Beach litter along various sand dune habitats in the southern Adriatic (E Mediterranean).

Science.gov (United States)

Šilc, Urban; Küzmič, Filip; Caković, Danka; Stešević, Danijela

2018-03-01

Marine litter accumulates on sandy beaches and is an important environmental problem, as well as a threat to habitat types that are among the most endangered according to EU legislation. We sampled 120 random plots (2 × 2 m) in spring 2017 to determine the distribution pattern of beach litter along the zonation of habitat types from sea to the inland. The most frequent litter items were plastic, polystyrene and glass. A clear increase of litter cover along the sea-inland gradient is evident, and foredunes and pine forests have the highest cover of litter. Almost no litter was present in humid dune slacks. Shoreline and recreational activities are the major source of beach litter, while ocean/waterway activities are more important in the aphytic zone and strandline. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Invasive plants on disturbed Korean sand dunes

Science.gov (United States)

Kim, Kee Dae

2005-01-01

The sand dunes in coastal regions of South Korea are important ecosystems because of their small size, the rare species found in this habitat, and the beautiful landscapes they create. This study investigated the current vegetative status of sand dunes on three representative coasts of the Korean peninsula, and on the coasts of Cheju Island, and assessed the conditions caused by invasive plants. The relationships between the degree of invasion and 14 environmental variables were studied. Plots of sand dunes along line transects perpendicular to the coastal lines were established to estimate vegetative species coverage. TWINSPAN (Two-Way Indicator Species Analysis), CCA (Canonical Correspondence Analysis), and DCCA (Detrended Canonical Correspondence Analysis) were performed to classify communities on sand dunes and assess species composition variation. Carex kobomugi, Elymus mollis, and Vitex rotundifolia were found to be the dominant species plotted on the east, the west, and the peripheral coasts of Cheju Island, respectively. Vegetation on the south coast was totally extinct. The 19 communities, including representative C. kobomugi, C. kobomugi- Ixeris repens, C. kobomugi- Oenothera biennis, E. mollis, Lolium multiflorum- Calystegia soldanella, and V. rotundifolia- C. kobomugi, were all classified according to TWINSPAN. Oenothera biennis and L. multiflorum were exotics observed within these native communities. CCA showed that invasive native and exotic species distribution was segregated significantly, according to disturbance level, exotic species number, gravel, sand and silt contents, as well as vegetation size. It further revealed that human disturbance can strongly favor the settlement of invasive and exotic species. Restoration options to reduce exotic plants in the South Korean sand dune areas were found to be the introduction of native plant species from one sand dune into other sand dune areas, prohibition of building and the introduction of exotic

Sand Dunes with Frost

Science.gov (United States)

2004-01-01

9 May 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of frost-covered sand dunes in the north polar region of Mars in early spring, 2004. The dunes indicate wind transport of sand from left to right (west to east). These landforms are located near 78.1oN, 220.8oW. This picture is illuminated by sunlight from the lower left and covers an area about 3 km (1.9 mi) across.

Miramar (Goa) Beach Management Project: An Oceanographic Evaluation

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas, A.; Ingole, B.S.

implications of sand dunes, significance of benthic biodiversity, knowledge of coastal geological processes and restoration of degraded sand dunes should form an integral part of any beach management strategy....

Dunes Around Khnifiss Lagoon (Tarfaya, SW of Morocco): Composition, Itinerary In Dune Fields, Effects on Dunes' Colours and Morphodynamic

Science.gov (United States)

Adnani, M.; Azzaoui, M. A.; Elbelrhiti, H.; Ahmamou, M.; Masmoudi, L.

2015-12-01

Dunes around Khnifiss lagoon (28° 3'N, 12°13'W) show different colors ranging from black at the beach, whitish yellow in transverse dunes near the beach to reddish at the mega barchans situated few kilometers in the SW. The scientific question is about the abundance of different dunes in the same environmental conditions. The present work aims to investigate the factors that influence dunes color change, and then at which degree these factors could control dunes stability. To highlight the difference in color observed at the dune fields then to characterize dunes mineralogy, Landsat TM images were used in addition to mineralogical analysis that was carried out for the black grains samples originated from megabarchans. Optic Microscope and SEM- EDS data was adopted, in addition to physico-chemical analysis provided by Electronic Microprobe. Grain size and shape analysis were conducted to characterize the different types of grains of sand. 3/1 Landsat image band ratio allowed iron oxide distinction, the results revealed the importance of iron oxide concentration. Furthermore, mineralogical and physico-chemical analysis revealed (i) a high grade of oxides (Rutile, Ilmenite, Magnetite, Ulvöspinel) in samples, (ii) silicates (Quartz, Clinopyroxene, feldspar, Zircon), (iii) phosphate (apatite) and (iv) carbonate (calcite). The grain size analysis of the sand originated from the megabarchans reveals that there are three populations of sand. Black grains with a diameter less than 100μm and dominated by the magnetite, red ones composed mainly by the quartz with diameter between 100 and 180 μm and grains with diameter more than 180 μm are white and composed by carbonates. The threshold of motion of these different grains was calculated. It shows that these different grains have the same threshold of motion, which means that the grain size compensates the density. This explains the abundance of different populations of sand in the same environment. The dominance of iron

Singing Sand Dunes

Indian Academy of Sciences (India)

ble low-frequency (s. 75–105 Hz), that can some- times be heard up to 10 km away. Scientific in- vestigations suggest that the sustained low fre- quency sound of sand dunes that resembles a pure note from a musical instrument, is due to the synchronized motion of well-sorted dry sand grains when they spontaneously ...

A Wireless Sensor Network for the Real-Time Remote Measurement of Aeolian Sand Transport on Sandy Beaches and Dunes.

Science.gov (United States)

Pozzebon, Alessandro; Cappelli, Irene; Mecocci, Alessandro; Bertoni, Duccio; Sarti, Giovanni; Alquini, Fernanda

2018-03-08

Direct measurements of aeolian sand transport on coastal dunes and beaches is of paramount importance to make correct decisions about coast management. As most of the existing studies are mainly based on a statistical approach, the solution presented in this paper proposes a sensing structure able to orient itself according to wind direction and directly calculate the amount of wind-transported sand by collecting it and by measuring its weight. Measurements are performed remotely without requiring human action because the structure is equipped with a ZigBee radio module, which periodically sends readings to a local gateway. Here data are processed by a microcontroller and then transferred to a remote data collection centre, through GSM technology. The ease of installation, the reduced power consumption and the low maintenance required, make the proposed solution able to work independently, limiting human intervention, for all the duration of the expected experimental campaign. In order to analyze the cause-effect relationship between the transported sand and the wind, the sensing structure is integrated with a multi-layer anemoscope-anemometer structure. The overall sensor network has been developed and tested in the laboratory, and its operation has been validated in field through a 48 h measurement campaign.

A Wireless Sensor Network for the Real-Time Remote Measurement of Aeolian Sand Transport on Sandy Beaches and Dunes

Science.gov (United States)

Cappelli, Irene; Mecocci, Alessandro; Alquini, Fernanda

2018-01-01

Direct measurements of aeolian sand transport on coastal dunes and beaches is of paramount importance to make correct decisions about coast management. As most of the existing studies are mainly based on a statistical approach, the solution presented in this paper proposes a sensing structure able to orient itself according to wind direction and directly calculate the amount of wind-transported sand by collecting it and by measuring its weight. Measurements are performed remotely without requiring human action because the structure is equipped with a ZigBee radio module, which periodically sends readings to a local gateway. Here data are processed by a microcontroller and then transferred to a remote data collection centre, through GSM technology. The ease of installation, the reduced power consumption and the low maintenance required, make the proposed solution able to work independently, limiting human intervention, for all the duration of the expected experimental campaign. In order to analyze the cause-effect relationship between the transported sand and the wind, the sensing structure is integrated with a multi-layer anemoscope-anemometer structure. The overall sensor network has been developed and tested in the laboratory, and its operation has been validated in field through a 48 h measurement campaign. PMID:29518060

Sediment Source Fingerprinting of the Lake Urmia Sand Dunes.

Science.gov (United States)

Ahmady-Birgani, Hesam; Agahi, Edris; Ahmadi, Seyed Javad; Erfanian, Mahdi

2018-01-09

Aeolian sand dunes are continuously being discovered in inner dry lands and coastal areas, most of which have been formed over the Last Glacial Maximum. Presently, due to some natural and anthropogenic implications on earth, newly-born sand dunes are quickly emerging. Lake Urmia, the world's second largest permanent hypersaline lake, has started shrinking, vast lands comprising sand dunes over the western shore of the lake have appeared and one question has been playing on the minds of nearby dwellers: where are these sand dunes coming from, What there was not 15 years ago!! In the present study, the determination of the source of the Lake Urmia sand dunes in terms of the quantifying relative contribution of each upstream geomorphological/lithological unit has been performed using geochemical fingerprinting techniques. The findings demonstrate that the alluvial and the fluvial sediments of the western upstream catchment have been transported by water erosion and they accumulated in the lower reaches of the Kahriz River. Wind erosion, as a secondary agent, have carried the aeolian sand-sized sediments to the sand dune area. Hence, the Lake Urmia sand dunes have been originating from simultaneous and joint actions of alluvial, fluvial and aeolian processes.

Observations regarding the movement of barchan sand dunes in the Nazca to Tanaca area of southern Peru

Science.gov (United States)

Parker Gay, S.

1999-03-01

Significant studies of sand dunes and sand movement made in coastal southern Peru in 1959-1961 [Gay, S.P., 1962. Origen, distribución y movimiento de las arenas eólicas en el área de Yauca a Palpa. Boletin de la Sociedad Geologica del Perú 37, 37-58] have never been published in the English language and consequently have never been referred to in the standard literature. These studies contain valuable information, not developed by later workers in this field, that may be of broad general interest. For example, using airphotos of barchan dunes and plotting the rates of movement vs. dune widths, the author quantified the deduction of Bagnold [Bagnold, R.A., 1941. The Physics of Blown Sand and Desert Dunes. Methuen, London.] that the speed of barchan movement is inversely proportional to barchan size (as characterized by height or width). This led to the conclusion that all barchans in a given dune field, regardless of size, sweep out approximately equal areas in equal times. Another conclusion was that collisions between smaller, overtaking dunes and larger dunes in front of them do not result in destruction or absorption of the smaller dunes if the collision is a `sideswipe'. The dunes simply merge into a compound dune for a time, and the smaller dune then moves on intact, i.e., passes, the larger dune, whilst retaining its approximate original size and shape. Another result of the 1959-1961 studies was a map that documents the Pacific coast beaches as the source of the sand ( Fig. 1), which is then blown inland through extensive dune fields of barchans and other dune forms in great clockwise-sweeping paths, to its final resting place in huge sand masses, sometimes called `sand seas' [Lancaster, N., 1995. Geomorphology of Desert Dunes. Routledge, London], at higher elevations 20 to 60 km from the coast. A minor, but nevertheless interesting, discovery was a small heavy mineral dune located directly in the lee of a large barchan, evidently formed by the winnowing

Microbial Characterization of Qatari Barchan Sand Dunes.

Directory of Open Access Journals (Sweden)

Sara Abdul Majid

Full Text Available This study represents the first characterization of sand microbiota in migrating barchan sand dunes. Bacterial communities were studied through direct counts and cultivation, as well as 16S rRNA gene and metagenomic sequence analysis to gain an understanding of microbial abundance, diversity, and potential metabolic capabilities. Direct on-grain cell counts gave an average of 5.3 ± 0.4 x 105 cells g-1 of sand. Cultured isolates (N = 64 selected for 16S rRNA gene sequencing belonged to the phyla Actinobacteria (58%, Firmicutes (27% and Proteobacteria (15%. Deep-sequencing of 16S rRNA gene amplicons from 18 dunes demonstrated a high relative abundance of Proteobacteria, particularly enteric bacteria, and a dune-specific-pattern of bacterial community composition that correlated with dune size. Shotgun metagenome sequences of two representative dunes were analyzed and found to have similar relative bacterial abundance, though the relative abundances of eukaryotic, viral and enterobacterial sequences were greater in sand from the dune closer to a camel-pen. Functional analysis revealed patterns similar to those observed in desert soils; however, the increased relative abundance of genes encoding sporulation and dormancy are consistent with the dune microbiome being well-adapted to the exceptionally hyper-arid Qatari desert.

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.

UAV-imaging to model growth response of marram grass to sand burial: Implications for coastal dune development

Science.gov (United States)

Nolet, Corjan; van Puijenbroek, Marinka; Suomalainen, Juha; Limpens, Juul; Riksen, Michel

2018-04-01

Vegetated coastal dunes have the capacity to keep up with sea-level rise by accumulating and stabilizing wind-blown sand. In Europe, this is attributed to marram grass (Ammophila arenaria), a coastal grass species that combines two unique advantages for dune-building: (1) a very high tolerance to burial by wind-blown sand, and (2) more vigorous growth due to positive feedback to sand burial. However, while these vegetation characteristics have been demonstrated, observational data has not been used to model a function to describe the growth response of Ammophila to sand burial. Studies that model coastal dune development by incorporating positive feedback, as a result, may be hampered by growth functions that are unvalidated against field data. Therefore, this study aims to parameterize an empirical relationship to model the growth response of Ammophila to burial by wind-blown sand. A coastal foredune along a nourished beach in the Netherlands was monitored from April 2015 to April 2016. High-resolution geospatial data was acquired using an Unmanned Aerial Vehicle (UAV). Growth response of Ammophila, expressed by changes in Normalized Difference Vegetation Index (Δ NDVI) and vegetation cover (Δ Cover), is related to a sand burial gradient by fitting a Gaussian function using nonlinear quantile regression. The regression curves indicate an optimal burial rate for Ammophila of 0.31 m of sand per growing season, and suggest (by extrapolation of the data) a maximum burial tolerance for Ammophila between 0.78 (for Δ Cover) and 0.96 m (for Δ NDVI) of sand per growing season. These findings are advantageous to coastal management: maximizing the potential of Ammophila to develop dunes maximizes the potential of coastal dunes to provide coastal safety.

Delineating Beach and Dune Morphology from Massive Terrestrial Laser Scanning Data Using the Generic Mapping Tools

Science.gov (United States)

Zhou, X.; Wang, G.; Yan, B.; Kearns, T.

2016-12-01

Terrestrial laser scanning (TLS) techniques have been proven to be efficient tools to collect three-dimensional high-density and high-accuracy point clouds for coastal research and resource management. However, the processing and presenting of massive TLS data is always a challenge for research when targeting a large area with high-resolution. This article introduces a workflow using shell-scripting techniques to chain together tools from the Generic Mapping Tools (GMT), Geographic Resources Analysis Support System (GRASS), and other command-based open-source utilities for automating TLS data processing. TLS point clouds acquired in the beach and dune area near Freeport, Texas in May 2015 were used for the case study. Shell scripts for rotating the coordinate system, removing anomalous points, assessing data quality, generating high-accuracy bare-earth DEMs, and quantifying beach and sand dune features (shoreline, cross-dune section, dune ridge, toe, and volume) are presented in this article. According to this investigation, the accuracy of the laser measurements (distance from the scanner to the targets) is within a couple of centimeters. However, the positional accuracy of TLS points with respect to a global coordinate system is about 5 cm, which is dominated by the accuracy of GPS solutions for obtaining the positions of the scanner and reflector. The accuracy of TLS-derived bare-earth DEM is primarily determined by the size of grid cells and roughness of the terrain surface for the case study. A DEM with grid cells of 4m x 1m (shoreline by cross-shore) provides a suitable spatial resolution and accuracy for deriving major beach and dune features.

Coastal monitoring solutions of the geomorphological response of beach-dune systems using multi-temporal LiDAR datasets (Vendée coast, France)

Science.gov (United States)

Le Mauff, Baptiste; Juigner, Martin; Ba, Antoine; Robin, Marc; Launeau, Patrick; Fattal, Paul

2018-03-01

sites, explained mainly by beach orientation and local factors. Despite variable site-specific mechanisms, the recovery processes redistribute the available sand more on the upper parts of the beach, producing significant deposition generally in the form of embryo dunes. The monitoring of the beach and dune systems with airborne LiDAR datasets reveals that the three study sites show diverse behaviours during the first period likely associated with storms, while the analysis show more homogenous beach responses during the second period likely associated with a recovery phase.

Measurements of Dune Parameters on Titan Suggest Differences in Sand Availability

Science.gov (United States)

Stewart, Brigitte W.; Radebaugh, Jani

2014-11-01

The equatorial region of Saturn’s moon Titan has five large sand seas with dunes similar to large linear dunes on Earth. Cassini Radar SAR swaths have high enough resolution (300 m) to measure dune parameters such as width and spacing, which helps inform us about formation conditions and long-term evolution of the sand dunes. Previous measurements in locations scattered across Titan have revealed an average width of 1.3 km and spacing of 2.7 km, with variations by location. We have taken over 1200 new measurements of dune width and spacing in the T8 swath, a region on the leading hemisphere of Titan in the Belet Sand Sea, between -5 and -9 degrees latitude. We have also taken over 500 measurements in the T44 swath, located on the anti-Saturn hemisphere in the Shangri-La Sand Sea, between 0 and 20 degrees latitude. We correlated each group of 50 measurements with the average distance from the edge of the dune field to obtain an estimate of how position within a dune field affects dune parameters. We found that in general, the width and spacing of dunes decreases with distance from the edge of the dune field, consistent with similar measurements in sand seas on Earth. We suggest that this correlation is due to the lesser availability of sand at the edges of dune fields. These measurements and correlations could be helpful in determining differences in sand availability across different dune fields, and along the entire equatorial region of Titan.

Formation of aeolian dunes on Anholt, Denmark since AD 1560

DEFF Research Database (Denmark)

Clemmensen, Lars B; Bjørnsen, Mette; Murray, Andrew

2007-01-01

Sand dunes on the island of Anholt (Denmark) in the middle of Kattegat form a relatively barren, temperate climate Aeolian system, locally termed the "Desert". The dunes have developed on top of a raised beach ridge system under the influence of dominant winds from westerly directions. They are r......Sand dunes on the island of Anholt (Denmark) in the middle of Kattegat form a relatively barren, temperate climate Aeolian system, locally termed the "Desert". The dunes have developed on top of a raised beach ridge system under the influence of dominant winds from westerly directions....... They are relatively coarse-grained with an average mean grain size of 480 µm. The last phase of aeolian activity and dune formation on Anholt started after AD 1560, when the local pine forest was removed. Historical sources report intense sand mobilization in the 17th century, and new optically stimulated...... in the beginning of the 20th century probably records a temporary decrease in storminess. Ground-penetrating radar mapping of the internal structures in two dunes in the western part of the Desert (a parabolic dune and a linear dune) indicates the importance of north-westerly (storm) winds during dune formation...

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.

Beach Sand Analysis for Indicators of Microbial Contamination

Science.gov (United States)

Traditional beach monitoring has focused on water quality, with little attention paid to health risks associated with beach sand. Recent research has reported that fecal indicator bacteria, as well as human pathogens can be found in beach sand and may constitute a risk to human h...

Provenance of Holocene calcareous beach-dune sediments, Western Eyre Peninsula, Great Australian Bight, Australia

Science.gov (United States)

James, Noel P.; Bone, Yvonne

2017-07-01

Much of western Eyre Peninsula adjacent to the Great Australian Bight is veneered with siliceous and calcareous Quaternary aeolian dunes. The lengthy coastline adjacent to this cool-water carbonate factory is a series of Precambrian crystalline bedrock-Pleistocene aeolianite headlands that separate many long, sweeping, Holocene carbonate sand beaches and their backbeach dunes. Incessant SW waves, rolling swells, and onshore winds have resulted in > 350 km of semi-continuous calcareous strandline aeolian sands. The sediment is composed of quartz grains, Cenozoic limestone clasts, and relict particles (extraclasts) but the deposits are overwhelmingly dominated by contemporaneous biofragments from offshore. These skeletal grains are, in order of relative abundance, molluscs > benthic foraminifers > coralline algae > bryozoans, and echinoids. Benthic foraminifers are mostly small (especially rotaliids and miliolids) but the large relict symbiont-bearing protistMarginopora vertebralis, which grew in the latter stages of MIS 2, is present locally. There are no significant onshore-offshore trends within individual beach-dune complexes. There is, however, a prominent spatial partitioning, with extraclast-rich sediments in the north and biofragment-rich deposits in the south. This areal trend is interpreted to result from more active seafloor carbonate production in the south, an area of conspicuous seasonal nutrient upwelling and profound nektic and benthic biological productivity. The overall system is strikingly similar to Holocene and Pleistocene aeolianites along the inboard margin of the Lacepede Shelf and Bonney Coast some 500 km to the southeast, implying a potential universality to the nature of cool-water carbonate aeolianite deposition. The composition of these cool-water aeolianites is more multifaceted than those formed on warm-water, shallow flat-topped platforms, largely because of the comparatively deep, temperate shelf, the high-energy wave and swell

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...

Dynamic dune management, integrating objectives of nature development and coastal safety: Examples from the Netherlands

Science.gov (United States)

Arens, Sebastiaan M.; Mulder, Jan P. M.; Slings, Quirinus L.; Geelen, Luc H. W. T.; Damsma, Petra

2013-10-01

This paper discusses and compares results of management interventions to remobilise dunes and obtain more autonomous changes in foredunes resulting from a change in coastal defence policy. In recent decades, nature conservation managers tried to restore aeolian dynamics and dune mobility landward of foredunes to maintain threatened, rare pioneer species. Results indicate that destabilisation activities yielded an important increase of blowing sand and its effects on ecology but with a limited effect on the desired integral remobilization of dunes. Roots remaining in the sand after removal of vegetation and soil is one of the main problems. Follow up removal of roots for 3 to 5 years seems to be essential, but it is not clear whether the dunes will remain mobile in the long term. In 1990 the Dutch government decided to maintain the position of the coastline by artificial sand nourishment. An intensive management of the foredunes was no longer required. Consequently, natural processes in the foredunes revived, and the sediment budget of the beach-dune system changed. Two main types of responses are visible. In some areas, increased input of sand resulted in the development of embryonic dunes seaward of the former foredunes, leading to increased stabilisation of the former foredunes. In other areas, development of embryonic dunes was insignificant despite the increased sand input, but wind erosion features developed in the foredunes, and the environment was more dynamic. The reasons for the differences are not clear, and the interaction between shoreface, beach and dunes is still poorly understood. Until now, attempts to mobilise the inner dunes were independent of changes made to the foredunes. We argue that an integrated, dynamic approach to coastal management, taking account of all relevant functions (including safety and natural values) and the dune-beach system as a whole, may provide new and durable solutions. An integrated approach would ideally provide fresh

The plight of the beaches of Greece

Science.gov (United States)

Ewing, L.; Foteinis, S.; Kalligeris, N.; Palaiologou, A.; Synolakis, C. E.

2008-12-01

The coastlines of the Greece are rapidly retreating at a rate that has increased substantially in the past decade. We describe here specific examples of rapid erosion and we speculate as to the causes. In some instances, erosion is advancing at a rate of 1m/year. As in other parts of the Mediterranean, the causes are anthropogenic and include sand mining from the beaches and rivers, poor design of coastal structures that create reflection patterns that focus waves on vulnerable areas, removal of sand dunes to build roads, and coastal construction too close to shoreline. The underlying problem is the complete lack of any semblance of coastal zone management in Greece and antiquated legislation. We conclude that unless urgent salvage measures to protect the beaches and end sand mining and dune removal, several beaches will disappear within the next decade.

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.

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.

