, Washington, D.C. (United States); Burrow, Mat [Atlantic Council, Washington, D.C. (United States); Keith, Bruce [United States Military Academy, West Point, NY (United States)

2016-01-01

The Integrated Human Futures Project provides a set of analytical and quantitative modeling and simulation tools that help explore the links among human social, economic, and ecological conditions, human resilience, conflict, and peace, and allows users to simulate tradeoffs and consequences associated with different future development and mitigation scenarios. In the current study, we integrate five distinct modeling platforms to simulate the potential risk of social unrest in Egypt resulting from the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile in Ethiopia. The five platforms simulate hydrology, agriculture, economy, human ecology, and human psychology/behavior, and show how impacts derived from development initiatives in one sector (e.g., hydrology) might ripple through to affect other sectors and how development and security concerns may be triggered across the region. This approach evaluates potential consequences, intended and unintended, associated with strategic policy actions that span the development-security nexus at the national, regional, and international levels. Model results are not intended to provide explicit predictions, but rather to provide system-level insight for policy makers into the dynamics among these interacting sectors, and to demonstrate an approach to evaluating short- and long-term policy trade-offs across different policy domains and stakeholders. The GERD project is critical to government-planned development efforts in Ethiopia but is expected to reduce downstream freshwater availability in the Nile Basin, fueling fears of negative social and economic impacts that could threaten stability and security in Egypt. We tested these hypotheses and came to the following preliminary conclusions. First, the GERD will have an important short-term impact on water availability, food production, and hydropower production in Egypt, depending on the short- term reservoir fill rate. Second, the GERD will have a very small impact on

Assessing metal contamination in recent creek sediments using fractionation technique along Mumbai coast, India

Digital Repository Service at National Institute of Oceanography (India)

Fernandes, L.L.; Nayak, G.N.

nitrogen) and sediment components (sand, silt, clay). A sequential extraction procedure was also applied to understand the partitioning of trace metals among the different fractions of the sediment. Together with this data, pollution indices were also...

Parasitic Contamination of Commonly Consumed Fresh Leafy Vegetables in Benha, Egypt

Directory of Open Access Journals (Sweden)

Maysa Ahmad Eraky

2014-01-01

Full Text Available This study evaluated the degree of parasitic contamination of vegetables which are commercialized and consumed fresh in Benha, Egypt. It included 530 vegetables: lettuce, watercress, parsley, green onion, and leek. Vegetables were collected randomly from markets within Benha. Samples were washed in saline, and the resulting washing solution was filtered and centrifuged to concentrate the parasitic stages. Sediments and supernatants were examined by iodine and modified Ziehl-Neelsen stained smears. Intestinal parasites were detected in 157/530 (29.6% samples. Giardia lamblia cysts were the most prevalent parasite (8.8% followed by Entamoeba spp. cysts (6.8%, Enterobius vermicularis eggs (4.9%, various helminth larvae (3.6%, Hymenolepis nana eggs (2.8%, Hymenolepis diminuta eggs (2.1%, and Ascaris lumbricoides eggs (0.6%. The highest contaminated vegetable was lettuce (45.5% followed by watercress (41.3%, parsley (34.3%, green onion (16.5%, and leek (10.7%. These results indicate a significant seasonal variation (P<0.05, with highest prevalence in summer (49% and the lowest in winter (10.8%. These findings provide evidence for the high risk of acquiring parasitic infection from the consumption of raw vegetables in Benha, Egypt. Effective measures are necessary to reduce parasitic contamination of vegetables.

Holocene marine transgression as interpreted from bathymetry and sand grain size parameters off Gopalpur

Digital Repository Service at National Institute of Oceanography (India)

Rao, K.M.; Rajamanickam, G.V.; Rao, T.C.S.

Grain size statistical parameters of the surface sediment samples collected from the innershelf off Gopalpur were calculated using graphic and moment methods. Fine-grained sand present up to 15 m water depth shows symmetrical skewness and good...

Modification of Yellow River Sediment Based Stabilized Earth Bricks

Directory of Open Access Journals (Sweden)

Junxia Liu

2016-12-01

Full Text Available This paper presents an experimental study on the microstructure and performance of stabilized earth bricks prepared from the Yellow River sediment. The sediment is modified by inorganic cementitious material, polymer bonding agent, and jute fibre. The results show that the sediment is preliminarily consolidated when the mixture ratio of activated sediment/cementitious binder/sand is 65/25/10. Compressive strength and softening coefficient of stabilized earth bricks is further improved by polymer bonding agent and jute fibre. SEM images and EDS spectral analysis indicate that there is indeed synergy among inorganic hydration products, polymer network and jute fibre to strengthen the sediment.

Channel Morphology and Bed Sediment Characteristics Before and After Habitat Enhancement Activities in the Uridil Property, Platte River, Nebraska, Water Years 2005-2008

Science.gov (United States)

Kinzel, Paul J.

2009-01-01

Fluvial geomorphic data were collected by the United States Geological Survey from July 2005 to June 2008 (a time period within water years 2005 to 2008) to monitor the effects of habitat enhancement activities conducted in the Platte River Whooping Crane Maintenance Trust's Uridil Property, located along the Platte River, Nebraska. The activities involved the removal of vegetation and sand from the tops of high permanent islands and the placement of the sand into the active river channel. This strategy was intended to enhance habitat for migratory water birds by lowering the elevations of the high islands, thereby eliminating a visual obstruction for roosting birds. It was also thought that the bare sand on the lowered island surfaces could serve as potential habitat for nesting water birds. Lastly, the project supplied a local source of sediment to the river to test the hypothesis that this material could contribute to the formation of lower sandbars and potential nesting sites downstream. Topographic surveys on the islands and along river transects were used to quantify the volume of removed sand and track the storage and movement of the introduced sand downstream. Sediment samples were also collected to map the spatial distribution of river bed sediment sizes before and after the management activities. While the project lowered the elevation of high islands, observations of the sand addition indicated the relatively fine-grained sand that was placed in the active river channel was rapidly transported by the flowing water. Topographic measurements made 3 months after the sand addition along transects in the area of sediment addition showed net aggradation over measurements made in 2005. In the year following the sand addition, 2007, elevated river flows from local rain events generally were accompanied by net degradation along transects within the area of sediment addition. In the spring of 2008, a large magnitude flow event of approximately 360 cubic meters per

{sup 137}Cs in northern Adriatic sediments

Energy Technology Data Exchange (ETDEWEB)

Barisic, D; Lulic, S; Vdovic, N; Vertacnik, A [Center for Marine Research - Department Zagreb, ' Ruder Boskovic' Institute, Zagreb (Croatia); Juracic, M [Department of Geology, Faculty of Natural Sciences, University of Zagreb, Zagreb (Croatia)

1996-01-01

The activity of {sup 137}Cs in shallow northern Adriatic sediments was obtained on the basis of measurement results from 25 sediment box cores, sampled during the Adriatic Scientific COoperation Program (ASCOP) 16 cruise in the summer 1990. {sup 137}Cs was determined in surface sediments (0-3 cm) and 12-15 cm-deep sediment. It was found that the lowest caesium concentrations correspond to sands, which are spread along the Croatian coast. Parallel to the Italian coast, {sup 137}Cs concentrations in pelites are the highest. It seems that the influence of Po River is significant for {sup 137}Cs activities in recent marine sediments along Italian coast south of Po River delta. Significantly higher {sup 137}Cs activities in 0-3 cm sediment layer can be attributed to the deposition caused by Chernobyl accident. (author)

Sediment type affects competition between a native and an exotic species in coastal China.

Science.gov (United States)

Li, Hong-Li; Wang, Yong-Yang; An, Shu-Qing; Zhi, Ying-Biao; Lei, Guang-Chun; Zhang, Ming-Xiang

2014-10-23

Different types of sediments in salt marsh have different physical and chemical characters. Thus sediment type plays a role in plant competition and growth in salt marsh ecosystems. Spartina anglica populations have been increasingly confined to upper elevation gradients of clay, and the niche sediment has changed. Because the niches of S. anglica and the native species Scirpus triqueter overlap, we conducted a greenhouse experiment to test the hypothesis that plant competition has changed under different types of sediments. Biomass and asexual reproduction were analyzed, and inter- and intraspecific competition was measured by log response ratio for the two species in both monoculture and combination under three sediment types (sand, clay and mixture of sand and clay). For S. anglica, biomass, ramet number and rhizome length in combination declined significantly compared with those in monoculture, and the intensity of interspecific competition was significantly higher than that of intraspecific competition under all sediments. For S. triqueter, the intensities of intra- and interspecific competition were not significantly different. This indicates that S. triqueter exerts an asymmetric competitive advantage over S. anglica across all sediments, but especially clay. Thus the sediment type changes competition between S. anglica and S. triqueter.

Effective control of modified palygorskite to NH4+-N release from sediment.

Science.gov (United States)

Chen, Lei; Zheng, Tianyuan; Zhang, Junjie; Liu, Jie; Zheng, Xilai

2014-01-01

Sediment capping is an in situ treatment technology that can effectively restrain nutrient and pollutant release from the sediment in lakes and reservoirs. Research on sediment capping has focused on the search for effective, non-polluting and affordable capping materials. The efficiency and mechanism of sediment capping with modified palygorskite in preventing sediment ammonia nitrogen (NH4+-N) release to surface water were investigated through a series of batch and sediment capping experiments. Purified palygorskite and different types of modified palygorskite (i.e. heated, acid-modified and NaCI-modified palygorskite) were used in this investigation. Factors affecting control efficiency, including the temperature, thickness and grain size of the capping layer, were also analysed. The batch tests showed that the adsorption of NH4+-N on modified palygorskite achieved an equilibration in the initial 45 min, and the adsorption isotherm followed the Freundlich equation. Sediment capping experiments showed that compared with non-capped condition, covering the sediment with modified palygorskite and sand both inhibited NH4+-N release to the overlying water. Given its excellent chemical stability and strong adsorption, heated palygorskite, which has a NH4+-N release inhibition ratio of 41.3%, is a more effective sediment capping material compared with sand. The controlling effectiveness of the modified palygorskite increases with thicker capping layer, lower temperature and smaller grain size of the capping material.

Pesticide sorption by low organic carbon sediments: A sceening for seven herbicides

DEFF Research Database (Denmark)

Madsen, Lene; Lindhardt, Bo; Rosenberg, Per

2000-01-01

The sorption of seven pesticides in 10 Danish aquifer sediments has been studied. These sediments all have a total organic carbon (TOC) content below 1 g kg(-1), and include carbonate-bearing and carbonate-free Quatenary sand deposits and a Cretaceous chalk aquifer. Batch experiments were carried...

Automatic classification techniques for type of sediment map from multibeam sonar data

Science.gov (United States)

Zakariya, R.; Abdullah, M. A.; Che Hasan, R.; Khalil, I.

2018-02-01

Sediment map can be important information for various applications such as oil drilling, environmental and pollution study. A study on sediment mapping was conducted at a natural reef (rock) in Pulau Payar using Sound Navigation and Ranging (SONAR) technology which is Multibeam Echosounder R2-Sonic. This study aims to determine sediment type by obtaining backscatter and bathymetry data from multibeam echosounder. Ground truth data were used to verify the classification produced. The method used to analyze ground truth samples consists of particle size analysis (PSA) and dry sieving methods. Different analysis being carried out due to different sizes of sediment sample obtained. The smaller size was analyzed using PSA with the brand CILAS while bigger size sediment was analyzed using sieve. For multibeam, data acquisition includes backscatter strength and bathymetry data were processed using QINSy, Qimera, and ArcGIS. This study shows the capability of multibeam data to differentiate the four types of sediments which are i) very coarse sand, ii) coarse sand, iii) very coarse silt and coarse silt. The accuracy was reported as 92.31% overall accuracy and 0.88 kappa coefficient.

Mapping sexual harassment in Egypt | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

2017-03-28

Mar 28, 2017 ... More than 95 per cent of women in Egypt have experienced sexual harassment at ... HarassMap's map of Cairo shows the location and type of incidents that ... HarassMap: Mapping Sexual Harassment and Violence in Egypt.

Stiffness Evolution in Frozen Sands Subjected to Stress Changes

KAUST Repository

Dai, Sheng; Santamarina, Carlos

2017-01-01

Sampling affects all soils, including frozen soils and hydrate-bearing sediments. The authors monitor the stiffness evolution of frozen sands subjected to various temperature and stress conditions using an oedometer cell instrumented with P-wave transducers. Experimental results show the stress-dependent stiffness of freshly remolded sands, the dominant stiffening effect of ice, creep after unloading, and the associated exponential decrease in stiffness with time. The characteristic time for stiffness loss during creep is of the order of tens of minutes; therefore it is inevitable that frozen soils experience sampling disturbances attributable to unloading. Slow unloading minimizes stiffness loss; conversely, fast unloading causes a pronounced reduction in stiffness probably attributable to the brittle failure of ice or ice-mineral bonding.

Stiffness Evolution in Frozen Sands Subjected to Stress Changes

KAUST Repository

Dai, Sheng

2017-04-21

Sampling affects all soils, including frozen soils and hydrate-bearing sediments. The authors monitor the stiffness evolution of frozen sands subjected to various temperature and stress conditions using an oedometer cell instrumented with P-wave transducers. Experimental results show the stress-dependent stiffness of freshly remolded sands, the dominant stiffening effect of ice, creep after unloading, and the associated exponential decrease in stiffness with time. The characteristic time for stiffness loss during creep is of the order of tens of minutes; therefore it is inevitable that frozen soils experience sampling disturbances attributable to unloading. Slow unloading minimizes stiffness loss; conversely, fast unloading causes a pronounced reduction in stiffness probably attributable to the brittle failure of ice or ice-mineral bonding.

Sediment Transport and erosion modeling at Heaundae Beach in Korea.

Science.gov (United States)

Do, K.; Yoo, J.; McCall, R. T.

2016-12-01

The sand pocket beaches with two headlands are global features, but it's not easy to predict berm and dune erosion due to alongshore variation of water depth. This study investigates the sediment transport and morphological change using available wave and beach profile data, as well as to assess the applicability of the XBeach morphological model (Roelvink et al., 2009). The Haeundae is small pocket beach, 1.4 km long, located in the southern corner of the Korean Peninsula. The Korea Institute of Ocean Science and Technology (KIOST) measured beach profile along 27 survey lines. The beach profiles were surveyed five times from 17 June 2014 to 10 October 2014. For this duration, a wave gauge (AWAC) was installed at a depth about 23 m off the coast of Haeundae Beach. Severe four storms attacked Haeundae Beach for this duration and these storms lasted about 1 2 days with a peak significant wave height of 2.5 4.0 m. The placed sand is fairly sorted and its median diameter is 0.23 mm. 2DH coastal morphological model, XBeach developed to simulate dune erosion due to storm impacts. The model is based on the nonlinear shallow water equation and resolves nearshore hydrodynamics by employing a 2DH description of wave groups and infragravity motions. In this study, the numerical model XBeach was compared with the field data and used to estimate the sediment transport pattern on the sand pocket beach. The numerical model resulted in a comparable prediction in the west-part, but the east-part cannot reproduce the erosion and accretion of the sand, partly due to complex bathymetry and the lack of sediment. This limitation needs to be improved to use measured sand thickness data in future study

An-integrated seismic approach to de-risk hydrocarbon accumulation for Pliocene deep marine slope channels, offshore West Nile Delta, Egypt

Science.gov (United States)

Othman, Adel A. A.; Bakr, Ali; Maher, Ali

2017-12-01

The Nile Delta basin is a hydrocarbon rich province that has hydrocarbon accumulations generated from biogenic and thermogenic source rocks and trapped in a clastic channel reservoirs ranging in age from Pliocene to Early Cretaceous. Currently, the offshore Nile Delta is the most active exploration and development province in Egypt. The main challenge of the studied area is that we have only one well in a channel system exceeds fifteen km length, where seismic reservoir characterization is used to de-risk development scenarios for the field by discriminating between gas sand, water sand and shale. Extracting the gas-charged geobody from the seismic data is magnificent input for 3D reservoir static modelling. Seismic data, being non-stationary in nature, have varying frequency content in time. Spectral decomposition analysis unravels the seismic signal into its initial constituent frequencies. Frequency decomposition of a seismic signal aims to characterize the time-dependent frequency response of subsurface rocks and reservoirs for imaging and mapping of bed thickness, geologic discontinuities and channel connectivity. Inversion feasibility study using crossplot between P-wave impedance (Ip) and S-wave impedance (Is) which derived from well logs (P-wave velocity, S-wave velocity and density) is applied to investigate which inversion type would be sufficient enough to discriminate between gas sand, water sand and shale. Integration between spectral analysis, inversion results and Ip vs. Is crossplot cutoffs help to generate 3D lithofacies cubes, which used to extract gas sand and water sand geobodies, which is extremely wonderful for constructing facies depositional static model in area with unknown facies distribution and sand connectivity. Therefore de-risking hydrocarbon accumulation and GIIP estimation for the field became more confident for drilling new development wells.

Field measurements of mean and turbulent airflow over a barchan sand dune

Science.gov (United States)

Weaver, Corinne M.; Wiggs, Giles F. S.

2011-05-01

Advances in our knowledge of the aeolian processes governing sand dune dynamics have been restricted by a reliance on measures of time-averaged airflow, such as shear velocity ( u*). It has become clear that such measures are incapable of explaining the complete dynamics of sediment transport across dune surfaces. Past evidence from wind tunnel and modelling studies has suggested that in some regions on a dune's surface the sediment transport might be better explained through investigations of the turbulent nature of the airflow. However, to date there have been no field studies providing data on the turbulent characteristics of the airflow around dunes with which to support or refute such hypotheses. The field investigation presented here provides mean and turbulent airflow measurements across the centre-line of a barchan sand dune in Namibia. Data were collected using arrays of sonic anemometers and were compared with sand flux data measured using wedge-shaped traps. Results support previously published data derived from wind tunnels and numerical models. The decline in mean wind velocity at the upwind toe of the dune is shown to coincide with a rise in turbulence, whilst mean velocity acceleration on the upper slope corresponds with a general decline in measured turbulence. Analysis of the components of Reynold shear stress ( -u'¯w'¯) and normal stresses ( u¯ and w2 ¯) supports the notion that the development of flow turbulence along the dune centre-line is likely to be associated with the interplay between streamline curvature and mean flow deceleration/acceleration. It is suggested that, due to the nature of its calculation, turbulence intensity is a measure of less practical use than direct assessments of the individual components of Reynolds stress, particularly the instantaneous horizontal streamwise component ( u2 ¯) and shear stress ( -uw¯). Whilst, increases in Reynolds shear stress and the horizontal streamwise component of stress in the toe

Crustal structure of northern Egypt from joint inversion of receiver functions and surface wave dispersion velocities

Science.gov (United States)

Badawy, Ahmed; Hegazi, Mona; Gaber, Hanan; Korrat, Ibrahim

2018-01-01

In this study, we used a combined inversion of body wave receiver functions and surface wave dispersion measurements to provide constraints on the crustal structure of northern Egypt. The two techniques are complementary to each other: receiver functions (RFs) are sensitive to shear-wave velocity contrasts, while surface wave dispersion (SWD) measurements are sensitive to finite variations of shear-wave velocity with depth. A database of 122 teleseismic events digitally recorded by the Egyptian National Seismological Network (ENSN) stations has been used as well. To enhance the resulting RFs at each ENSN station, the H-k stacking method was applied. A joint inversion process between the resulting receiver functions and the surface wave dispersion curves was applied as well. We have produced three averaged velocity structure models for distinct geographic and tectonic provinces namely Sinai, eastern desert, and western desert from east to the west respectively. These models will deeply help in estimation the epicenter distance of earthquake, focal mechanism solutions, and earthquake hazard analysis in northern Egypt. An obvious image of the subsurface structure has been determined which shows that generally the crustal structure of northern Egypt consists of three layers covered with a sequence of sediments that differs in thickness from across the region except in the Sharm area where the sedimentary cover is absent. The obtained results indicate that crustal thickness differs from east to west and reaches its maximum value of about 36 km at Siwa station (SWA) in the western desert and its minimum value of about 28 km at Sharm station (SHR) of the southern tip of the Sinai Peninsula. The Vp/Vs ratio varies between 1.71 and 2.07 in northern Egypt. Generally, the high values (1.93) of (Vp/Vs) at SWA station may reflect the well-known rich aquifer with fully saturated sediments of the Swia Oasis in the Western Desert. Moreover, the highest value (2.07) of (Vp/Vs) at

Crustal structure of northern Egypt from joint inversion of receiver functions and surface wave dispersion velocities

Science.gov (United States)

Badawy, Ahmed; Hegazi, Mona; Gaber, Hanan; Korrat, Ibrahim

2018-05-01

In this study, we used a combined inversion of body wave receiver functions and surface wave dispersion measurements to provide constraints on the crustal structure of northern Egypt. The two techniques are complementary to each other: receiver functions (RFs) are sensitive to shear-wave velocity contrasts, while surface wave dispersion (SWD) measurements are sensitive to finite variations of shear-wave velocity with depth. A database of 122 teleseismic events digitally recorded by the Egyptian National Seismological Network (ENSN) stations has been used as well. To enhance the resulting RFs at each ENSN station, the H-k stacking method was applied. A joint inversion process between the resulting receiver functions and the surface wave dispersion curves was applied as well. We have produced three averaged velocity structure models for distinct geographic and tectonic provinces namely Sinai, eastern desert, and western desert from east to the west respectively. These models will deeply help in estimation the epicenter distance of earthquake, focal mechanism solutions, and earthquake hazard analysis in northern Egypt. An obvious image of the subsurface structure has been determined which shows that generally the crustal structure of northern Egypt consists of three layers covered with a sequence of sediments that differs in thickness from across the region except in the Sharm area where the sedimentary cover is absent. The obtained results indicate that crustal thickness differs from east to west and reaches its maximum value of about 36 km at Siwa station (SWA) in the western desert and its minimum value of about 28 km at Sharm station (SHR) of the southern tip of the Sinai Peninsula. The Vp/Vs ratio varies between 1.71 and 2.07 in northern Egypt. Generally, the high values (1.93) of (Vp/Vs) at SWA station may reflect the well-known rich aquifer with fully saturated sediments of the Swia Oasis in the Western Desert. Moreover, the highest value (2.07) of (Vp/Vs) at

Mediterranean Energy Perspectives, Egypt - Executive summary

International Nuclear Information System (INIS)

2011-01-01

Egypt is a significant oil producer and a rapidly growing natural gas producer. Its strategic location makes it an important transit corridor for world energy markets. Mediterranean Energy Perspectives - Egypt provides insights into the country's energy situation today and over the next two decades. It presents detailed data and analysis of interest to those who have a stake in both the supply and demand side of the energy equation. It is the first in-depth country review in OME's Mediterranean Energy Perspectives (MEP) series. The publication draws upon the extensive expertise of the Observatoire Mediterraneen de l'Energie (OME) and its members. MEP-Egypt is a unique and comprehensive analysis of the energy sector in Egypt. It contains data from the early days of its energy industry up to today as well as a view on its evolution to 2030 based on the supply and demand model developed by OME (Mediterranean Energy Model). Current efforts related to renewable energy sources are carefully considered as they are key issues for the Egyptian energy sector and for the whole economic and environment future of the country. MEP-Egypt presents: - Historical and forecast data on the supply and demand balance for each segment of the Egyptian energy sector. - Past, present and future of oil and gas exploration and discoveries. - Oil and gas fields: production and development. - Oil and gas production profiles and prospects to 2030. - Detailed information on refineries, pipelines, LNG terminals and storage facilities. - Evolution of electricity generation and installed capacity. - Developments of innovative and renewable energy sources. - Prospects for CO 2 emissions and sustainable development. - Fiscal regime of the energy industry. - Alternative energy scenarios: a Conservative scenario, a Proactive scenario and two High Economic Growth variants. MEP-Egypt has been prepared by a joint-team of Egyptian industry experts and OME staff, supported by related companies, institutions

Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough

Science.gov (United States)

Santamarina, J.C.; Dai, Shifeng; Terzariol, M.; Jang, Jeonghwan; Waite, William F.; Winters, William J.; Nagao, J.; Yoneda, J.; Konno, Y.; Fujii, T.; Suzuki, K.

2015-01-01

Natural hydrate-bearing sediments from the Nankai Trough, offshore Japan, were studied using the Pressure Core Characterization Tools (PCCTs) to obtain geomechanical, hydrological, electrical, and biological properties under in situ pressure, temperature, and restored effective stress conditions. Measurement results, combined with index-property data and analytical physics-based models, provide unique insight into hydrate-bearing sediments in situ. Tested cores contain some silty-sands, but are predominantly sandy- and clayey-silts. Hydrate saturations Sh range from 0.15 to 0.74, with significant concentrations in the silty-sands. Wave velocity and flexible-wall permeameter measurements on never-depressurized pressure-core sediments suggest hydrates in the coarser-grained zones, the silty-sands where Sh exceeds 0.4, contribute to soil-skeletal stability and are load-bearing. In the sandy- and clayey-silts, where Sh < 0.4, the state of effective stress and stress history are significant factors determining sediment stiffness. Controlled depressurization tests show that hydrate dissociation occurs too quickly to maintain thermodynamic equilibrium, and pressure–temperature conditions track the hydrate stability boundary in pure-water, rather than that in seawater, in spite of both the in situ pore water and the water used to maintain specimen pore pressure prior to dissociation being saline. Hydrate dissociation accompanied with fines migration caused up to 2.4% vertical strain contraction. The first-ever direct shear measurements on never-depressurized pressure-core specimens show hydrate-bearing sediments have higher sediment strength and peak friction angle than post-dissociation sediments, but the residual friction angle remains the same in both cases. Permeability measurements made before and after hydrate dissociation demonstrate that water permeability increases after dissociation, but the gain is limited by the transition from hydrate saturation

Joint Egypt/United States report on Egypt/United States cooperative energy assessment. Volume 5 of 5 Vols. Annexes 11--13

Energy Technology Data Exchange (ETDEWEB)

1979-04-01

The principal features of the existing environment of Egypt are characterized and the main problem areas identified in Annex 11. The environmental, health, and associated social issues that must be considered in choosing from among the options available to Egypt for meeting projected future energy needs are identified. The environmental impacts associated with these options are discussed and observations are made of alternte ways to minimize environmental insults. Annex 12, Manpower, analyzes the energy-related manpower situation of Egypt. Manpower education and training resources of Egypt; the existing manpower base of Egypt; manpower needs of the energy strategies; a comparison of manpower needs and existing manpower base; and the underlying economic and social factors that will make Egypt energy facility development very difficult to plan and execute are discussed. Annex 13 summarizes a preliminary analysis of the capital, labor, materials, and equipment resources required to implement alternative Egyptian energy futures and documents the assessment of several Egyptian energy development programs selected by the DOE. It egins with brief overviews of the ESPM model and data base. It then describes the method by which the system was adapted to Egyptian conditions and the results of this modification. The comparison Case energy development program is described, followed by a summary of ESPM-derived facility and resource requirements. Finally, the sensitivity of these results to several alternative energy strategies is illustrated.

Spatial patterns of cyanobacterial mat growth on sand ripples

Science.gov (United States)

Mariotti, G.; Klepac-Ceraj, V.; Perron, J. T.; Bosak, T.

2016-02-01

Photosynthetic microbial mats produce organic matter, cycle nutrients, bind pollutants and stabilize sediment in sandy marine environments. Here, we investigate the influence of bedforms and wave motion on the growth rate, composition and spatial variability of microbial mats by growing cyanobacterial mats on a rippled bed of carbonate sand in a wave tank. The tank was forced with an oscillatory flow with velocities below the threshold for sediment motion yet able to induce a porewater flow within the sediment. Different spatial patterns developed in mats depending on the initial biochemistry of the water medium. When growing in a medium rich in nitrogen, phosphorous and micronutrients, mats grew faster on ripple troughs than on ripple crests. After two months, mats covered the bed surface uniformly, and the microbial communities on the crests and in the troughs had similar compositions. Differences in bed shear stress and nutrient availability between crests and troughs were not able to explain the faster growth in the troughs. We hypothesize that this growth pattern is due to a "strainer" effect, i.e. the suspended bacteria from the inoculum were preferentially delivered to troughs by the wave-induced porewater flow. In the experiments initiated in a medium previously used up by a microbial mat and thus depleted in nutrients, mats grew preferentially on the ripple crests. This spatial pattern persisted for nearly two years, and the microbial composition on troughs and crests was different. We attribute this pattern to the upwelling of porewater in the crests, which increased the delivery of nutrients from sediment to the cyanobacteria on the bed surface. Thus, the macroscopic patterns formed by photosynthetic microbial mats on sand ripples may be used to infer whether mats are nutrient-limited and whether they are recently colonized or older than a month.

LDC nuclear power: Egypt

International Nuclear Information System (INIS)

Selim, M.E.S.

1982-01-01

This chapter reviews the evolution of Egypt's nuclear program, the major factors that influenced the successive series of nuclear decisions, and the public debate over the far-reaching program attempted by the late President Anwar El-Sadat. Egypt's program is important, not only because it was the first Arab country to enter the nuclear age, but because it is an ambitious program that includes the installation of eight reactors at a time when many countries are reducing their commitment to nuclear power. Major obstacles remain in terms of human, organizational, and natural resource constraints. 68 references, 1 table

Holocene sediment distribution on the inner continental shelf of northeastern South Carolina: implications for the regional sediment budget and long-term shoreline response

Science.gov (United States)

Denny, Jane F.; Schwab, William C.; Baldwin, Wayne E.; Barnhardt, Walter A.; Gayes, Paul T.; Morton, R.A.; Warner, John C.; Driscoll, Neal W.; Voulgaris, George

2013-01-01

High-resolution geophysical and sediment sampling surveys were conducted offshore of the Grand Strand, South Carolina to define the shallow geologic framework of the inner shelf. Results are used to identify and map Holocene sediment deposits, infer sediment transport pathways, and discuss implications for the regional coastal sediment budget. The thickest deposits of Holocene sediment observed on the inner shelf form shoal complexes composed of moderately sorted fine sand, which are primarily located offshore of modern tidal inlets. These shoal deposits contain ~67 M m3 of sediment, approximately 96% of Holocene sediment stored on the inner shelf. Due to the lack of any significant modern fluvial input of sand to the region, the Holocene deposits are likely derived from reworking of relict Pleistocene and older inner-shelf deposits during the Holocene marine transgression. The Holocene sediments are concentrated in the southern part of the study area, due to a combination of ancestral drainage patterns, a regional shift in sediment supply from the northeast to the southwest in the late Pleistocene, and proximity to modern inlet systems. Where sediment is limited, only small, low relief ridges have formed and Pleistocene and older deposits are exposed on the seafloor. The low-relief ridges are likely the result of a thin, mobile veneer of sediment being transported across an irregular, erosional surface formed during the last transgression. Sediment textural trends and seafloor morphology indicate a long-term net transport of sediment to the southwest. This is supported by oceanographic studies that suggest the long-term sediment transport direction is controlled by the frequency and intensity of storms that pass through the region, where low pressure systems yield net along-shore flow to the southwest and a weak onshore component. Current sediment budget estimates for the Grand Strand yield a deficit for the region. Volume calculations of Holocene deposits on the

The Light-Field of Microbenthic Communities - Radiance Distribution and Microscale Optics of Sandy Coastal Sediments Rid A-1977-2009

DEFF Research Database (Denmark)

KUHL, M.; JØRGENSEN, BB

1994-01-01

radiance distribution. Comparison of light fields in wet and dry quartz sand showed that the lower refractive index of air than of water caused a more forward-biased scattering in wet sand. Light penetration was therefore deeper and surface irradiance reflectance was lower in wet sand than in dry sand......The light field in coastal sediments was investigated at a spatial resolution of 0.2-0.5 mm by spectral measurements (450-850 nm) of field radiance and scalar irradiance using fiber-optic microprobes. Depth profiles of field radiance were measured with radiance microprobes at representative angles...... relative to vertically incident collimated light in rinsed quartz sand and in a coastal sandy sediment colonized by microalgae. Upwelling and downwelling components of irradiance and scalar irradiance were calculated from the radiance distributions. Calculated total scalar irradiance agreed well...

Develop Accurate Methods for Characterizing and Quantifying Cohesive Sediment Erosion Under Combined Current-Wave Conditions

Science.gov (United States)

2017-09-01

majority of contaminated sediments are a mixture of sand, silt, and clay . These sediments are often referred to as cohesive because, unlike pure sand...number:  2 18 p p c ρ d Sk f μ (2) where ρp is the particle density, dp is the particle diameter, µ is the dynamic viscosity , and fc is a...using the viscous timescale, 2τν ut =+ , where uτ is the friction velocity, and ν the kinematic viscosity , as t+ provides an estimate of the strain

How did the AD 1755 tsunami impact on sand barriers across the southern coast of Portugal?

DEFF Research Database (Denmark)

Costa, Pedro J. M.; Costas, Susana; Gonzalez-Villanueva, R.

2016-01-01

1755 tsunami flood on a coastal segment located within the southern coast of Portugal. In particular, the work focuses on deciphering the impact of the tsunami waves over a coastal sand barrier enclosing two lowlands largely inundated by the tsunami flood. Erosional features documented by geophysical...... above mean sea level). Our work highlights the usefulness of erosional imprints preserved in the sediment record to interpret the impact of the extreme events on sand barriers....

Egypt's fundamentalists say condoms immoral.

Science.gov (United States)

Soliman, S

1995-06-01

The first AIDS case in Egypt was reported almost 10 years ago, yet Egypt still does not have reliable statistics on the HIV/AIDS epidemic (officially, 513 HIV infections and 88 AIDS cases; more likely, 3000 and 10,000, respectively). HIV/AIDS bears a stigma. The government claims that every HIV-infected Egyptian acquired the infection through a blood transfusion while in the Gulf or through sexual intercourse in Europe. Cultural, social, and religious norms that discourage promiscuity may explain the low HIV/AIDS rate but these same taboos put women at risk by making it difficult for them to protect themselves. Islamic fundamentalist women reinforce the Islamic principle of forbidding sex education. They consider AIDS a plague of immoral Western society. They refuse to accept the fact that many men do not practice safer sex. These women consider condoms immoral. They think God will curse women who refuse to have sexual intercourse at their husbands' bidding. Many nongovernmental organizations consider an intensive education program as the only means to avert disaster. Egypt has yet to implement its model AIDS program. All hospitals in Cairo and some hospitals in rural areas have equipment to test for HIV. Surveillance systems have been limited to high risk groups. In Egypt, it is mandatory to test foreigners for HIV. Prisoners, prostitutes, homosexuals, and blood donors are tested randomly without their consent. Positive results are often reported to authorities before the persons learn their HIV status. A campaign for widespread sex education is the only action recommended so far. It includes a mass media component and community meetings and conferences. An Egyptian physician has found an anti-viral drug that stimulates the immune system, but his work does not receive much coverage outside Egypt. Egyptians need to tackle their cultural taboos about discussion of sex to curb the HIV/AIDS epidemic.

Bedform development in mixed sand-mud: The contrasting role of cohesive forces in flow and bed

Science.gov (United States)

Baas, Jaco H.; Davies, Alan G.; Malarkey, Jonathan

2013-01-01

The majority of subaqueous sediment on Earth consists of mixtures of cohesive clay and cohesionless sand and silt, but the role of cohesion on the development and stability of sedimentary bedforms is poorly understood. The results of new laboratory flume experiments on bedform development in cohesive, mixed sand-mud beds are compared with the results of previous experiments in which cohesive forces in high concentration clay flows dominated bedform development. Even though both series of mixed sand-mud experiments were conducted at similar flow velocities, the textural and structural properties of the bedforms were sufficiently different to permit the designation of key criteria for identifying bedform generation under cohesive flows against bedform generation on cohesive substrates. These criteria are essential for improving bedform size predictions in sediment transport modelling in modern sedimentary environments and for the reconstruction of depositional processes in the geological record. The current ripples developing on the cohesive, mixed sand-mud beds, with bed mud fractions of up to 18%, were significantly smaller than equivalent bedforms in noncohesive sand. Moreover, the bedform height showed a stronger inversely proportional relationship with initial bed mud fraction than the bedform wavelength. This is in contrast with the bedforms developing under the cohesive clay flows, which tend to increase in size with increasing suspended clay concentration until the flow turbulence is fully suppressed. Selective removal of clay from the mixed beds, i.e., clay winnowing, was found to be an important process, with 82-100% clay entrained into suspension after 2 h of bedform development. This winnowing process led to the development of a sand-rich armouring layer. This armouring layer is inferred to have protected the underlying mixed sand-mud from prolonged erosion, and in conjunction with strong cohesive forces in the bed may have caused the smaller size of the

Laboratory Study of Quaternary Sediment Resistivity Related to Groundwater Contamination at Mae-Hia Landfill, Mueang District, Chiang Mai Province

Science.gov (United States)

Sichan, N.