Erosion in the Beaches of Crete

Science.gov (United States)

Synolakis, C. E.; Foteinis, S.; Voukouvalas, V.; Kalligeris, N.

2009-04-01

In the past decade, erosion rates for the coastlines of Greece are rapidly increasing. Many beaches on the northern coast of the island have substantially retreated, while others have disappeared or will disappear within the present or the following decade if no action is taken. For the better understanding and visualization of the current situation, specific examples of rapid erosion are described and afterwards we speculate as to the causes. We infer that, as in other parts of the Mediterranean, the causes are anthropogenic and include removal of sand dunes to build roads, sand mining from beaches and rivers, permanent building construction within the active coastal zone, on or too close to shoreline, and poor design of coastal structures. The reason behind the rapid erosion of Greece coastlines is the complete lack of any semblance of coastal zone management and antiquated legislation. We conclude that unless urgent measures for the protection and even salvation of the beaches are taken and if the sand mining and dune removal does not stop, then several beaches will disappear within the present and the following decade.

Presence of Campylobacter and Salmonella in sand from bathing beaches.

Science.gov (United States)

Bolton, F J; Surman, S B; Martin, K; Wareing, D R; Humphrey, T J

1999-02-01

The purpose of this study was to determine the presence of thermophilic Campylobacter spp. and Salmonella spp. in sand from non-EEC standard and EEC standard designated beaches in different locations in the UK and to assess if potentially pathogenic strains were present. Campylobacter spp. were detected in 82/182 (45%) of sand samples and Salmonella spp. in 10/182 (6%). Campylobacter spp. were isolated from 46/92 (50%) of samples from non-EEC standard beaches and 36/90 (40%) from EEC standard beaches. The prevalence of Campylobacter spp. was greater in wet sand from both types of beaches but, surprisingly, more than 30% of samples from dry sand also contained these organisms. The major pathogenic species C. jejuni and C. coli were more prevalent in sand from non-EEC standard beaches. In contrast, C. lari and urease positive thermophilic campylobacters, which are associated with seagulls and other migratory birds, were more prevalent in sand from EEC standard beaches. Campylobacter isolates were further characterized by biotyping and serotyping, which confirmed that strains known to be of types associated with human infections were frequently found in sand on bathing beaches.

Changes of Bulgarian Coastal Dune Landscape under Anthropogenic Impact

Science.gov (United States)

Palazov, A.; Young, R.; Stancheva, M.; Stanchev, H.

2012-04-01

and erosion of the beach itself. Typically dunes are located behind sand beaches and they are part of the beach-dune systems. Such type of dune reduction could be driven by combination of many factors, both natural ones (such as severe storms, erosion, heavy rains or flooding) and human impacts (large number of installed coast-protection structures along the coast, which interrupt the sediment transport, create new sedimentary deficit and generate erosion). During the recent years most of the Bulgarian beaches have progressively eroded and their areas have significantly been decreased. ii) Dunes that have been reduced/damaged and lost due to expanded tourist and housing infrastructures/developments and due to afforestaion activities. The principal sources of human impacts on sand dunes in Bulgaria are rapid coastal urbanization over the recent years (i.e., hotel and residential constructions, roads, parking structures, and other related infrastructure), unregulated camping and "temporary" constructions on the dunes, a lax regulatory environment that tolerates the re-zoning of protected sand dunes to "agricultural" areas. At most recreational sites there were wide coastal dunes, which however have been destroyed during tourist constructions. Such are dunes at the most famous Bulgarian sea resorts of Golden Sands and Sunny Beach in the areas of Varna and Nessebar. As a consequence, major areas along the Bulgarian coast were completely urbanized by hotels and other infrastructures and large sand dune systems were damaged. iii) Dunes located at still undeveloped coastal sections: yet they are naturally preserved and unthreatened by human pressure boom. These are just a few dune sites: at the northernmost portion of the Bulgarian coast (in the area of Durankulak), at the central part in the region of the largest Bulgarian river, Kamchia River, and along the southernmost coastline (in the area of Veleka River). Although sand dunes in Bulgaria are protected areas and

Estimation of sand dune thickness using a vertical velocity profile

International Nuclear Information System (INIS)

Al-Shuhail, Abdullatif A.

2004-01-01

Previous field and mathematical studies have shown that sand dunes may have vertical velocity profiles (i.e. continuous increase of velocity with depth). Therefore, computing the dunes thickness using conventional seismic refraction methods that assume a vertically homogeneous layer will likely produce some errors. The purpose of this study is to quantify the effect of the vertical velocity profile in a sand dune on the process of thickness estimation using seismic refraction data. First, the time distance (T-X) data of the direct wave in the dune is calculated using a vertical velocity profile, V (z), derived from Hertz-Mindlin contact theory. Then the thickness is estimated from the calculated T-X data, intercept time and velocity of the refractor at the dune's base assuming a constant velocity in the dune. The error in the estimated thickness due to the constant-velocity assumption increases with increasing thickness and decreasing porosity of the dune. For sand dunes with porosities greater than 0.2 and thickness less than 200 meter, the error is less than 15%. (author)

CFD evaluation of erosion rate around a bridge near a sand dune

Science.gov (United States)

He, Wei; Huang, Ning; Dun, Hongchao; Wang, Wenbo

2017-04-01

This study performs a series of simulations through solving the Navier-Stokes equations and the RNG k-ε turbulence model to investigate the wind erosion rates around a bridge in a desert area with sand dunes. The digital elevation model of sand dunes and the bridge model are obtained respectively from hypsographic map and construction drawings. Through combining them into the CFD software of Fluent the simulation zone was formed. The data of wind speed obtained from field observation is fitted into a logarithm format, which was imported into Fluent model as a inlet wind speed condition. Then, the effect of Dun-Go railway on wind-blown sand movement of the neighbouring environment is simulated. The results exhibit that affected by both the sand dune and bridge, the flow field is in a complex condition. It is also shown that the bridge in upstream of the sand dune will not increase the sand transport rate intensively, but change both wind velocity gradient and turbulence kinetic energy over surface of sand dune. On the other hand, when the bridge is built downstream the sand dune, simulation results show that sand deposition rate would be decreased in reference region downstream the pier.

Sand transport in urbanized beaches - models and reality

International Nuclear Information System (INIS)

Pineiro, G.; Norbis, W.; Panario, D.

2012-01-01

The general objective is to quantify the wind transport of sand in the urbanized beaches. The specific objectives include testing and calibration of the wind velocity as well as the classification of the beaches according to the magnitude and the direction of sand transport

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

Episodic Late Holocene dune movements on the sand-sheet area, Great Sand Dunes National Park and Preserve, San Luis Valley, Colorado, USA

Science.gov (United States)

Forman, S. L.; Spaeth, M.; Marín, L.; Pierson, J.; Gómez, J.; Bunch, F.; Valdez, A.

2006-07-01

The Great Sand Dunes National Park and Preserve (GSDNPP) in the San Luis Valley, Colorado, contains a variety of eolian landforms that reflect Holocene drought variability. The most spectacular is a dune mass banked against the Sangre de Cristo Mountains, which is fronted by an extensive sand sheet with stabilized parabolic dunes. Stratigraphic exposures of parabolic dunes and associated luminescence dating of quartz grains by single-aliquot regeneration (SAR) protocols indicate eolian deposition of unknown magnitude occurred ca. 1290-940, 715 ± 80, 320 ± 30, and 200-120 yr ago and in the 20th century. There are 11 drought intervals inferred from the tree-ring record in the past 1300 yr at GSDNPP potentially associated with dune movement, though only five eolian depositional events are currently recognized in the stratigraphic record. There is evidence for eolian transport associated with dune movement in the 13th century, which may coincide with the "Great Drought", a 26-yr-long dry interval identified in the tree ring record, and associated with migration of Anasazi people from the Four Corners areas to wetter areas in southern New Mexico. This nascent chronology indicates that the transport of eolian sand across San Luis Valley was episodic in the late Holocene with appreciable dune migration in the 8th, 10-13th, and 19th centuries, which ultimately nourished the dune mass against the Sangre de Cristo Mountains.

Laboratory studies of dune sand for the use of construction industry in Sri Lanka

Science.gov (United States)

de Silva Jayawardena, Upali; Wijesuriya, Roshan; Abayaweera, Gayan; Viduranga, Tharaka

2015-04-01

With the increase of the annual sand demand for the construction industry the excessive excavation of river sand is becoming a serious environmental problem in Sri Lanka. Therefore, it is necessary to explore the possibility for an alternative to stop or at least to minimize river sand mining activities. Dune sand is one of the available alternative materials to be considered instead of river sand in the country. Large quantities of sand dunes occur mainly along the NW and SE coastal belt which belong to very low rainfall Dry Zone coasts. The height of dune deposits, vary from 1m to about 30 meters above sea level. The objective of this paper is to indicate some studies and facts on the dune sand deposits of Sri Lanka. Laboratory studies were carried out for visual observations and physical properties at the initial stage and then a number of tests were carried out according to ASTM standards to obtain the compressive strength of concrete cylinders and mortar cubes mixing dune sand and river sand in different percentages keeping a constant water cement ratio. Next the water cement ratio was changed for constant dune sand and river sand proportion. Microscopic analysis shows that the dune sand consist of 95 % of quartz and 5 % of garnet, feldspar, illmenite and other heavy minerals with clay, fine dust, fine shell fragments and organic matters. Grains are sub-rounded to angular and tabular shapes. The grain sizes vary from fine to medium size of sand with silt. The degree of sorting and particle size observed with dune sands are more suited with the requirement of fine aggregates in the construction industry. The test result indicates that dune sand could be effectively used in construction work without sieving and it is ideal for wall plastering due to its'-uniformity. It could also be effectively used in concrete and in mortars mixing with river sand. The best mixing ratio is 75% dune sand and 25% river sand as the fine aggregate of concrete. For mortar the mixing

Properties of dune sand concrete containing coffee waste

Directory of Open Access Journals (Sweden)

Mohamed Guendouz

2018-01-01

Full Text Available In the last years, an increase of coffee beverages consumption has been observed all over the world; and its consumption increases the waste coffee grounds which will become an environmental problems. Recycling of this waste to produce new materials like sand concrete appears as one of the best solutions for reduces the problem of pollution. This work aims to study the possibility of recycling waste coffee grounds (Spent Coffee Grounds (SCG as a fine aggregate by replacing the sand in the manufacturing of dune sand concrete. For this; sand concrete mixes were prepared with substitution of sand with the spent coffee grounds waste at different percentage (0%, 5%, 10%, 15% and 20% by volume of the sand in order to study the influence of this wastes on physical (Workability, bulk density and porosity, mechanical (compressive and flexural strength and Thermal (Thermal conductivity and thermal diffusivity properties of dune sand concrete. The results showed that the use of spent coffee grounds waste as partial replacement of natural sand contributes to reduce workability, bulk density and mechanical strength of sand concrete mixes with an increase on its porosity. However, the thermal characteristics are improved and especially for a level of 15% and 20% of substitution. So, it is possible to obtain an insulating material which can be used in the various types of structural components. This study ensures that reusing of waste coffee grounds in dune sand concrete gives a positive approach to reduce the cost of materials and solve some environmental problems.

The role of vegetation in shaping dune morphology

Science.gov (United States)

Duran Vinent, O.; Moore, L. J.; Young, D.

2012-12-01

. Consistent with field observations, we find that basic dune morphology is primarily determined by grass species, with linear or hummocky dunes being built by some species, while others may prevent dune formation. We also find that the evolution of coastal dune morphology is controlled by at least two bio-geomorphic couplings: (1) between vegetation growth and sand transport, which leads to a positive feedback for dune growth, as certain beach grasses maximize growth under sand accretion, which means that an ever denser vegetation implies an ever higher accretion rate; and (2) between vegetation growth and shoreline position through the sand influx. While the first coupling is responsible for dune formation, the second one determines when dunes stop growing and thus controls final dune size. This is particularly relevant for accreting/eroding coastlines where we find that dune size, and thus coastal protection, is maximized for relatively small accretion rates while larger accretion rates lead to formation of a new, smaller dune ridge at the beach.

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

Coastal dune dynamics in response to excavated foredune notches

Science.gov (United States)

Ruessink, B. G.; Arens, S. M.; Kuipers, M.; Donker, J. J. A.

2018-04-01

Dune management along developed coasts has traditionally focussed on the suppression of the geomorphic dynamics of the foredune to improve its role in sea defence. Because a stabilized foredune acts as an almost total barrier to aeolian transport from the beach, the habitat diversity in the more landward dunes has degraded. With the overarching objective to mitigate this undesirable loss in biodiversity, dune management projects nowadays increasingly intend to restore aeolian dynamics by reconnecting the beach-dune system with notches excavated through the foredune. Here, we use repeat topographic survey data to examine the geomorphic response of a coastal dune system in the Dutch National Park Zuid-Kennemerland to five notches excavated in 2012-2013 within an 850-m stretch of the 20-m high established foredune. The notches were dug in a V-shape (viewed onshore), with a width between approximately 50 and 100 m at the top, a (cross-dune) length between 100 and 200 m, and excavation depths between 9 and 12.5 m. The 1 × 1 m digital terrain models, acquired with airborne Lidar and UAV photogrammetry, illustrate that during the 3-year survey period the notches developed into a U-shape because of wall deflation, and that up to 8-m thick and 150-m long depositional lobes formed landward of the notches. Sand budget computations showed that the sand volume of the entire study area increased by about 22,750 m3/year, which, given the 850-m width of the study area, corresponds to an aeolian input from the beach of approximately 26.5 m3/m/year. Between 2006 and 2012 all wind-blown beach sand deposited on the seaward side of the foredune; since 2013, the notches have caused 75% of the sand to be deposited landward of the foredune. This highlights that the notches are highly effective conduits for aeolian transport into the back dunes. Future monitoring is required to determine for how long the notches will stimulate aeolian dynamics and if (and when) vegetation eventually

Mineralogy and Genesis of Heavy Minerals in Coastal Dune Sands, South Eastern Qatar

OpenAIRE

Nasir, Sobhi J. [صبحي جابر نصر; El-Kassas, Ibrahim A.; Sadiq, A. Ali M.

1999-01-01

Large amounts of aeolian sand occur in the southeastern coastal zone of Qatar Peninsula as sand dunes accumulated in a vast sand field locally called " Niqyan Qatar ". The present work, carried out on a sand dune belt of this field near Mesaied Industrial City, revealed the distribution of heavy minerals shows a regional variability induced by provenance and local variability reflecting genetic differences. The studied dune sands are rich in shells of pelecypods, with the light mineral assemb...

Reconstruction of the coastal morphodynamics of the Fulong-beach dune field in north-eastern Taiwan

Science.gov (United States)

Dörschner, Nina; Böse, Margot; Frechen, Manfred

2010-05-01

The Fulong-beach dune field is located at the north-eastern coast of Taiwan. Built up of medium and fine grained quartz rich sand, it represents a unique feature of only few kilometres along the east coast of Taiwan. This unique sedimentological regime makes the area most perfectly suitable for age estimations by optically stimulated luminescence (OSL). The dune field is crossed by the Shuangsi-river, which flows into the Pacific Ocean. The coastal area is subjected to very dynamic conditions in the transition zone between land and sea. Due to the constant force of marine and aeolian processes from tides, weather and sediment accumulation by rivers, it is a continuously changing area. Taiwan is located in a very active tectonic zone with high elevation rates, which reach from 4 mm per year at the east coast up to 7 mm per year in the southern parts of the island. Furthermore Taiwan is affected by medial 3.8 typhoons per year and minor earthquakes nearly occur every day (LIN ET AL. 2006). The consequences are high rates of erosion and sediment transport during very short time periods. The Fulong-beach coastal area is densely populated and proud for being a tourism destination. At the northern end of the dune field the Lungmen nuclear power plant is currently under construction. Four separate dune ridges could be identified from a digital elevation model and from field mapping. During the field campaign in October and November 2009 17 samples were taken for OSL-dating (MURRAY ET AL. 1995) out of the four dune ridges as well as out of a more than 30 m high elevated outcrop cut by the Shuangsi-river. The measurement and the evaluation of the OSL-samples will provide us an insight into the duration and intensity of the processes affecting the coastal area of Taiwan during the Holocene. We will give an outline during the poster presentation of the methodical approach and the morphodynamical processes affecting the Fulong-beach dune field in north-eastern Taiwan

Numerical simulation of wind-sand movement in the reversed flow region of a sand dune with a bridge built downstream.

Science.gov (United States)

He, Wei; Huang, Ning; Xu, Bin; Wang, Wenbo

2018-04-23

A bridge built inside the reversed flow region of a sand dune will change the characteristics of wind-sand movement in this region. The Reynolds-averaged Navier-Stokes simulation and discrete particle tracing are used to simulate the wind-sand movement around a sand dune with a bridge built inside the reversed region. Three cases with different bridge positions are studied. The results show that 1) compared with the isolated dune case, a tall bridge built at the leeward toe leads to an increase in the deposition rate on the leeward slope and a longer reversed flow region downstream of the sand dune; meanwhile, the high speed of crosswind on the bridge indicates that some measures should be taken to protect trains from strong crosswind; 2) a low bridge at the leeward toe has little effect on the sand deposition and reversed flow region of the dune; however, low sand transport rate and crosswind speed on the bridge show that anti-crosswind/sand measures should be taken according to the actual situation and 3) a low bridge on the leeward slope has little effect on the length of reversed flow region, however, high crosswind speed and sand flux on the bridge reveal the need of anti-crosswind/sand measures on the bridge. Moreover, the bridges in the reversed flow region increase the sand flux near the leeward crest; as a result, the moving patterns of the sand dune are changed.

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

A case study on dune response to infragravity waves

Science.gov (United States)

Li, Wenshan; Wang, Hui; Li, Huan; Wu, Shuangquan; Li, Cheng

2017-08-01

A series of numerical simulations were conducted using the process-based model XBeach to investigate dune response under normal and getting rid of infragravity wave conditions with different slopes. Erosion volume upside the dune toe and dune top recession are set as indicators for dune vulnerability as well as defence capacity for its front-beach. Results show that both dune erosion volume and dune top recession decrease with gentler dune slopes. Of all the simulation cases, dune with a face slope of 1/1 lost most sand and supplied most sand for lower-bed. The presence of infragravity waves is validated to be crucial to dune vulnerability. The dune erosion volume is shown to decrease by 44.5%∼61.5% and the dune top recession decreased by 0%∼45.5% correspondingly, in the case that infragravity motion is not taken into account during simulation for different dune slopes.

Petrology of dune sand derived from basalt on the Ka'u Desert, Hawaii

Science.gov (United States)

Gooding, J. L.

1982-01-01

Dune sand from the Ka'u Desert, southwest flank of Kilauea volcano, Hawaii, is moderately well-sorted (median = 1.60 Phi, deviation = 0.60, skewness = 0.25, kurtosis = 0.68) and composed mostly of frosted subangular particles of basalt glass ('unfractionated' olivine-normative tholeitte), olivine, lithic fragments (subophitic and intersertal basalts; magnetite-ilmenite-rich basalts), reticular basalt glass, magnetite, ilmenite, and plagioclase, in approximately that order of abundance. Quantitative lithological comparison of the dune sand with sand-sized ash from the Keanakakoi Formation supports suggestions that the dune sand was derived largely from Keanakakoi ash. The dune sand is too well sorted to have been emplaced in its present form by base-surge but could have evolved by post-eruption reworking of the ash.

Integrating multi-disciplinary field and laboratory methods to investigate the response and recovery of beach-dune systems in Ireland to extreme events

Science.gov (United States)

Farrell, E.; Lynch, K.; Wilkes Orozco, S.; Castro Camba, G.; Scullion, A.

2017-12-01

This two year field monitoring project examines the response and recovery of 1.2km of a coastal beach-dune system in the west coast of Ireland (The Maharees, Brandon Bay, Co. Kerry) to storms. The results from this project initiated a larger scale study to assess the long term evolution of Brandon Bay (12km) and patterns of meso-scale rotation. On a bay scale historic shoreline analyses were completed using historic Ordnance Survey maps, aerial photography, and DGPS surveys inputted to the Digital Shoreline Analysis System. These were coupled with a GSTA-wavemeter experiment that collected 410 sediment samples along the beach and nearshore to identify preferred sediment transport pathways along the bay. On a local scale (1.2km) geomorphological changes of the beach and nearshore were monitored using repeated monthly DGPS surveys and drone technology. Topographical data were correlated with atmospheric data obtained from a locally installed automatic weather station, oceanographic data from secondary sources, and photogrammetry using a camera installed at the site collecting pictures every 10 minutes during daylight hours. Changes in surface elevation landward of the foredune from aeolian processes were measured using five pin transects across the dune. The contribution of local blowout dynamics were measured using drone imagery and structure-from-motion technology. The results establish that the average shoreline recession along the 1.2 km site is 72 m during the past 115 years. The topographic surveys illustrate that natural beach building processes initiate system recovery post storms including elevated foreshores and backshores and nearshore sand bar migration across the entire 1.2 km stretch of coastline. In parallel with the scientific work, the local community have mobilized and are working closely with the lead scientists to implement short term coastal management strategies such as signage, information booklets, sand trap fencing, walkways, wooden

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.

Stratigraphy and landsnail faunas of Late Holocene coastal dunes, Tokerau Beach, northern New Zealand

International Nuclear Information System (INIS)

Brook, F.J.

1999-01-01

At least four depositional episodes, each involving cycles of dune instability and sand accumulation followed by stabilisation and soil formation, are represented in a Holocene dune sequence at Tokerau Beach. The first depositional episode followed the maximum post-glacial sea level rise at 6500 years BP, probably with formation of a narrow dune belt landward of the present coastline. The second depositional episode resulted in extensive progradation of the dune belt to about the present coastline from c. 3000-2000 years BP, followed by dune stabilisation and soil formation from c. 2000-900 years BP. The third depositional episode involved vertical dune accretion at c. 900-600 years BP, followed by stabilisation and soil formation after c. 600 years BP. The fourth depositional episode, after 240 years BP, resulted in further vertical dune accretion and localised extensive erosion and reworking of pre-existing dune deposits. Fossil landsnail faunas indicate that there was patchy sandfield and shrubland vegetation of the dune belt from c. 3000-2000 years BP, followed by a mosaic of shrubland and forest from c. 2000-900 years BP. After 900 years BP there was a progressive reversion to patchy shrubland vegetation, but an extensive shrubland cover again became established at c. 600 years BP and persisted until c. 450 years BP, when it was replaced by patchy shrubland and sandfield vegetation. Dune progradational phases in the first two depositional episodes correlate with and probably developed primarily in response to changes in sea level, whereas subsequent alternating phases of dune stabilisation and build-up are inferred to have resulted in part from the influence of long term cyclical variation in prevailing local wind and wave regimes in Doubtless Bay. Two stratigraphically distinct, exotic, sea-rafted pumice units are represented in the Tokerau dune sequence: Tokerau pumice (new), which has a primary depositional age of c. 3000 years BP, and Loisels pumice, which

Variability of sediment transport in beach and coastal dune environments, Brittany, France

Science.gov (United States)

Regnauld, Hervé; Louboutin, Roland

2002-06-01

On the coasts of Brittany (English Channel and Bay of Biscay), barrier systems were surveyed between 1995 and 2000. The beach profiles have a very high variability, which cannot be statistically explained by linear correlation with the wind, the waves, or the tides. The behaviour of the profile is represented on a phase diagram (speed of profile change: Y-axis, thickness of the profile: X-axis). The points in the center of the profile "rotate" around an average equilibrium which is seldom measured in the field. The seaward edge of the beaches oscillates between loss and gain, but with a net positive budget. The landward top of the beach displays a range of oscillations. The dunes always have a positive budget. The whole behaviour of the system is explained if the precise succession of anticyclonic and cyclonic winds is taken into account. Long periods of easterly winds (offshorewards) tend to produce a calm sea and to increase tidal sediment settling on the seafloor. If an onshore westerly storm occurs just after such a period, it hits a sediment-rich environment and produces a net accumulation on both the beach and the dunes. Periods of westerly calm to moderate winds do not help accumulation: a full going storm will hit a depleted environment and produce erosion. The speed of dune accretion and the budget of the beaches seem to partly depend on the ratio of cyclonic to anticyclonic conditions.