2007-12-01

This study was aimed to understand the nature of the resistivity value of the sediment when it is contaminated, in order to use the information solving the obscure interpretation in the field. The pilot laboratory experiments were designed to simulate various degree of contamination and degree of saturation then observe the resulting changes in resistivity. The study was expected to get a better understanding of how various physical parameters effect the resistivity values in term of mathematic function. And also expected to apply those obtained function to a practical quantitatively interpretation. The sediment underlying the Mae-Hia Landfill consists of clay-rich material, with interfingerings of colluvium and sandy alluvium. A systematic study identified four kinds of sediment, sand, clayey sand, sandy clay, and clay. Representative sediment and leachate samples were taken from the field and returned to the laboratory. Both the physical and chemical properties of the sediments and leachate were analyzed to delineate the necessary parameters that could be used in Archie's equation. Sediment samples were mixed with various concentration of leachate solutions. Then the resistivity values were measured at various controlled steps in the saturation degree in a well- calibrated six-electrode model resistivity box. The measured resistivity values for sand, clayey sand, sandy clay when fully and partly saturated were collected, then plotted and fitted to Archie's equation, to obtain a mathematical relationship between bulk resistivity, porosity, saturation degree and resistivity of pore fluid. The results fit well to Archie's equation, and it was possible to determine all the unknown parameters representative of the sediment samples. For sand, clayey sand, sandy clay, and clay, the formation resistivity factors (F) are 2.90, 5.77, 7.85, and 7.85 with the products of cementation factor (m) and the pore geometry factors (a) (in term of -am) are 1.49, -1.63, -1.92, -2

Comparison of estuarine sediment record with modelled rates of sediment supply from a western European catchment since 1500

Science.gov (United States)

Poirier, Clément; Poitevin, Cyril; Chaumillon, Éric

2016-09-01

Marine and estuarine sediment records reporting impacts of historical land use changes exist worldwide, but they are rarely supported by direct quantified evidence of changes in denudation rates on the related catchments. Here we implement a spatially-resolved RUSLE soil erosion model on the 10 000 km2 Charente catchment (France), supplied with realistic scenarios of land-cover and climate changes since 1500, and compare the results to a 14C-dated estuarine sediment record. Despite approximations, the model correctly predicts present-day Charente river sediment load. Back-cast modelling suggests that the Charente catchment is an interesting case where the sediment supply did not change despite increase in soil erosion resulting from 18th-century deforestation because it was mitigated by drier climate during the same period. Silt-sand alternations evidenced in the sediment record were correlated with sub-decadal rainfall variability.

Single Finds. The case of Roman Egypt

DEFF Research Database (Denmark)

Christiansen, Erik

2006-01-01

Survery of single or stray finds from Roman Egypt and discussion of them as evidence for the circulation and use of coins......Survery of single or stray finds from Roman Egypt and discussion of them as evidence for the circulation and use of coins...

Salafis in Political Life of Egypt

Directory of Open Access Journals (Sweden)

- Сабери Фахиме

2015-12-01

Full Text Available In today's world Salafism, which has evolved from insignificant and apolitical to the very influential movement is the subject of active discussion. This article discusses and analyzes the historical background, the conditions of formation and propagation of Salafi movement in Egypt. In addition, the author disclosed the role and the place of this movement in modern political life of Egypt.

Shoreline accretion and sand transport at groynes inside the Port of Richards Bay.

CSIR Research Space (South Africa)

Schoonees, JS

2006-01-01

Full Text Available on the accretion adjacent to two of the groynes and on the sediment transport rates at these groynes. Tides, beach slopes, winds, wave climate, current regime, and sand grain sizes were documented. The one site is “moderately protected” from wave action while...

Modeling the influence of storms on sand wave formation : A linear stability approach

NARCIS (Netherlands)

Campmans, G.H.P.; Roos, P.C.; de Vriend, H.J.; Hulscher, S.J.M.H.

2017-01-01

We present an idealized process-based morphodynamic model to study the effect of storms on sand wave formation. To this end, we include wind waves, wind-driven flow and, in addition to bed load transport, suspended load sediment transport. A linear stability analysis is applied to systematically

Effect of bioremediation agents on oil biodegradation in medium-fine sand

International Nuclear Information System (INIS)

Croft, B.C.; Swannell, R.P.J.; Grant, A.L.; Lee, K.

1995-01-01

A spill of weathered Arabian light crude oil on an intertidal sand zone was simulated in the laboratory. Respirometry, chemical, and microbiological methods were employed to assess the effectiveness of two bioremediation agents: a slow-release inorganic (Max Bac) and an oleophilic organic fertilizer (Inipol EAP22). Inipol EAP22 stimulated additional CO 2 evolution, and significantly increased both the total chemoheterotrophic population and the number of hydrocarbon-degrading microorganisms. At the end of the experiment, the residual oil extracted from the Inipol-treated sand was significantly more biodegraded, based on the application of the conserved biomarkers (phytane and 17α, 21β hopane), than that removed from the other sand columns, albeit by a relatively small amount. The results suggested that Inipol EAP22 stimulated the chemoheterotrophic and hydrocarbon-degrading microbial population and, after a lag phase, encouraged oil biodegradation in fine sandy sediments subjected to a vertical tidal cycle

Wave-induced ripple development in mixed clay-sand substrates

Science.gov (United States)

Wu, Xuxu; Parsons, Daniel; Baas, Jaco H.; Mouazé, Dominique; McLelland, Stuart; Amoudry, Laurent; Eggenhuisen, Jorris; Cartigny, Matthieu; Ruessink, Gerben

2016-04-01

This paper reports on a series of experiments that aim to provide a fuller understanding of ripple development within clay-sand mixture substrates under oscillatory flow conditions. The work was conducted in the Total Environment Simulator at the University of Hull and constituted 6 separate runs, in which 5 runs were conducted under identical sets of regular waves (an additional run was conducted under irregular waves, but is not discussed in present paper). The bed content was systematically varied in its composition ranging from a pure sand bed through to a bed comprising 7.4% clay. A series of state-of-the-art measurements were employed to quantify interactions of near-bed hydrodynamics, sediment transport, and turbulence over rippled beds formed by wave action, during and after, each run. The experimental results demonstrate the significant influence of the amount of cohesive clay materials in the substrate on ripple evolution under waves. Most importantly, addition of clay in the bed dramatically slowed down the rate of ripple development and evolution. The equilibrium time of each run increased exponentially from 30 minutes under the control conditions of a pure sand bed, rising to ~350 minutes for the bed with the highest fraction of clay. The paper discusses the slower ripple growth rates with higher cohesive fractions, via an influence on critical shear, but highlights that the end equilibrium size of ripples is found to be independent of increasing substrate clay fraction. The suspended particles mass (SPM) concentration indicates that clay particles were suspended and winnowed by wave action. Additionally, laser granulometry of the final substrates verified that ripple crests were composed of pure sand layers that were absent at ripple troughs, reflecting a relatively higher winnowing efficiency at wave ripples crest. The winnowing process and its efficiency is inexorably linked to wave ripple development and evolution. The implications of the results

Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus.

Directory of Open Access Journals (Sweden)

Bob Laarhoven

Full Text Available An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv. The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml, 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin. With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates.

Sediment Dispersal on the Topset of a Tectonically Active Shelf-edge Delta: an Interplay Between Sediment Supply and Subsidence, as Demonstrated for the Selenga River, Lake Baikal, Russia

Science.gov (United States)

Nittrouer, J. A.; Dong, T. Y.

2017-12-01

The Selenga River delta (Lake Baikal, Russia), located adjacent to an active rift margin and filling the world's deepest lake, represents one of the few examples of a modern shelf-edge system. Research into sediment dispersal on the Selenga delta was undertaken with the aim of linking topset morphodynamics and sediment accumulation patterns with the production of stratigraphy. The subaerial delta is constructed of three active lobes that receive varying amounts of water and sediment, distributed among a nine-order bifurcating channel network. Data from multiple expeditions include bathymetric and water-discharge measurements, side-scan images of the bed and banks, sediment samples, and bankline composition (including sediment type and vegetation). This information is analyzed to evaluate spatial variability in: 1. channel geometry, 2. boundary shear stress, 3. bedform size, and 4. bed sediment composition. The delta possesses downstream sediment fining, whereby median channel bed size decreases by two orders of magnitude over thirty kilometers, from a predominantly gravel and sand mixture near the delta apex to silt and fine sand at the lake interface. The location of gravel termination among distributary channels coincides with a reduction in sediment-transport capacity, as assessed by measurements of boundary shear stress. Interestingly, backwater hydrodynamics, which operate as important influences on bed grain size for many deltas, is not a major influence on the Selenga system. Instead, a non-linear downstream decrease in boundary shear stress arises due to partitioning of water among the bifurcating channel network. As has been documented in previous studies, gravel and coarse sand are absent on the delta foreset and bottomset (i.e., the rift axis), despite a continuous sediment feed from upstream that should provide the supply necessary to increase bed slope and enhance transport capacity over the delta. To reconcile this discrepancy, a tectonic timescale is

Uranium-series dated authigenic carbonates and Acheulian sites in southern Egypt

International Nuclear Information System (INIS)

Szabo, B.J.; McHugh, W.P.; Schaber, G.G.; Breed, C.S.; Haynes, C.V.

1989-01-01

Field investigations in southern Egypt have yielded Acheulian artifacts in situ in authigenic carbonate deposits (CaCO 3 -cemented alluvium) along the edges of now-aggraded paleovalleys (Wadi Arid and Wadi Safsaf). Uranium-series dating of 25 carbonate samples from various localities as far apart as 70 kilometers indicates that widespread carbonate deposition occurred about 45, 141 and 212 ka (thousand years ago). Most of the carbonate appears to have been precipitated from groundwater, which suggests that these three episodes of deposition may be related to late Pleistocene humid climates that facilitated human settlement in this now hyperarid region. Carbonate cements from sediments containing Acheulian artifacts provide a minimum age of 212 ka for early occupation of the paleovalleys. 16 refs., 3 figs., 2 tabs

Developing an interactive Tool for evaluating sand nourishment strategies along the Holland coast in perspective of benthos, fish nursery and dune quality

NARCIS (Netherlands)

Baptist, M.J.; Wolfshaar, van de K.E.; Huisman, B.J.A.; Groot, de A.V.; Boer, de W.; Ye, Q.

2012-01-01

Sand nourishments can affect the coastal ecosystem in various ways. Direct effects are the burial of benthic species under a layer of sand. In the direct vicinity, suffocation of benthos can occur due to the settling of a plume of suspended sediment particles. A plume of fine particles may also

Literature Review of Unconsolidated Sediment in San Francisco Bay and Nearby Pacific Ocean Coast

Directory of Open Access Journals (Sweden)

Barry R. Keller

2009-09-01

Full Text Available A review of the geologic literature regarding sedimentation in the San Francisco Bay estuarine system shows that the main part of the bay occupies a structural tectonic depression that developed in Pleistocene time. Eastern parts, including San Pablo Bay and Suisun Bay, have had sedimentation throughout late Mesozoic and Tertiary. Carquinez Strait and the Golden Gate may represent antecedent stream erosion. Sedimentation has included estuarine, alluvial, and eolian deposition. The ages of estuarine deposition includes the modern high sea level stand and earlier Pleistocene interglacial periods. Sediment sources can be generally divided into the Coast Ranges, particularly the Franciscan Complex, and “Sierran.” Much of the estuarine system is floored by very fine sediment, with local areas of sand floor. Near the Golden Gate, sediment size decreases in both directions away from the deep channel. Bedforms include sand waves (submarine dunes, flat beds, and rock and boulders. These are interpreted in terms of dominant transport directions. Near the Golden Gate is an ebb-tidal delta on the outside (including San Francisco bar and a flood-tidal delta on the inside (parts of Central Bay. The large tidal prism causes strong tidal currents, which in the upper part of the estuary are normally much stronger than river currents, except during large floods. Cultural influences have altered conditions, including hydraulic mining debris, blasting of rocks, dredging of navigation channels, filling of the bay, and commercial sand mining. Many of these have served to decrease the tidal prism, correspondingly decreasing the strength of tidal currents.

Status of fertility control in Egypt.

Science.gov (United States)

Hefnawi, F I

1982-01-01

The concern for fertility control is not alien to the cultural and religious heritage of Egypt. Historically, Egyptian interest in fertility dates to the Pharoahs. Contraceptive recipes written at least 15-18 centuries B.C. have been found. Romans may have borrowed some of the more effective methods from Egypt when it became part of the Roman Empire as evidenced by the decline in size of aristocratic Roman families at the beginning of the Christian era. Muslim conquerors of Egypt encouraged fertility control. In the 9th century differences of opinion about the legality of contraception appeared among the interpreters of Islamic law. Some methods found in the writings of Muslim doctors as al-Razi and Avicenna still survive in the folk medicine of Egypt. In modern times use of barrier methods of contraception were encouraged by family planning organizations in Egypt. The medical profession was not deeply involved since these methods did not require much medical assistance. In 1936 a religiouss verdict declared contraception to be a lawful act of Islam. National programs in family planning in the 1960's encouraged the use of the Lippes Loop IUD. The medical problem of blood loss associated with the IUD caused anxiety because of the high incidence of anemia in the female Egyptian population. There was also a cultural limitation on the wide use of the IUD. "Spotting" due to the IUD resulted in females being ritually unclean and therefore unfit to pray or observe the Islamic fast. The Pill, initially favored caused complications due to its effect on breast milk which is the universal source of nutrition for infants in Egypt. Replacement of the Pill by depo-provera injections during the post partum period of lactation is a practical solution. Permanent sterilization is limited to females and only performed when medically indicated. Abortion is illegal and permitted only as a therapeutic measure.

Relationship of bifenthrin sediment concentrations to grain size and total organic carbon in California waterbodies: implications for ecological risk.

Science.gov (United States)

Hall, Lenwood W; Anderson, Ronald D

2014-12-01

A summary analysis of data sets from six California waterbodies was conducted to determine the relationship of bifenthrin sediment concentrations to: % sand/gravel; % silt; % clay; % silt/clay and % total organic carbon (TOC). The relationship of TOC to % sand/gravel, % silt, % clay, and % silt/clay was also analyzed. Statistically significant and meaningful direct relationships were reported between bifenthrin and % TOC, % silt, % clay and % silt/clay while a significant and meaningful inverse relationship was reported between bifenthrin and % sand/gravel. A significant and meaningful inverse relationship was reported between % TOC and % sand/gravel, while a significant and meaningful direct relationship was reported between % TOC and % silt, % clay and % silt/clay. Significant bifenthrin sediment concentrations would not be expected in non-depositional (sand/gravel) areas which have been reported to be dominant in various streams in California's Central Valley and are also the preferred habitat for many benthic macroinvertebrate taxa.

Management of Disused Radioactive Sealed Sources in Egypt - 13512

International Nuclear Information System (INIS)

Mohamed, Y.T.; Hasan, M.A.; Lasheen, Y.F.

2013-01-01

The future safe development of nuclear energy and progressive increasing use of sealed sources in medicine, research, industry and other fields in Egypt depends on the safe and secure management of disused radioactive sealed sources. In the past years have determined the necessity to formulate and apply the integrated management program for radioactive sealed sources to assure harmless and ecological rational management of disused sealed sources in Egypt. The waste management system in Egypt comprises operational and regulatory capabilities. Both of these activities are performed under legislations. The Hot Laboratories and Waste Management Center HLWMC, is considered as a centralized radioactive waste management facility in Egypt by law 7/2010. (authors)

SEAFLOOR SEDIMENT CHARACTERISTICS AND HEAVY MINERAL OCCURENCES AT BETUMPAK CAPE AND ADJACENT AREA, BANGKA STRAIT, BANGKA BELITUNG PROVINCE

Directory of Open Access Journals (Sweden)

Rohendi Rohendi

2017-07-01

Full Text Available Thirty seafloor of sediment samples have been taken by using gravity corer and grab sampler at Betumpak Cape, and adjacent area of Bangka Belitung. The result of grain size analyses show that there are four sediment units: gravelly sand, gravelly muddy sand, silt and silty sand. Identification of Scanning Electron Microscope (SEM image on several samples shows the presence of clay mineral such as smectite, alunite, chlorite etc., may resulted from plagioclase weathering of granite. Based on heavy mineral analyses, its highest content is found at MTK-27 (northwest of Betumpak Cape. High content of apatite (0.94% wt and 1.07% wt is found on coarse sand fractions (115-170 mesh at MTK-29 (northeast Ular Cape and MTK-30 (north of Ular Cape. Generally, the heavy mineral accumulation is occurred on medium sand fraction (60-80 mesh as magnetite (7.86% wt, ilmenite (4.9% wt and zircon (1.32% wt. Based on these data, it shows that heavy mineral is accumulated on medium to coarse sand.

Wind-blown sand on beaches: an evaluation of models

Science.gov (United States)

Sherman, Douglas J.; Jackson, Derek W. T.; Namikas, Steven L.; Wang, Jinkang

1998-03-01

Five models for predicting rates of aeolian sand transport were evaluated using empirical data obtained from field experiments conducted in April, 1994 at a beach on Inch Spit, Co. Kerry, Republic of Ireland. Measurements were made of vertical wind profiles (to derive shear velocity estimates), beach slope, and rates of sand transport. Sediment samples were taken to assess characteristics of grain size and surface moisture content. Estimates of threshold shear velocity were derived using grain size data. After parsing the field data on the basis of the quality of shear velocity estimation and the occurrence of blowing sand, 51 data sets describing rates of sand transport and environmental conditions were retained. Mean grain diameter was 0.17 mm. Surface slopes ranged from 0.02 on the foreshore to about 0.11 near the dune toe. Mean shear velocities ranged from 0.23 m s -1 (just above the observed transport threshold) to 0.65 m s -1. Rates of transport ranged from 0.02 kg m -1 h -1 to more than 80 kg m -1 h -1. These data were used as input to the models of Bagnold [Bagnold, R.A., 1936. The Movement of Desert Sand. Proc. R. Soc. London, A157, 594-620], Kawamura [Kawamura, R., 1951. Study of Sand Movement by Wind. Translated (1965) as University of California Hydraulics Engineering Laboratory Report HEL 2-8, Berkeley], Zingg [Zingg, A.W., 1953. Wind tunnel studies of the movement of sedimentary material. Proc. 5th Hydraulics Conf. Bull. 34, Iowa City, Inst. of Hydraulics, pp. 111-135], Kadib [Kadib, A.A., 1965. A function for sand movement by wind. University of California Hydraulics Engineering Laboratory Report HEL 2-8, Berkeley], and Lettau and Lettau [Lettau, K. and Lettau, H., 1977. Experimental and Micrometeorological Field Studies of Dune Migration. In: K. Lettau and H. Lettau (Eds.), Exploring the World's Driest Climate. University of Wisconsin-Madison, IES Report 101, pp. 110-147]. Correction factors to adjust predictions of the rate of transport to account

Environmental Impacts of Sand Exploitation. Analysis of Sand Market

Directory of Open Access Journals (Sweden)

Marius Dan Gavriletea

2017-06-01

Full Text Available Sand is an indispensable natural resource for any society. Despite society’s increasing dependence on sand, there are major challenges that this industry needs to deal with: limited sand resources, illegal mining, and environmental impact of sand mining. The purpose of this paper is twofold: to present an overview of the sand market, highlighting the main trends and actors for production, export and import, and to review the main environmental impacts associated with sand exploitation process. Based on these findings, we recommend different measures to be followed to reduce negative impacts. Sand mining should be done in a way that limits environmental damage during exploitation and restores the land after mining operations are completed.

Views of Ancient Egypt. Teacher's Guide. School Arts: Looking/Learning.

Science.gov (United States)

Downs, Linda; Brenner, Carla

This teaching guide discusses ancient Egyptian culture, the lithographs made by Napoleon's scientists in 1798-99 to study and record every aspect of Egypt, the world's subsequent fascination with Egypt, ancient Egyptian architecture, Egyptian writing, and archeologists' illustrations of Egypt. The guide suggests activities for elementary school,…

Coupled geophysical characterization of shallow fluvio-clastic sediments in Agwagune, southeastern Nigeria

Science.gov (United States)

Akpan, Anthony E.; Ekwok, Stephen E.; Ebong, Ebong D.; George, Anthony M.; Okwueze, Emeka E.