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.

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.

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...

Demography and monitoring of Welsh's milkweed (Asclepias welshii) at Coral Pink Sand Dunes

Science.gov (United States)

Brent C. Palmer; L. Armstrong

2001-01-01

Results are presented of a 12-year monitoring program on the Coral Pink Sand Dunes and Sand Hills populations of the threatened Welsh's milkweed, Asclepias welshii N & P Holmgren. The species is an early sera1 member of the dune flora, colonizing blowouts and advancing with shifting dunes. When an area stabilizes and other vegetation encroaches, A. welshii is...

Sand mining impacts on long-term dune erosion in southern Monterey Bay

Science.gov (United States)

Thornton, E.B.; Sallenger, Abby; Sesto, Juan Conforto; Egley, L.; McGee, Timothy; Parsons, Rost

2006-01-01

Southern Monterey Bay was the most intensively mined shoreline (with sand removed directly from the surf zone) in the U.S. during the period from 1906 until 1990, when the mines were closed following hypotheses that the mining caused coastal erosion. It is estimated that the yearly averaged amount of mined sand between 1940 and 1984 was 128,000 m3/yr, which is approximately 50% of the yearly average dune volume loss during this period. To assess the impact of sand mining, erosion rates along an 18 km range of shoreline during the times of intensive sand mining (1940–1990) are compared with the rates after sand mining ceased (1990–2004). Most of the shoreline is composed of unconsolidated sand with extensive sand dunes rising up to a height of 46 m, vulnerable to the erosive forces of storm waves. Erosion is defined here as a recession of the top edge of the dune. Recession was determined using stereo-photogrammetry, and LIDAR and GPS surveys. Long-term erosion rates vary from about 0.5 m/yr at Monterey to 1.5 m/yr in the middle of the range, and then decrease northward. Erosion events are episodic and occur when storm waves and high tides coincide, allowing swash to undercut the dune and resulting in permanent recession. Erosion appears to be correlated with the occurrence of El Niños. The calculated volume loss of the dune in southern Monterey Bay during the 1997–98 El Niño winter was 1,820,000 m3, which is almost seven times the historical annual mean dune erosion of 270,000 m3/yr. The alongshore variation in recession rates appears to be a function of the alongshore gradient in mean wave energy and depletions by sand mining. After cessation of sand mining in 1990, the erosion rates decreased at locations in the southern end of the bay but have not significantly changed at other locations.

Seasonal variations in heavy mineral placer sand from Kalbadevi Bay, Ratnagiri, Maharashtra

Digital Repository Service at National Institute of Oceanography (India)

Valsangkar, A.B.

spaced at ~1.5 km apart (Fig. 1). More details are given in Valsangkar (2005). Beach samples were obtained by push cores from the different beach environment that included dune, berm, hide tide (HT), mid tide (MT) and low tide (LT) area. The samples...) decreased to 12 % during post-monsoon season. Increase of sand content with depth in bern environment is therefore considered related to deposition due to wave and current action. May, 2K4; BP-02 0 20 40 60 80 100 120 Dune Berm HT MT LT Sand % 0-5 5...

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

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

Basic study on the estimating the value of sand beach using amenities replace

OpenAIRE

Shin, B-S; Kim, K-H.

2013-01-01

The sand beach along the east coast of Korea offers beautiful scenery with high-quality sand for leisure, and is also famous for white-sand and pine-trees both of which are important scenic resources. Furthermore, the sand beach helps to maintain natural environment of the coastal area and has the function of a disaster prevention system against high waves. There are two major value evaluation methods, Travel Cost Method and Contingent Valuation Method, to assess the value of sand beach. Cont...

Plant functional traits and diversity in sand dune ecosystems across different biogeographic regions

Science.gov (United States)

Mahdavi, P.; Bergmeier, E.

2016-07-01

Plant species of a functional group respond similarly to environmental pressures and may be expected to act similarly on ecosystem processes and habitat properties. However, feasibility and applicability of functional groups in ecosystems across very different climatic regions have not yet been studied. In our approach we specified the functional groups in sand dune ecosystems of the Mediterranean, Hyrcanian and Irano-Turanian phytogeographic regions. We examined whether functional groups are more influenced by region or rather by habitat characteristics, and identified trait syndromes associated with common habitat types in sand dunes (mobile dunes, stabilized dunes, salt marshes, semi-wet sands, disturbed habitats). A database of 14 traits, 309 species and 314 relevés was examined and trait-species, trait-plot and species-plot matrices were built. Cluster analysis revealed similar plant functional groups in sand dune ecosystems across regions of very different species composition and climate. Specifically, our study showed that plant traits in sand dune ecosystems are grouped reflecting habitat affiliation rather than region and species pool. Environmental factors and constraints such as sand mobility, soil salinity, water availability, nutrient status and disturbance are more important for the occurrence and distribution of plant functional groups than regional belonging. Each habitat is shown to be equipped with specific functional groups and can be described by specific sets of traits. In restoration ecology the completeness of functional groups and traits in a site may serve as a guideline for maintaining or restoring the habitat.

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)

Observations of Interannual Dune Morphological Evolution With Comparisons to Shoreline Change Along the Columbia River Littoral Cell

Science.gov (United States)

Doermann, L.; Kaminsky, G. M.; Ruggiero, P.

2006-12-01

Beach topographic data have been collected along the 160 km-long Columbia River Littoral Cell in southwest Washington and northwest Oregon, USA as part of the Southwest Washington Coastal Erosion Study and a NANOOS pilot project. The monitoring program includes the collection of cross-shore beach profiles at 49 sites for each of the 34 seasons since 1997 (with few exceptions), enabling the investigation of the seasonal to interannual morphological variability of this high-energy coast. We focus here on the dunes backing the beaches, aiming to quantitatively describe the wide variety of characteristics they exhibit, as well as to relate dune evolution to shoreline change. To analyze the large volume of high-quality data, we use automated algorithms and systematic processes to identify the location of the dune toe, crest, and face, and calculate a volume (where enough data are available) and beach width for each survey. We define the position of the dune face as the elevation half-way between the average dune toe and average dune crest elevations at each profile location, and beach width as the horizontal distance between the 2-m contour (~MSL) and the dune toe. Much like shoreline proxies lower on the beach profile, (e.g., the 3-m contour), the location of the dune toe shows large seasonal variability with onshore deposition of sand in summer months and offshore sand transport in the winter. However, the location of the dune face and the elevation of the dune crest are much less variable and are useful in describing the evolution of the dune/beach system in the horizontal and vertical directions, respectively, over interannual time scales. On beaches with the highest shoreline change rates in the study area, the dune face follows the progradational trend of the shoreline with the dune face prograding at approximately 25-50% of the rate of the shoreline. Along many of these beaches that experienced severe erosion during the El Niño of 1997/98, the dune face

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

Temporal development of vegetation and geomorphology in a man-made beach-dune system by natural processes

DEFF Research Database (Denmark)

Vestergaard, Peter

2006-01-01

with F. rubra and the invasive alien Rosa rugosa. It was concluded, that the main trends in the geomorphological and vegetational development of the man-made beach-dune system is similar to the development in natural dunes. In the future, further accretion and seaward dune formation may be expected...

Microbiological and mycological beach sand quality in a volcanic environment: Madeira archipelago, Portugal

Energy Technology Data Exchange (ETDEWEB)

Pereira, Elisabete; Figueira, Celso; Aguiar, Nuno; Vasconcelos, Rita [Universidade da Madeira, Caminho da Penteada, 9020-105 Funchal (Portugal); Vasconcelos, Sílvia [Laboratório Regional de Veterinária e Segurança Alimentar, Caminho das Quebradas de Baixo n° 79, 9000-254 Funchal (Portugal); Calado, Graça [Laboratório de Saúde Pública, IASaúde, Rua das Pretas n° 1, 9004-515 Funchal (Portugal); Brandão, João [Instituto Nacional de Saúde Dr. Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa (Portugal); Prada, Susana, E-mail: susana@uma.pt [Universidade da Madeira, Caminho da Penteada, 9020-105 Funchal (Portugal); Centro de Vulcanologia e Avaliação de Riscos Geológicos, Universidade dos Açores, Rua da Mãe de Deus, Edifício do Complexo Científico, 3° Andar — Ala Sul, 9500-321 Ponta Delgada (Portugal)

2013-09-01

Madeira forms a mid-Atlantic volcanic archipelago, whose economy is largely dependent on tourism. There, one can encounter different types of sand beach: natural basaltic, natural calcareous and artificial calcareous. Microbiological and mycological quality of the sand was analyzed in two different years. Bacterial indicators were detected in higher number in 2010 (36.7% of the samples) than in 2011 (9.1%). Mycological indicators were detected in a similar percentage of samples in 2010 (68.3%) and 2011 (75%), even though the total number of colonies detected in 2010 was much higher (827 in 41 samples) than in 2011 (427 in 66 samples). Enterococci and potentially pathogenic and allergenic fungi (particularly Penicillium sp.) were the most common indicators detected in both years. Candida sp. yeast was also commonly detected in the samples. The analysis of the 3rd quartile and maximum numbers of all indicators in samples showed that artificial beaches tend to be more contaminated than the natural ones. However, a significant difference between the variables was lacking. More monitoring data (number of bathers, sea birds, radiation intensity variation, and a greater number of samples) should be collected in order to confirm if these differences are significant. In general, the sand quality in the archipelago's beaches was good. As the sand may be a vector of diseases, an international common set of indicators and values and a compatible methodologies for assessing sand contamination, should be defined, in order to provide the bather's with an indication of beach sand quality, rather than only the water. - Highlights: • Microbial indicators were studied in the beach sands of Madeira archipelago. • Differences between years may be attributed to extreme weather. • Sand of artificial beaches has higher levels of microbial contamination. • Microbial analysis of the sand showed that the beaches have mainly good quality.

Microbiological and mycological beach sand quality in a volcanic environment: Madeira archipelago, Portugal

International Nuclear Information System (INIS)

Pereira, Elisabete; Figueira, Celso; Aguiar, Nuno; Vasconcelos, Rita; Vasconcelos, Sílvia; Calado, Graça; Brandão, João; Prada, Susana

2013-01-01

Madeira forms a mid-Atlantic volcanic archipelago, whose economy is largely dependent on tourism. There, one can encounter different types of sand beach: natural basaltic, natural calcareous and artificial calcareous. Microbiological and mycological quality of the sand was analyzed in two different years. Bacterial indicators were detected in higher number in 2010 (36.7% of the samples) than in 2011 (9.1%). Mycological indicators were detected in a similar percentage of samples in 2010 (68.3%) and 2011 (75%), even though the total number of colonies detected in 2010 was much higher (827 in 41 samples) than in 2011 (427 in 66 samples). Enterococci and potentially pathogenic and allergenic fungi (particularly Penicillium sp.) were the most common indicators detected in both years. Candida sp. yeast was also commonly detected in the samples. The analysis of the 3rd quartile and maximum numbers of all indicators in samples showed that artificial beaches tend to be more contaminated than the natural ones. However, a significant difference between the variables was lacking. More monitoring data (number of bathers, sea birds, radiation intensity variation, and a greater number of samples) should be collected in order to confirm if these differences are significant. In general, the sand quality in the archipelago's beaches was good. As the sand may be a vector of diseases, an international common set of indicators and values and a compatible methodologies for assessing sand contamination, should be defined, in order to provide the bather's with an indication of beach sand quality, rather than only the water. - Highlights: • Microbial indicators were studied in the beach sands of Madeira archipelago. • Differences between years may be attributed to extreme weather. • Sand of artificial beaches has higher levels of microbial contamination. • Microbial analysis of the sand showed that the beaches have mainly good quality

Wavelength dependence of the bidirectional reflectance distribution function (BRDF) of beach sands.

Science.gov (United States)

Doctor, Katarina Z; Bachmann, Charles M; Gray, Deric J; Montes, Marcos J; Fusina, Robert A

2015-11-01

The wavelength dependence of the dominant directional reflective properties of beach sands was demonstrated using principal component analysis and the related correlation matrix. In general, we found that the hyperspectral bidirectional reflectance distribution function (BRDF) of beach sands has weak wavelength dependence. Its BRDF varies slightly in three broad wavelength regions. The variations are more evident in surfaces of greater visual roughness than in smooth surfaces. The weak wavelength dependence of the BRDF of beach sand can be captured using three broad wavelength regions instead of hundreds of individual wavelengths.

The Sources of Moisture in the Sand Dunes – The Example of the Western Sahara Dune Field

Directory of Open Access Journals (Sweden)

Żmudzka Elwira

2014-09-01

Full Text Available Climatic and meteorological conditions may limit the aeolian transport within barchans. An explanation of that issue was the main goal of the investigation held in Western Sahara dune fields located around Tarfaya and Laâyoune. Particular attention was paid to the factors causing the moisture content rising of the sand dune surface layer, which could influence the wind threshold shear velocity in the aeolian transport. The wetted surface layer of sand, when receiving moisture from precipitation or suspensions, reduces the aeolian transport, even in case of wind velocity above 4-5 m s-1. Fog and dew condensation does not affect the moisture of deeper sand layers, what occurs after rainfall.

Application of the ERICA Integrated Approach to the Drigg coastal sand dunes

International Nuclear Information System (INIS)

Wood, M.D.; Marshall, W.A.; Beresford, N.A.; Jones, S.R.; Howard, B.J.; Copplestone, D.; Leah, R.T.

2008-01-01

The EC-funded project 'Environmental Risks from Ionising Contaminants: Assessment and Management' (ERICA) developed an 'Integrated Approach' for assessing the impact of ionising radiation on ecosystems. This paper presents the application of the ERICA Integrated Approach, supported by a software programme (the ERICA Tool) and guidance documentation, to an assessment of the Drigg coastal sand dunes (Cumbria, UK). Targeted sampling provided site-specific data for sand dune biota, including amphibians and reptiles. Radionuclides reported included 90 Sr, 99 Tc, 137 Cs, 238 Pu, 239+240 Pu and 241 Am. Site-specific data were compared to predictions derived using the ERICA Tool. Some under- and over-predictions of biota activity concentrations were identified but can be explained by the specific ecological characteristics and contamination mechanism of the dunes. Overall, the results indicated no significant impact of ionising radiation on the sand dune biota and the Integrated Approach was found to be a flexible and effective means of conducting a radiation impact assessment

Establishment of vesicular-arbuscular mycorrhizal fungi and other microorganisms on a beach replenishment site in Florida.

Science.gov (United States)

Sylvia, D M; Will, M E

1988-02-01

Beach replenishment is a widely used method of controlling coastal erosion. To reduce erosional losses from wind, beach grasses are often planted on the replenishment sands. However, there is little information on the microbial populations in this material that may affect plant establishment and growth. The objectives of this research were to document changes in the populations of vesicular-arbuscular mycorrhizal (VAM) fungi and other soil microorganisms in replenishment materials and to determine whether roots of transplanted beach grasses become colonized by beneficial microbes. The study was conducted over a 2-year period on a replenishment project in northeastern Florida. Three sampling locations were established at 1-km intervals along the beach. Each location consisted of three plots: an established dune, replenishment sand planted with Uniola paniculata and Panicum sp., and replenishment sand left unplanted. Fungal and bacterial populations increased rapidly in the rhizosphere of beach grasses in the planted plots. However, no bacteria were recovered that could fix significant amounts of N(2). The VAM fungi established slowly on the transplanted grasses. Even after two growing seasons, levels of root colonization and sporulation were significantly below those found in the established dune. There was a shift in the dominant VAM fungi found in the planted zone with respect to those in the established dunes. The most abundant species recovered from the established dunes were Glomus deserticola, followed by Acaulospora scrobiculata and Scutellospora weresubiae. The VAM fungi that colonized the planted zone most rapidly were Glomus globiferum, followed by G. deserticola and Glomus aggregatum.

Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in Southwestern Saudi Arabian Dune Sand

KAUST Repository

Mughal, Iqra

2013-05-01

In arid lands, a major contribution to water loss is by soil water evaporation. Desert sand dunes in arid regions are devoid of runoff and have high rates of infiltration. Rainwater is commonly stored within them because of the low permeability soils in the underlying desert pavement. In such cases, moisture is confined in the sand dune below a depth, termed as the “extinction depth”, where it is protected from evaporation during long dry periods. Moreover, desert sand dunes have sparse vegetation, which results in low transpiration losses from the stored water. The water accumulated below the extinction depth of the sand dunes can be utilized for various purposes such as in irrigation to support desert agriculture. In this study, field experiments were conducted in Western Saudi Arabia to monitor the soil moisture gradients and determine the diffusive extinction depth of dune sand. The dune sand was saturated with water and was exposed to natural conditions (evaporation and precipitation). The decline of the water level in the sand column was continuously recorded using transducers and sensors installed at different depths monitored the temporal variation of temperature and moisture content within the sand. The hydrological simulator HYDRUS-1D was used to construct the vertical profiles of soil water content and temperature and the results obtained from HYDRUS-1D were compared to the gradients monitored by the sensors.

A comparison of seed banks across a sand dune successional gradient at Lake Michigan dunes (Indiana, USA)

Science.gov (United States)

Leicht-Young, S. A.; Pavlovic, N.B.; Grundel, R.; Frohnapple, K.J.

2009-01-01

In habitats where disturbance is frequent, seed banks are important for the regeneration of vegetation. Sand dune systems are dynamic habitats in which sand movement provides intermittent disturbance. As succession proceeds from bare sand to forest, the disturbance decreases. At Indiana Dunes National Lakeshore, we examined the seed banks of three habitat types across a successional gradient: foredunes, secondary dunes, and oak savanna. There were differences among the types of species that germinated from each of the habitats. The mean seed bank density increased across the successional gradient by habitat, from 376 to 433 to 968 seeds m-2, but with foredune and secondary dune seed bank densities being significantly lower than the savanna seed bank density. The number of seeds germinated was significantly correlated with soil organic carbon, demonstrating for this primary successional sequence that seed density increases with stage and age. The seed bank had much lower species richness than that of the aboveground vegetation across all habitats. Among sites within a habitat type, the similarity of species germinated from the seed banks was very low, illustrating the variability of the seed bank even in similar habitat types. These results suggest that restoration of these habitats cannot rely on seed banks alone. ?? 2008 Springer Science+Business Media B.V.

A methodological approach to assess beach-dune system susceptibility to erosion. Cases studies from Valdelagrana spit (Spain) and Campomarino beach (Italy).

Science.gov (United States)

Rizzo, Angela; Aucelli, Pietro P. C.; Gracia, Javier F.; Anfuso, Giorgio; Rosskopf, Carmen M.

2016-04-01

Dunes provide many important services to coastal areas, such as coastal erosion mitigation, coastal flooding protection and biological diversity. Their dynamic equilibrium and geomorphological evolution are the result of the interaction between marine and aeolian processes. Moreover, coastal dunes are characterized by a high ecological value, being a narrow strip between marine and terrestrial ecosystems and are habitats considered of community interest by the Habitats Directive 92/43/EEC. In the meantime, the significant increase of human pressure on coastal environments during the last decades has caused a strong alteration and an increase of the fragility and fragmentation of these habitats. This paper presents a methodological approach for the assessment of the beach-dune system susceptibility to erosion. The aim is to identify, at the local scale, the degree of susceptibility of coastal stretches in order to evaluate the degree of exposure of human settlements and natural environments located behind the dune system and to support actuations to appropriately improve dune management and conservation. A coastal susceptibility matrix and a corresponding Coastal Susceptibility Index (CSI) are proposed. Following the assumption that a good index should be based on a minimum amount of essential information (Cooper and McLaughlin, 1998), possibly already available or easy to be obtained (Villa and McLeod, 2002), the proposed index consisted into eight variables concerning existing beach and dune conditions, covering geomorphological, physical and anthropogenic aspects. Each variable was inserted into a GIS system and overlapped with the others through a logical overlay operation. The resulting layer was reclassified according to the formula proposed by Rangel and Anfuso (2015) allowing to calculate the CSI, which ranged from 1 (null/very low susceptibility) to 5 (very high susceptibility). In a further step, the predominant processes occurred in the last decades were

Factors influencing the natural regeneration of the pioneering shrub Calligonum mongolicum in sand dune stabilization plantations in arid deserts of northwest China.

Science.gov (United States)

Fan, Baoli; McHugh, Allen David; Guo, Shujiang; Ma, Quanlin; Zhang, Jianhui; Zhang, Xiaojuan; Zhang, Weixing; Du, Juan; Yu, Qiushi; Zhao, Changming

2018-03-01

Calligonum mongolicum is a successful pioneer shrub to combat desertification, which is widely used for vegetation restoration in the desert regions of northwest China. In order to reveal the limitations to natural regeneration of C. mongolicum by asexual and sexual reproduction, following the process of sand dune stabilization, we assessed clonal shoots, seedling emergence, soil seed bank density, and soil physical characteristics in mobile and stabilized sand dunes. Controlled field and pot experiments were also conducted to assess germination and seedling emergence in different dune soil types and seed burial depths. The population density of mature C. mongolicum was significantly different after sand dune stabilization. Juvenile density of C. mongolicm was much lower in stabilized sand dunes than mobile sand dune. There was no significant difference in soil seed bank density at three soil depths between mobile and stabilized sand dunes, while the emergence of seedlings in stabilized dunes was much lower than emergence in mobile dunes. There was no clonal propagation found in stabilized dunes, and very few C. mongolicum seedlings were established on stabilized sand dunes. Soil clay and silt content, air-filled porosity, and soil surface compaction were significantly changed from mobile sand dune to stabilized dunes. Seedling emergence of C. mongolicm was highly dependent on soil physical condition. These results indicated that changes in soil physical condition limited clonal propagation and seedling emergence of C. mongolicum in stabilized sand dunes. Seed bank density was not a limiting factor; however, poor seedling establishment limited C. mongolicum's further natural regeneration in stabilized sand dunes. Therefore, clonal propagation may be the most important mode for population expansion in mobile sand dunes. As a pioneer species C. mongolicum is well adapted to propagate in mobile sand dune conditions, it appears unlikely to survive naturally in

Moving sands along a headland-embayed beach system (Algarve, Southern Portugal)

Science.gov (United States)

Oliveira, Sónia; Horta, João; Nascimento, Ana; Gomes, Ana; Veiga-Pires, Cristina; Moura, Delminda

2015-04-01

Resilience of embayed and pocket beaches located at the southernmost coast of Portugal is currently a major question to coastal management of this region. In fact, several among those beaches have been artificially fed aiming to increase the width of the beach allowing people to maintain a safe distance to the unstable rocky cliffs. The sand is dredged from the offshore (ca. 2 miles from the shoreline) representing high costs for the Portuguese government. For how long will the artificial feeding solve the problem? Which beaches are worth being nourished taking into account the morphosedimentary processes? The present work is the result of a field experiment aiming to study the efficiency of the alongshore sedimentary transport between successive embayed beaches. The experiment was performed in the very indented rocky coast of the Algarve region (Southern Portugal) and comprised two field campaigns, both in 2014, during spring tides in March and November. The Algarve coast experiences a semi-diurnal meso-tidal regime ranging from 1.3 m during neap tides to 3.5 m at spring tides and the waves approach from WSW (232°) during 72% of observations along the year, almost normal to the study area shoreline. The wave and current characteristics (significant height-Hs and Period-T for waves, velocity and direction for currents) were measured during three and six tidal cycles respectively for the first and second campaign, using two pressure transducers and one electromagnetic current meter. We used sand painted with orange fluorescent dye (100 kg in March and 200 kg in November) as tracer to track the movement of the sand along the coast. The marked sand was placed on the beach face of the westernmost beach of the study area during the first low tide of each campaign. Following, hundreds of sediment samples were collected during low tide, through the monitored period, in the nodes of a georeferenced square mesh of 10 x 20 m covering three embayed beaches. Later in the

Application of the ERICA Integrated Approach to the Drigg coastal sand dunes

Energy Technology Data Exchange (ETDEWEB)

Wood, M.D. [Institute for Sustainable Water Integrated Management and Ecosystem Research (SWIMMER)/School of Biological Sciences, Nicholson Building, University of Liverpool, Liverpool, Merseyside L69 3GP (United Kingdom)], E-mail: mwood@liv.ac.uk; Marshall, W.A. [Westlakes Scientific Consulting Ltd., Princess Royal Building, Westlakes Science and Technology Park, Moor Row, Cumbria CA24 3LN (United Kingdom); Beresford, N.A. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, Lancashire LA1 4AP (United Kingdom); Jones, S.R. [Westlakes Scientific Consulting Ltd., Princess Royal Building, Westlakes Science and Technology Park, Moor Row, Cumbria CA24 3LN (United Kingdom); Howard, B.J. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, Lancashire LA1 4AP (United Kingdom); Copplestone, D. [Environment Agency, P.O. Box 12, Richard Fairclough House, Knutsford Road, Latchford, Warrington, Cheshire WA4 1HG (United Kingdom); Leah, R.T. [Institute for Sustainable Water Integrated Management and Ecosystem Research (SWIMMER)/School of Biological Sciences, Nicholson Building, University of Liverpool, Liverpool, Merseyside L69 3GP (United Kingdom)

2008-09-15

The EC-funded project 'Environmental Risks from Ionising Contaminants: Assessment and Management' (ERICA) developed an 'Integrated Approach' for assessing the impact of ionising radiation on ecosystems. This paper presents the application of the ERICA Integrated Approach, supported by a software programme (the ERICA Tool) and guidance documentation, to an assessment of the Drigg coastal sand dunes (Cumbria, UK). Targeted sampling provided site-specific data for sand dune biota, including amphibians and reptiles. Radionuclides reported included {sup 90}Sr, {sup 99}Tc, {sup 137}Cs, {sup 238}Pu, {sup 239+240}Pu and {sup 241}Am. Site-specific data were compared to predictions derived using the ERICA Tool. Some under- and over-predictions of biota activity concentrations were identified but can be explained by the specific ecological characteristics and contamination mechanism of the dunes. Overall, the results indicated no significant impact of ionising radiation on the sand dune biota and the Integrated Approach was found to be a flexible and effective means of conducting a radiation impact assessment.

Disturbance of beach sediment by off-road vehicles

Science.gov (United States)

Anders, Fred J.; Leatherman, Stephen P.

1987-10-01

A three-year investigation was undertaken to examine the effects of off-road vehicles (ORVs) on the beach at Fire Island, New York. Within the National Seashore over 45,000 vehicle trips per year are concentrated in the zone seaward of the dune toe. The experimental approach was adopted in order to assess the environmental effects of ORVs. Specially developed instrumentation was used to measure the direct displacement of sand by vehicles traversing the beach. Direct displacement data were reduced graphically and analyzed by stepwise linear regression. The results of 89 field experiments (788 cases) showed that slope, sand compaction, and number of vehicle passes in the same track were the principal factors controlling the measured net seaward displacement of sand. The data suggest that ORV use levels within the National Seashore could be contributing to the overall erosion rate by delivering large quantities of sand to the swash zone (max. of 119,300 m3/yr). However, with proper management downslope movement of sand could be reduced by an order of magnitude. While vehicular passage over the open beach displaces sand seaward, it is not known if such activity actually increases the amount of erosion, measured as net loss to the beach face.

Arbuscular mycorrhizal fungi associated with psammophilic vegetation in Mediterranean coastal sand dunes

Energy Technology Data Exchange (ETDEWEB)

Camprubi, A.; Calvet, C.; Cabot, P.; Pitet, M.; Estaun, V.

2010-07-01

This study was conducted in order to characterize the natural albacore's mycorrhizal (AM) biodiversity from Mediterranean sand dune ecosystems and to protect in a collection this biodiversity. The occurrence of AM fungi associated with sand dune plant species in three Mediterranean locations on the north-eastern coast of Spain was examined in one well preserved coastal sand dune and in two embrionary dunes recently protected from public access. Traditional taxonomy and molecular techniques were used to identify the AM fungal species present in these ecosystems. The species identified and isolated were: Scutellospora persica (Kiosk and Walker) Walker and Sanders, Glomus ambisporum Smith and Schenck, Glomus diaphanum Morton and Walker, Glomus clarum Nicolson and Schenck, Glomus intraradices Schenck and Smith, Glomus microaggregatum Koske, Gemma and Olexia and Gigaspora margarita Becker and Hall. Spores of Glomus were the most abundant in the direct soil extraction samples. The molecular analysis indicates that the most abundant fungi forming AM in the roots belonged to the Gigasporaceae group followed by fungi of Glomus group A and Glomus group B. The highest diversity of fungi and abundance of the AM fungal spores was found in the well preserved and undisturbed dune systems. (Author) 26 refs.

Impacts of storm chronology on the morphological changes of the Formby beach and dune system, UK

Science.gov (United States)

Dissanayake, P.; Brown, J.; Karunarathna, H.

2015-07-01

Impacts of storm chronology within a storm cluster on beach/dune erosion are investigated by applying the state-of-the-art numerical model XBeach to the Sefton coast, northwest England. Six temporal storm clusters of different storm chronologies were formulated using three storms observed during the 2013/2014 winter. The storm power values of these three events nearly halve from the first to second event and from the second to third event. Cross-shore profile evolution was simulated in response to the tide, surge and wave forcing during these storms. The model was first calibrated against the available post-storm survey profiles. Cumulative impacts of beach/dune erosion during each storm cluster were simulated by using the post-storm profile of an event as the pre-storm profile for each subsequent event. For the largest event the water levels caused noticeable retreat of the dune toe due to the high water elevation. For the other events the greatest evolution occurs over the bar formations (erosion) and within the corresponding troughs (deposition) of the upper-beach profile. The sequence of events impacting the size of this ridge-runnel feature is important as it consequently changes the resilience of the system to the most extreme event that causes dune retreat. The highest erosion during each single storm event was always observed when that storm initialised the storm cluster. The most severe storm always resulted in the most erosion during each cluster, no matter when it occurred within the chronology, although the erosion volume due to this storm was reduced when it was not the primary event. The greatest cumulative cluster erosion occurred with increasing storm severity; however, the variability in cumulative cluster impact over a beach/dune cross section due to storm chronology is minimal. Initial storm impact can act to enhance or reduce the system resilience to subsequent impact, but overall the cumulative impact is controlled by the magnitude and number

Aeolian sand transport and its effects on the stability of Miramar-Caranzalem beach

Digital Repository Service at National Institute of Oceanography (India)

Reddy, G.V.; Sastry, J.S.

Removal of sand by wind from the beach at Miramar-Caranzalem, Goa, has been found to effect its stability over a relatively longer time scale. This aeolian sand transport has been computed for this strip of the beach utilising the relation between...

Monazite, the basic raw material for rare earth beneficiation from beach sands

International Nuclear Information System (INIS)

Bashir, V.S.

1988-01-01

The largest monazite deposits in the world are the readily accessible placers in beach, bar and dune sands along the west and east coasts of India. The commercial monazite deposits in India are natural concentration of monazite with other valuable minerals like ilmenite, rutile, zircon, garnet, sillimanite, etc. in the beach placers. These high grade accruals deposited to 1 - 1.5 m depth are selectively collected using labour intensive methods and processed for individual mineral recovery. All known methods of physical concentration of minerals are used for separating monazite and other valuable minerals. These make use of the five important physical properties of the minerals, viz., electrical conductivity, magnetic susceptibility, specific gravity, surface characteristics and grain size distribution. The Indian Rare Earths (IRE) are operating three minerals beneficiation plants - two in the western coast at Chavara in Kerala and Manavalakurichi in Tamilnadu and one in the eastern coast of Chatrapur in Orissa State. Due to intensive selective mining all these years, there is considerable depletion in the quality of beach accruals which if fed directly to the processing plants will considerably affect their efficiency. Therefore, IRE has introduced integrated mining systems using dredge and pre-concentrate the dredge spoils to the required grade using spiral plants before feeding to the dry mills in the above plants. IRE has also advanced plans to exploit the 5 million m.t. monazite reserves in the country. (author) 2 figs., 1 tab

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.

Ecogeomorphology of Sand Dunes Shaped by Vegetation

Science.gov (United States)

Tsoar, H.

2014-12-01

Two dune types associated with vegetation are known: Parabolic and Vegetated Linear Dunes (VLDs), the latters are the dominant dune type in the world deserts. Parabolic dunes are formed in humid, sub-humid and semi-arid environments (rather than arid) where vegetation is nearby. VLDs are known today in semiarid and arid lands where the average yearly rainfall is ≥100 mm, enough to support sparse cover of vegetation. These two dune types are formed by unidirectional winds although they demonstrate a different form and have a distinct dynamics. Conceptual and mathematical models of dunes mobility and stability, based on three control parameters: wind power (DP), average annual precipitation (p), and the human impact parameter (μ) show that where human impact is negligible the effect of wind power (DP) on vegetative cover is substantial. The average yearly rainfall of 60-80 mm is the threshold of annual average rainfall for vegetation growth on dune sand. The model is shown to follow a hysteresis path, which explains the bistability of active and stabilized dunes under the same climatic conditions with respect to wind power. We have discerned formation of parabolic dunes from barchans and transverse dunes in the coastal plain of Israel where a decrease in human activity during the second half of the 20th century caused establishment of vegetation on the crest of the dunes, a process that changed the dynamics of these barchans and transverse dunes and led to a change in the shape of the windward slope from convex to concave. These dunes gradually became parabolic. It seems that VLDs in Australia or the Kalahari have always been vegetated to some degree, though the shrubs were sparser in colder periods when the aeolian erosion was sizeable. Those ancient conditions are characterized by higher wind power and lower rainfall that can reduce, but not completely destroy, the vegetation cover, leading to the formation of lee (shadow) dunes behind each shrub. Formation of

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.

Turbulent Flow and Sand Dune Dynamics: Identifying Controls on Aeolian Sediment Transport

Science.gov (United States)

Weaver, C. M.; Wiggs, G.

2007-12-01

Sediment transport models are founded on cubic power relationships between the transport rate and time averaged flow parameters. These models have achieved limited success and recent aeolian and fluvial research has focused on the modelling and measurement of sediment transport by temporally varying flow conditions. Studies have recognised turbulence as a driving force in sediment transport and have highlighted the importance of coherent flow structures in sediment transport systems. However, the exact mechanisms are still unclear. Furthermore, research in the fluvial environment has identified the significance of turbulent structures for bedform morphology and spacing. However, equivalent research in the aeolian domain is absent. This paper reports the findings of research carried out to characterise the importance of turbulent flow parameters in aeolian sediment transport and determine how turbulent energy and turbulent structures change in response to dune morphology. The relative importance of mean and turbulent wind parameters on aeolian sediment flux was examined in the Skeleton Coast, Namibia. Measurements of wind velocity (using sonic anemometers) and sand transport (using grain impact sensors) at a sampling frequency of 10 Hz were made across a flat surface and along transects on a 9 m high barchan dune. Mean wind parameters and mass sand flux were measured using cup anemometers and wedge-shaped sand traps respectively. Vertical profile data from the sonic anemometers were used to compute turbulence and turbulent stress (Reynolds stress; instantaneous horizontal and vertical fluctuations; coherent flow structures) and their relationship with respect to sand transport and evolving dune morphology. On the flat surface time-averaged parameters generally fail to characterise sand transport dynamics, particularly as the averaging interval is reduced. However, horizontal wind speed correlates well with sand transport even with short averaging times. Quadrant

Dew Measurements along a Longitudinal Sand Dune Transect

NARCIS (Netherlands)

Jacobs, A.F.G.; Heusinkveld, B.G.; Berkowicz, S.

2000-01-01

In a desert environment dew can serve as an important source of moisture for plants, biological crusts, insects and small animals. A measurement programme was carried out within a sand dune belt situated in the northwestern Negev desert, Israel, to measure daily amounts of dew deposition as well as

Seasonal geomorphic processes and rates of sand movement at Mount Baldy dune in Indiana, USA

Science.gov (United States)

Kilibarda, Zoran; Kilibarda, Vesna

2016-12-01

Winds are very strong, frequent, and have high energy (annual DP ∼800 VU) along the southern shores of Lake Michigan, allowing the coexistence of fixed and active dunes. Six years (2007-13) of monitoring Mount Baldy in the Indiana Dunes National Lakeshore reveals that this is the most active coastal dune in the Great Lakes region. This paper documents aeolian processes and changes in the dune's morphology that occur temporarily, following storms, or seasonally, due to weather (climate) variations. Most of the sand transport in this area takes place during strong storms with gale force (>17.5 m/s) winds, which occur in the autumn and winter months. A single storm, such as the October 28-31, 2013 event, can contribute 25% of the annual sand transport and dune movement inland. In its most active year (June 1, 2011 through May 31, 2012), Mount Baldy moved inland on average 4.34 m, with a maximum of 6.52 m along the blowout's axis (155° azimuth). During this particularly active season, there were six storms with sustained gale force winds, winter air temperatures were warmer than average, and shelf ice on Lake Michigan lasted only one day. The dune is least active during the summer season, when the winds are weakest. The late fall and winter winds are the strongest. But in a typical year, most of the dune's advance inland takes place during the spring thaw when sand is released from over-steepened and lumpy slip face, allowing it to avalanche to the toe of the slip face. However, with a warming air temperatures, a reduction in the duration of winter shelf ice, and rising Lake Michigan levels, the annual rates of sand transport and dune movement may increase. The recent Mount Baldy management strategy, which includes planting vegetation and installing wind barriers on the dune's stoss side in an effort to fix the dune and stop its further movement inland, may potentially cause the destruction of the mobile sand, open dune habitat, resulting in the extinction of rare

Comparing different methods for fast screening of microbiological quality of beach sand aimed at rapid-response remediation.

Science.gov (United States)

Testolin, Renan C; Almeida, Tito C M; Polette, Marcus; Branco, Joaquim O; Fischer, Larissa L; Niero, Guilherme; Poyer-Radetski, Gabriel; Silva, Valéria C; Somensi, Cleder A; Corrêa, Albertina X R; Corrêa, Rogério; Rörig, Leonardo R; Itokazu, Ana Gabriela; Férard, Jean-François; Cotelle, Sylvie; Radetski, Claudemir M

2017-05-15

There is scientific evidence that beach sands are a significant contributor to the pathogen load to which visitors are exposed. To develop beach quality guidelines all beach zones must be included in microbiological evaluations, but monitoring methods for beach sand quality are relatively longstanding, expensive, laborious and require moderate laboratory infrastructure. This paper aimed to evaluate the microorganism activity in different beach zones applying and comparing a classical method of membrane filtration (MF) with two colorimetric screening methods based on fluorescein (FDA) and tetrazolium (TTC) salt biotransformation to evaluate a new rapid and low-cost method for beach sand microbiological contamination assessments. The colorimetric results can help beach managers to evaluate rapidly and at low cost the microbiological quality of different beach zones in order to decide whether remedial actions need to be adopted to prevent exposure of the public to microbes due to beach sand and/or water contamination. Copyright © 2017. Published by Elsevier Ltd.

Radiological maps in beach sands along some coastal regions of Turkey

International Nuclear Information System (INIS)

Kucukomeroglu, B.; Karadeniz, A.; Damla, N.; Yesilkanat, C.M.; Cevik, U.

2016-01-01

In the present research, the gamma-emitting radionuclides in beach sands along the coastal regions of the Ordu, Giresun and Trabzon provinces, Turkey have been determined. The natural and anthropogenic radionuclide concentrations of the samples have been measured employing a germanium (HPGe) detector with high resolution and purity. The activity for 238 U, 232 Th, 40 K and 137 Cs of the samples were found to vary in the range from below detection limit (BDL) to 65 Bq·kg −1 , from BDL to 28 Bq·kg −1 , from 9 to 1936 Bq·kg −1 and from BDL to 22 Bq·kg −1 , respectively. The activity concentrations were compared with those in the literature. The associated radiological hazard indices were estimated, and were compared to the internationally recommended values. The radiological map of beach sand in the surveyed area was imaged. The data presented in the study are crucial since they constitute a baseline for the radiological mapping of the region in the future. - Highlights: • The natural and anthropogenic radionuclide concentrations in beach sands were analyzed. • The associated radiological hazard indices were estimated. • The results were evaluated to check the compatibility of national and international values. • The radiological maps of beach sand were produced. • The findings demonstrate that the obtained values were less than the internationally accepted recommended limits.

Sand Dune Dynamics on Mars: Integration of Surface Imaging, Wind Measurements, and Orbital Remote Sensing

Science.gov (United States)

Bridges, N.; Sullivan, R. J., Jr.; Ewing, R. C.; Newman, C. E.; Ayoub, F.; Lapotre, M. G. A.; van Beek, J.

2016-12-01

In early 2016, the Mars Science Laboratory rover completed the first in situ investigation of an active dune field on another planetary body, the "Bagnold Dunes" in Gale Crater. During the campaign, a series of Mastcam and RMI time-series images of local sand patches, dump piles, ripples, and the lee face and margin of Namib Dune (a barchan in the Bagnold field) were acquired. These were at cadences of a sol or more that were generally at nearly the same local time, and intra-sol imaging bridged by continuous wind measurements from REMS. The dune field has also been imaged 16 times by HiRISE since 2008. By combining the two datasets, long term dune dynamics over the whole field can be compared to small-scale and short-term observations on the surface. From HiRISE, Namib Dune and other barchans and longitudinal dunes to the south and west migrate generally toward the south to southeast. The most active sand deposits are the longitudinal and barchans dunes, with the highest ripple migration rates found on the highest elevations. Rippled sand patches exhibit little of no motion. From MSL, the scrambling of grains on the surfaces of local rippled sand patches and Namib Dune is obvious over periods as short as a single sol, with light-toned grains showing the greatest tendency. On the lee face of Namib, images show grain scrambling, one case of modification to a secondary grainflow, and possibly ripple motion over 3-16 sols. At the dune margin, grain scrambling and one major slump on the lee face of a dune ripple are seen. The daytime REMS record shows wind speeds up to 20 m/s with confidence. As yet, we do not have a demonstrable correlation between measured wind speeds and changes, suggesting that short term gusts or non-aeolian processes acting as triggers may precede significant activity. The changes, occurring in a low flux season based on HiRISE analysis and global circulation models, indicate an active surface at all times of the year to some degree.

Intertidal benthic community ecology of sand-dwelling macroinvertebrates of Goa beaches

Digital Repository Service at National Institute of Oceanography (India)

Harkantra, S.N.; Parulekar, A.H.

Studies on the intertidal ecology of two sandy beaches of Goa along the western coast of India revealed the presence of 47 species of macroinvertebrates belonging to 32 families. The open beach at Candolim, characterized by coarse sand-grain size...

Analysis of wind-blown sand movement over transverse dunes.

Science.gov (United States)

Jiang, Hong; Huang, Ning; Zhu, Yuanjian

2014-12-01

Wind-blown sand movement often occurs in a very complicated desert environment where sand dunes and ripples are the basic forms. However, most current studies on the theoretic and numerical models of wind-blown sand movement only consider ideal conditions such as steady wind velocity, flat sand surface, etc. In fact, the windward slope gradient plays a great role in the lift-off and sand particle saltation. In this paper, we propose a numerical model for the coupling effect between wind flow and saltating sand particles to simulate wind-blown sand movement over the slope surface and use the SIMPLE algorithm to calculate wind flow and simulate sands transport by tracking sand particle trajectories. We furthermore compare the result of numerical simulation with wind tunnel experiments. These results prove that sand particles have obvious effect on wind flow, especially that over the leeward slope. This study is a preliminary study on windblown sand movement in a complex terrain, and is of significance in the control of dust storms and land desertification.

Hurricane Irma's Effects on Dune and Beach Morphology at Matanzas Inlet, Atlantic Coast of North Florida: Impacts and Inhibited Recovery?

Science.gov (United States)

Adams, P. N.; Conlin, M. P.; Johnson, H. A.; Paniagua-Arroyave, J. F.; Woo, H. B.; Kelly, B. P.

2017-12-01

During energetic coastal storms, surge from low atmospheric pressure, high wave set-up, and increased wave activity contribute to significant morphologic change within the dune and upper beach environments of barrier island systems. Hurricane Irma made landfall on the southwestern portion of the Florida peninsula, as a category 4 storm on Sept 10th, 2017 and tracked northward along the axis of the Florida peninsula for two days before dissipating over the North American continent. Observations along the North Florida Atlantic coast recorded significant wave heights of nearly 7 m and water levels that exceeded predictions by 2 meters on the early morning of Sept. 11th. At Fort Matanzas National Monument, the dune and upper beach adjacent to Matanzas Inlet experienced landward retreat during the storm, diminishing the acreage of dune and scrub habitat for federally-listed endangered and threatened animal species, including the Anastasia beach mouse, gopher tortoises, and several protected shore birds. Real Time Kinematic (RTK) GPS surveys, conducted prior to the passage of the storm (Sept. 8) and immediately after the storm (Sept. 13) document dune scarp retreat >10 m in places and an average retreat of 7.8 m (+/- 5.2 m) of the 2-m beach contour, attributable to the event, within the study region. Although it is typical to see sedimentary recovery at the base of dunes within weeks following an erosive event of this magnitude, our follow up RTK surveys, two weeks (Sept. 26) and five weeks (Oct. 19) after the storm, document continued dune retreat and upper beach lowering. Subsequent local buoy observations during the offshore passage of Hurricanes Jose, Maria (Sept. 17 and 23, respectively) and several early-season Nor'easters recorded wave heights well above normal (2-3 meters) from the northeast. The lack of recovery may reveal a threshold vulnerability of the system, in which the timing of multiple moderate-to-high wave events, in the aftermath of a land falling

Sand dune of Ruby, Arizona, an anthropogenically created biodiversity hotspot for wasps and their velvet ant parasitoids

Science.gov (United States)

Justin O. Schmidt

2013-01-01

A large artificial sand dune composed of finely crushed mine tailings was produced by deep mining operations at Ruby, Arizona. Today, the ghost town of Ruby is an important historical location and biodiversity refuge, with the newly formed dune forming the core of the refuge. The dune provides ideal nesting habitat for at least 13 species of sand-loving wasps,...