2018-07-01

Geophysical investigation performed using electrical resistivity tomography (ERT), vertical electrical sounding (VES), seismic refraction (SRF) and ground penetrating radar (GPR) techniques were used to constrain and characterize shallow lithologic units in the Cross River bank (CRB) in southeastern Nigeria. Results show that the upper layer sediments comprise a 3-5-layered lithostratigraphic sequence with high clayey content. Around the Cross River bank (CRB), the top sediments consist of loose, silty and clayey sands with low resistivities (sediments have no reasonable continuity beyond the vicinity of the CRB. The low attenuating indurated silts/sands characterized by low resistivities (channels truncate their lateral continuities. The lacustrine clays characterized by low resistivities (2400 m/s) make up the third layer. The clayey sediments impede vertical percolation of groundwater forcing it to accumulate at the bottom of the second layer resulting in high static water levels of 5 m elsewhere. Hydraulic gradient in the Cross River bed (CRBD) and in the coastal groundwater drives groundwater flow into the CRBD through macropores. The sediments become unstable when these macropores become enlarged as more materials are continuously transmitted through them.

Gender, Sibship Composition, and Education in Egypt

Science.gov (United States)

Tfaily, Rania

2016-01-01

This article examines the relationship between gender, sibship, and education over time in Egypt, focusing on how the number, sex, and birth order configuration of siblings affected boys' and girls' education during 1991-2008, a period characterized by significant social and economic changes in Egypt. This study disaggregates schooling into…

Origin of amphibole-rich beach sands from Tila-Mati, Karwar, central-west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Mislankar, P.G.; Iyer, S.D.

The pocket beach at Tila-Mati, Karwar, central west coast of India, is characterised by the occurrence of amphibole-rich (chiefly tremolite-actinolite) coarse sand in the zone of minimal impact of waves and currents. In the total sediment, grain...

Rainwater in Egypt: quantity, distribution and harvesting

Directory of Open Access Journals (Sweden)

H.I. ABDEL-SHAFY

2010-11-01

Full Text Available Egypt has limited water resources, and it will be under water stress within the year 2030. Therefore, Egypt should consider the natural and non-conventional water resources to overcome such problem. Rain harvesting is one solution; but not all; particularly on the north coast by the Mediterranean Sea and the Red sea. In this paper, the rainwater issue is reviewed and discussed in terms of the quantities and distribution at different selected areas in Egypt. The amount of rain falls at different location in Egypt was collected for a period of 16 months. The data indicated that rainfall in Egypt is very scarce, with an annual average of 12 mm and ranges from 0 mm/year in the desert to 200 mm/year in the north coastal region. The maximum total amount of rain does not exceed 1.8 billion m3per year. However, the average annual amount of rainfall water that is effectively utilized for agriculture purposes is estimated to be 1 billion m3. Harvesting pilot plant was constructed and implemented in Alexandria directly on the Mediterranean Sea. The harvested rain was used for irrigation and treated for drinking. It was, therefore, recommended to develop sustainable catchments at appropriate locations in the rain-fed areas at the north coast as well as cost effective grafting of the indigenous technologies with the innovative techniques.

Study of Morphologic Change in Poyang Lake Basin Caused by Sand Dredging Using Multi-temporal Landsat Images and DEMs

Science.gov (United States)

Qi, S.; Zhang, X.; Wang, D.; Zhu, J.; Fang, C.

2014-11-01

Sand dredging has been practiced in rivers, lakes, harbours and coastal areas in recent years in China mostly because of demand from construction industry as building material. Sand dredging has disturbed aquatic ecosystems by affecting hydrological processes, increasing content of suspended sediments and reducing water clarity. Poyang Lake, connecting with Yangtze River in the lower reaches of the Yangtze River, is the largest fresh water lake in China. Sand dredging in Poyang Lake has been intensified since 2001 because such practice was banned in Yangtze River and profitable. In this study, the morphologic change caused by sand dredging in Poyang Lake basin was analysed by overlaying two DEMs acquired in 1952 and 2010 respectively. Since the reflectance of middle infrared band for sand dredging vessel is much higher than that of water surface, sand dredging vessels were showed as isolated grey points and can be counted in the middle infrared band in 12 Landsat images acquired in flooding season during 2000~2010. Another two Landsat images (with low water level before 2000 and after 2010) were used to evaluate the morphologic change by comparing inundation extent and shoreline shape. The following results was obtained: (1) vessels for sand dredging are mainly distributed in the north of Poyang Lake before 2007, but the dredging area was enlarged to the central region and even to Gan River; (2) sand dredging area reached to about 260.4 km2 and is mainly distributed in the north of Songmen Mountain and has been enlarged to central of Poyang Lake from the distribution of sand vessels since 2007. Sand dredged from Poyang Lake was about 1.99 × 109 m3 or 2448 Mt assuming sediment bulk density of 1.23 t m-3. It means that the magnitude of sand mining during 2001-2010 is almost ten times of sand depositions in Poyang Lake during 1955-2010; (3) Sand dredging in Poyang Lake has alternated the lake capacity and discharge section area, some of the watercourse in the

Preliminary evaluation of the physical impacts of a nearshore sand extraction project

International Nuclear Information System (INIS)

Anctil, F.; Ouellet, Y.

1991-01-01

A review is presented of the potential physical impacts of a nearshore sand extraction project in the Gulf of St. Lawrence. In Canada, sand extraction is mainly limited to the Beaufort Sea area, where in 1982 alone 15 million tonnes of aggregate was dredged to satisfy the requirements of offshore petroleum exploration; but there is much experience in nearshore dredging in Europe. Criteria related to impacts, developed for conditions prevailing in the North Sea (England) and the Gulf of Gascogne (France) are adapted to meet the more moderate hydrodynamic impacts of an extraction project in the Gulf of St. Lawrence. Potential impacts of extraction projects include destruction of sand bars or dunes, direct erosion resulting from beach drawdown or sedimentation interference, and impacts on littoral drift due to modified wave refraction patterns. Three schemes for the sand extraction are considered, and from the results, a fourth scheme is elaborated in such a way as to limit the negative impacts to the minor category. 17 refs., 5 figs., 4 tabs

Provenance and geological significance of red mud and other clastic sediments of the Mugnano cave (Montagnola Senese, Italy

Directory of Open Access Journals (Sweden)

Iacoviello Francesco

2012-07-01

Full Text Available The Mugnano cave is characterized by a thick clastic sedimentary fill showing a great variability of sedimentary facies, ranging from clay to coarse-grained sand deposits. This paper deals with combined sedimentological and mineralogical (XRD and SEM studies of these sediments and bedrock insoluble residues in order to understand the origin and geological significance of cave deposits, with particular attention to red mud sediments, often considered as the residue of host rock dissolution. Three different sedimentary facies were recognized: i YS, yellow sand with occasionally shell fragments, testifying the arrival of sediments from the surrounding landscape; ii RS, red laminated mud; iii GS, grey and red-grey mud and sand, dolomite-rich sediments. Furthermore, the results obtained in the present study allowed the identification of two fingerprint minerals: i quartz, present only as traces in the limestone host-rock, and ii dolomite, certainly related to the incomplete bedrock dissolution. Results obtained by this multidisciplinary approach testify that no one of the investigated sediments is representative of a completely autochthonous sedimentation (i.e. accumulation of insoluble residue of limestone in a cave environment. In fact, all the three sedimentary facies show a bulk composition rich in quartz, a mineral indicating an external origin for these sediments. Also the grey sediments, despite of their high content of bedrock- related dolomite, are quite rich in quartz and they testify the mixing of autochthonous and allocthonous sediments. The clay fraction of cave sediments shows strong compositional similarities with bedrock insoluble residue and consequently its analysis cannot be considered as a clear proxy for distinguishing between different parent materials. Therefore, the origin of these cave deposits is dominantly related to external sediments inputs, with terra rossa surface soils as the most probable parent material for red mud

Optical Dating of Holocene Dune Sands in the Ferris Dune Field, Wyoming

Science.gov (United States)

Stokes, Stephen; Gaylord, David R.

1993-05-01

Optical dating of late Quaternary quartz dune sands from the Clear Creek portion of Ferris dune field, Wyoming, demonstrates the considerable potential of the technique as a chronostratigraphic tool. A sequence of radiocarbon-dated Holocene interdune strata permit optical dating of the intercalated dune sand to be tested; the concordance is good. The optical dates for the aeolian deposits not datable by radiocarbon suggest that aeolian sedimentation at Clear Creek peaked during two relatively short phases at ca. 8500 and 4000 yr B.P. The dates indicate that aeolian accumulation maxima (at least in the Clear Creek area) may not be synchronous with previously defined phases of marked aridity.

Urology and the scientific method in ancient Egypt.

Science.gov (United States)

Gordetsky, Jennifer; O'Brien, Jeanne

2009-03-01

To examine the practice of urology in ancient Egypt using various sources, including the Edwin Smith and Ebers Papyri. The sources of knowledge of ancient Egyptian medicine include medical papyri, paleopathology, art, and hieroglyphic carvings. A brief overview of the medical system in ancient Egypt was completed, in addition to an examination of the training and specialization of the physician in the ancient world. Urologic diseases treated in ancient Egypt and some of the first documented urologic surgeries are presented. Finally, we studied the role of the physician-priest and the intertwined use of religion and magic in ancient Egyptian medicine. The same medical conditions urologists treat in the office today were methodically documented thousands of years ago. Medical papyri show evidence that the ancient Egyptians practiced medicine using a scientific method based on the clinical observation of disease. This has been exemplified by the Edwin Smith Surgical Papyrus, a collection of surgical cases that gives a diagnosis, treatment, and prognosis for each ailment, and the discovery of medical specialization in ancient Egypt, giving us perhaps the world's first urologists. Intertwined with the scientific method was also the rich mysticism and religion of ancient Egypt, which were integral components of the healing process. We present an overview of the practice of urology in ancient Egypt, in terms of both pharmacologic and surgical intervention, as well as with a look into the religion of medicine practiced at that time.

Renewable energy potential from biomass residues in Egypt

Energy Technology Data Exchange (ETDEWEB)

Said, N.; Zamorano, M. [Civil Engineering Dept., Univ. of Granada, Campus de Fuentenueva, Granada (Spain); El-Shatoury, S.A. [Botany Dept., Faculty of Sciences, Suez Canal Univ., Ismailia (Egypt)

2012-11-01

Egypt has been one of the developing countries following successful programs for the development of renewable energy resources, with special emphasis on solar, wind and biomass. Utilization of biomass as a source of energy is important from energetic as well as environmental viewpoint. Furthermore, Egypt produces millions of biomass waste every year causing pollution and health problems. So, the incorporation of biomass with other renewable energy will increase the impact of solving energy and environmental problem. There is a good potential for the utilization of biomass energy resources in Egypt. Four main types of biomass energy sources are included in this study: agricultural residues, municipal solid wastes, animal wastes and sewage sludge. Analysis of the potential biomass resource quantity and its theoretical energy content has been computed according to literature review. The agriculture crop residue represents the main source of biomass waste with a high considerable amount of the theoretical potential energy in Egypt. Rice straw is considered one of the most important of such residue due to its high amount and its produced energy through different conversion techniques represent a suitable candidate for crop energy production in Egypt.

Distribution, diversity and abundance of bacterial laccase-like genes in different particle size fractions of sediments in a subtropical mangrove ecosystem.

Science.gov (United States)

Luo, Ling; Zhou, Zhi-Chao; Gu, Ji-Dong

2015-10-01

This study investigated the diversity and abundance of bacterial lacasse-like genes in different particle size fractions, namely sand, silt, and clay of sediments in a subtropical mangrove ecosystem. Moreover, the effects of nutrient conditions on bacterial laccase-like communities as well as the correlation between nutrients and, both the abundance and diversity indices of laccase-like bacteria in particle size fractions were also studied. Compared to bulk sediments, Bacteroidetes, Caldithrix, Cyanobacteria and Chloroflexi were dominated in all 3 particle-size fractions of intertidal sediment (IZ), but Actinobacteria and Firmicutes were lost after the fractionation procedures used. The diversity index of IZ fractions decreased in the order of bulk > clay > silt > sand. In fractions of mangrove forest sediment (MG), Verrucomicrobia was found in silt, and both Actinobacteria and Bacteroidetes appeared in clay, but no new species were found in sand. The declining order of diversity index in MG fractions was clay > silt > sand > bulk. Furthermore, the abundance of lacasse-like bacteria varied with different particle-size fractions significantly (p clay > silt in both IZ and MG fractions. Additionally, nutrient availability was found to significantly affect the diversity and community structure of laccase-like bacteria (p fractions (p < 0.05). Therefore, this study further provides evidence that bacterial laccase plays a vital role in turnover of sediment organic matter and cycling of nutrients.

Renewable-energy applications in Egypt

International Nuclear Information System (INIS)

Hammad, M.A.

2005-01-01

The paper illustrates the main activities carried out concerning development and application of renewable-energy technologies in Egypt. Main attention is devoted to biogas technology, solar and wind energy technologies. The main constraints for implementation of renewable-energy technologies in Egypt and the activities carried out for its release are highlighted. The coordination between the Islamic and other developing countries is highly needed, to achieve marked progress in implementation of renewable energy and sustainable development. Establishment of a network for renewable energy among the Islamic countries can play an active role in these aspects. (author)

Women in Post-Revolutionary Egypt

DEFF Research Database (Denmark)

Nielsen, Mette Toft; Hervik, Peter

and in drawings. Based on the analysis of this material the reader gets insights into personal experiences, believes and opinions of a diverse group of women in terms of age, economic class, education, geography, culture, religion, ethnicity, marital status, and political orientation. The detail-rich empirical......This book addresses how identity, structures, and agency affect women’s everyday lives in post-revolutionary Egypt. The authors analyse the topic both on a macro- as well as on a micro-level. Through interviews and workshops, women around Egypt express their own experiences in dialogue, in groups...

Sediment Transport on Continental Shelves: Storm Bed Formation and Preservation in Heterogeneous Sediments

Science.gov (United States)

2012-01-01

occurred during the Cretaceous period. The simulated storm bed for such an extratropical cyclone that lasts 4 days was deposited as deep as 75 m and had...Int. Assoc. Sedimentol. Spec. Publ. (2012) 44, 295-310 Sediment transport on continental shelves: storm bed formation and preservation in...xDept. of Earth Science, Memorial University of Newfoundland, St. Johns, Newfoundland, Canada ABSTRACT Many storm beds are constructed of silt/sand

Scattering from inclusions in Marine Sediments: SAX04 Data/Model Comparisons

National Research Council Canada - National Science Library

Ivakin, Anatoliy N

2008-01-01

.... Analysis of the sediment samples showed presence of a small volume portion of arger particles, such as coarse sand fraction and shell fragments, which were considered as inclusions, or sparsely...

Microsatellite analysis of Fasciola spp. in Egypt.

Science.gov (United States)

Dar, Yasser; Amer, Said; Courtioux, Bertrand; Dreyfuss, Gilles

2011-12-01

Recently, the topic of diversity in Fasciola population in Egypt is controversial. The present study was performed to study the genetic diversity of isolated flukes based on microsatellites markers. Fasciola worms were collected from different hosts and geographical locations in Egypt. Control samples of Fasciola hepatica from France as well as Fasciola gigantica from Cameroon were included in the study. Collected flukes were identified morphologically and subjected for analysis using four microsatellite markers. Results of microsatellite profile (FM1 and FM2) proved that both species of Fasciola are distributed in Egypt irrespective of geographical location and host. Nevertheless, the microsatellite profile of some analyzed loci (FM2 and FM3) proved that Egyptian flukes showed more alleles compared to the reference ones. Differences of microsatellite profile in Egyptian isolates than that of corresponding reference samples indicate the remarkable diversity of these isolates. The present results highlighted the utility of microsatellite profile to discriminate between Fasciola species and to elucidate the diversity within the species. To our knowledge, this is the first time to study microsatellite polymorphism in Fasciola populations in Egypt.

Bottom currents and sediment waves on a shallow carbonate shelf, Northern Carnarvon Basin, Australia

Science.gov (United States)

Belde, Johannes; Reuning, Lars; Back, Stefan

2017-04-01

The modern seafloor of the Australian Northwest Shelf between Exmouth and Dampier was analyzed for large scale sedimentary bedforms on 3D seismic reflection data. The Carnarvon MegaSurvey of Petroleum Geo-Services (PGS), a merged dataset of multiple industrial 3D seismic reflection surveys with a total size of 49,717 km2, offers an extensive view of the continental shelf, slope and rise of the Northern Carnarvon Basin. Over the shelf two fields of large scale sediment waves were observed in water depths between 55-130 m, where the seafloor may be influenced by different processes including internal waves, tides and storms. Based on the dimensions and orientations of the sediment waves the dominant direction and approximate strength of local bottom currents could be estimated. Information on local sediment grain-size distribution was provided by the auSEABED database allowing a classification of the observed sediment waves into sand- or mudwaves. The first sediment wave field is positioned northwest of the Montebello Islands where the shelf is comparatively narrow and local sediment is mainly sand-sized. It most likely formed by increased bottom currents induced by the diversion of tidal flows around the islands. The second sediment wave field is located north of the Serrurier and Bessieres Islands within a local seafloor depression. Local sediments are poorly sorted, containing significant amounts of mud and gravel in addition to the mainly sand-sized grains. The coarser sediment fraction could have been reworked to sandwaves by cyclone-induced bottom currents. Alternatively, the finer sediment fraction could form mudwaves shaped by less energetic along-slope oriented currents in the topographic depression. The sediment waves consist partially of carbonate grains such as ooids and peloids that formed in shallow water during initial stages of the post glacial sea-level rise. These stranded carbonate grains thus formed in a different environment than the sediment

Trends in suspended-sediment loads and concentrations in the Mississippi River Basin, 1950–2009

Science.gov (United States)

Heimann, David C.; Sprague, Lori A.; Blevins, Dale W.

2011-01-01

Trends in loads and concentrations of suspended sediment and suspended sand generally were downward for stations within the Mississippi River Basin during the 60-, 34-, and 12-year periods analyzed. Sediment transport in the lower Mississippi River has historically been, and continues to be, most closely correlative to sediment contributions from the Missouri River, which generally carried the largest annual suspended-sediment load of the major Mississippi River subbasins. The closure of Fort Randall Dam in the upper Missouri River in 1952 was the single largest event in the recorded historical decline of suspended-sediment loads in the Mississippi River Basin. Impoundments on tributaries and sediment reductions as a result of implementation of agricultural conservation practices throughout the basin likely account for much of the remaining Mississippi River sediment transport decline. Scour of the main-stem channel downstream from the upper Missouri River impoundments is likely the largest source of suspended sand in the lower Missouri River. The Ohio River was second to the Missouri River in terms of sediment contributions, followed by the upper Mississippi and Arkansas Rivers. Declines in sediment loads and concentrations continued through the most recent analysis period (1998–2009) at available Mississippi River Basin stations. Analyses of flow-adjusted concentrations of suspended sediment indicate the recent downward temporal changes generally can be explained by corresponding decreases in streamflows.