Thermal biology of Liolaemus occipitalis (Squamata, Tropiduridae in the coastal sand dunes of Rio Grande do Sul, Brazil

Directory of Open Access Journals (Sweden)

C. S. Bujes

Full Text Available The thermal biology of the small sand lizard, Liolaemus occipitalis, was studied in the coastal sand dunes at Quintão Beach (Palmares do Sul, Rio Grande do Sul, Brazil; 30° 24' S and 50° 17' W, between September, 1998 and August, 1999. Liolaemus occipitalis presented a mean body temperature of 30.89 °C (SD = 4.43 °C; min = 16.4 °C; max = 40.2 °C; N = 270, that varied on a daily and seasonal basis according to microhabitat thermal alterations. The substrate temperature was the main heat source for thermoregulation of L. occipitalis as in all seasons of the year it was responsible for the animals' temperature variation (82% of the collected lizards in the spring; 60% in the summer; 84% in the fall and 68% in the winter. The results indicate that L. occipitalis is a saxicolous, thigmothermic and heliothermic species that regulates its body temperature through behavioral mechanisms.

Isolation, identification, and pathological effects of beach sand bacterial extract on human skin keratinocytes in vitro

Directory of Open Access Journals (Sweden)

Fazli Subhan

2018-01-01

Full Text Available Background Beaches are recreational spots for people. However, beach sand contains harmful microbes that affect human health, and there are no established methods for either sampling and identifying beach-borne pathogens or managing the quality of beach sand. Method This study was conducted with the aim of improving human safety at beaches and augmenting the quality of the beach experience. Beach sand was used as a resource to isolate bacteria due to its distinctive features and the biodiversity of the beach sand biota. A selected bacterial isolate termed FSRS was identified as Pseudomonas stutzeri using 16S rRNA sequencing and phylogenetic analysis, and the sequence was deposited in the NCBI GenBank database under the accession number MF599548. The isolated P. stutzeri bacterium was cultured in Luria–Bertani growth medium, and a crude extract was prepared using ethyl acetate to examine the potential pathogenic effect of P. stutzeri on human skin. A human skin keratinocyte cell line (HaCaT was used to assess cell adhesion, cell viability, and cell proliferation using a morphological analysis and a WST-1 assay. Result The crude P. stutzeri extract inhibited cell adhesion and decreased cell viability in HaCaT cells. We concluded that the crude extract of P. stutzeri FSRS had a strong pathological effect on human skin cells. Discussion Beach visitors frequently get skin infections, but the exact cause of the infections is yet to be determined. The beach sand bacterium P. stutzeri may, therefore, be responsible for some of the dermatological problems experienced by people visiting the beach.

Evaluation of beach grooming techniques on Escherichia coli density in foreshore sand at North Beach, Racine, WI

Science.gov (United States)

Kinzelman, Julie L.; Whitman, Richard L.; Byappanahalli, Muruleedhara N.; Jackson, Emma; Bagley, Robert C.

2003-01-01

Elevated levels of Escherichia coli(E. coli) in bathing waters at North Beach, a popular recreational site in Racine, Wisconsin, have been a persistent problem often resulting in the issuance of poor water quality advisories. Moreover, waterfowl (mostly Larus delawarensis and L. argentatus) in nearshore and offshore areas are common and may serve as non-point sources for bacterial contamination of recreational waters. Current beach management practice involves daily mechanical grooming of the nearshore sand for aesthetics and removal of hazardous debris. However, this practice has not been evaluated in terms of its effects on E. coli loading to beach sand and potential introduction to contiguous swimming water. In this study, we tested E. coli responses to three treatments: mechanical groomer, daily and twice weekly hand raking, and a control (no raking/grooming). A randomized block design consisted of replicated treatments and one control (10 each), for a total of 40 blocks sampled daily for 10 days. Foreshore sand samples were collected by hand coring to an average depth of 10 cm. Median E. colirecovered were 73 (mechanically groomed), 27 (hand-raked daily), 32 (hand-raked twice weekly), and 22 (control) colony-forming units (CFU) per gram dry weight sand. E. colicounts in sand that was groomed were significantly higher than hand rakings and control (p grooming efficacy and the importance of understanding non-point sources of bacterial contamination.

A bright intra-dune feature on Titan and its implications for sand formation and transport

Science.gov (United States)

MacKenzie, Shannon; Barnes, Jason W.; Rodriguez, Sebastien; Cornet, Thomas; Brossier, Jeremy; Soderblom, Jason M.; Le Mouélic, Stephane; Sotin, Christophe; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger Nelson; Nicholson, Philip D.; Baines, Kevin

2017-10-01

Organic sands cover much of Titan’s equatorial belt, gathered into longitudinal dunes about a kilometer wide and hundreds of kilometers long. At the end of the Cassini era, questions of how such a vast volume of saltable material is or was created on Titan remain unanswered. At least two possible mechanisms suggested for forming sand-sized particles involve liquids: (1) evaporite deposition and erosion and (2) flocculation of material within a lake. Transporting sand from the lakes and seas of Titan’s poles to the equatorial belt is not strongly supported by Cassini observations: the equatorial belt sits higher than the poles and no sheets or corridors of travelling sand have been identified. Thus, previous sites of equatorial surface liquids may be of interest for understanding sand formation, such as the suggested paleoseas Tui and Hotei Regio. A newly identified feature in the VIMS data sits within the Fensal dune field but is distinct from the surrounding sand. We investigate this Bright Fensal Feature (BFF) using data from Cassini VIMS and RADAR. Specifically, we find spectral similarities between the BFF and both sand and Hotei Regio. The RADAR cross sectional backscatter is similar to neighboring dark areas, perhaps sand covered interdunes. We use this evidence to constrain the BFF’s formation history and discuss how this intra-dune feature may contribute to the processes of sand transport and supply.

76 FR 9309 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Sand...

Science.gov (United States)

2011-02-17

... Washington. At known locations in British Columbia, the sand verbena moth occurs in small satellite patches... of beach dune habitat remain at the type locality for the sand verbena moth, making this species... and, therefore, the sand verbena moth are adversely affected by the construction of artificial...

How extensive is the effect of modern farming on bird communities in a sand dune desert?

Directory of Open Access Journals (Sweden)

Faris Khoury

2009-12-01

Full Text Available Bird community structure and diversity measures in sand dune habitats far from and close to modern farms in Wadi Araba, south-west Jordan, were compared using 52 line transects for breeding birds and habitat variables. A change in the bird community of sand dunes surrounding farming projects was measured to a distance of 1 km, but could neither be related to changes in habitat structure nor to the activity of op- portunistic predators (Red Fox as these did not vary significantly between the two samples. The farms included lines of trees and offered a constant source of water, which attracted a variety of opportunistic species, thus increasing bird diversity and total bird abundances. The absence of characteristic ground-dwelling species of open sand dune habitats in the structurally intact sand dunes surrounding farms was likely to be the result of localized, but effectively far-reaching habitat modification (farms acting as barriers and/or competition with some of the opportunistic species, which were common around farms.

Cluster analysis of radionuclide concentrations in beach sand

NARCIS (Netherlands)

de Meijer, R.J.; James, I.; Jennings, P.J.; Keoyers, J.E.

This paper presents a method in which natural radionuclide concentrations of beach sand minerals are traced along a stretch of coast by cluster analysis. This analysis yields two groups of mineral deposit with different origins. The method deviates from standard methods of following dispersal of

Texture and composition of the Rosa Marina beach sands (Adriatic coast, southern Italy: a sedimentological/ecological approach

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Moretti Massimo

2016-06-01

Full Text Available Beach sands from the Rosa Marina locality (Adriatic coast, southern Italy were analysed mainly microscopically in order to trace the source areas of their lithoclastic and bioclastic components. The main cropping out sedimentary units were also studied with the objective to identify the potential source areas of lithoclasts. This allowed to establish how the various rock units contribute to the formation of beach sands. The analysis of the bioclastic components allows to estimate the actual role of organisms regarding the supply of this material to the beach. Identification of taxa that are present in the beach sands as shell fragments or other remains was carried out at the genus or family level. Ecological investigation of the same beach and the recognition of sub-environments (mainly distinguished on the basis of the nature of the substrate and of the water depth was the key topic that allowed to establish the actual source areas of bioclasts in the Rosa Marina beach sands. The sedimentological analysis (including a physical study of the beach and the calculation of some statistical parameters concerning the grain-size curves shows that the Rosa Marina beach is nowadays subject to erosion.

Nourishment of perched sand dunes and the issue of erosion control in the Great Lakes

Science.gov (United States)

Marsh, William M.

1990-09-01

Although limited in coverage, perched sand dunes situated on high coastal bluffs are considered the most prized of Great Lakes dunes. Grand Sable Dunes on Lake Superior and Sleeping Bear Dunes on Lake Michigan are featured attractions of national lakeshores under National Park Service management. The source of sand for perched dunes is the high bluff along their lakeward edge. As onshore wind crosses the bluff, flow is accelerated upslope, resulting in greatly elevated levels of wind stress over the slope brow. On barren, sandy bluffs, wind erosion is concentrated in the brow zone, and for the Grand Sable Bluff, it averaged 1 m3/yr per linear meter along the highest sections for the period 1973 1983. This mechanism accounts for about 6,500 m3 of sand nourishment to the dunefield annually and clearly has been the predominant mechanism for the long-term development of the dunefield. However, wind erosion and dune nourishment are possible only where the bluff is denuded of plant cover by mass movements and related processes induced by wave erosion. In the Great Lakes, wave erosion and bluff retreat vary with lake levels; the nourishment of perched dunes is favored by high levels. Lake levels have been relatively high for the past 50 years, and shore erosion has become a major environmental issue leading property owners and politicians to support lake-level regulation. Trimming high water levels could reduce geomorphic activity on high bluffs and affect dune nourishment rates. Locally, nourishment also may be influenced by sediment accumulation associated with harbor protection facilities and by planting programs aimed at stabilizing dunes.

Agglomeration of a comprehensive model for the wind-driven sand transport at the Belgian Coast

Science.gov (United States)

Strypsteen, Glenn; Rauwoens, Pieter

2016-04-01

Although a lot of research has been done in the area of Aeolian transport, it is only during the last years that attention has been drawn to Aeolian transport in coastal areas. In these areas, the physical processes are more complex, due to a large number of transport limiting parameters. In this PhD-project, which is now in its early stage, a model will be developed which relates the wind-driven sand transport at the Belgian coast with physical parameters such as the wind speed, humidity and grain size of the sand, and the slope of beach and dune surface. For the first time, the interaction between beach and dune dynamics is studied at the Belgian coast. The Belgian coastline is only 67km long, but densely populated and therefore subject to coastal protection and safety. The coast mostly consists of sandy beaches and dikes. Although, still 33km of dunes exist, whose dynamics are far less understood. The overall research approach consists of three pathways: (i) field measurements, (ii) physical model tests, and (iii) numerical simulations. Firstly and most importantly, several field campaigns will provide accurate data of meteo-marine conditions, morphology, and sand transport events on a wide beach at the Belgian Coastline. The experimental set-up consists of a monitoring station, which will provide time series of vegetation cover, shoreline position, fetch distances, surficial moisture content, wind speed and direction and transport processes. The horizontal and vertical variability of the event scale Aeolian sand transport is analyzed with 8 MWAC sand traps. Two saltiphones register the intensity and variations of grain impacts over time. Two meteo-masts, each with four anemometers and one wind vane, provide quantitative measurements of the wind flow at different locations on the beach. Surficial moisture is measured with a moisture sensor. The topography measurements are typically done with laser techniques. To start, two sites are selected for measurement

Geochemistry of dark coastal heavy-mineral beaches sand (Annaba ...

African Journals Online (AJOL)

Acer

3 Institute of Earth and Environmental Science, University of Potsdam, ... Some beaches are characterized by a red-brownish sand colour, the Ain Achir and the ... The occurrence of clays has been determined using the methyl-blue method.

Intertidal beach sands as monitors for heavy metal pollution in coastal water bodies

International Nuclear Information System (INIS)

Lacerda, L.D. de; Pfeiffer, W.C.; Fiszman, M.

Intertidal beach sands were investigated for their use as indicators of metal transport in a contaminated water body, Sepetiba Bay, Rio de Janeiro, Brazil, and are proposed as an alternative and rapid screening method to determine metal pollution status of coastal areas. The results showed that, at least for Cu, Cr, Zn and Pb, beach sands can be included in the existing environmental monitoring programs for heavy metal pollution in water bodies. (Author) [pt

Geologic framework influences on the geomorphology of an anthropogenically modified barrier island: Assessment of dune/beach changes at Fire Island, New York

Science.gov (United States)

Lentz, E.E.; Hapke, C.J.

2011-01-01

Antecedent geology plays a crucial role in determining the inner-shelf, nearshore, and onshore geomorphology observed in coastal systems. However, the influence of the geologic framework on a system is difficult to extract when evaluating responses to changes due to storms and anthropogenic modifications, and few studies have quantified the potential for these influences in dune/beach environments. This study evaluates topographic change to the dune/beach system at Fire Island, New York over a ten year period (1998-2008) at two sites representing eastern and western reaches of the island where morphology has been shown to vary. The sites are situated along swaths of coast eroding differentially and where the inner shelf geologic framework differs substantially. Fewer large storms occurred in the first half of the study period, compared with the later part of the study period which includes several severe and prolonged extratropical storms. Additionally, a major beach replenishment project was conducted at one of the study sites. Topographic data from LiDAR and RTK GPS surveys are used to construct high-resolution 3D surfaces, which are used to determine volumetric change and to extract 2D alongshore features and profiles for analysis. The study sites help to further characterize morphologic differences between eastern and western reaches of the island. The western site displays higher sand volumes, lower dunes, and a lower gradient profile slope when compared with the eastern site. In addition to these fundamental morphologic differences, the two sites also differ significantly in their response to coastal storms and in the fact that their replenishment histories are different. The replenished areas show reduced vulnerability to storms through minimal volume loss and shoreline accretion that should be considered when evaluating the response of replenished areas to episodic events. We propose that site-specific differences evident throughout the study period can be

The role of the reef–dune system in coastal protection in Puerto Morelos (Mexico

Directory of Open Access Journals (Sweden)

G. L. Franklin

2018-04-01

Full Text Available Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef–dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH. Wave hindcast information, tidal level, and a measured beach profile of the reef–dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore

The role of the reef-dune system in coastal protection in Puerto Morelos (Mexico)

Science.gov (United States)

Franklin, Gemma L.; Torres-Freyermuth, Alec; Medellin, Gabriela; Allende-Arandia, María Eugenia; Appendini, Christian M.

2018-04-01

Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef-dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH). Wave hindcast information, tidal level, and a measured beach profile of the reef-dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore reef slope) is warranted.

Erosion reasons and rate on accumulative Polish dune coast caused by the January 2012 storm surge

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Tomasz A. Łabuz

2014-03-01

Full Text Available The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5 m3 per square metre with an average toe retreat of 1.4 m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8. Dune erosion did not occur on coasts with beaches higher than 3.2 m or on lower ones covered by embryo dunes.

Microbiological and mycological beach sand quality in a volcanic environment: Madeira archipelago, Portugal.

Science.gov (United States)

Pereira, Elisabete; Figueira, Celso; Aguiar, Nuno; Vasconcelos, Rita; Vasconcelos, Sílvia; Calado, Graça; Brandão, João; Prada, Susana

2013-09-01

Madeira forms a mid-Atlantic volcanic archipelago, whose economy is largely dependent on tourism. There, one can encounter different types of sand beach: natural basaltic, natural calcareous and artificial calcareous. Microbiological and mycological quality of the sand was analyzed in two different years. Bacterial indicators were detected in higher number in 2010 (36.7% of the samples) than in 2011 (9.1%). Mycological indicators were detected in a similar percentage of samples in 2010 (68.3%) and 2011 (75%), even though the total number of colonies detected in 2010 was much higher (827 in 41 samples) than in 2011 (427 in 66 samples). Enterococci and potentially pathogenic and allergenic fungi (particularly Penicillium sp.) were the most common indicators detected in both years. Candida sp. yeast was also commonly detected in the samples. The analysis of the 3rd quartile and maximum numbers of all indicators in samples showed that artificial beaches tend to be more contaminated than the natural ones. However, a significant difference between the variables was lacking. More monitoring data (number of bathers, sea birds, radiation intensity variation, and a greater number of samples) should be collected in order to confirm if these differences are significant. In general, the sand quality in the archipelago's beaches was good. As the sand may be a vector of diseases, an international common set of indicators and values and a compatible methodologies for assessing sand contamination, should be defined, in order to provide the bather's with an indication of beach sand quality, rather than only the water. Copyright © 2013 Elsevier B.V. All rights reserved.

Design of preconcentration flow-sheet for processing Bhimunipatnam beach sands using pilot plant experiments and computer simulation

International Nuclear Information System (INIS)

Padmanabhan, N.P.H.; Sridhar, U.

1993-01-01

Simulation was carried out using a beach sand beneficiation plant simulator software, SANDBEN, currently being developed in Indian School of Mines, Dhanbad, and the results were compared and analyzed with those obtained by actual pilot plant experiments on a beach sand sample from Bhimunipatnam deposit. The software is discussed and its capabilities and limitations are highlighted. An optimal preconcentrator flow-sheet for processing Bhimunipatnam beach sand was developed by simulation and using the results of the pilot plant experiments. (author). 13 refs., 2 tabs., 3 figs

Survival potential of Escherichia coli and Enterococci in subtropical beach sand: implications for water quality managers.

Science.gov (United States)

Hartz, A; Cuvelier, M; Nowosielski, K; Bonilla, T D; Green, M; Esiobu, N; McCorquodale, D S; Rogerson, A

2008-01-01

Fecal bacteria have traditionally been used as indicator organisms to monitor the quality of recreational waters. Recent work has questioned the robustness of traditional indicators, particularly at seawater bathing beaches. For example, a study of Florida beaches found unexpectedly high abundances of Escherichia coli, fecal coliforms, and enterococci in beach sand. The aim of the present study was to explain these abundances by assessing the survival of E. coli and enterococci in beach sand relative to seawater. We used a combination of quantitative laboratory mesocosm experiments and field observations. Results suggested that E. coli and enterococci exhibited increased survivability and growth in sand relative to seawater. Because fecal bacteria are capable of replicating in sand, at least under controlled laboratory conditions, the results suggest that sand may be an important reservoir of metabolically active fecal organisms. Experiments with "natural" mesocosms (i.e., unsterilized sand or water rich in micropredators and native bacteria) failed to show the same increases in fecal indicators as was found in sterile sand. It is postulated that this was due to predation and competition with indigenous bacteria in these "natural" systems. Nonetheless, high populations of indicators were maintained and recovered from sand over the duration of the experiment as opposed to the die-off noted in water. Indicator bacteria may wash out of sand into shoreline waters during weather and tidal events, thereby decreasing the effectiveness of these indicators as predictors of health risk and complicating the interpretations for water quality managers.

Effect of sillimanite beach sand composition on mullitization and ...

Indian Academy of Sciences (India)

Unknown

Effect of sillimanite beach sand composition on mullitization and properties of Al2O3–SiO2 system ... Presence of zircon in Z-variety increases the hardness and fracture toughness. Alumina addition ... The ratio of charge to grinding media was ...

Water Quality, Weather and Environmental Factors Associated with Fecal Indicator Organism Density in Beach Sand at Two Recreational Marine Beaches

Science.gov (United States)

Recent studies showing an association between fecal indicator organisms (FIOs and gastrointestinal (GI) illness among beachgoers wit sand contact have important public health implicatons because of the large numbers of people who recreate at beaches and engage in sand contact act...

Erosion and its rate on an accumulative Polish dune coast: the effects of the January 2012 storm surge

Directory of Open Access Journals (Sweden)

Tomasz A. Łabuz

2014-01-01

Full Text Available The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5 m3 per square metre with an average toe retreat of 1.4 m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8. Dune erosion did not occur on coasts with beaches higher than 3.2 m or on lower ones covered by embryo dunes.

Rip Currents, Mega-Cusps, and Eroding Dunes

OpenAIRE

Thornton, E.B.; MacMahan, J.; Sallenger, A.H.

2006-01-01

Submitted to Marine Geology 1 November 2006 Dune erosion is shown to occur at the embayment of beach mega-cusps O(200m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18 km shoreline in southern Mont...

Sheet-gravel evidence for a late Holocene tsunami run-up on beach dunes, Great Barrier Island, New Zealand

Science.gov (United States)

Nichol, Scott L.; Lian, Olav B.; Carter, Charles H.

2003-01-01

A semi-continuous sheet of granule to cobble-size clasts forms a distinctive deposit on sand dunes located on a coastal barrier in Whangapoua Bay, Great Barrier Island, New Zealand. The gravel sheet extends from the toe of the foredune to 14.3 m above mean sea level and 200 m landward from the beach. Clasts are rounded to sub-rounded and comprise lithologies consistent with local bedrock. Terrestrial sources for the gravel are considered highly unlikely due to the isolation of the dunes from hillslopes and streams. The only source for the clasts is the nearshore to inner shelf of Whangapoua Bay, where gravel sediments have been previously documented. The mechanism for transport of the gravel is unlikely to be storm surge due to the elevation of the deposit; maximum-recorded storm surge on this coast is 0.8 m above mean high water spring tide. Aeolian processes are also discounted due to the size of clasts and the elevation at which they occur. Tsunami is therefore considered the most probable mechanism for gravel transport. Minimum run-up height of the tsunami was 14.3 m, based on maximum elevation of gravel deposits. Optical ages on dune sands beneath and covering the gravel allow age bracketing to 0-4.7 ka. Within this time frame, numerous documented regional seismic and volcanic events could have generated the tsunami, notably submarine volcanism along the southern Kermadec arc to the east-southeast of Great Barrier Island where large magnitude events are documented for the late Holocene. Radiocarbon ages on shell from Maori middens that appear to have been reworked by tsunami run-up constrain the age of this event to post ca. 1400 AD. Regardless of the precise age of this event, the well-preserved nature of the Whangapoua gravel deposit provides for an improved understanding of the high degree of spatial variability in tsunami run-up.

The vertical structure of airflow turbulence characteristics within a boundary layer during wind blown sand transport over a beach

Science.gov (United States)

Lee, Z. S.; Baas, A. C.; Jackson, D.; Cooper, J. A.; Lynch, K.; Delgado-Fernandez, I.; Beyers, M.

2010-12-01

Recent studies have suggested the significant role of boundary layer turbulence and coherent flow structures on sand transport by wind over beaches and desert dunes. Widespread use of sonic anemometry and high-frequency sand transport sensors and traps have facilitated a move beyond the basic monitoring of shear velocities and bulk sediment transport to more detailed measurements at much higher spatio-temporal resolutions. In this paper we present results of a small-scale point-location field study of boundary layer turbulence and shear stresses conducted under obliquely onshore winds over a beach at Magilligan Strand, Northern Ireland. High-frequency (25 Hz) 3D wind vector measurements were collected at five different heights between 0.13 and 1.67 metres above the bed using sonic anemometry for durations of several hours, and the associated sand transport response was measured using an array of Safires. The wind data are used to investigate the vertical structure of Reynolds shear stresses and burst-sweep event characteristics, as well as a comparison with the standard logarithmic (law-of-the-wall) wind profile. The study explores the identification and selection of a characteristic event duration based on integral time-scales as well as spectral analysis, and includes an assessment of the issues involved with data rotations for yaw, pitch, and roll corrections relative to flow streamlines, and the subsequently derived turbulence parameters based on fluctuating vector components (u’, v’, w’). Results show how the contributions to shear stress and the average pitch of bursts and sweeps changes as a function of height above the bed, indicating the transformation of top-down turbulent eddies as they travel toward the surface. A comparison between the turbulence data and the synchronous sand transport events, meanwhile, reveals the potential effects of enhanced saltation layer roughness feedback on eddies close to the bed.