Anatomy of a shoreface sand ridge revisted using foraminifera: False Cape Shoals, Virginia/North Carolina inner shelf

Science.gov (United States)

Robinson, Marci M.; McBride, Randolph A.

2008-01-01

Certain details regarding the origin and evolution of shelf sand ridges remain elusive. Knowledge of their internal stratigraphy and microfossil distribution is necessary to define the origin and to determine the processes that modify sand ridges. Fourteen vibracores from False Cape Shoal A, a well-developed shoreface-attached sand ridge on the Virginia/North Carolina inner continental shelf, were examined to document the internal stratigraphy and benthic foraminiferal assemblages, as well as to reconstruct the depositional environments recorded in down-core sediments. Seven sedimentary and foraminiferal facies correspond to the following stratigraphic units: fossiliferous silt, barren sand, clay to sandy clay, laminated and bioturbated sand, poorly sorted massive sand, fine clean sand, and poorly sorted clay to gravel. The units represent a Pleistocene estuary and shoreface, a Holocene estuary, ebb tidal delta, modern shelf, modern shoreface, and swale fill, respectively. The succession of depositional environments reflects a Pleistocene sea-level highstand and subsequent regression followed by the Holocene transgression in which barrier island/spit systems formed along the Virginia/North Carolina inner shelf not, vert, ~5.2 ka and migrated landward and an ebb tidal delta that was deposited, reworked, and covered by shelf sand.

How sedimentation affects rift segment interaction during oblique extension: a 4D analogue modelling study

Science.gov (United States)

Zwaan, Frank; Schreurs, Guido; Adam, Jürgen

2017-04-01

During the early stages of rifting, rift segments may form along non-continuous and/or offset pre-existing weaknesses. It is important to understand how these initial rift segments interact and connect to form a continuous rift system. Previous modelling of rift interaction structures has shown the dominant influence of oblique extension, promoting rift segment linkage (e.g. Zwaan et al., 2016) and eventual continent break-up (Brune et al., 2012). However, these studies did not incorporate sedimentation, which can have important implications for rift evolution (e.g. Bialas and Buck, 2009). Here we present a series of analogue model experiments investigating the influence of sedimentation on rift interaction structures under oblique extension conditions. Our set-up involves a base of compressed foam and plexiglass that forces distributed extension in the overlying analogue materials when the model sidewalls move apart. A sand layer simulates the brittle upper crust and a viscous sand/silicone mixture the ductile lower crust. One of the underlying base plates can move laterally allowing oblique extension. Right-stepping offset and disconnected lines of silicone (seeds) on top of the basal viscous serve as inherited structures since the strong sand cover is locally thinner. We apply syn-rift sediments by filling in the developing rift and transfer zone basins with sand at fixed time steps. Models are run either with sedimentation or without to allow comparison. The first results suggest that the gross structures are similar with or without sedimentation. As seen by Zwaan et al. (2016), dextral oblique extension promotes rift linkage because rift propagation aligns itself perpendicular to the extension direction. This causes the rift segments to grow towards each other and to establish a continuous rift structure. However, the structures within the rift segments show quite different behaviour when sedimentation is applied. The extra sediment loading in the rift basin

Reassessment and comparison of natural radioactivity levels in relation to granulometric contents of recently excavated major river sediments

International Nuclear Information System (INIS)

Ramasamy, V.; Suresh, G.; Rajkumar, P.; Murugesan, S.; Mullainathan, S.; Meenakshisundaram, V.

2012-01-01

River sediment depositions on the bottom of rivers most frequently consist of sand and gravel particles, which make them particularly valuable for the building construction. Knowledge of radioactivity present in building material enables one to assess any possible radiological hazard to mankind by the use of such materials. The natural radionuclide ( 238 U, 232 Th and 40 K) contents have been analyzed for the recently excavated sediment samples of Cauvery, Vellar, Ponnaiyar and Palaru rivers with an aim of evaluating the radiation hazard nature. To know the radiological characteristics of the sediment, the different radiological parameters are calculated. Natural radioactivity level is higher in Palaru river and it is lower in Vellar river sediments. In all the rivers, concentration of 238 U is decreased, and concentrations of 232 Th and 40 K are increased towards the river mouth. Granulometric analysis shows that the sand is the main constituent in all the river sediment samples. Content of sand is gradually decreased, and contents of silt and clay are gradually increased towards the river mouth. Cluster analysis was carried out to find the similarity level between the radioactivity and granulometric measurements. The radioactivity level of all the four river sediments mainly depends upon the contents of silt and clay. Averages of the all calculated radiation hazard indices are lower than recommended level in Cauvery, Vellar and Ponnaiyar river sediments. Therefore, the sediment of the above rivers does not pose any significant radiological threat to the population when it is used as a building construction material. (author)

The Antiquities Trade in Egypt 1880-1930

DEFF Research Database (Denmark)

Hagen, Frederik Norland; Ryholt, Kim

these objects came to be here. The book presents the first in-depth analysis of this market during its “golden age” in Egypt in the late 19th and early 20th Century. It is primarily based on the archival material of the Danish Egyptologist H. O. Lange (1863-1943) who, during two prolonged stays in Egypt (1899...

Sequential Subterranean Transport of Excavated Sand and Foraged Seeds in Nests of the Harvester Ant, Pogonomyrmex badius.

Directory of Open Access Journals (Sweden)

Walter R Tschinkel

Full Text Available During their approximately annual nest relocations, Florida harvester ants (Pogonomyrmex badius excavate large and architecturally-distinct subterranean nests. Aspects of this process were studied by planting a harvester ant colony in the field in a soil column composed of layers of 12 different colors of sand. Quantifying the colors of excavated sand dumped on the surface by the ants revealed the progress of nest deepening to 2 m and enlargement to 8 L in volume. Most of the excavation was completed within about 2 weeks, but the nest was doubled in volume after a winter lull. After 7 months, we excavated the nest and mapped its structure, revealing colored sand deposited in non-host colored layers, especially in the upper 30 to 40 cm of the nest. In all, about 2.5% of the excavated sediment was deposited below ground, a fact of importance to sediment dating by optically-stimulated luminescence (OSL. Upward transport of excavated sand is carried out in stages, probably by different groups of ants, through deposition, re-transport, incorporation into the nest walls and floors and remobilization from these. This results in considerable mixing of sand from different depths, as indicated in the multiple sand colors even within single sand pellets brought to the surface. Just as sand is transported upward by stages, incoming seeds are transported downward to seed chambers. Foragers collect seeds and deposit them only in the topmost nest chambers from which a separate group of workers rapidly transports them downward in increments detectable as a "wave" of seeds that eventually ends in the seed chambers, 20 to 80 cm below the surface. The upward and downward transport is an example of task-partitioning in a series-parallel organization of work carried out by a highly redundant work force in which each worker usually completes only part of a multi-step process.

Effects of sand fences on coastal dune vegetation distribution

Science.gov (United States)

Grafals-Soto, Rosana

2012-04-01

Sand fences are important human adjustments modifying the morphology of developed shores. The effects of sand fences on sediment transport and deposition in their initial stages have been well studied, but little is known about the effect of deteriorated sand fences that have become partially buried low scale barriers within the dune, potentially benefiting vegetation growth by protecting it from onshore stress. Data on vegetation, topography and fence characteristics were gathered at three dune sites in Ocean City, New Jersey on September 2007 and March 2008 to evaluate the effect of fences within the dune on vegetation distribution. Variables include: distance landward of dune toe, degree of sheltering from onshore stressors, net change in surface elevation (deposition or erosion), vegetation diversity and density, presence of remnant fence, and distance landward of fence. Results for the studied environment reveal that 1) vegetation diversity or density does not increase near remnant fences because most remnants are lower than average vegetation height and can not provide shelter; but 2) vegetation distribution is related to topographic variables, such as degree of sheltering, that are most likely the result of sand accretion caused by fence deployment. Fence deployment that prioritizes the creation of topographically diverse dunes within a restricted space may increase the diversity and density of the vegetation, and the resilience and value of developed dunes. Managers should consider the benefits of using sand fences on appropriately wide beaches to create a protective dune that is also diverse, functional and better able to adapt to change.

Mitigation options for the industrial sector in Egypt

Energy Technology Data Exchange (ETDEWEB)

Gelil, I.A.; El-Touny, S.; Korkor, H. [Organization for Energy Conservation and Planning (OECP), Cairo (Egypt)

1996-12-31

Though its contribution to the global Greenhouse gases emission is relatively small, Egypt has signed and ratified the United Nations Framework Convention on Climate Change (UN FCCC) and has been playing an active role in the international efforts to deal with such environmental challenges. Energy efficiency has been one of the main strategies that Egypt has adopted to improve environmental quality and enhance economic competitiveness. This paper highlights three initiatives currently underway to improve energy efficiency of the Egyptian industry. The first is a project that has been recently completed by OECP to assess potential GHG mitigation options available in Egypt`s oil refineries. The second initiative is an assessment of GHG mitigation potential in the Small and Medium size Enterprises (SME) in the Mediterranean city of Alexandria. The third one focuses on identifying demand side management options in some industrial electricity consumers in the same city.

Clay minerals and Sr-Nd isotopes of the sediments along the western margin of India and their implication for sediment provenance

Digital Repository Service at National Institute of Oceanography (India)

Kessarkar, P.M.; Rao, V.P.; Ahmad, S; Babu, G.A.

- gion is occupied by Recent alluvium and the Warkala beds (ferruginised sand stones with inter- calated clays) of Tertiary age. Extensive laterisation of the parent rocks is a characteristic feature in western India. Bauxite- and laterite...^Nd isotopes of the sediments along the western margin of India and their implication for sediment provenance Pratima M. Kessarkar a , V. Purnachandra Rao a;C3 , S.M. Ahmad b , G. Anil Babu b a National Institute of Oceanography, Dona Paula, Goa 403 004, India...

The Geodiversity in Drift Sand Landscapes of The Netherlands

Science.gov (United States)

van den Ancker, Hanneke; Jungerius, Pieter Dirk; Riksen, Michel

2015-04-01

The authors carried out detailed field studies of more than twelve drift sand landscapes in The Netherlands. The objective of these studies was to restore Natura-2000 values by restoring the wind activity. Active drift sands occur almost exclusively in The Netherlands, Natura 2000 habitat 2330 'Inland dunes with open Corynephorus and Agrostis grasslands', for which reason our country is largely responsible for this European landscape. Active drift sands had almost disappeared for two reasons: first, the stabilization of the drift sands by air pollution, mainly nitrogen, which stimulates the growth of algae and grasses that initiate soil formation, and second, by the growth of forests surrounding the sands, which decreases the wind force. The restoration studies revealed differences in the geodiversity between and within the drift sand areas. Whereas the drift sands on geological and soil maps show as almost homogenous areas, they have in fact highly variable geo-conditions of which examples will be given. These geodiversity aspects concern differences in geomorphological structure, origin, sediments and age of the drift sands. Differences in wind and water erosion, trampling and soil formation add to the geodiversity within the drift sand areas. Especially in the primary stages of succession the differences in geodiversity are relevant for the Natura-2000 values. We discerned three main types of active sands. Firstly, the impressive drift sands with large parabolic dune structures, often consisting of series of interlocking parabolic dunes. They developed from the northeast towards the southwest, against the direction of the dominant wind, and must have taken centuries to develop. Small parts of these systems are still active, other parts show different degrees of soil formation. Their origin is still unclear but probably dates from medieval times (Heidinga, 1985, Jungerius & Riksen, 2008). Second are the drift sand areas with irregular hills from 0.5 to about 2

Design and maintenance of a network for collecting high-resolution suspended-sediment data at remote locations on rivers, with examples from the Colorado River

Science.gov (United States)

Griffiths, Ronald E.; Topping, David J.; Andrews, Timothy; Bennett, Glenn E.; Sabol, Thomas A.; Melis, Theodore S.

2012-01-01

Management of sand and finer sediment in fluvial settings has become increasingly important for reasons ranging from endangered-species habitat to transport of sediment-associated contaminants. In all rivers, some fraction of the suspended load is transported as washload, and some as suspended bed material. Typically, the washload is composed of silt-and-clay-size sediment, and the suspended bed material is composed of sand-size sediment. In most rivers, as a result of changes in the upstream supply of silt and clay, large, systematic changes in the concentration of the washload occur over time, independent of changes in water discharge. Recent work has shown that large, systematic, discharge-independent changes in the concentration of the suspended bed material are also present in many rivers. In bedrock canyon rivers, such as the Colorado River in Grand Canyon National Park, changes in the upstream tributary supply of sand may cause large changes in the grain-size distribution of the bed sand, resulting in changes in both the concentration and grain-size distribution of the sand in suspension. Large discharge-independent changes in suspended-sand concentration coupled to discharge-independent changes in the grain-size distribution of the suspended sand are not unique to bedrock canyon rivers, but also occur in large alluvial rivers, such as the Mississippi River. These systematic changes in either suspended-silt-and-clay concentration or suspended-sand concentration may not be detectable by using conventional equal-discharge- or equal-width-increment measurements, which may be too infrequently collected relative to the time scale over which these changes in the sediment load are occurring. Furthermore, because large discharge-independent changes in both suspended-silt-and-clay and suspended-sand concentration are possible in many rivers, methods using water discharge as a proxy for suspended-sediment concentration (such as sediment rating curves) may not produce

Residual diesel measurement in sand columns after surfactant/alcohol washing

International Nuclear Information System (INIS)

Martel, R.; Gelinas, P.J.

1996-01-01

A new simple gravimetric technique has been designed to determine residual oil saturation of complex hydrocarbon mixtures (e.g., diesel) in sand column experiments because reliable methods are lacking. The He/N 2 technique is based on drying of sand columns by circulating helium gas to drag oil droplets in a cold trap (liquid nitrogen). With this technique, residual diesel measurement can be performed easily immediately after alcohol/surfactant washing and in the same lab. For high residual diesel content in Ottawa sand (25 to 30 g/kg), the technique is much more accurate (± 2% or 600 mg/kg) than the standard analytical methods for the determination of mineral oil and grease. The average relative error on partial diesel dissolution in sand column estimated after alcohol/surfactant flooding (residual saturation of 10 to 15 g/kg) is as low as 5%. The precision of the He/N 2 technique is adequate to compare relative efficiency of washing solutions when partial extraction of residual oil in Ottawa sand columns is performed. However, this technique is not adapted for determination of traces of oil in sediment or for environmental control of contaminated soils. Each diesel determination by the He/N 2 technique costs less than $8 in chemical products (helium and liquid nitrogen). A simple laboratory drying setup can be built for less than $400 which makes this technique valuable for diesel analyses when a large number of tests are required

Franchising in the Middle East: The Example of Egypt

OpenAIRE

Elsaman, Radwa S.

2017-01-01

With the largest population in the Arab Middle East and a central location between Europe and East Asia, Egypt offers one of the biggest sources of franchising markets in the world for new business opportunities. Egypt, however, does not have specialized laws regulating franchising, which results in real challenges for investors who are seeking to franchise their businesses in Egypt, along with their legal advisors. It also creates problems for the courts who must rule on disputes arising fro...

Dating pleistocene fossil coastal sand dunes by thermoluminescence

International Nuclear Information System (INIS)

Poupeau, G.; Souza, J.H.; Soliani Junior, E.; Loss, E.L.

1983-01-01

It was shown recently that sunlight exposure is able to bleach most of the geological thermoluminescence (TL) of wind transported sediments. This property has been used in an attempt to date dunes from the well developed recent quaternary coastal dunes system of Rio Grande do Sul. Preliminary results presented here, show that TL dating on fossil sand dunes from Rio Grande do Sul should be possible in a time range from present to at least 50.000 yr and possibly more than 100.000 yr. (Author) [pt

Tech Talk for Social Studies Teachers: Ancient Egypt.

Science.gov (United States)

Pahl, Ronald H.

1998-01-01

Presents an annotated bibliography of 10 Web sites concerning ancient Egypt that have materials appropriate for social studies classes. Includes virtual tours of Egypt and specific temples, explorations of the pyramids, archaeological and geographic information, and information on the Egyptian "Book of the Dead." (MJP)

Spatial and temporal variations of aeolian sediment input to the tributaries (the Ten Kongduis) of the upper Yellow River

Science.gov (United States)

Yang, Hui; Shi, Changxing

2018-02-01

The Ten Kongduis of the upper Yellow River, located in Inner Mongolia, northern China, is an area with active wind-water coupled erosion and hence one of the main sediment sources of the Yellow River. In this study, we analyzed the characteristics of spatial and temporal variations of aeolian sediment input to the river channel. For this purpose, three segments of sand dune-covered banks of the Maobula and the Xiliugou kongduis were investigated three times from November 2014 to November 2015 using a 3-D laser scanner, and the displacement of banks of desert reaches of three kongduis was derived from interpreting remote sensing images taking in the years from 2005 to 2015. The data of the surveyed sand dunes reveal that the middle kongduis were fed by aeolian sand through the sand dunes moving towards the river channels. The amount of aeolian sediment input was estimated to be about 14.94 × 104 t/yr in the Maobula Kongdui and about 5.76 × 104 t/yr in the Xiliugou Kongdui during the period from November 2014 to November 2015. According to the interpretation results of remote sensing images, the amount of aeolian sediment input to the Maobula Kongdui was about 15.74 × 104 t in 2011 and 18.2 × 104 t in 2012. In the Xiliugou Kongdui, it was in the range of 9.52 × 104 - 9.99 × 104 t in 2012 and in the springs of 2013 and 2015. In the Hantaichuan Kongdui, it was 7.04 × 104 t in 2012, 7.53 × 104 t in the spring of 2013, and 8.52 × 104 t in the spring of 2015. Owing to the changes in wind and rainfall, both interseasonal and interannual sediment storage and release mechanisms exist in the processes of aeolian sand being delivered into the kongduis. However, all of the aeolian sediment input to the Ten Kongduis should be delivered downstream by the river flows during a long term.

Bed topography and sand transport responses to a step change in discharge and water depth

Science.gov (United States)

Ephemeral streams with sand and gravel beds may inherit bed topography caused by previous flow events, resulting in bed topography that is not in equilibrium with flow conditions, complicating the modeling of flow and sediment transport. Major flow events, resulting from rainfall with high intensity...

Sorption kinetics of TNT and RDX in anaerobic freshwater and marine sediments: Batch studies.