Quantifying wind blown landscapes using time-series airborne LiDAR at White Sands Dune Field, New Mexico

Science.gov (United States)

Ewing, R. C.

2011-12-01

Wind blown landscapes are a default geomorphic and sedimentary environment in our solar system. Wind sand dunes are ubiquitous features on the surfaces of Earth, Mars and Titan and prevalent within the aeolian rock records of Earth and Mars. Dunes are sensitive to environmental and climatic changes and a complete understanding of this system promises a unique, robust and quantitative record of paleoclimate extending to the early histories of these worlds. However, our understanding of how aeolian dune landscapes evolve and how the details of the wind are recorded in cross-strata is limited by our lack of understanding of three-dimensional dune morphodynamics related to changing boundary conditions such as wind direction and magnitude and sediment source area. We use airborne LiDAR datasets over 40 km2 of White Sands Dune Field collected from June 2007, June 2008, January 2009, September 2009 and June 2010 to quantify 1) three-dimensional dune geometries, 2) annual and seasonal patterns of erosion and deposition across dune topography, 3) spatial changes in sediment flux related to position within the field, 4) spatial changes in sediment flux across sinuous crestlines and 5) morphologic changes through dune-dune interactions. In addition to measurements, we use the LiDAR data along with wind data from two near-by weather stations to develop a simple model that predicts depositional and stratigraphic patterns on dune lee slopes. Several challenges emerged using time series LiDAR data sets at White Sands Dune Field. The topography upon which the dunes sit is variable and rises by 16 meters over the length of the dune field. In order to compare individual dune geometries across the field and between data sets a base surface was interpolated from local minima and subtracted from the dune topography. Co-registration and error calculation between datasets was done manually using permanent vegetated features within the active dune field and structures built by the

DIVERSITY OF ARBUSCULAR MYCORRHIZAL FUNGI ALONG A SAND DUNE STABILIZATION GRADIENT: A CASE STUDY AT PRAIA DE JOAQUINA, ILHA DE SANTA CATARINA, SOUTH BRAZIL

Science.gov (United States)

Species diversity of abuscular mycorrhizal fungi (AMF) was assessed along a dunes stabilization gradient (embyonic dune, foredune and fixed dune) at Praia da Joaquina (Joaquina Beach), Ilha de Santa Catarina. These dunes served as a case study to assess whether diversity and myc...

Compaction and Collapse Characteristics of Dune Sand Stabilized with Lime-Silica Fume Mix

Directory of Open Access Journals (Sweden)

Mohammed Y. Fattah

2016-04-01

Full Text Available The purpose of this research is to assess the suitability of dune sands as construction materials. Moreover, such a goal is considered beneficial in determining appropriate methods for soil stabilization or ground improvement and to assessing the suitability of dune sands as subgrade layer for carrying roads and rail foundation. Dune sand samples were collected from a region in Baiji area in Salah-Aldeen governorate, North of Iraq. A grey-colored densified silica fume (SF and lime (L are used. Three percentages are used for lime (3%, 6%, and 9%, and four rates are used for silica fume (3%, 6%, 9% and 12% and the maximum percentage of silica fume is mixed with the proportions of lime. Unsoaked California Bearing Ratio (CBR on compacted dune sands treated dune sands with L-SF by mixing and cured for one day. The increasing in CBR ranged between 443 – 707% at 2.54 mm penetration and 345 – 410% at 5.08 mm penetration.     Resumen El propósito de esta investigación es evaluar el uso de arena de dunas como materiales de construcción. Además, este objetivo permite determinar los métodos apropiados para la estabilización del suelo, el mejoramiento del terreno y la evaluación de pertinencia de la arena de dunas en capas subbase para carreteras y cimientos férreos. Se recolectaron muestras de arena de dunas en el área de Baiji, del comisionado Salah-Aldeen, al norte de Irak. Se utilizó vapor de óxido de silicio (SF, en inglés, grisáceo y densificado, y óxido de calcio (L. Se utilizaron tres porcentajes para el óxido de calcio (3 %, 6 % y 9 %, y cuatro para el óxido de silicio (3 %, 6 %,  9% y 12% y el máximo porcentaje del óxido de silicio se mezcló con las proporciones de óxido de calcio. Se realizó en seco el Ensayo de Relación de Soporte de California (del inglés California Bearing Ratio, CBR en arena de dunas compactada y tratada con la mezcla L-SF curada durante un día. El incremento en el ensayo CBR osciló entre 443

Modeling aeolian dune and dune field evolution

Science.gov (United States)

Diniega, Serina

Aeolian sand dune morphologies and sizes are strongly connected to the environmental context and physical processes active since dune formation. As such, the patterns and measurable features found within dunes and dune fields can be interpreted as records of environmental conditions. Using mathematical models of dune and dune field evolution, it should be possible to quantitatively predict dune field dynamics from current conditions or to determine past field conditions based on present-day observations. In this dissertation, we focus on the construction and quantitative analysis of a continuum dune evolution model. We then apply this model towards interpretation of the formative history of terrestrial and martian dunes and dune fields. Our first aim is to identify the controls for the characteristic lengthscales seen in patterned dune fields. Variations in sand flux, binary dune interactions, and topography are evaluated with respect to evolution of individual dunes. Through the use of both quantitative and qualitative multiscale models, these results are then extended to determine the role such processes may play in (de)stabilization of the dune field. We find that sand flux variations and topography generally destabilize dune fields, while dune collisions can yield more similarly-sized dunes. We construct and apply a phenomenological macroscale dune evolution model to then quantitatively demonstrate how dune collisions cause a dune field to evolve into a set of uniformly-sized dunes. Our second goal is to investigate the influence of reversing winds and polar processes in relation to dune slope and morphology. Using numerical experiments, we investigate possible causes of distinctive morphologies seen in Antarctic and martian polar dunes. Finally, we discuss possible model extensions and needed observations that will enable the inclusion of more realistic physical environments in the dune and dune field evolution models. By elucidating the qualitative and

Geomorphology and anthropogenic impact including military constraints in a microtidal wave-dominated embayment in south western Sardinia (Porto Pino beach, SCI ITB040025, Mediterranean Sea). Implications for beach management.

Science.gov (United States)

De Muro, Sandro; Buosi, Carla; Pusceddu, Nicola; Frongia, Paolo; Passarella, Marinella; Ibba, Angelo

2016-04-01

impact. The coastal dunes vulnerability status of this three parts was assessed using the Dune Vulnerability Index (DVI) based on 57 variables that described geomorphological condition, marine influence, aeolian influence, vegetation condition, and human effects. Results reveal the lowest vulnerability value in the area undergone military constraints. Blowouts, breaches in the coastal dune system and deflation areas are observed in the first and second part where there is the greatest human transit to allow users access of the beach. The main pressures and threats identified that determine significant impacts on dune habitats are: transit of vehicles in the dune with the subsequent degradation of vegetation and the triggering of deflation processes; setting of infrastructure on the dune; removal of seagrass banquettes. In particular, the impact of trucks used to remove banquettes is significant on subaerial beach morphology. This traffic flattens the berms, modifies sand permeability and reduces organic sediment input to the shore. This study has allowed to highlight the geomorphological processes, the anthropic pressure and the coastal dune vulnerability of this coastal area in order to mitigate the impacts.

The Influences of a Clay Lens on the Hyporheic Exchange in a Sand Dune

Directory of Open Access Journals (Sweden)

Chengpeng Lu

2018-06-01

Full Text Available A laboratory flume simulating a riverbed sand dune containing a low-permeability clay lens was constructed to investigate its influence on the quality and quantity of hyporheic exchange. By varying the depths and spatial locations of the clay lens, 24 scenarios and one blank control experiment were created. Dye tracers were applied to visualize patterns of hyporheic exchange and the extent of the hyporheic zone, while NaCl tracers were used to calculate hyporheic fluxes. The results revealed that the clay lens reduces hyporheic exchange and that the reduction depends on its spatial location. In general, the effect was stronger when the lens was in the center of the sand dune. The effect weakened when the lens was moved near the boundary of the sand dune. A change in horizontal location had a stronger influence on the extent of the hyporheic zone compared with a change in depth. The size of the hyporheic zone changed with the depth and position of the clay lens. There was a maximum of hyporheic extent with the lens at a depth of 0.1 m caused by changes of water flow paths.

Visible/near-infrared spectral diversity from in situ observations of the Bagnold Dune Field sands in Gale Crater, Mars

Science.gov (United States)

Johnson, Jeffrey R.; Achilles, Cherie; Bell, James F.; Bender, Steve; Cloutis, Edward; Ehlmann, Bethany; Fraeman, Abigail; Gasnault, Olivier; Hamilton, Victoria E.; Le Mouélic, Stéphane; Maurice, Sylvestre; Pinet, Patrick; Thompson, Lucy; Wellington, Danika; Wiens, Roger C.

2017-12-01

As part of the Bagnold Dune campaign conducted by Mars Science Laboratory rover Curiosity, visible/near-infrared reflectance spectra of dune sands were acquired using Mast Camera (Mastcam) multispectral imaging (445-1013 nm) and Chemistry and Camera (ChemCam) passive point spectroscopy (400-840 nm). By comparing spectra from pristine and rover-disturbed ripple crests and troughs within the dune field, and through analysis of sieved grain size fractions, constraints on mineral segregation from grain sorting could be determined. In general, the dune areas exhibited low relative reflectance, a weak 530 nm absorption band, an absorption band near 620 nm, and a spectral downturn after 685 nm consistent with olivine-bearing sands. The finest grain size fractions occurred within ripple troughs and in the subsurface and typically exhibited the strongest 530 nm bands, highest relative reflectances, and weakest red/near-infrared ratios, consistent with a combination of crystalline and amorphous ferric materials. Coarser-grained samples were the darkest and bluest and exhibited weaker 530 nm bands, lower relative reflectances, and stronger downturns in the near-infrared, consistent with greater proportions of mafic minerals such as olivine and pyroxene. These grains were typically segregated along ripple crests and among the upper surfaces of grain flows in disturbed sands. Sieved dune sands exhibited progressive decreases in reflectance with increasing grain size, as observed in laboratory spectra of olivine size separates. The continuum of spectral features observed between the coarse- and fine-grained dune sands suggests that mafic grains, ferric materials, and air fall dust mix in variable proportions depending on aeolian activity and grain sorting.

Study of Black Sand Particles from Sand Dunes in Badr, Saudi Arabia Using Electron Microscopy

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Haider Abbas Khwaja

2015-08-01

Full Text Available Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic sand. The study used multiple high resolution electron microscopies to study the morphologies, emission source types, size, and elemental composition of the particles, and to evaluate the presence of surface “coatings or contaminants” deposited or transported by the black sand particles. White sand was comprised of natural coarse particles linked to wind-blown releases from crustal surfaces, weathering of igneous/metamorphic rock sources, and volcanic activities. Black sand particles exhibited different morphologies and microstructures (surface roughness compared with the white sand and volcanic sand. Morphological Scanning Electron Microscopy (SEM and Laser Scanning Microscopy (LSM analyses revealed that the black sand contained fine and ultrafine particles (50 to 500 nm ranges and was strongly magnetic, indicating the mineral magnetite or elemental iron. Aqueous extracts of black sands were acidic (pH = 5.0. Fe, C, O, Ti, Si, V, and S dominated the composition of black sand. Results suggest that carbon and other contaminant fine particles were produced by fossil-fuel combustion and industrial emissions in heavily industrialized areas of Haifa and Yanbu, and transported as cloud condensation nuclei to Douf Mountain. The suite of techniques used in this study has yielded an in-depth characterization of sand particles. Such information will be needed in future environmental, toxicological, epidemiological, and source apportionment studies.

Seabed Gradient Controlling Onshore Transport Rates of Surf Sand during Beach Retreat by Sea Level Rise

Science.gov (United States)

Lee, Hee Jun; Yi, Hi-Il

2018-03-01

A simple relationship is proposed for the onshore transport rates of surf-zone sand to evaluate the beach retreat caused by sea level rise. It suggests that the preservation potential of surf sand is proportional inversely to the seabed gradient during beach retreat. According to this relationship, the erosional remnants of surf sand would be more readily developed on a gentler shelf collectively as transgressive sand sheets. This finding may explain the previous studies regarding the Korean shelves that proposed that the Holocene transgressive sand sheets (HTSS) occur not in the steep eastern shelf but in the gentle western shelf. In line with such presence/absence of the HTSS are the results from some coastal seismic profiles obtained in the present study. The profiles indicate that sand deposits are restricted within the nearshore in the eastern coast, whereas they are persistently traceable to the offshore HTSS in the western coast. Tide is proven to have a negligible influence on the total duration of surf-zone processes. This study may be useful in predicting the consequences of the beach retreat that takes place worldwide as sea levels rise as a result of global warming.

The investigation of radionuclides distributions in beach sand by ...

African Journals Online (AJOL)

The investigation of radionuclides distributions in beach sand by means of GIS techniques. ... The PDF file you selected should load here if your Web browser has a PDF reader plug-in installed (for example, a recent version of Adobe Acrobat Reader). If you would like more information about how to print, save, and work ...

Grain-size variations on a longitudinal dune and a barchan dune

Science.gov (United States)

Watson, Andrew

1986-01-01

The grain-size characteristics of the sand upon two dunes—a 40 m high longitudinal dune in the central Namib Desert and a 6.0 m high barchan in the Jafurah sand sea of Saudi Arabia—vary with position on the dunes. On the longitudinal dune, median grain size decreases, sorting improves and the grain-size distributions are less skewed and more normalized toward the crest. Though sand at the windward toe is distinct, elsewhere on the dune the changes in grain-size characteristics are gradual. An abrupt change in grain size and sorting near the crest—as described by Bagnold (1941, pp. 226-229)—is not well represented on this dune. Coarse grains remain as a lag on concave slope units and small particles are winnowed from the sand on the steepest windward slopes near the crest. Avalanching down slipfaces at the crest acts only as a supplementary grading mechanism. On the barchan dune median grain size also decreases near the crest, but sorting becomes poorer, though the grain-size distributions are more symmetric and more normalized. The dune profile is a Gaussian curve with a broad convex zone at the apex upon which topset beds had accreted prior to sampling. Grain size increases and sorting improves down the dune's slipface. However, this grading mechanism does not influence sand on the whole dune because variations in wind regime bring about different modes of dune accretion. On both dunes, height and morphology appear to influence significantly the grain-size characteristics.

Field Evaluation/Demonstration of a Multisegmented Dewatering System for Accreting Beach Sand in a High-Wave-Energy Environment

National Research Council Canada - National Science Library

Curtis, William

1998-01-01

This study documents the use of beach dewatering systems to accrete beach sand and minimize erosion, and to develop quantitative guidance for constructing and operating beach dewatering installations...

Method of Relating Grain Size Distribution to Hydraulic Conductivity in Dune Sands to Assist in Assessing Managed Aquifer Recharge Projects: Wadi Khulays Dune Field, Western Saudi Arabia

KAUST Repository

Lopez Valencia, Oliver Miguel; Jadoon, Khan; Missimer, Thomas

2015-01-01

Planning for use of a dune field aquifer for managed aquifer recharge (MAR) requires that hydraulic properties need to be estimated over a large geographic area. Saturated hydraulic conductivity of dune sands is commonly estimated from grain size

Laboratory coupling tests for optimum land streamer design over sand dunes surface

KAUST Repository

Almalki, Hashim; Alata, Mohanad; Alkhalifah, Tariq Ali

2012-01-01

The cost of data acquisition in land is becoming a major issue as we strive to cover larger areas with seismic surveys at high resolution. Over sand dunes the problem is compounded by the week coupling obtain using geophones, which often forces us

Ground-Water Flow Direction, Water Quality, Recharge Sources, and Age, Great Sand Dunes National Monument, South-Central Colorado, 2000-2001

Science.gov (United States)

Rupert, Michael G.; Plummer, Niel

2004-01-01

Great Sand Dunes National Monument is located in south-central Colorado along the eastern edge of the San Luis Valley. The Great Sand Dunes National Monument contains the tallest sand dunes in North America; some rise up to750 feet. Important ecological features of the Great Sand Dunes National Monument are palustrine wetlands associated with interdunal ponds and depressions along the western edge of the dune field. The existence and natural maintenance of the dune field and the interdunal ponds are dependent on maintaining ground-water levels at historic elevations. To address these concerns, the U.S. Geological Survey conducted a study, in collaboration with the National Park Service, of ground-water flow direction, water quality, recharge sources, and age at the Great Sand Dunes National Monument. A shallow unconfined aquifer and a deeper confined aquifer are the two principal aquifers at the Great Sand Dunes National Monument. Ground water in the unconfined aquifer is recharged from Medano and Sand Creeks near the Sangre de Cristo Mountain front, flows underneath the main dune field, and discharges to Big and Little Spring Creeks. The percentage of calcium in ground water in the unconfined aquifer decreases and the percentage of sodium increases because of ionic exchange with clay minerals as the ground water flows underneath the dune field. It takes more than 60 years for the ground water to flow from Medano and Sand Creeks to Big and Little Spring Creeks. During this time, ground water in the upper part of the unconfined aquifer is recharged by numerous precipitation events. Evaporation of precipitation during recharge prior to reaching the water table causes enrichment in deuterium (2H) and oxygen-18 (18O) relative to waters that are not evaporated. This recharge from precipitation events causes the apparent ages determined using chlorofluorocarbons and tritium to become younger, because relatively young precipitation water is mixing with older waters

Radiogenic heavy minerals in Brazilian beach sand

International Nuclear Information System (INIS)

Malanca, A.

1998-01-01

Sand samples collected on the beaches of the 'radioactive' Brazilian town of Guarapari were first separated by flotation in bromoform and successively divided into various magnetic fractions with a Franz isodynamic separator. concentrations of background radionuclides in samples of monazite, ilmenite, and zircon were determined by a γ-ray spectrometer. Chemical composition of monazite, ilmenite and magnetite were assessed by means of an electron microprobe. Monazite resulted to be relatively rich in ThO 2 whose abundance ranged from 5.3 to 7.7 (wt%). (author)

Sand Dune Ridge Alignment Effects on Surface BRF over the Libya-4 CEOS Calibration Site

Directory of Open Access Journals (Sweden)

Yves M. Govaerts

2015-02-01

Full Text Available The Libya-4 desert area, located in the Great Sand Sea, is one of the most important bright desert CEOS pseudo-invariant calibration sites by its size and radiometric stability. This site is intensively used for radiometer drift monitoring, sensor intercalibration and as an absolute calibration reference based on simulated radiances traceable to the SI standard. The Libya-4 morphology is composed of oriented sand dunes shaped by dominant winds. The effects of sand dune spatial organization on the surface bidirectional reflectance factor is analyzed in this paper using Raytran, a 3D radiative transfer model. The topography is characterized with the 30 m resolution ASTER digital elevation model. Four different regions-of-interest sizes, ranging from 10 km up to 100 km, are analyzed. Results show that sand dunes generate more backscattering than forward scattering at the surface. The mean surface reflectance averaged over different viewing and illumination angles is pretty much independent of the size of the selected area, though the standard deviation differs. Sun azimuth position has an effect on the surface reflectance field, which is more pronounced for high Sun zenith angles. Such 3D azimuthal effects should be taken into account to decrease the simulated radiance uncertainty over Libya-4 below 3% for wavelengths larger than 600 nm.

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

Dynamics of Unusual Debris Flows on Martian Sand Dunes

Science.gov (United States)

Miyamoto, Hideaki; Dohm, James M.; Baker, Victor R.; Beyer, Ross A.; Bourke, Mary

2004-01-01

Gullies that dissect sand dunes in Russell impact crater often display debris flow-like deposits in their distal reaches. The possible range of both the rheological properties and the flow rates are estimated using a numerical simulation code of a Bingham plastic flow to help explain the formation of these features. Our simulated results are best explained by a rapid debris flow. For example, a debris flow with the viscosity of 10(exp 2) Pa s and the yield strength of 10(exp 2) Pa can form the observed deposits with a flow rate of 0.5 cu m/s sustained over several minutes and total discharged water volume on the order of hundreds of cubic meters, which may be produced by melting a surface layer of interstitial ice within the dune deposits to several centimeters depth.

Natural and anthropogenic factors affecting freshwater lenses in coastal dunes of the Adriatic coast

Science.gov (United States)

Cozzolino, Davide; Greggio, Nicolas; Antonellini, Marco; Giambastiani, Beatrice Maria Sole

2017-08-01

This study characterizes the near-shore portion of the shallow coastal aquifer included in the Ravenna area (Northern Italy) with special attention to the roles of coastal dunes as freshwater reservoirs and their buffer on groundwater salinity. The paper focuses on the presence and evolution of freshwater lenses below coastal dunes and highlights the existing differences between preserved natural dunes and dunes strongly affected by human intervention. The influence that multiple natural and anthropogenic factors, such as land cover, local drainage network, and beach erosion have on the presence, size and evolution of the freshwater lenses in the aquifer is quantified and discussed. The methodology includes multiple seasonal monitoring and sampling campaigns of physical (water level, salinity, and temperature) and chemical (major cations and anions) groundwater parameters. Results indicate that freshwater lenses, where existing, are limited in thickness (about 1-2 m). Proximity to drainage ditches as well as limited dune elevation and size do not allow the formation and permanent storage of large freshwater lenses in the aquifer below the dunes. The pine forest land cover, that replaced the typical bush or sand cover, intensifies evapotranspiration reducing net infiltration and freshwater storage. The cation species distribution in the water shows that a freshening process is ongoing in preserved natural sites with stable or advancing beaches, whereas a salinization process is ongoing in anthropogenic-impacted areas with strongly-fragmented dune systems. Currently, the thin freshwater lenses in the shallow Ravenna coastal aquifer are limited in space and have no relevance for irrigation or any other human activity. The dune-beach system, however, is the recharge zone of the coastal aquifer and its protection is important to reduce water and soil salinization, which in turn control the health of the whole coastal ecosystem.

The role of streamline curvature in sand dune dynamics: evidence from field and wind tunnel measurements

Science.gov (United States)

Wiggs, Giles F. S.; Livingstone, Ian; Warren, Andrew

1996-09-01

Field measurements on an unvegetated, 10 m high barchan dune in Oman are compared with measurements over a 1:200 scale fixed model in a wind tunnel. Both the field and wind tunnel data demonstrate similar patterns of wind and shear velocity over the dune, confirming significant flow deceleration upwind of and at the toe of the dune, acceleration of flow up the windward slope, and deceleration between the crest and brink. This pattern, including the widely reported upwind reduction in shear velocity, reflects observations of previous studies. Such a reduction in shear velocity upwind of the dune should result in a reduction in sand transport and subsequent sand deposition. This is not observed in the field. Wind tunnel modelling using a near-surface pulse-wire probe suggests that the field method of shear velocity derivation is inadequate. The wind tunnel results exhibit no reduction in shear velocity upwind of or at the toe of the dune. Evidence provided by Reynolds stress profiles and turbulence intensities measured in the wind tunnel suggest that this maintenance of upwind shear stress may be a result of concave (unstable) streamline curvature. These additional surface stresses are not recorded by the techniques used in the field measurements. Using the occurrence of streamline curvature as a starting point, a new 2-D model of dune dynamics is deduced. This model relies on the establishment of an equilibrium between windward slope morphology, surface stresses induced by streamline curvature, and streamwise acceleration. Adopting the criteria that concave streamline curvature and streamwise acceleration both increase surface shear stress, whereas convex streamline curvature and deceleration have the opposite effect, the relationships between form and process are investigated in each of three morphologically distinct zones: the upwind interdune and concave toe region of the dune, the convex portion of the windward slope, and the crest-brink region. The

Sand erosion at the toe of a gabion-protected dune face

NARCIS (Netherlands)

Chapman, A.