Science.gov (United States)

Ariyarathna, Thivanka; Vlahos, Penny; Tobias, Craig; Smith, Richard

2016-01-01

Examination of the partitioning of explosives onto sediment in marine environments is critical to predict the toxicological impacts of worldwide explosive-contaminated sites adjacent to estuaries, wetlands, and the coastal ocean. Marine sediments have been identified as sites of enhanced munitions removal, yet most studies addressing these interactions focus on soils and freshwater sediments. The present study measured the kinetics of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) sorption onto 2 marine sediments of varying grain sizes (silt vs sand) and organic carbon (OC) content. Abiotic sediment sorption tests were performed at 23 °C, 15 °C, and 4 °C by spiking TNT and RDX solutions directly into anaerobic sediment slurries. Marine sediments showed significantly higher compound uptake rates (0.30-0.80 h(-1) ) than freshwater silt (0.0046-0.0065 h(-1) ) for both compounds, probably because of lower compound solubilities and a higher pH in marine systems. Equilibrium partition constants are on the same order of magnitude for marine silt (1.1-2.0 L kg(-1) sediment) and freshwater silt (1.4-3.1 L kg(-1) sediment) but lower for marine sand (0.72-0.92 L kg(-1) sediment). Total organic carbon content in marine sediments varied linearly with equilibrium partition constants for TNT and was moderately linear for RDX. Uptake rates and equilibrium constants of explosives are inversely correlated to temperature regardless of sediment type because of kinetic barriers associated with low temperatures. © 2015 SETAC.

Egypt's policy concerning food irradiation research and technology

International Nuclear Information System (INIS)

Roushdy, H.M.

1978-01-01

The paper reviews current research in Egypt in the field of radiation preservation of food to accumulate the necessary data for drafting Egypts' policy towards prospects for application. Research activities in Egypt have been oriented to solving problems of local economic importance, e.g. inhibition of sprouting in potatoes, onions and garlic, extension of shelf-life of vegetables and fruits, disinfestation of stored grains and grain products, preservation of meat, meat products, fish, fats and oils, and elimination of parasites and microorganisms from animal feed. Extensive studies have been performed to determine the lowest radiation level required for short-term storage, changes in organoleptic, physical, chemical and microbiological values of irradiated food and wholesomeness studies to give evidence of the safety of irradiated food for human consumption. The paper summarizes Egypt's national planning for the transfer of such new technology, the establishment of the National Centre for Radiation Research and Technology to build up the national infrastructure for food irradiation research and application, and the formation of a Supreme Committee for Radiation Preservation of Food. Finally, the paper also surveys the locally available irradiators and correlates the design, capacity and capital cost against the actual needs of Egypt and the experience acquired. (author)

Future studies and research in Egypt. Overview, examples, perspectives

Energy Technology Data Exchange (ETDEWEB)

Goell, Edgar

2012-02-15

During the last decade there have been several distinct activities and efforts with regards to future research in Egypt. Several institutions and capacities have been created. Although these capacities do not always meet high scientific standards, their results and studies offer important and well-grounded elements for future-oriented discussions and political decisions. Not least because of the Egypt revolt which started in January 2011 and the ongoing complex and conflicting societal struggles in Egypt the objective needs as well as the demand for systematic future thinking and future studies will very likely increase further. For that reason this report presents an overview about the context conditions, experiences and forms of future research in Egypt. The major challenges as well as the major issues are described. The main part is the description of the most important institutions, which are conducting future research, their projects and in addition two concrete projects, which try to practice Sustainable Development in different ways. Finally, several (self-)critical assessments and perspectives from selected experts of the future research community in Egypt will be presented.

Factors Affecting Accidents Risks among Truck Drivers In Egypt

Directory of Open Access Journals (Sweden)

Elshamly Ahmed Fathalla

2017-01-01

Full Text Available Egypt is ranked among the countries with the highest rates of road accidents. According to the American Chamber of Commerce more than 96% of Egypt's goods are transported by trucks and due to their large volume and excessive weight, the severity and number of truck accident fatalities are much higher than other vehicles in Egypt. The present study aims at identifying truck driver's behavior and its influence on crash involvement. Due to the shortage in recording accident data and the inaccurate road accident audit, data was collected from several governorates in Egypt through questionnaire. Questionnaire forms were filled out through personal interviews with truck drivers. The total number of respondents was 643. The final analysis was made on the 615 questionnaires with complete answers. The data was analyzed and logistic regression was applied to accident related data to examine the contributing factors affecting accident occurrence of truck drivers. Results showed that fatigue in terms of driving hours (continuous and total and lack of sleep, drug use during driving, and driver obesity are the most influencing factors on the occurrence of truck accidents in Egypt. The findings of this research highlight the important role human factors have on the risk of crash involvement amongst Egypt's truck drivers and the need to improve their work conditions.

Develop Accurate Methods for Characterizing And Quantifying Cohesive Sediment Erosion Under Combined Current Wave Conditions: Project ER 1497

Science.gov (United States)

2017-09-01

majority of contaminated sediments are a mixture of sand, silt, and clay . These sediments are often referred to as cohesive because, unlike pure sand...number:  2 18 p p c ρ d Sk f μ (2) where ρp is the particle density, dp is the particle diameter, µ is the dynamic viscosity , and fc is a...using the viscous timescale, 2τν ut =+ , where uτ is the friction velocity, and ν the kinematic viscosity , as t+ provides an estimate of the strain

Understanding coastal morphodynamic patterns from depth-averaged sediment concentration

NARCIS (Netherlands)

Ribas, F.; Falques, A.; de Swart, H. E.; Dodd, N.; Garnier, R.; Calvete, D.

This review highlights the important role of the depth-averaged sediment concentration (DASC) to understand the formation of a number of coastal morphodynamic features that have an alongshore rhythmic pattern: beach cusps, surf zone transverse and crescentic bars, and shoreface-connected sand

Egypt--United States cooperative energy assessment: report on preliminary discussions

Energy Technology Data Exchange (ETDEWEB)

1978-04-01

Egyptian and U.S. Government representatives met in Cairo during the period of February 14-22, 1978 to discuss a cooperative Egypt-U.S. assessment of the energy demand and supply options available to Egypt. This report summarizes those preliminary discussions. The discussions accomplished the following: the background and objectives of the U.S. initiative for a cooperative energy assessment with Egypt were explained; Egyptian electric energy activities and their priorities were presented; methods under consideration for the systematic identification and assessment of energy options available to Egypt were explained; the cooperation of Egyptian energy resource and planning organizations was assured; and arrangements to carry out the cooperative assessment were planned.

Patch behaviour and predictability properties of modelled finite-amplitude sand ridges on the inner shelf

NARCIS (Netherlands)

Vis-star, N.C.; de Swart, H.E.; Calvete, D.

2008-01-01

The long-term evolution of shoreface-connected sand ridges is investigated with a nonlinear spectral model which governs the dynamics of waves, currents, sediment transport and the bed level on the inner shelf. Wave variables are calculated with a shoaling-refraction model instead of using a

Chenier plain development: feedbacks between waves, mud and sand

Science.gov (United States)

Nardin, W.; Fagherazzi, S.

2015-12-01

Cheniers are sandy ridges parallel to the coast established by high energy waves. Here we discuss Chenier plains ontogeny through dimensional analysis and numerical results from the morphodynamic model Delft3D-SWAN. Our results show that wave energy and shelf slope play an important role in the formation of Chenier plains. In our numerical experiments waves affect Chenier plain development in three ways: by winnowing sediment from the mudflat, by eroding mud and accumulating sand over the beach during extreme wave events. We further show that different sediment characteristics and wave climates can lead to three alternative coastal landscapes: strand plains, mudflats, or the more complex Chenier plains. Low inner-shelf slopes are the most favorable for strand plain and Chenier plain formation, while high slopes decrease the likelihood of mudflat development and preservation.

Integration of bed characteristics, geochemical tracers, current measurements, and numerical modeling for assessing the provenance of beach sand in the San Francisco Bay Coastal System

Science.gov (United States)

Barnard, Patrick L.; Foxgrover, Amy C.; Elias, Edwin P.L.; Erikson, Li H.; Hein, James R.; McGann, Mary; Mizell, Kira; Rosenbauer, Robert J.; Swarzenski, Peter W.; Takesue, Renee K.; Wong, Florence L.; Woodrow, Donald L.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

Over 150 million m3 of sand-sized sediment has disappeared from the central region of the San Francisco Bay Coastal System during the last half century. This enormous loss may reflect numerous anthropogenic influences, such as watershed damming, bay-fill development, aggregate mining, and dredging. The reduction in Bay sediment also appears to be linked to a reduction in sediment supply and recent widespread erosion of adjacent beaches, wetlands, and submarine environments. A unique, multi-faceted provenance study was performed to definitively establish the primary sources, sinks, and transport pathways of beach-sized sand in the region, thereby identifying the activities and processes that directly limit supply to the outer coast. This integrative program is based on comprehensive surficial sediment sampling of the San Francisco Bay Coastal System, including the seabed, Bay floor, area beaches, adjacent rock units, and major drainages. Analyses of sample morphometrics and biological composition (e.g., Foraminifera) were then integrated with a suite of tracers including 87Sr/86Sr and 143Nd/144Nd isotopes, rare earth elements, semi-quantitative X-ray diffraction mineralogy, and heavy minerals, and with process-based numerical modeling, in situ current measurements, and bedform asymmetry to robustly determine the provenance of beach-sized sand in the region.

Framing Egypt : Roman literary perceptions of Egypt from Cicero to Juvenal

NARCIS (Netherlands)

Leemreize, M.E.C.

2016-01-01

This is a comprehensive study of Roman literary references to Egypt without preference for one particular period, author or subject, in contrast to most previous scholarship. In doing so, it shows that these references vary greatly, are context-dependent, and cannot be rightly understood when

IDRC in Egypt

International Development Research Centre (IDRC) Digital Library (Canada)

Some current activities. In Egypt, IDRC-supported research focuses on job creation, shaping climate change adaptation, enhancing women's safety and political participation, and testing the power of social media to address sexual harassment. □ Job creation after the Arab Spring. Funding: $112,400. Duration: 2012–2013.

Change in morphology and modern sediment thickness on the inner continental shelf offshore of Fire Island, New York between 2011 and 2014: Analysis of hurricane impact

Science.gov (United States)

Schwab, William C.; Baldwin, Wayne E.; Warner, John C.; List, Jeffrey; Denny, Jane F.; Liste Munoz, Maria; Safak, Ilgar

2017-01-01

Seafloor mapping investigations conducted on the lower shoreface and inner continental shelf offshore of Fire Island, New York in 2011 and 2014, the period encompassing the impacts of Hurricanes Irene and Sandy, provide an unprecedented perspective regarding regional inner continental shelf sediment dynamics during large storm events. Analyses of these studies demonstrate that storm-induced erosion and sediment transport occurred throughout the study area in water depths up to 30 m. Acoustic backscatter patterns were observed to move from ~1 m to 450 m with a mean of 20 m and movement tended to decrease with increasing water depth. These patterns indicate that both of the primary inner continental shelf sedimentary features in the study area, linear sorted bedforms offshore of eastern Fire Island and shoreface-attached sand ridges offshore of central and western Fire island, migrated alongshore to the southwest. The migration of the sorted bedforms represents the modification of an active ravinement surface and is thought to have liberated a significant volume of sediment. Comparison of isopach maps of sediment thickness show that the volume of modern sediment composing the lower shoreface and shoreface-attached sand ridges decreased by ~2.8 × 106 m3 across the ~73 km2 of common seafloor mapped in both surveys. However, a similar analysis for the relatively calmer 15-yr period prior to 2011 revealed significant accretion. This allows speculation that the shoreface-attached sand ridges are maintained over decadal timescales via sediment supplied through erosion of Pleistocene outwash and lower Holocene transgressive channel-fill deposits exposed on the inner continental shelf, but that the sand ridges also periodically erode and move to the southwest during large storm events. Analyses show that significant storminduced erosion and sediment transport occurs far seaward of the 5 to 9 m depth of closure assumed for Fire Island, where it is thought that an onshore

Conditions and processes affecting sand resources at archeological sites in the Colorado River corridor below Glen Canyon Dam, Arizona

Science.gov (United States)

East, Amy E.; Collins, Brian D.; Sankey, Joel B.; Corbett, Skye C.; Fairley, Helen C.; Caster, Joshua J.

2016-05-17

This study examined links among fluvial, aeolian, and hillslope geomorphic processes that affect archeological sites and surrounding landscapes in the Colorado River corridor downstream from Glen Canyon Dam, Arizona. We assessed the potential for Colorado River sediment to enhance the preservation of river-corridor archeological resources through aeolian sand deposition or mitigation of gully erosion. By identifying locally prevailing wind directions, locations of modern sandbars, and likely aeolian-transport barriers, we determined that relatively few archeological sites are now ideally situated to receive aeolian sand supply from sandbars deposited by recent controlled floods. Whereas three-fourths of the 358 river-corridor archeological sites we examined include Colorado River sediment as an integral component of their geomorphic context, only 32 sites currently appear to have a high degree of connectivity (coupled interactions) between modern fluvial sandbars and sand-dominated landscapes downwind. This represents a substantial decrease from past decades, as determined by aerial-photograph analysis. Thus, we infer that recent controlled floods have had a limited, and declining, influence on archeological-site preservation.

Egypt-United States Relations

National Research Council Canada - National Science Library

Mark, Clyde R

2003-01-01

.... Experience gained from Egyptian-U.S. joint military exercises proved valuable in easing coordination during the February 1991 Desert Storm operation to reverse Iraqi aggression against Kuwait. Egypt is seen by U.S...

Egypt-United States Relations

National Research Council Canada - National Science Library

Mark, Clyde R

2005-01-01

.... Experience gained from Egyptian-U.S. joint military exercises proved valuable in easing coordination during the February 1991 Desert Storm operation to reverse Iraqi aggression against Kuwait. Egypt is seen by U.S...

Opportunities for woody crop production using treated wastewater in Egypt

Science.gov (United States)

R.S. Zalesny; S.R.  Evett; N.F. Kandil; C.  Soriano; John Stanturf

2011-01-01

The Nile River provides nearly 97% of Egypt’s freshwater supply. Egypt’s share of Nile waters is fixed at 55.5 billion cubic meters annually. As a result, Egypt will not be able to meet increasing water demand using freshwater from the Nile and has been developing non-conventional wastewater reuse strategies to meet future demands. The USAID Mission in Cairo began...

A Visual Basic program to plot sediment grain-size data on ternary diagrams

Science.gov (United States)

Poppe, L.J.; Eliason, A.H.

2008-01-01

Sedimentologic datasets are typically large and compiled into tables or databases, but pure numerical information can be difficult to understand and interpret. Thus, scientists commonly use graphical representations to reduce complexities, recognize trends and patterns in the data, and develop hypotheses. Of the graphical techniques, one of the most common methods used by sedimentologists is to plot the basic gravel, sand, silt, and clay percentages on equilateral triangular diagrams. This means of presenting data is simple and facilitates rapid classification of sediments and comparison of samples.The original classification scheme developed by Shepard (1954) used a single ternary diagram with sand, silt, and clay in the corners and 10 categories to graphically show the relative proportions among these three grades within a sample. This scheme, however, did not allow for sediments with significant amounts of gravel. Therefore, Shepard's classification scheme was later modified by the addition of a second ternary diagram with two categories to account for gravel and gravelly sediment (Schlee, 1973). The system devised by Folk (1954, 1974)\\ is also based on two triangular diagrams, but it has 21 categories and uses the term mud (defined as silt plus clay). Patterns within the triangles of both systems differ, as does the emphasis placed on gravel. For example, in the system described by Shepard, gravelly sediments have more than 10% gravel; in Folk's system, slightly gravelly sediments have as little as 0.01% gravel. Folk's classification scheme stresses gravel because its concentration is a function of the highest current velocity at the time of deposition as is the maximum grain size of the detritus that is available; Shepard's classification scheme emphasizes the ratios of sand, silt, and clay because they reflect sorting and reworking (Poppe et al., 2005).The program described herein (SEDPLOT) generates verbal equivalents and ternary diagrams to

Tidal modulated flow and sediment flux through Wax Lake Delta distributary channels: Implications for delta development

Directory of Open Access Journals (Sweden)

K. Hanegan

2015-03-01

Full Text Available In this study, a Delft3D model of the Wax Lake Delta was developed to simulate flow and sediment flux through delta distributary channels. The model was calibrated for tidal constituents as well as velocity and sediment concentration across channel transects. The calibrated model was then used to simulate full spring–neap tidal cycles under constant low flow upstream boundary conditions, with grain size variation in suspended load represented using two sediment fractions. Flow and sediment flux results through distributary channel cross-sections were examined for spatial and temporal variability with the goal of characterizing the role of tides in sediment reworking and delta development. The Wax Lake Delta has prograded through channel extension, river mouth bar deposition, and channel bifurcation. Here we show that tidal modulation of currents influences suspended sand transport, and spatial acceleration through distributary channels at low tides is sufficient to suspend sand in distal reaches during lower flows. The basinward-increasing transport capacity in distributary channels indicates that erosive channel extension could be an important process, even during non-flood events.

Soft sediment deformation structures in the Maastrichtian Ajali Formation Western Flank of Anambra Basin, Southern Nigeria

Science.gov (United States)

Olabode, Solomon Ojo

2014-01-01

Soft sediment deformation structures were recognized in the Maastrichtian shallow marine wave to tide influenced regressive sediments of Ajali Formation in the western flank of Anambra basin, southern Nigerian. The soft sediment deformation structures were in association with cross bedded sands, clay and silt and show different morphological types. Two main types recognised are plastic deformations represented by different types of recumbent folds and injection structure represented by clastic dykes. Other structures in association with the plastic deformation structures include distorted convolute lamination, subsidence lobes, pillars, cusps and sand balls. These structures are interpreted to have been formed by liquefaction and fluidization mechanisms. The driving forces inferred include gravitational instabilities and hydraulic processes. Facies analysis, detailed morphologic study of the soft sediment deformation structures and previous tectonic history of the basin indicate that the main trigger agent for deformation is earthquake shock. The soft sediment deformation structures recognised in the western part of Anambra basin provide a continuous record of the tectonic processes that acted on the regressive Ajali Formation during the Maastrichtian.

Field observations of artificial sand and oil agglomerates

Science.gov (United States)

Dalyander, Patricia (Soupy); Long, Joseph W.; Plant, Nathaniel G.; McLaughlin, Molly R.; Mickey, Rangley C.

2015-01-01

Oil that comes into the surf zone following spills, such as occurred during the 2010 Deepwater Horizon (DWH) blowout, can mix with local sediment to form heavier-than-water sand and oil agglomerates (SOAs), at times in the form of mats a few centimeters thick and tens of meters long. Smaller agglomerates that form in situ or pieces that break off of larger mats, sometimes referred to as surface residual balls (SRBs), range in size from sand-sized grains to patty-shaped pieces several centimeters (cm) in diameter. These mobile SOAs can cause beach oiling for extended periods following the spill, on the scale of years as in the case of DWH. Limited research, including a prior effort by the U.S. Geological Survey (USGS) investigating SOA mobility, alongshore transport, and seafloor interaction using numerical model output, focused on the physical dynamics of SOAs. To address this data gap, we constructed artificial sand and oil agglomerates (aSOAs) with sand and paraffin wax to mimic the size and density of genuine SOAs. These aSOAs were deployed in the nearshore off the coast of St. Petersburg, Florida, during a field experiment to investigate their movement and seafloor interaction. This report presents the methodology for constructing aSOAs and describes the field experiment. Data acquired during the field campaign, including videos and images of aSOA movement in the nearshore (1.5-meter and 0.5-meter water depth) and in the swash zone, are also presented in this report.