1992-01-01

The purpose of this research project was to study the manner in which erosion takes place the the toe of a dune slope protected by gabions, and to examine the response of the gabions to this erosion. A sand slope overlaid by model gabions was subjected to wave attack in a hydraulic flume, and

Ilmenite Mineral's Recovery from Beach Sand Tailings

International Nuclear Information System (INIS)

Mulaba-Bafubiandi, Antoine F.; Mukendi-Ngalula, David; Waanders, Frans B.

2002-01-01

The mineral ilmenite is the major source of rutile for industrial use and is of interest to paint and fertiliser industries. Enormous unutilised tailing dams lie on the eastern coast of the South Africa. Although covered by a simulation of the original indigenous vegetation, these tailings are still ilmenite bearing and of economic value. Tailings emanating from beach sand mineral slimes dams of the Kwazulu-Natal area (South Africa) have been processed. Screening, flotation, spiral concentration and magnetic separation methods were used either separately or successively. The present work sheds light on alternative routes for the extraction of the ilmenite, from these tailings. It moreover points out the usefulness of the Moessbauer spectroscopy in the mineral processing product monitoring. Tailings from the beach sands were used in the present study after the economic industrial minerals zirconia, ilmenite and rutile had been extracted in previous mining operations. About 61% natural ilmenite recovery was observed in the flotation concentrate of a Humphrey Spiral concentrate while a 62% recovery of hematite was found in the flotation tailings. The combination of screening, spiral concentration and magnetic separation, and flotation yielded a product with the highest ilmenite and hematite concentration being 71% and 19%, respectively. A natural ilmenite mineral, containing 87% ilmenite and 13% hematite, could be produced and extracted from the tailings of the flotation process, collected subsequently to the spiral concentration and the initial screening.

INVESTIGATION OF GEOTECHNICAL SPECIFICATIONS OF SAND DUNE SOIL: A CASE STUDY AROUND BAIJI IN IRAQ

Directory of Open Access Journals (Sweden)

Abbas J. Al-Taie

2013-11-01

Full Text Available ABSTRACT: While more than half the land surface of Iraq consists of deserts covered mainly with sand dunes, little research has taken place to study the characteristics and the behavior of dune soils. This paper directed toward studying the geotechnical properties of dune sands taken from Baiji city (northwest of Iraq. A vast laboratory testing program was carried out to achieve the purpose of this paper. The physical tests, chemical tests, X-ray diffraction analysis, permeability test, compaction characteristics, compressibility and collapsibility tests; and shear strength tests were included in this program. The results indicate that soil of Baiji sand dune exhibits prefer engineering properties according to their state. As such, this soil is considered suitable for use in geotechnical constructions. ABSTRAK: Walaupun lebih separuh daripada bumi Iraq terdiri daripada gurun yang dipenuhi dengan bukit-bukit pasir, tidak banyak penyelidikan dijalankan untuk mengkaji sifat-sifat dan ciri-ciri tanah pasir  tersebut. Kertas kerja ini menyelidik sifat geoteknikal bukit pasir yang diambil dari pekan Baiji (di bahagian barat utara Iraq.  Program penyelidikan makmal yang menyeluruh telah  dijalankan bagi mencapai objektif kajian ini. Ujian fizikal, ujian kimia, analisis belauan sinar-x, ujian kebolehtelapan, ciri pemadatan, faktor ketermampatan, ujian keruntuhan dan ujian kekuatan ricih diambilkira dalam program ini. Keputusan menunjukkan bahawa tanih bukit pasir Baiji mengutamakan ciri kejuruteraan berdasarkan keadaannya. Oleh itu, tanah ini dianggap sesuai untuk kegunaan pembinaan geoteknikal.

Sedimentology, geochemistry and rock magnetic properties of beach sands in Galapagos Islands - implications for nesting marine turtles

Science.gov (United States)

Perez-Cruz, L.; Urrutia-Fucugauchi, J.; Vazquez-Gutierrez, F.; Carranza-Edwards, A.

2007-12-01

Marine turtles are well known for their navigation ability in the open ocean and fidelity to nesting beaches. Green turtle adult females migrate from foraging areas to island nesting beaches, traveling hundreds or thousands of kilometers each way. The marine turtle breeding in the Galapagos Islands is the Green Sea Turtle (Chelonia mydas agassisi); fairly common throughout the islands but with nesting sites located at Las Bachas (Santa Cruz), Barahona and Quinta Playa (Isabela), Salinas (Baltra), Gardner Bay (Española) and Bartolomé Islet. In order to characterize and to identify the geochemical signature of nesting marine turtle beaches in Galapagos Islands, sedimentological, geochemical and rock magnetic parameters are used. A total of one hundred and twenty sand samples were collected in four beaches to relate compositional characteristics between equivalent areas, these are: Las Bachas, Salinas, Barahona and Quinta Playa. Grain size is evaluated using laser particle analysis (Model Coulter LS 230). Bulk ICP-MS geochemical analysis is performed, following trace elements are analyzed: Al, V, Cr, Co, Ni, Cu, Zn, Cd, Ba, Pb, Fe, Mn, K, Na, Mg, Sr, Ca and Hg; and low-field magnetic susceptibility is measured in all samples at low and high frequencies. Granulometric analysis showed that Barahona and Quinta Playa are characterized for fine grained sands. In contrast, Salinas and Las Bachas exhibit medium to coarse sands. Trace metals concentrations and magnetic susceptibility show different distribution patterns in the beach sands. Calcium is the most abundant element in the samples. In particular, Co, K, and Na show similar concentrations in the four beaches. Las Bachas beach shows highest concentrations of Pb and Hg (maximum values 101.1 and 118.5 mg/kg, respectively), we suggest that the enrichment corresponds to an anthropogenic signal. Salinas beach samples show high concentrations of Fe, V, Cr, Zn, Mn and the highest values of magnetic susceptibility (maximum

A proxy late Holocene climatic record deduced from northwest Alaskan beach ridges

International Nuclear Information System (INIS)

Mason, O.K.; Jordan, J.W.

1991-01-01

A climatically-sensitive, oscillatory pattern of progradation and erosion is revealed in late Holocene accretionary sand ridge and barrier island complexes of Seward Peninsula, northwest Alaska. Archaeological and geological radiocarbon dates constrain the authors chronology for the Cape Espenberg beach ridge plain and the Shishmaref barrier islands, 50 km to the southwest. Cape Espenberg, acts as the depositional sink for the northeastward longshore transport system and contains the oldest sedimentary deposits: based on 3700±90 B.P. (β-23170) old grass from a paleosol capping a low dune facies. The oldest date on the Shishmaref barrier islands is 1550±70 B.P. (β-23183) and implies that the modem barrier is a comparatively recent phenomenon. Late Holocene sedimentation varies between intervals of erosion and rapid progradation. During erosional periods higher dunes are built atop beach ridges: as between 3000-2000 yrs. BP and intermittently from 1000 BP to the present. At other times, rapid progradation predominated, generating wide swales and low beach ridges without dunes. Tentatively, dune formation is correlative with the Neo-glacial and Little Ice Age glacial advances and increased alluviation in north Alaska. Rapid progradation is contemporaneous with warmer intervals of soil and peat formation atop alluvial terraces, dated to ca. 4000-3500 and 2000-1000 yrs. B.P. In the record of the last 1000 years, dune building is correlative with heightened storminess, as reflected in northwest Alaska tree-ring chronologies and weather anomalies such as spring dust storms and winter thunderstorms in East Asian locations

TL studies of quaternary biogenic carbonate deposits of Saurashtra, Western India

International Nuclear Information System (INIS)

Patel, M.P.; Bhatt, Nilesh; Murthy, K.V.R.

1992-01-01

The quaternary biogenic carbonate deposits of Saurashtra, coastal as well as inland, comprise the beach rocks, miliolites and the stabilised sand dunes. The beach rocks contain the varieties of megafossils and broken shell fragments while the miliolites are granular made up of medium to fine grained, well sorted, abraded to finely abraded and even pelletised microfossils and shell fragments. The various constituents of the beach rocks and miliolites are cemented together by a fine calcite cement. The carbonate sand dunes contain relatively less amount of biogenic material and are rich in quartz. Age wise, the well consolidated beach rocks and miliolites are older (middle to later upper pleistocene) as compared to poorly consolidated coastal stabilised younger sand dunes (holocene). Chemically the former are rich in CaCO 3 while the latter are rich in SiO 2 . TL studies of the representative samples of beach rocks, miliolites and sand dunes clearly suggest that the glow curves of beach rocks and miliolites differ from that of sand dunes. Again, the existence of close similarity between the ATL/NTL curves for beach rocks and miliolites substantiate their close affinity in the field. (author). 14 refs., 2 tabs., 2 figs

Interaction of petroleum mulching, vegetation restoration and dust fallout on the conditions of sand dunes in southwest of Iran

Science.gov (United States)

Azoogh, Liela; Khalili moghadam, Bijan; Jafari, Siroos

2018-06-01

In the past half-century, petroleum mulching-biological fixation (PM-BF) practices have been employed to stabilize sand dunes in Iran. However, the effects of PM-BF practices on the attributes of sand dunes and the dispersion of heavy metals of mulch have been poorly understood. To this end, three regions treated with PM-BF for 5, 20, and 40 years and a control region with no PM-BF were studied. Samples of soil properties were taken at the depths of 0-10 cm and 10-50 cm, with three replications, in Khuzestan Province. The results showed that PM-BF practices promoted the restoration of vegetation cover in the sand dunes. In addition, these practices increased the deposition of dust particles, gradually increasing the magnitudes of palygorskite and smectite clays over time. The interactions between dust deposition and PM-BF practices significantly altered the chemical and physical properties of the dunes. PM-BF practices increased soil organic matter (184-287%), cation exchangeable capacity (142-209%), electrical conductivity (144-493%), clay content (134-196%), and penetration resistance (107-170%) compared to the region with no PM-BF practices. Furthermore, petroleum mulching significantly increased the amount of Ni (1.19%), Cd (1.55%), Pb (1.08%), Cu (1.34%), Zn (1.38%), Mn (1.66%), and Fe (1.15%). However, in the long term, these elements will probably leach linearly as a consequence of an increase in organic matter and soil salinity in the light texture of sand dunes.

Probabilistic estimation of dune retreat on the Gold Coast, Australia

Science.gov (United States)

Palmsten, Margaret L.; Splinter, Kristen D.; Plant, Nathaniel G.; Stockdon, Hilary F.

2014-01-01

Sand dunes are an important natural buffer between storm impacts and development backing the beach on the Gold Coast of Queensland, Australia. The ability to forecast dune erosion at a prediction horizon of days to a week would allow efficient and timely response to dune erosion in this highly populated area. Towards this goal, we modified an existing probabilistic dune erosion model for use on the Gold Coast. The original model was trained using observations of dune response from Hurricane Ivan on Santa Rosa Island, Florida, USA (Plant and Stockdon 2012. Probabilistic prediction of barrier-island response to hurricanes, Journal of Geophysical Research, 117(F3), F03015). The model relates dune position change to pre-storm dune elevations, dune widths, and beach widths, along with storm surge and run-up using a Bayesian network. The Bayesian approach captures the uncertainty of inputs and predictions through the conditional probabilities between variables. Three versions of the barrier island response Bayesian network were tested for use on the Gold Coast. One network has the same structure as the original and was trained with the Santa Rosa Island data. The second network has a modified design and was trained using only pre- and post-storm data from 1988-2009 for the Gold Coast. The third version of the network has the same design as the second version of the network and was trained with the combined data from the Gold Coast and Santa Rosa Island. The two networks modified for use on the Gold Coast hindcast dune retreat with equal accuracy. Both networks explained 60% of the observed dune retreat variance, which is comparable to the skill observed by Plant and Stockdon (2012) in the initial Bayesian network application at Santa Rosa Island. The new networks improved predictions relative to application of the original network on the Gold Coast. Dune width was the most important morphologic variable in hindcasting dune retreat, while hydrodynamic variables, surge and

PANTAI PASIR PADI (PADDY SAND BEACH OF BANGKA ISLAND; CRABS (Scopimera sp POPULATION, FEEDING BEHAVIOUR AND THEIR BIRD PREDATOR

Directory of Open Access Journals (Sweden)

Hanifa Marisa

2016-11-01

Full Text Available An observation about beach crab (Scopimera sp population, their feeding behaviour and predator bird had been done at October 9 th, 2014 in Pantai Pasir Padi, Eastern Bangka Island beach, near Pangkal Pinang town. Ten 1 meter square plots were put at sandy beach and number of Scopimera sp be counted by the number of their hole nest home. Their feeding behaviour observed directly by eye-watching and video making. The threatening of bird predator was noted too.  The investigation find out that the mean of crabs population is 17 individu/m2 .  They come out from home hole for feeding around by sieving wet sand that be taken by front legs, obsorb organic nutrious material by mouth and kick residual sand to behind legs, move it as a small sand ball to right of left back side.  Production of small ball sand were about 15 - 30 balls /per minute. For making the nest hole, bigger sand ball were produced about 7 – 9 ball/minute; ball colour is same with under layer beach sand; quite grey. The crabs run instinctivey fast, when the threat come from their natural enemy, predator bird, Actitis hypoleucos.  Bird searching behaviour look adapted to the fast run of crab. Keywords: Scopimera sp, Actitis hypoleucos, small sand ball, predator, behaviour

A field study of flow turbulence and sediment transport dynamics on a beach surface in the lee of a coastal foredune under offshore winds

Science.gov (United States)

Baas, A. C.; Jackson, D.; Cooper, J. A.; Lynch, K.; Delgado-Fernandez, I.; Beyers, M.; Lee, Z. S.

2010-12-01

The past decade has seen a growing body of research on the relation between turbulence in the wind and the resultant transport of sediment over active sand surfaces. Widespread use of sonic anemometry and high-frequency sand transport sensors and traps have facilitated recent field studies over dunes and beach surfaces, to move beyond monitoring of mean wind speed and bulk transport to more detailed measurements at much higher spatio-temporal resolutions. In this paper we present results of a field study conducted in the recirculation flow and re-attachment zone on a beach behind a foredune at Magilligan Strand, Northern Ireland. The offshore winds over the foredune at this site are associated with flow separation and reversal located over the beach surface in the lee of the dune row, often strong enough to induce sand transport toward the toe of the foredune (‘against’ the overall offshore flow). The re-attachment and recirculation zone are associated with strongly turbulent fluid flow and complex streamlines that do not follow the underlying topography. High frequency (25 Hz) wind and sand transport data were collected at a grid of point locations distributed over the beach surface between 35 m to 55 m distance from the 10 m high dune crest, using ultrasonic anemometers at 0.5 m height and co-located load cell traps and Safires at the bed surface. The wind data are used to investigate the role of Reynolds shear stresses and quadrant analysis techniques for identifying burst-sweep events in relation to sand transport events. This includes an assessment of the issues involved with data rotations for yaw, pitch, and roll corrections relative to complex flow streamlines, and the subsequently derived turbulence parameters based on fluctuating vector components (u’, v’, w’). Results illustrate how transport may exist under threshold mean velocities because of the role played by coherent flow structures, and the findings corroborate previous findings that

On the Internal Structure of Mobile Barchan Sand Dunes due to Granular Processes

Science.gov (United States)

Vriend, N. M.; Arran, M.; Louge, M. Y.; Hay, A. G.; Valance, A.

2017-12-01

In this work, we visualize the internal structure of mobile barchan desert dunes at the avalanche scale. We reveal an intriguing history of dune building using a novel combination of local sand sampling and advanced geophysical techniques resulting in high resolution measurements of individual avalanche events. Due to progressive rebuilding, granular avalanching, erosional and depositional processes, these marching barchan dunes are reworked every few years and a characteristic zebra-pattern (figure 1a), orientated parallel to the slipface at the angle of repose, appears at regular intervals. We present scientific data on the structure obtained from several mobile barchan dunes of different sizes during recent desert field campaigns (2014, 2015, 2017) in a mobile barchan dune field in Qatar (25.01°N, 51.34°E in the AlWakrah municipality). The site has been equipped with a weather station and has been regularly visited by a multidisciplinary research team in recent years (e.g. [1]). By applying high-frequency (1200 MHz) ground penetrating radar (GPR) transects across the midline (figure 1b) we map the continuous evolution of this cross-bedding at high resolution deep within the dune. The GPR reveals a slope reduction of the slipface near the base of the dune; evidence of irregular wind reversals; and the presence of a harder aeolian cap around the crest and extending to the brink. The data is supplemented with granulometry from layers stabilized by dyed water injection and uncovered by excavating vertical walls perpendicular to old buried avalanches. We attribute visible differences in water penetration between adjacent layers to fine particle segregation processes in granular avalanches. This work was made possible by the support of NPRP grant 6-059-2-023 from the Qatar National Research Fund to MYL and AGH, and a Royal Society Dorothy Hodgkin Research Fellowship to NMV. We thank Jean-Luc Métayer for performing detailed particle size distribution measurements

Mineralogical characterization of beach sand minerals: traditional and modern approaches

International Nuclear Information System (INIS)

Krishnamurthy, P.

2016-01-01

Precise identification of beach sand minerals is an essential prerequisite for the reserve estimation of a given deposit and also in the subsequent evaluation of the process flow sheet for its optimal recovery. Traditional methods that are used for the identification of the beach sand minerals such as magnetite, hematite, ilmenite, rutile, anatase, zircon, garnet, sillimanite, monazite, quartz and others include heavy liquid separation (bromoform and methylene iodide) and studying the optical properties of the grains from different fractions so as to identify the specific phases in a sample. Grain counting of specific minerals from a given sievefraction under a petrological microscope to estimate the mode and their subsequent conversion in to weight percent fractions forms the critical second stage that is followed by the reserve estimates. These methodologies are tedious and time consuming often involving a few days for a single sample. The paper introduces the numerous instrumental methods (XRF, XRD - Rietveld and CCSEM) of mineral speciation and their qualification in with case studies from the west coast deposits in India

Measuring the spatial variation in surface moisture on a coastal beach with an infra-red terrestrial laser scanner

Science.gov (United States)

Smit, Yvonne; Donker, Jasper; Ruessink, Gerben

2016-04-01

Coastal sand dunes provide essential protection against marine flooding. Consequently, dune erosion during severe storms has been studied intensively, resulting in well-developed erosion models for use in scientific and applied projects. Nowadays there is growing awareness that similarly advanced knowledge on dune recovery and growth is needed to predict future dune development. For this reason, aeolian sand transport from the beach into the dunes has to be investigated thoroughly. Surface moisture is a major factor limiting aeolian transport on sandy beaches. By increasing the velocity threshold for sediment entrainment, pick-up rates reduce and the fetch length increases. Conventional measurement techniques cannot adequately characterize the spatial and temporal distribution of surface moisture content required to study the effects on aeolian transport. Here we present a new method for detecting surface moisture at high temporal and spatial resolution using the RIEGL VZ-400 terrestrial laser scanner (TLS). Because this TLS operates at a wavelength near a water absorption band (1550 nm), TLS reflectance is an accurate parameter to measure surface soil moisture over its full range. Three days of intensive laser scanning were performed on a Dutch beach to illustrate the applicability of the TLS. Gravimetric soil moisture samples were used to calibrate the relation between reflectance and surface moisture. Results reveal a robust negative relation for the full range of possible surface moisture contents (0% - 25%). This relation holds to about 80 m from the TLS. Within this distance the TLS typically produces O(106-107) data points, which we averaged into soil moisture maps with a 0.25x0.25 m resolution. This grid size largely removes small moisture disturbances induced by, for example, footprints or tire tracks, while retaining larger scale trends. As the next step in our research, we will analyze the obtained maps to determine which processes affect the spatial and

Beach morphodynamics and types of foredune erosion generated by storms along the Emilia-Romagna coastline, Italy

Science.gov (United States)

Armaroli, Clara; Grottoli, Edoardo; Harley, Mitchell D.; Ciavola, Paolo

2013-10-01

The objectives of this study are to examine the response of a dune and beach system on the Adriatic coastline in northern Italy to the arrival of storms, compare it with seasonal (months) and medium-term (3-year) morphodynamic change, and evaluate results predicted by the numerical model XBeach. The studied coastline stretches 4 km from the Bevano River mouth to the north of the site to the township of Lido di Classe to the south, where the beach is protected by coastal structures. Fieldwork consisted of topographic profile surveys using RTK-DGPS technology (7 times over an approx. 3-year period). 103 samples of surface sediment were collected along 20 of the cross-shore profiles at 6 distinct cross-shore positions, selected on the basis of morphological beach characteristics. Data analyses of dune and beach slopes enabled the study area to be divided into 6 separate morphological zones using the spatial (longshore and cross-shore) variation of morphologies located on the backshore and intertidal beach observed in a preliminary survey of the area. Other criteria were a spatial consistency in beach slopes and/or presence/absence of intertidal morphologies identified in the aerial photographs and Lidar data. The swash zone slope did not show any significant variability for the entire area. A weak seasonal trend in the variability of the mean foredune slope was observed, with steeper slopes typically during winter and flatter slopes during summer. Analysis of grain size revealed that the beach sediment is well-sorted fine sand tending to medium, with a decreasing trend in size from the Bevano River mouth southwards towards Lido di Classe. According to the Masselink and Short (1993) classification, the natural part of the study site has an Intermediate Barred Beach (IBB) and following the Short (1999) classification, results in a modally LBT (longshore bar-trough) or LTT (low tide terrace) with a small section being TBR (transverse bar and rip). Storms are considered

Mapping the base of sand dunes using a new design of land-streamer for static correction applications

KAUST Repository

Almalki, H.

2012-05-16

The complex near-surface structure is a major problem in land seismic data. This is more critical when data acquisition takes place over sand dune surfaces, where the base of the sand acts as a trap for energy and, depending on its shape, can considerably distort conventionally acquired seismic data. Estimating the base of the sand dune surface can help model the sand dune and reduce its harmful influence on conventional seismic data. Among the current methods to do so are drilling upholes and using conventional seismic data to apply static correction. Both methods have costs and limitations. For upholes, the cost factor and their inability to provide a continuous model is well realized. Meanwhile, conventional seismic data lack the resolution necessary to obtain accurate modeling of the sand basement. We developed a method to estimate the sand base from land-streamer seismic acquisition that is developed and geared to sand surfaces. Seismic data acquisition took place over a sand surface in the Al-Thumamah area, where an uphole is located, using the developed land-streamer and conventional spiked geophone systems. Land-streamer acquisition not only provides a more efficient data acquisition system than the conventional spiked geophone approach, but also in our case, the land-streamer provided better quality data with a broader frequency bandwidth. Such data enabled us to do accurate near-surface velocity estimation that resulted in velocities that are very close to those measured using uphole methods. This fact is demonstrated on multiple lines acquired near upholes, and agreement between the seismic velocities and the upholes is high. The stacked depth seismic section shows three layers. The interface between the first and second layers is located at 7 m depth, while the interface between second and third layers is located at 68 m depth, which agrees with the uphole result. 2012 The Author(s).