Updating radiation protection regulations in Egypt

International Nuclear Information System (INIS)

Gomaa, M.A.; El-Naggar, A.M.

1996-01-01

The aim of this treatise is to present -the rational steps taken in the process of updating the Radiation Protection Regulations in Egypt. The contents of the review will include a historical synopsis, and the current state of art regarding competent authorities. Furthermore, the various committees formed with responsibilities for specific issues are indicated, including the role of the Ministry of Health (MOH), and that of the Atomic Energy Authority (AEA). Finally, the efforts made towards updating the radiation Protection Regulations in Egypt are highlighted. (author)

Importance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets

Science.gov (United States)

Griffiths, Ronald E.; Topping, David J.

2017-11-01

Sediment budgets are an important tool for understanding how riverine ecosystems respond to perturbations. Changes in the quantity and grain size distribution of sediment within river systems affect the channel morphology and related habitat resources. It is therefore important for resource managers to know if a river reach is in a state of sediment accumulation, deficit or stasis. Many sediment-budget studies have estimated the sediment loads of ungaged tributaries using regional sediment-yield equations or other similar techniques. While these approaches may be valid in regions where rainfall and geology are uniform over large areas, use of sediment-yield equations may lead to poor estimations of loads in regions where rainfall events, contributing geology, and vegetation have large spatial and/or temporal variability. Previous estimates of the combined mean-annual sediment load of all ungaged tributaries to the Colorado River downstream from Glen Canyon Dam vary by over a factor of three; this range in estimated sediment loads has resulted in different researchers reaching opposite conclusions on the sign (accumulation or deficit) of the sediment budget for particular reaches of the Colorado River. To better evaluate the supply of fine sediment (sand, silt, and clay) from these tributaries to the Colorado River, eight gages were established on previously ungaged tributaries in Glen, Marble, and Grand canyons. Results from this sediment-monitoring network show that previous estimates of the annual sediment loads of these tributaries were too high and that the sediment budget for the Colorado River below Glen Canyon Dam is more negative than previously calculated by most researchers. As a result of locally intense rainfall events with footprints smaller than the receiving basin, floods from a single tributary in semi-arid regions can have large (≥ 10 ×) differences in sediment concentrations between equal magnitude flows. Because sediment loads do not

Early pleistocene sediments at Great Blakenham, Suffolk, England

Science.gov (United States)

Gibbard, P. L.; Allen, P.; Field, M. H.; Hallam, D. F.

Detailed investigation of a fine sediment sequence, the College Farm Silty Clay Member, that overlies the Creeting Sands (Early Pleistocene) in Suffolk, is presented. The sedimentary sequence is thought to represent a freshwater pool accumulation in a small coastal embayment. Palaeobotanical investigation of the sediment indicates that it accumulated during the late temperate substage of a temperate (interglacial) event. The occurrence of Tsuga pollen, associated with abundant remains of the water fern Azolla tegeliensis indicate that the deposits are of Early Pleistocene age and are correlated with a later part of the Antian-Bramertonian Stage. Correlation with Tiglian TO substage in The Netherlands' sequence is most likely. The sediments' normal palaeomagnetic polarity reinforces the biostratigraphical correlation.

The concentration of "1"3"7Cs and organic carbon on sediment at Rat island in Indian ocean

International Nuclear Information System (INIS)

Muslim; Reza Agung Arjana; Wahyu Retno Prihatiningsih

2016-01-01

Rat Island is one of the islands in Indonesia, located in the Indian Ocean, about 10 kilometers west of Bengkulu, which has a beautiful scenery both on its land and on the seabed, making it a favorite tourist in Bengkulu. The purpose of this study was to determine the condition of "1"3"7Cs in sediments and its relation to the total carbon and sediment texture. Sediment sampling carried out on 17 September 2014 at six stations where three stations are still relatively close to The Rat island with water depth of ≤ 1 m and 3 others are far from Rat Island waters with a depth of 14-18 meters. Sediment texture and TOC content at waters depth of ≤ 1 m is sand and its TOC contents were <5.5%. On other hand at water depth of 14-18 meters sediment texture are silt sand mixture and the TOC content were ≥6%. The concentration of "1"3"7Cs in sediment were influenced by texture characteristic and TOC content. (author)

Soft-Sediment Deformation Structures Interpreted as Seismites in the Kolankaya Formation, Denizli Basin (SW Turkey)

Science.gov (United States)

Topal, Savaş; Özkul, Mehmet

2014-01-01

The NW-trending Denizli basin of the SW Turkey is one of the neotectonic grabens in the Aegean extensional province. It is bounded by normal faults on both southern and northern margins. The basin is filled by Neogene and Quaternary terrestrial deposits. Late Miocene- Late Pliocene aged Kolankaya formation crops out along the NW trending Karakova uplift in the Denizli basin. It is a typical fluviolacustrine succession that thickens and coarsens upward, comprising poorly consolidated sand, gravelly sand, siltstone and marl. Various soft-sediment deformation structures occur in the formation, especially in fine- to medium grained sands, silts and marls: load structures, flame structures, clastic dikes (sand and gravely-sand dike), disturbed layers, laminated convolute beds, slumps and synsedimentary faulting. The deformation mechanism and driving force for the soft-sediment deformation are related essentially to gravitational instability, dewatering, liquefaction-liquidization, and brittle deformation. Field data and the wide lateral extent of the structures as well as regional geological data show that most of the deformation is related to seismicity and the structures are interpreted as seismites. The existence of seismites in the Kolankaya Formation is evidence for continuing tectonic activity in the study area during the Neogene and is consistent with the occurrence of the paleoearthquakes of magnitude >5. PMID:25152909

Joint Egypt/United States report on Egypt/United States cooperative energy assessment. Volume 1 of 5 Vols. Executive summary, main report and appendices

Energy Technology Data Exchange (ETDEWEB)

1979-04-01

The International Energy Assessment Program between Egypt and the U.S. was formulated from mid-March to mid-July, 1978. The assessment identified energy demand and supply options for Egypt that are consistent with its indigenous energy resources; assessed Egypt's ability to effectively use those options; and identified measures by which Egypt's energy-planning activities could be improved. The assessment addressed all known and potential energy supply options (oil, gas, coal, oil shale, hydroelectric, nuclear power, geothermal, solar, wind, and biomass). Using the Reference Energy System, two future energy supply/demand balances are constructed (for 1985 and the year 2000) and these are compared with a historical (1975) supply/demand balance. The feasibility of each of the options is established in terms of the availability of the required resources and of the processing, conversion, transport, and utilization technology.

Latest paleocene benthic extinction event on the southern tethyan shelf (Egypt): Foraminiferal stable isotopic (delta C-13,delta O-18) records

OpenAIRE

Schmitz, B; Speijer, Robert; Aubry, MP

1996-01-01

The dramatic global extinction of 35%-50% of benthic foraminifera species in the deep sea in the latest Paleocene and associated negative excursions in delta(13)C and delta(18)O may be related to spreading of warm, saline bottom water from subtropical Tethyan shallow regions over the sea floor worldwide, Our study of neritic sections in Egypt shows that in the southern shallow Tethys, a prominent long-term change in bottom-water chemistry, sedimentation, and benthic foraminifera fauna was ini...

Predicting development of undrained shear strength in soft oil sands tailings

Energy Technology Data Exchange (ETDEWEB)

Masala, S. [Klohn Crippen Berger, Calgary, AB (Canada); Matthews, J. [Shell Canada Ltd., Calgary, AB (Canada)

2010-07-01

This PowerPoint presentation discussed a method of predicting the development of undrained shear strength in soft oil sands tailings. Phenomenology charts of oil sands tailings ponds were used to present the suspension, density, stresses and hydrostatic behaviour of tailings. Sedimentation and consolidation processes were discussed. The charts demonstrated how the tailings slurry settles and consolidates, releases water and dissipates pore pressures. The slurry then develops intergranular stresses and increases in density. The increases correlate with increased resistance to deformation and decreased compressibility and hydraulic conductivity. A critical state soil mechanics (CSSM) was used to characterize the soft oil sands tailings. Undrained strength was determined using the concept of the undrained strength ratio (USR). The USR was determined using traditional geotechnical investigation methods. Settling of the non-consolidated (NC) soil deposits was simulated using the finite strain consolidation theory. The model was based on the premise that current effective stresses control undrained shear strength in the NC deposits. Case studies were used to demonstrate the predictive framework. tabs, figs.

Application of radiometric analysis in the study of provenance and transport processes of Brazilian coastal sediments

International Nuclear Information System (INIS)

Carvalho, C.; Anjos, R.M.; Veiga, R.; Macario, K.

2011-01-01

Natural gamma radiation of beach sand deposits was measured along the south coast of Rio de Janeiro State, Brazil, with the aim of studying the provenance and transport processes of sediments in this area. Concentrations of thorium, uranium and potassium were evaluated using γ-ray spectrometry and a behavioral study of eTh/eU and eTh/K cross plots was performed, reflecting the mineralogical properties of beach sands, as well as their history of transport and sorting processes. The results show that such technique can be efficiently used to map heavy mineral distributions and to distinguish the different origins of coastal sediments disclosing the influence of nearby rivers. - Research highlights: → Based on the natural γ-ray analyses of beach sand, high concentrations of heavy minerals have been found around the Mambucaba River deltaic complex, located in the South of Rio de Janeiro State, Brazil. → Concentrations of thorium, uranium and potassium concentration can give information on the mineral composition and provenance of beach sands and consequently investigate heavy mineral deposits.

Application of radiometric analysis in the study of provenance and transport processes of Brazilian coastal sediments

Energy Technology Data Exchange (ETDEWEB)

Carvalho, C. [Laboratorio de Radioecologia (LARA), Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-346 Niteroi, RJ (Brazil); Anjos, R.M., E-mail: meigikos@if.uff.b [Laboratorio de Radioecologia (LARA), Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-346 Niteroi, RJ (Brazil); Veiga, R.; Macario, K. [Laboratorio de Radioecologia (LARA), Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/no, Gragoata, 24210-346 Niteroi, RJ (Brazil)

2011-02-15

Natural gamma radiation of beach sand deposits was measured along the south coast of Rio de Janeiro State, Brazil, with the aim of studying the provenance and transport processes of sediments in this area. Concentrations of thorium, uranium and potassium were evaluated using {gamma}-ray spectrometry and a behavioral study of eTh/eU and eTh/K cross plots was performed, reflecting the mineralogical properties of beach sands, as well as their history of transport and sorting processes. The results show that such technique can be efficiently used to map heavy mineral distributions and to distinguish the different origins of coastal sediments disclosing the influence of nearby rivers. - Research highlights: {yields} Based on the natural {gamma}-ray analyses of beach sand, high concentrations of heavy minerals have been found around the Mambucaba River deltaic complex, located in the South of Rio de Janeiro State, Brazil. {yields} Concentrations of thorium, uranium and potassium concentration can give information on the mineral composition and provenance of beach sands and consequently investigate heavy mineral deposits.

The role of bio-physical cohesive substrates on sediment winnowing and bedform development

Science.gov (United States)

Ye, Leiping; Parsons, Daniel; Manning, Andrew

2017-04-01

Existing sediment transport and bedform size predictions for natural open-channel flows in many environments are seriously impeded by a lack of process-based knowledge concerning the dynamics of complex bed sediment mixtures comprising cohesionless sand and biologically-active cohesive muds. A series of flume experiments (14 experimental runs) with different substrate mixtures of sand-clay-EPS (Extracellular Polymeric Substance) are combined with a detailed estuarine field survey (Dee estuary, NW England) to investigate the development of bedform morphologies and characteristics of suspended sediment over bio-physical cohesive substrates. The experimental results indicate that winnowing and sediment sorting can occur pervasively in bio-physical cohesive sediment - flow systems. Importantly however, the evolution of the bed and bedform dynamics, and hence turbulence production, is significantly reduced as bed substrate cohesivity increases. The estuarine subtidal zone survey also revealed that the bio-physical cohesion provided by both the clay and microorganism fractions in the bed plays a significant role in controlling the interactions between bed substrate and sediment suspension, deposition and bedform generation. The work will be presented here concludes by outlining the need to extend and revisit the effects of cohesivity in morphodynamic systems and the sets of parameters presently used in numerical modelling, particularly in the context of the impact of climate change on estuarine and coastal systems.

Large-scale dam removal on the Elwha River, Washington, USA: source-to-sink sediment budget and synthesis

Science.gov (United States)

Warrick, Jonathan A.; Bountry, Jennifer A.; East, Amy E.; Magirl, Christopher S.; Randle, Timothy J.; Gelfenbaum, Guy R.; Ritchie, Andrew C.; Pess, George R.; Leung, Vivian; Duda, Jeff J.

2015-01-01

Understanding landscape responses to sediment supply changes constitutes a fundamental part of many problems in geomorphology, but opportunities to study such processes at field scales are rare. The phased removal of two large dams on the Elwha River, Washington, exposed 21 ± 3 million m3, or ~ 30 million tonnes (t), of sediment that had been deposited in the two former reservoirs, allowing a comprehensive investigation of watershed and coastal responses to a substantial increase in sediment supply. Here we provide a source-to-sink sediment budget of this sediment release during the first two years of the project (September 2011–September 2013) and synthesize the geomorphic changes that occurred to downstream fluvial and coastal landforms. Owing to the phased removal of each dam, the release of sediment to the river was a function of the amount of dam structure removed, the progradation of reservoir delta sediments, exposure of more cohesive lakebed sediment, and the hydrologic conditions of the river. The greatest downstream geomorphic effects were observed after water bodies of both reservoirs were fully drained and fine (silt and clay) and coarse (sand and gravel) sediments were spilling past the former dam sites. After both dams were spilling fine and coarse sediments, river suspended-sediment concentrations were commonly several thousand mg/L with ~ 50% sand during moderate and high river flow. At the same time, a sand and gravel sediment wave dispersed down the river channel, filling channel pools and floodplain channels, aggrading much of the river channel by ~ 1 m, reducing river channel sediment grain sizes by ~ 16-fold, and depositing ~ 2.2 million m3 of sand and gravel on the seafloor offshore of the river mouth. The total sediment budget during the first two years revealed that the vast majority (~ 90%) of the sediment released from the former reservoirs to the river passed through the fluvial system and was discharged to the coastal

grain size analysis of beach sediment along the barrier bar lagoon

African Journals Online (AJOL)

PROF EKWUEME

sediment are medium grain and deposited in a moderate energy condition hence more stable to ... The grain size and amount of sand on a beach depends on wave energy and geological ..... Recent and Pleistocene history of Southeast.

Physico - chemical Up-grading studies of uraniferous xenotime mineral from ferruginous siltstone sediments of Um hamd, Um bogma area, sinai, Egypt

International Nuclear Information System (INIS)

Abdel-Monem, H.M.; Elassy, I.E.; Bishay, A.F.; El-Kammar, A.M.

1998-01-01

The exposed paleozoic deposits at Um Bogma area in west central sinai contain three main units namely; the lower sandstone, the middle carbonate and the upper sandstone. These units are composed of intercalation of clay minerals, sand, carbonate and iron oxides.The upper layers of the lower sandstone and the base of the middle carbonate units contain possible resources of anomalously uraniferous xenotime (YPO 4 ). Xenotime, being preferentially concentrated with the very fine grain sizes, is more abundant in the argillaceous sediments. The associated clay minerals are represented by kaolinite the non-clay minerals include hematite, goethite and quartz.The up-grading of uraniferous xenotime from a bulk head sample assaying 1.44% Y 2 O 3 was performed by collaborative technological processes that include; liquid/liquid separation using two immiscible liquids (CCI 4 and H 2 O) and finally acid leaching. By applying the proposed flowsheet, more than 90% of xenotime is recovered with an assay value of more than 45% Y 2 O 3 . The simplicity of the proposed flowsheet allows it to be adopted to semi-industrial or even industrial purposes

The EU and Constitutionalism in Egypt

DEFF Research Database (Denmark)

Seeberg, Peter

2013-01-01

of the unrest in Egypt followed by an analysis of the European-Egyptian relationship over the last two years divided in three parts: Egypt and the ENP-UfM complex, the Muslim Brotherhood and the Egyptian political transformation process seen in a European perspective and finally the migration issue...... in the context of Egyptian-European relations. The article argues that the EU policies, which earlier have been dominated by a pragmatic approach towards the Mubarak regime, now have to be rethought considering an Egyptian polity, where the contours of a new constitutionalism are developing....

Egypt

DEFF Research Database (Denmark)

The book covers Egyptian history from the Predynastic to the late Roman Period. It also introduces early contemporary literary references to ancient Egypt and uses a number of theoretical approaches to interrogate the archaeological and textual data. Egyptology and Egyptian archaeology are often...... to demonstrate the emerging interdisciplinary nature in Ancient Egyptian studies and the first to suggest new avenues of approach whilst seeking to open a discussion about how the Egyptian past can be known and understood. The book engages with wider trends from the humanities, which have found currency...

Long-term evolution of sand waves in the Marsdiep inlet. II: Relation to hydrodynamics

Science.gov (United States)

Buijsman, Maarten C.; Ridderinkhof, Herman

2008-05-01

A discussion is presented about the mechanisms that govern the spatial and seasonal variability in sand-wave height and migration speed in the 4 km wide Marsdiep tidal inlet, the Netherlands. Since 1998, current velocities and water depths have been recorded with an ADCP that is mounted under the ferry 'Schulpengat'. In this paper, the current measurements were used to explain the sand-wave observations presented in Buijsman and Ridderinkhof [this issue. Long-term evolution of sand waves in the Marsdiep inlet. I: high-resolution observations. Continental Shelf Research, doi: 10.1016/j.csr.2007.10.011]. Across nearly the entire inlet, the sand waves migrate in the flood direction. In the flood-dominated southern part of the inlet, the 'measured' (i.e. based on sand-wave shape and migration speed) and predicted bedload transport agree in direction, magnitude, and trends, whereas in the ebb-dominated northern part the predicted bedload and suspended load transport is opposite to the sand-wave migration. In the southern part, 55% of the bedload transport is due to tidal asymmetries and 45% due to residual currents. In addition to the well-known tidal asymmetries, asymmetries that arise from the interaction of M2 and its overtides with S2 and its compound tides are also important. It is hypothesised that in the northern part of the inlet the advection of suspended sand and lag effects govern the sand-wave migration. The relative importance of suspended load transport also explains why the sand waves have smaller lee-slope angles, are smaller, more rounded, and more three-dimensional in the northern half of the inlet. The sand waves in this part of the inlet feature the largest seasonal variability in height and migration speed. This seasonal variability may be attributed to the tides or a seasonal fluctuation in fall velocity. In both cases sediment transport is enhanced in winter, increasing sand-wave migration and decreasing sand-wave height. The influence of storms

Sediment transport and development of banner banks and sandwaves in an extreme tidal system: Upper Bay of Fundy, Canada

Science.gov (United States)

Li, Michael Z.; Shaw, John; Todd, Brian J.; Kostylev, Vladimir E.; Wu, Yongsheng

2014-07-01

Multibeam sonar mapping and geophysical and geological groundtruth surveys were coupled with tidal current and sediment transport model calculations to investigate the sediment transport and formation processes of the complex seabed features off the Cape Split headland in the upper Bay of Fundy. The Cape Split banner bank, composed of coarse to very coarse sand, is a southwest-northeast oriented, large tear-drop shaped sand body with superimposed sand waves that show wavelengths from 15 to 525 m and heights from 0.5 to 19 m. Isolated and chains of barchan dunes occur on top of a shadow bank to the southeast of the banner bank. The barchan dunes are composed of well-sorted medium sand and are oriented northwest-southeast. Their mean height and width are 1.5 and 55 m, respectively. A gravel bank, with an elongated elliptical shape and west-east orientation, lies in the Minas Passage erosional trough east of the headland to form the counterpart to the sandy Cape Split banner bank. The southern face is featureless but the northern face is covered by gravel megaripples. Tidal model predictions and sediment transport calculations show that the formation of the banner bank and the gravel bank are due to the development of the transient counter-clockwise and clockwise tidal eddies respectively to the west and east of the headland. The formation of barchan dunes is controlled by the nearly unidirectional flow regime in outer Scots Bay. Sand waves on the flanks of the Cape Split banner bank show opposite asymmetry and the barchan dunes are asymmetric to the northeast. The tidal current and sediment transport predictions corroborate bedform asymmetry to show that sand wave migration and net sediment transport is to southwest on the northern flank of the banner bank but to northeast on the southern bank. Long-term migration of the Scots Bay barchan dunes is to the northeast. Spring-condition tidal currents can cause frequent mobilization and high-stage transport over the

Considerations when ranking stochastically modeled oil sands resource models for mining applications

Energy Technology Data Exchange (ETDEWEB)

Etris, E.L. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Petro-Canada, Calgary, AB (Canada); Idris, Y.; Hunter, A.C. [Petro-Canada, Calgary, AB (Canada)

2008-10-15

Alberta's Athabasca oil sands deposit has been targeted as a major resource for development. Bitumen recovery operations fall into 2 categories, namely mining and in situ operations. Mining recovery is done above ground level and consists of open pit digging, disaggregation of the bitumen-saturated sediment through crushing followed by pipeline transport in a water-based slurry and then separation of oil, water and sediment. In situ recovery consists of drilling wells and stimulating the oil sands in the subsurface with a thermal treatment to reduce the viscosity of the bitumen and allow it to come to the surface. Steam assisted gravity drainage (SAGD) is the most popular thermal treatment currently in use. Resource models that simulate the recovery process are needed for both mining and in situ recovery operations. Both types can benefit from the advantages of a stochastic modeling process for resource model building and uncertainty evaluation. Stochastic modeling provides a realistic geology and allows for multiple realizations, which mining operations can use to evaluate the variability of recoverable bitumen volumes and develop mine plans accordingly. This paper described the processes of stochastic modelling and of determining the appropriate single realization for mine planning as applied to the Fort Hills oil sands mine which is currently in the early planning stage. The modeling exercise was used to estimate the in-place resource and quantify the uncertainty in resource volumes. The stochastic models were checked against those generated from conventional methods to identify any differences and to make the appropriate adaptations. 13 refs., 3 tabs., 16 figs.

Effects of coexistence between the blue mussel Mytilus edulis and eelgrass Zostera marina on sediment biogeochemistry and plant performance

DEFF Research Database (Denmark)

Vinther, H.F.; Norling, P.; Kristensen, Per Sand

2012-01-01

The habitat-modifying suspension-feeding mussel, Mytilus edulis, may have facilitating or inhibiting effects on seagrass meadows depending on the environmental conditions. We investigated the effects of M. edulis on sediment biogeochemistry in Zostera marina meadows under eutrophic conditions...... in Flensborg fjord, Denmark. Sediment and plant samples were collected at ten stations; five with Z. marina (Eelgrass) and five with Z. marina and M. edulis (Mixed) and at two unvegetated stations; one with mussels (Mussel) and one with sand (Sand). The Mixed sediment was enriched in fine particles (2-3 times...... significantly reduced at Mixed stations suggesting inhibiting effect of M. edulis on Z. marina. Negative correlations between eelgrass measures and sediment sulphide at Mixed stations indicate that presence of mussels increase sulphide invasion in the plants. A survey of 318 stations in Danish fjords suggests...

Changing Sediment Dynamics of a Mature Backbarrier Salt Marsh in Response to Sea-Level Rise and Storm Events

Directory of Open Access Journals (Sweden)

Mark Schuerch

2018-05-01

Full Text Available Our study analyses the long-term development of a tidal backbarrier salt marsh in the northern German Wadden Sea. The focus lies on the development of the high-lying, inner, mature part of the salt marsh, which shows a striking history of changing sediment dynamics. The analysis of high-resolution old aerial photographs and sampled sediment cores suggests that the mature part of the marsh was shielded by a sand barrier from the open sea for decades. The supply with fine-grained sediments occurred from the marsh inlet through the tidal channels to the inner salt marsh. Radiometric dating (210Pb and 137Cs reveals that the sedimentation pattern changed fundamentally around the early-mid 1980s when the sedimentation rates increased sharply. By analyzing the photographic evidence, we found that the sand barrier was breached during storm events in the early 1980s. As a result, coarse-grained sediments were brought directly through this overwash from the sea to the mature part of the salt marsh and increased the sedimentation rates. We show that the overwash and the channels created by these storm events built a direct connection to the sea and reduced the distance to the sediment source which promoted salt marsh growth and a supply with coarse-grained sediments. Consequently, the original sediment input from the tidal channels is found to play a minor role in the years following the breach event. The presented study showcases the morphological development of a mature marsh, which contradicts the commonly accepted paradigm of decreasing sedimentation rates with increasing age of the marsh. We argue that similar trends are likely to be observed in other backbarrier marshes, developing in the shelter of unstabilized sand barriers. It further highlights the question of how resilient these salt marshes are toward sea level rise and how extreme storm events interfere in determining the resilience of a mature salt marsh.

Morbidity, Mortality, and Seasonality of Influenza Hospitalizations in Egypt, November 2007-November 2014

OpenAIRE

Kandeel, Amr; Dawson, Patrick; Labib, Manal; Said, Mayar; El-Refai, Samir; El-Gohari, Amani; Talaat, Maha

2016-01-01

Background Influenza typically comprises a substantial portion of acute respiratory infections, a leading cause of mortality worldwide. However, influenza epidemiology data are lacking in Egypt. We describe seven years of Egypt?s influenza hospitalizations from a multi-site influenza surveillance system. Methods Syndromic case definitions identified individuals with severe acute respiratory infection (SARI) admitted to eight hospitals in Egypt. Standardized demographic and clinical data were ...

Reclaimability of the spent sand mixture – sand with bentonite – sand with furfuryl resin

Directory of Open Access Journals (Sweden)

J. Dańko

2011-04-01

Full Text Available Introduction of new binding materials and new technologies of their hardening in casting moulds and cores production requires theapplication of reclamation methods adequate to their properties as well as special devices realizing tasks. The spent sands circulationsystem containing the same kind of moulding and core sands is optimal from the point of view of the expected reclamation results.However, in the face of a significant variability of applied technologies and related to them various reclamation methods, the need - of theobtained reclamation products assessment on the grounds of systematic criteria and uniform bases – arises, with a tendency of indicatingwhich criteria are the most important for the given sand system. The reclaimability results of the mixture of the spent moulding sand withGeko S bentonite and the spent core sand with the Kaltharz 404U resin hardened by acidic hardener 100 T3, are presented in the paper.Investigations were performed with regard to the estimation of an influence of core sands additions (10 –25% on the reclaimed materialquality. Dusts and clay content in the reclaim, its chemical reaction (pH and ignition loss were estimated. The verification of the reclaiminstrumental assessment was performed on the basis of the technological properties estimation of moulding sand with bentonite, where the reclaimed material was used as a matrix.

Hepatitis C in Egypt – past, present, and future

Directory of Open Access Journals (Sweden)

Elgharably A

2016-12-01

Full Text Available Ahmed Elgharably,1,2 Asmaa I Gomaa,2 Mary ME Crossey,1,2 Peter J Norsworthy,1 Imam Waked,2 Simon D Taylor-Robinson1 1Division of Digestive Health, Department of Surgery and Cancer, St Mary’s Hospital, Imperial College London, London, UK; 2National Liver Institute, Menoufiya University, Shebeen El Kom, Egypt Abstract: Hepatitis C viral infection is endemic in Egypt with the highest prevalence rate in the world. It is widely accepted that the implementation of mass population antischistosomal treatment involving administration of tartar emetic injections (from 1950s to 1980s led to widespread infection. What is less well known, however, is that these schemes were implemented by the Egyptian Ministry of Health on the advice of the World Health Organization. There has been a spectrum of treatments to target the public health disaster represented by the hepatitis C problem in Egypt: from the use of PEGylated interferon to the recent use of direct acting antiviral drugs. Some new treatments have shown >90% efficacy. However, cost is a key barrier to access these new medicines. This is coupled with a growing population, limited resources, and a lack of infection control practices which means Egypt still faces significant disease control issues today. Keywords: hepatitis C, Egypt, schistosomiasis

Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam

Science.gov (United States)

Unverricht, Daniel; Szczuciński, Witold; Stattegger, Karl; Jagodziński, Robert; Le, Xuan Thuyen; Kwong, Laval Liong Wee

2013-11-01

The Mekong River Delta is among the Asian mega-deltas and is influenced by various factors including tides (meso-tidal system), waves, coastal currents, monsoon-driven river discharge and human impact (agriculture, fishing, sand dredging, tourism). The present study aims to document the seafloor relief, sediment distribution and sediment accumulation rates to interpret modern sediment transport directions and main sedimentation processes in the subaqueous Mekong Delta. The major results of this investigation include the detection of two delta fronts 200 km apart, one at the mouth of the Bassac River (the biggest branch of the Mekong Delta) and the other around Cape Ca Mau (most south-western end of the Mekong Delta). Additionally, a large channel system runs in the subaqueous delta platform parallel to the shore and between the two fronts. The sediment accumulation rates vary greatly according to the location in the subaqueous delta and have reached up to 10 cm/yr for the last century. A cluster analysis of surface sediment samples revealed two different sediment types within the delta including a well-sorted sandy sediment and a poorly sorted, silty sediment. In addition, a third end member with medium to coarse sand characterised the distant parts of the delta at the transition to the open shelf. The increase of organic matter and carbonate content to the bottom set area and other sedimentary features such as shell fragments, foraminiferas and concretions of palaeo-soils that do not occur in delta sediments, supported grain size-based classification. Beginning in front of the Bassac River mouth, sedimentary pattern indicates clockwise sediment transport alongshore in the western direction to a broad topset area and the delta front around Cape Ca Mau. Our results clearly show the large lateral variability of the subaqueous Mekong Delta that is further complicated by strong monsoon-driven seasonality. River, tidal and wave forcing vary at local and seasonal scales

Intrinsic rates of petroleum hydrocarbon biodegradation in Gulf of Mexico intertidal sandy sediments and its enhancement by organic substrates

International Nuclear Information System (INIS)

Mortazavi, Behzad; Horel, Agota; Beazley, Melanie J.; Sobecky, Patricia A.

2013-01-01

The rates of crude oil degradation by the extant microorganisms in intertidal sediments from a northern Gulf of Mexico beach were determined. The enhancement in crude oil degradation by amending the microbial communities with marine organic matter was also examined. Replicate mesocosm treatments consisted of: (i) controls (intertidal sand), (ii) sand contaminated with crude oil, (iii) sand plus organic matter, and (iv) sand plus crude oil and organic matter. Carbon dioxide (CO 2 ) production was measured daily for 42 days and the carbon isotopic ratio of CO 2 (δ 13 CO 2 ) was used to determine the fraction of CO 2 derived from microbial respiration of crude oil. Bacterial 16S rRNA clone library analyses indicated members of Actinobacteria, Bacteroidetes, and Chloroflexi occurred exclusively in control sediments whereas Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Firmicutes occurred in both control and oil contaminated sediments. Members of the hydrocarbon-degrading genera Hydrocarboniphaga, Pseudomonas, and Pseudoxanthomonas were found primarily in oil contaminated treatments. Hydrocarbon mineralization was 76% higher in the crude oil amended with organic matter treatment compared to the rate in the crude oil only treatment indicating that biodegradation of crude oil in the intertidal zone by an extant microbial community is enhanced by input of organic matter

Intrinsic rates of petroleum hydrocarbon biodegradation in Gulf of Mexico intertidal sandy sediments and its enhancement by organic substrates

Energy Technology Data Exchange (ETDEWEB)

Mortazavi, Behzad [University of Alabama, Department of Biological Sciences, Box 870344, University of Alabama, Tuscaloosa, AL 35487 (United States); Dauphin Island Sea Lab, 101 Bienville Boulevard, Dauphin Island, AL, 36528 (United States); Horel, Agota [University of Alabama, Department of Biological Sciences, Box 870344, University of Alabama, Tuscaloosa, AL 35487 (United States); Dauphin Island Sea Lab, 101 Bienville Boulevard, Dauphin Island, AL, 36528 (United States); Beazley, Melanie J.; Sobecky, Patricia A. [University of Alabama, Department of Biological Sciences, Box 870344, University of Alabama, Tuscaloosa, AL 35487 (United States)

2013-01-15

The rates of crude oil degradation by the extant microorganisms in intertidal sediments from a northern Gulf of Mexico beach were determined. The enhancement in crude oil degradation by amending the microbial communities with marine organic matter was also examined. Replicate mesocosm treatments consisted of: (i) controls (intertidal sand), (ii) sand contaminated with crude oil, (iii) sand plus organic matter, and (iv) sand plus crude oil and organic matter. Carbon dioxide (CO{sub 2}) production was measured daily for 42 days and the carbon isotopic ratio of CO{sub 2} (δ{sup 13}CO{sub 2}) was used to determine the fraction of CO{sub 2} derived from microbial respiration of crude oil. Bacterial 16S rRNA clone library analyses indicated members of Actinobacteria, Bacteroidetes, and Chloroflexi occurred exclusively in control sediments whereas Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Firmicutes occurred in both control and oil contaminated sediments. Members of the hydrocarbon-degrading genera Hydrocarboniphaga, Pseudomonas, and Pseudoxanthomonas were found primarily in oil contaminated treatments. Hydrocarbon mineralization was 76% higher in the crude oil amended with organic matter treatment compared to the rate in the crude oil only treatment indicating that biodegradation of crude oil in the intertidal zone by an extant microbial community is enhanced by input of organic matter.

Heavy mineral analysis for assessing the provenance of sandy sediment in the San Francisco Bay Coastal System

Science.gov (United States)

Wong, Florence L.; Woodrow, Donald L.; McGann, Mary

2013-01-01

Heavy or high-specific gravity minerals make up a small but diagnostic component of sediment that is well suited for determining the provenance and distribution of sediment transported through estuarine and coastal systems worldwide. By this means, we see that surficial sand-sized sediment in the San Francisco Bay Coastal System comes primarily from the Sierra Nevada and associated terranes by way of the Sacramento and San Joaquin Rivers and is transported with little dilution through the San Francisco Bay and out the Golden Gate. Heavy minerals document a slight change from the strictly Sierran-Sacramento mineralogy at the confluence of the two rivers to a composition that includes minor amounts of chert and other Franciscan Complex components west of Carquinez Strait. Between Carquinez Strait and the San Francisco Bar, Sierran sediment is intermingled with Franciscan-modified Sierran sediment. The latter continues out the Gate and turns southward towards beaches of the San Francisco Peninsula. The Sierran sediment also fans out from the San Francisco Bar to merge with a Sierran province on the shelf in the Gulf of the Farallones. Beach-sand sized sediment from the Russian River is transported southward to Point Reyes where it spreads out to define a Franciscan sediment province on the shelf, but does not continue southward to contribute to the sediment in the Golden Gate area.

A global vision for small business in Egypt | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

Egypt's Ministry of Finance in Enhancing Competitiveness of SMEs in Egypt: General ... SMEPol then supported the policy formulation process, in part by providing urgently needed ... Research also focused on strategies for increasing exports.

Challenges of ecosystem restoration in Louisiana - availability of sediment and its management

Science.gov (United States)

Khalil, S. M.; Freeman, A. M.

2015-03-01

Human intervention has impaired the Mississippi River's ability to deliver sediment to its delta wetlands, and as a consequence acute land loss in coastal Louisiana has resulted in an unprecedented ecocatastrophe. To mitigate this degradation, an unparalleled restoration effort is underway. For this effort to be successful and sustainable, various sediment input mechanisms must be integrated, including: building appropriate sediment-diversions; beneficially using the millions of cubic metres of sediment dredged annually from navigational channels; harvesting deposits of sand and suitable sediment from the river and offshore; and related sediment management activities that are compatible with other uses of the river. A comprehensive sediment management plan has been developed to identify and delineate potential sediment sources for restoration, and to provide a framework for managing sediment resources wisely, cost effectively, and in a systematic manner. The Louisiana Sediment Management Plan provides regional strategies for improved comprehensive management of Louisiana's limited sediment resources.

Study of various processes for marking sediments with gold-198; Etude de divers procedes de marquages de sediments par l'or 198

Energy Technology Data Exchange (ETDEWEB)

Jeanneau, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-12-15

The use of radioactive isotopes for the study of sediment deposits is based mainly on two methods: marking in the mass - a glass of an element which can be activated replaces the sediment; surface marking - a physico-chemical process is used to deposit a radio-element at the surface of the sediment. The second process is used in particular for sands when it is advantageous to have a large number of particles for statistical analysis. The aim of this work was to develop a rapid and simple method of marking which could be applied on the actual site of the experiment where equipment, may be limited. The method recommended for marking sand with gold-198 is a combination of the Petersen (treatment with tin chloride) and Campbell (treatment with silver) methods combined with prior treatments with nitric acid and caustic soda. Using this method it is possible to deposit 125 mg of gold per kilo of sediment with a yield of 95 per cent (i.e. 10 Ci/kg) using a hydrochloric acid solution containing gold. The problem of the solidity of the deposits, of their value and of their reproducibility is discussed from the point of view of the mineral constitution of the sand. (author) [French] L'utilisation d'isotopes radioactifs pour l'etude des deplacements sedimentaires fait, principalement appel a deux methodes: le marquage massique - un verre contenant un element activable remplace le sediment; le marquage superficiel - un traitement physico-chimique permet de deposer un radioelement a la surface du sediment. Le second procede est surtout employe pour les sables lorsqu'il est utile de disposer d'un grand nombre de grains pour des raisons statistiques. Le but de ce travail etait de mettre au point une methode simple et rapide de marquage pouvant etre appliquee sur le site meme de l'experience pour les utilisateurs disposant d'un equipement limite. Le procede preconise pour le marquage des sables par l'or 198 est une combinaison des methodes Petersen (traitement au chlorure d

Major, trace and REE geochemistry of recent sediments from lower Catumbela River (Angola)

Science.gov (United States)

Vinha, Manuela; Silva, M. G.; Cabral Pinto, Marina M. S.; Carvalho, Paula Cristina S.

2016-03-01