Mapping the base of sand dunes using a new design of land-streamer for static correction applications

KAUST Repository

Almalki, H.; Alkhalifah, Tariq Ali

2012-01-01

The complex near-surface structure is a major problem in land seismic data. This is more critical when data acquisition takes place over sand dune surfaces, where the base of the sand acts as a trap for energy and, depending on its shape, can

The Early Shorebird Will Catch Fewer Invertebrates on Trampled Sandy Beaches.

Science.gov (United States)

Schlacher, Thomas A; Carracher, Lucy K; Porch, Nicholas; Connolly, Rod M; Olds, Andrew D; Gilby, Ben L; Ekanayake, Kasun B; Maslo, Brooke; Weston, Michael A

2016-01-01

Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories.

Natural radionuclides present in the beach sands of Guarapari and Anchieta, EspÍrito Santo, Brazil

International Nuclear Information System (INIS)

Aguilar, Victor J.; Takahashi, Laura C.

2017-01-01

The natural radioactivity was determined in the Espírito Santo sands, in Brazil, in eight beaches from Anchieta and Guarapari. In the methodology, the sands of each beach were collected, sifted, dried in the oven, and conditioned in Marinellis. Its weight was measured on the scale, and stored for 30 days for their secular equilibrium. Then, the gamma spectrometry measurement was performed. The specific activities for each beach were calculated and the radioactive balance of the 238 U and 232 Th series was also studied. From the standard deviation of the estimated error (S), the chi-square distribution parameter (R 2 ), the coefficient of determination R 2 , R-sq, and the adjusted R 2 , R-sq (adj) was studied. In the results, a regression curve (fitted line plot) was performed on the quality adjustment with a 95% confidence interval for the values found in Neptune, Além, Coninhos, Onça, Três Praias, Morcego and Padres beaches. The R 2 measured presented values close to 1. The beach Areia Vermelha presented a specific activity with a percentage of 98.41% in relation to the other beaches and very high activity compared to the world average. (author)

Comparison between the measurements of Radon Gas Concentrations and γ-ray intensities in Exploring the Black Sands at El-Burullus Beach

International Nuclear Information System (INIS)

Abdel-Razek, Y.A; Bakhit, A.F

2009-01-01

Ten well-located monitoring stations along El-Burullus beach were chosen to measure radon gas concentrations in the beach sands below surface, and γ-ray intensities at 10 cm above the surface. These stations were chosen to represent apparent concentrations of the black sands. Sand samples were collected from the different stations and analyzed to study the relation between the concentrations of the heavy minerals and the measured radon concentrations or the measured γ-ray intensities at these stations. It was found that radon gas concentrations measured at 6:00 Pm were about 2.82 times those measured at 1 :00 Pm due to diurnal variation of temperature. Measurements of radon gas concentrations inside the beach sands are found to be more reliable in qualitative exploration of black sands than the measurements of γ-ray intensities above the shore sands due to the random arrangement of the layers of these sands below surface

The recovery of rare earth elements (REE) from beach sands

International Nuclear Information System (INIS)

Petrache, Cristina A.; Santos, Gabriel P. Jr.; Fernandez, Lourdes G.; Castillo, Marilyn K.; Tabora, Estrellita U; Intoy, Socorro P.; Reyes, Rolando Y.

2005-01-01

This preliminary study describes a metallurgical process that will extract, recover and produce REE oxides from beach sands obtained from Ombo, San Vicente, northern Palawan. The beach sands contain REE minerals of allanite and small amounts of monazite. Allanite is a sorosilicate mineral containing rare earths, thorium and uranium. Monazite is the anhydrous phosphate of cerium and the lanthanum group of rare earths with thorium commonly present in replacement for cerium and lanthanum. Collected beach sand were first pan-concentrated in-situ to produce heavy mineral concentrates. Screening using a 32 mesh (0.500 mm) sieve was done at the Nuclear Materials Research Laboratory to remove oversize sand particles. The -32 mesh fraction was treated with bromoform (sp. gr. 2.89) to separate the heavy minerals from siliceous gangue. Grinding to -325 mesh size (0.044mm) followed to liberate the minerals prior to leaching. Two acids leachants were used - concentrated HCl for the first trial and a mixture of concentrated HCl and HNO 3 (10:1 volume ratio) for the second trial. Both leaching trials were carried out at 180 o C for 7 hours or until dry. The resulting leached residues were re-dissolved in concentrated HCl and filtered. Ionquest R 801, an organophosphorous extractant, was added to the filtrate to separate the radioactive thorium from REE. Sodium hydroxide was added to the aqueous phase to precipitate the REE. After filtering the precipitate, it was dissolved in HCl. The acid solution was repeatedly extracted three (3) times with Ionquest R 801 to remove iron and other contaminants. Ammonium hydroxide was added to the final solution to precipitate the REE, which was then dried in the oven. The precipitate was calcined/roasted in the furnace at two different temperatures for different periods of time to burn off the organic matter and to form oxides. Results of the XRD analysis showed peaks of the calcined precipitate matching with the peaks of lanthanum oxide

Aeolian transport of seagrass (Posidonia oceanica) beach-cast to terrestrial systems

Science.gov (United States)

Jiménez, Maria A.; Beltran, Rafel; Traveset, Anna; Calleja, Maria Ll; Delgado-Huertas, Antonio; Marbà, Núria

2017-09-01

The annual export of the Mediterranean seagrass (Posidonia oceanica) litter to adjacent beaches and coastal dunes was quantified by examining the fortnight evolution of seagrass beach-cast volume on two beaches in the NW Mediterranean (Son Real and Es Trenc, Mallorca Island, Spain) for two years and analyzing the wind speed and direction obtained from the closest Meteorological Spanish Agency surface weather stations. The decomposition stage of the deposits was examined by analyzing the total hydrolysable amino acids, its percentage distribution and derived degradation indexes. Prevalent winds exceeding 6 m s-1, the coastline morphology and type of terrestrial vegetation determine the annual dynamics of the seagrass beach-cast. In the most protected beach (Son Real) the seagrass beach-cast remained nearly stationary during the two studied years while it exhibited wide annual fluctuations in the less protected one (Es Trenc). The amounts of P. oceanica wrack washed on Son Real and Es Trenc beaches, respectively, were estimated at 309 kg DW m coastline-1 yr-1 and 1359 kg DW m coastline-1 yr-1. They supplied between 20 kg CaCO3 m coastline-1 yr-1 and 47 kg CaCO3 m coastline-1 yr-1. Between 54% (Son Real) and 70% (Es Trenc) of seagrass beach-cast, respectively accounting for 1.5 kg N m coastline-1 yr-1 and 8.6 kg N m coastline-1 yr-1, were annually exported from the beaches to adjacent dune systems. Our results reveal that Mediterranean seagrass meadows might be an important source of materials, including sand and nutrients, for adjacent terrestrial systems, able to support their functioning.

Beach ridge sedimentology: field observation and palaeoenvironmental interpretation for Anegada Island, British Virgin Islands.

Science.gov (United States)

Cescon, Anna Lisa; Cooper, J. Andrew G.; Jackson, Derek W. T.

2014-05-01

Beach ridge landforms have been observed in different environments and in settings that range from polar to tropical. Their stratigraphy and sedimentology has received a limited amount of discussion in the literature (Tamura, 2012). In coastal geomorphology a beach ridge can be seen as a transitional deposit between onshore and offshore environments. They are regarded as representing high level wave action along a coastline. In the Caribbean the origin of beach ridges has been variously attributed to one of three extreme wave events: extreme swell, extreme storm or tsunami waves. Beach ridges are arranged in beach ridge plains where there is succession of the landforms and can be several kilometres long. Beach ridge accumulation is not continuous and the coast shows alternating accretion and erosion periods. The use of beach ridges as palaeostorm archives is therefore not straightforward. The temporal continuity of beach ridge formation is being assessed on the beach ridge plains of Anegada, British Virgin Islands (Lesser Antilles). This carbonate platform surrounded by a fringing reef contains two beach ridge plains. There are more than 30 ridges in the Atlantic facing- coast and around 10 in the south, Caribbean- facing coast. The sediments of the modern beaches are dominated by the sand fraction and are 100% biogenic origin due to the isolation of Anegada from terrestrial sediment sources. The beach ridge sections have been studied in different area of Anegada beach ridge plains and present low angle seaward-dipping bedding. The sand fraction is dominant in the stratigraphy with a few intact shells. At only one site were coral pebbles deposited in association with the sand fraction. Aeolian deposits represent the upper part of the beach ridges and reflect the stabilization of the beach ridges with ongoing accretion. The sedimentology of the contemporary beach and dunes will be discussed in terms of their implications for understanding beach ridge genesis and its

Assessment of beach and dune erosion and accretion using LiDAR: Impact of the stormy 2013-14 winter and longer term trends on the Sefton Coast, UK

Science.gov (United States)

Pye, Kenneth; Blott, Simon J.

2016-08-01

An important question for coastal management concerns the importance of individual storms and clusters of storms on longer term beach sediment budgets, beach and dune erosion, and coastal flood risk. Between October 2013 and March 2014 a series of deep Atlantic low pressure systems crossed the Northeast Atlantic, and strong winds, high waves and high water levels affected many coastal areas in the UK and other parts of western Europe. Net dune recession of up to 12.1 m occurred around Formby Point. On 5 December 2013 the highest water level ever recorded at Liverpool (6.22 m ODN) coincided with waves of Hs of 4.55 m and Tp of 9.3 s in Liverpool Bay. Wave trimming of the dune toe occurred along the entire length of the Sefton coast, but significant dune erosion occurred only where the upper beach (between the mean high water spring tide level and the dune toe) was dune system, mostly at Formby Point. However, some parts of the beach to the south of Formby Point gained sediment, indicating net north to south transport over the winter. When considered in a longer term context, the 2013-14 winter represents only a small perturbation on the longer-term coast trend of erosion at Formby Point and progradation to the north and south. Analysis of LiDAR data over a longer time period 1999-2014 indicated upper beach and dune sediment loss of 780 × 103 m3 from the north-central part of Formby Point, with net gains of 806 × 103 m3 and 2116 × 103 m3 in areas to the north and south, respectively. This indicates a net onshore transport of 2142 × 103 m3 from Liverpool Bay towards the coast between Birkdale and Altcar, with a further net total of 210 × 103 m3 transported towards the shore between Altcar and Crosby. In view of the demonstrated value of airborne LiDAR surveys for the quantification of storm impacts and longer term coastal changes, it is recommended that such surveys should be undertaken before and after each winter storm period, covering the area between mean low

Vegetated dune morphodynamics during recent stabilization of the Mu Us dune field, north-central China

Science.gov (United States)

Xu, Zhiwei; Mason, Joseph A.; Lu, Huayu

2015-01-01

The response of dune fields to changing environmental conditions can be better understood by investigating how changing vegetation cover affects dune morphodynamics. Significant increases in vegetation and widespread dune stabilization over the years 2000-2012 are evident in high-resolution satellite imagery of the Mu Us dune field in north-central China, possibly a lagged response to changing wind strength and temperature since the 1970s. These trends provide an opportunity to study how dune morphology changes with increasing vegetation stabilization. Vegetation expansion occurs mainly by expansion of pre-existing patches in interdunes. As vegetation spreads from interdunes onto surrounding dunes, it modifies their shapes in competition with wind-driven sand movement, primarily in three ways: 1) vegetation anchoring horns of barchans transforms them to parabolic dunes; 2) vegetation colonizes stoss faces of barchan and transverse dunes, resulting in lower dune height and an elongated stoss face, with shortening of barchan horns; and 3) on transverse dunes, the lee face is fixed by plants that survive sand burial. Along each of these pathways of stabilization, dune morphology tends to change from more barchanoid to more parabolic forms, but that transformation is not always completed before full stabilization. Artificial stabilization leads to an extreme case of "frozen" barchans or transverse dunes with original shapes preserved by rapid establishment of vegetation. Observations in the Mu Us dune field emphasize the point that vegetation growth and aeolian sand transport not only respond to external factors such as climate but also interact with each other. For example, some barchans lose sand mass during vegetation fixation, and actually migrate faster as they become smaller, and vegetation growth on a barchan's lower stoss face may alter sand transport over the dune in a way that favors more rapid stabilization. Conceptual models were generalized for the

Next-generation sequencing and culture-based techniques offer complementary insights into fungi and prokaryotes in beach sands.

Science.gov (United States)

Romão, Daniela; Staley, Christopher; Ferreira, Filipa; Rodrigues, Raquel; Sabino, Raquel; Veríssimo, Cristina; Wang, Ping; Sadowsky, Michael; Brandão, João

2017-06-15

A next-generation sequencing (NGS) approach, in conjunction with culture-based methods, was used to examine fungal and prokaryotic communities for the presence of potential pathogens in beach sands throughout Portugal. Culture-based fungal enumeration revealed low and variable concentrations of the species targeted (yeasts and dermatophytes), which were underrepresented in the community characterized by NGS targeting the ITS1 region. Conversely, NGS indicated that the potentially pathogenic species Purpureocillium liliacinum comprised nearly the entire fungal community. Culturable fecal indicator bacterial concentrations were low throughout the study and unrelated to communities characterized by NGS. Notably, the prokaryotic communities characterized revealed a considerable abundance of archaea. Results highlight differences in communities between methods in beach sand monitoring but indicate the techniques offer complementary insights. Thus, there is a need to leverage culture-based methods with NGS methods, using a toolbox approach, to determine appropriate targets and metrics for beach sand monitoring to adequately protect public health. Copyright © 2017. Published by Elsevier Ltd.

Natural radionuclides present in the beach sands of Guarapari and Anchieta, EspÍrito Santo, Brazil

Energy Technology Data Exchange (ETDEWEB)

Aguilar, Victor J.; Takahashi, Laura C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem; Fontainha, Críssia C.P.; Santos, Talita O.; Rocha, Zildete, E-mail: crissia@gmail.com, E-mail: zildete@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

The natural radioactivity was determined in the Espírito Santo sands, in Brazil, in eight beaches from Anchieta and Guarapari. In the methodology, the sands of each beach were collected, sifted, dried in the oven, and conditioned in Marinellis. Its weight was measured on the scale, and stored for 30 days for their secular equilibrium. Then, the gamma spectrometry measurement was performed. The specific activities for each beach were calculated and the radioactive balance of the {sup 238}U and {sup 232}Th series was also studied. From the standard deviation of the estimated error (S), the chi-square distribution parameter (R{sub 2}), the coefficient of determination R{sub 2}, R-sq, and the adjusted R{sub 2}, R-sq (adj) was studied. In the results, a regression curve (fitted line plot) was performed on the quality adjustment with a 95% confidence interval for the values found in Neptune, Além, Coninhos, Onça, Três Praias, Morcego and Padres beaches. The R{sub 2} measured presented values close to 1. The beach Areia Vermelha presented a specific activity with a percentage of 98.41% in relation to the other beaches and very high activity compared to the world average. (author)

View of sand dunes in the San Juan Province of Western Argentina

Science.gov (United States)

1975-01-01

A near vertical view of sand dunes in the San Juan Province of Western Argentina, as photographed from the Apollo spacecraft in Earth orbit during the joint U.S.-USSR Apollo Soyuz Test Project (ASTP) mission. The picture was taken at an altitude of 220 kilometers (136 statute miles). The photograph was taken at an altitude of 228 kilometers (141 statute miles).

Khnifiss Beach's Black Sand: Provenance and Transport Pathways Investigation Using Heavy Minerals' Characterization

Science.gov (United States)

Adnani, M.; Elbelrhiti, H.; Ahmamou, M.; Masmoudi, L.

2014-12-01

Arid areas in south of Morocco suffer from silting problem causing destruction of villages infrastructure, roads, agriculture land and oasis heritage. Black sand on Khnifiss beach near Tarfaya city (S-W Morocco) is marked by enrichment of heavy minerals. This later is an important fraction that could help to assess the provenance and transport pathways of sediment. The sand's origin investigation could be useful to fight against erosion and silting problems from the source of supply, to this end, mineralogical analysis was carried out in Khnifiss beach's sand using Optic Microscope and Scanning Electronic Microscope with dispersive energy (SEM- EDS), in addition to physico-chemical analysis provided by Electronic Microprobe. The results revealed: (i) a high grade of oxides (Rutile, Ilmenite, Magnetite, Ulvöspinel) in samples, (ii) silicates (Quartz, Clinopyroxene, feldspar, Zircon), (iii) phosphate (apatite) and (iv) carbonate (calcite). The dominance of iron oxides justifies the black sand's colour. Then, the mineral composition supposes interference between different origins: proximal source (Calcareous cliff) for calcite, distal sources of oxides and silicates are supposed to be eroded and carried by Drâa valley from granite and igneous rocks in Anti-Atlasic field. Another source supposed might be a proximal volcanic island (Canaries island).

Quantifying spatial and temporal trends in beach-dune volumetric changes using spatial statistics

Science.gov (United States)

Eamer, Jordan B. R.; Walker, Ian J.

2013-06-01

Spatial statistics are generally underutilized in coastal geomorphology, despite offering great potential for identifying and quantifying spatial-temporal trends in landscape morphodynamics. In particular, local Moran's Ii provides a statistical framework for detecting clusters of significant change in an attribute (e.g., surface erosion or deposition) and quantifying how this changes over space and time. This study analyzes and interprets spatial-temporal patterns in sediment volume changes in a beach-foredune-transgressive dune complex following removal of invasive marram grass (Ammophila spp.). Results are derived by detecting significant changes in post-removal repeat DEMs derived from topographic surveys and airborne LiDAR. The study site was separated into discrete, linked geomorphic units (beach, foredune, transgressive dune complex) to facilitate sub-landscape scale analysis of volumetric change and sediment budget responses. Difference surfaces derived from a pixel-subtraction algorithm between interval DEMs and the LiDAR baseline DEM were filtered using the local Moran's Ii method and two different spatial weights (1.5 and 5 m) to detect statistically significant change. Moran's Ii results were compared with those derived from a more spatially uniform statistical method that uses a simpler student's t distribution threshold for change detection. Morphodynamic patterns and volumetric estimates were similar between the uniform geostatistical method and Moran's Ii at a spatial weight of 5 m while the smaller spatial weight (1.5 m) consistently indicated volumetric changes of less magnitude. The larger 5 m spatial weight was most representative of broader site morphodynamics and spatial patterns while the smaller spatial weight provided volumetric changes consistent with field observations. All methods showed foredune deflation immediately following removal with increased sediment volumes into the spring via deposition at the crest and on lobes in the lee

Natural versus Urban dunes along the Emilia-Romagna coast, Northern Adriatic (Italy)

Science.gov (United States)

Corbau, Corinne; Simeoni, Umberto

2014-05-01

Beach-dune interaction models can be precious tools for land managers and policymakers. However, if the models are inaccurate, land use policies may be designed based on false pretences or assumptions leading to poor land management, long-term erosion and sustainability issues, and increased difficulties in maintaining the dynamic coastal systems. From the literature, it appears that even the most reliable beach-dunes interactions models are not applicable to all coastal systems (Short and Hesp, 1982; Psuty, 1988; Sherman and Bauer, 1993). The study aims to identify the morphological evolution of the Emilia-Romagna coastal dunes according to its natural and "human" characteristics and to classify groups of dunes with similar evolutionary patterns. The coastal area consists essentially of 130 km of low sandy coast, interrupted by vast lagoon areas, harbor jetties and numerous hard coastal defense structures that were built during the first half of the 20th century to protect the Emilia-Romagna coast against erosion. Today about 57% of the littoral is protected by hard defenses, which have modified the morphodynamic characteristics of the beach without inverting the negative coastal evolution's trend. From recent aerial photographs (2011), 62 coastal dunes have been identified and mapped. Furthermore, the dune analysis shows a variability of the "physical characteristics" of coastal-dune systems along the Emilia-Romagna coast. The dune height varies from 1 to 7 meters, the width of the beach and of the active dunes range respectively from 10 to 150 m and from 10 to 65 m. Three main factors may explain the variability of the "physical characteristics": 1- Firstly the frontal dunes may be of different states according to the classification of Hesp (2002) since they correspond to incipient foredunes, well-developed foredunes, blowouts, residual foredunes as well as reactivated relict foredunes, 2- This could also be related to a different orientation of the coastline

Effects of prolonged drought on the vegetation cover of sand dunes in the NW Negev Desert: Field survey, remote sensing and conceptual modeling

Science.gov (United States)

Siegal, Z.; Tsoar, H.; Karnieli, A.

2013-06-01

Luminescence dating of stable sand dunes in the large deserts of the world has shown several episodes of mobility during the last 30 k years. The logical explanation for the mobility of fixed dunes is severe drought. Though drought length can be estimated, the level of precipitation drop is unknown. The stabilized sand dunes of the northwestern Negev Desert, Israel have been under an unprecedented prolonged drought since 1995. This has resulted in a vast decrease of shrubs cover on the fixed sand dunes, which changes along the rainfall gradient. In the north, an average of 27% of the shrubs had wilted by 2009, and in the drier southern area, 68% of the shrubs had withered. This loss of shrubbery is not expected to induce dune remobilization because the existing bio-crust cover is not negatively affected by the drought. Eleven aerial photographs taken over the drier southern area from 1956 to 2005 show the change in shrub cover due to human impact and the recent severe drought.

Aeolian transport of seagrass ( Posidonia oceanica ) beach-cast to terrestrial systems

KAUST Repository

Jimé nez, Maria A.; Beltran, Rafel; Traveset, Anna; Calleja, Maria Ll; Delgado-Huertas, Antonio; Marbà , Nú ria

2017-01-01

The annual export of the Mediterranean seagrass (Posidonia oceanica) litter to adjacent beaches and coastal dunes was quantified by examining the fortnight evolution of seagrass beach-cast volume on two beaches in the NW Mediterranean (Son Real and Es Trenc, Mallorca Island, Spain) for two years and analyzing the wind speed and direction obtained from the closest Meteorological Spanish Agency surface weather stations. The decomposition stage of the deposits was examined by analyzing the total hydrolysable amino acids, its percentage distribution and derived degradation indexes. Prevalent winds exceeding 6 m s−1, the coastline morphology and type of terrestrial vegetation determine the annual dynamics of the seagrass beach-cast. In the most protected beach (Son Real) the seagrass beach-cast remained nearly stationary during the two studied years while it exhibited wide annual fluctuations in the less protected one (Es Trenc). The amounts of P. oceanica wrack washed on Son Real and Es Trenc beaches, respectively, were estimated at 309 kg DW m coastline−1 yr−1 and 1359 kg DW m coastline−1 yr−1. They supplied between 20 kg CaCO3 m coastline−1 yr−1 and 47 kg CaCO3 m coastline−1 yr−1. Between 54% (Son Real) and 70% (Es Trenc) of seagrass beach-cast, respectively accounting for 1.5 kg N m coastline−1 yr−1 and 8.6 kg N m coastline−1 yr−1, were annually exported from the beaches to adjacent dune systems. Our results reveal that Mediterranean seagrass meadows might be an important source of materials, including sand and nutrients, for adjacent terrestrial systems, able to support their functioning.

Aeolian transport of seagrass ( Posidonia oceanica ) beach-cast to terrestrial systems

KAUST Repository

Jiménez, Maria A.

2017-06-29

The annual export of the Mediterranean seagrass (Posidonia oceanica) litter to adjacent beaches and coastal dunes was quantified by examining the fortnight evolution of seagrass beach-cast volume on two beaches in the NW Mediterranean (Son Real and Es Trenc, Mallorca Island, Spain) for two years and analyzing the wind speed and direction obtained from the closest Meteorological Spanish Agency surface weather stations. The decomposition stage of the deposits was examined by analyzing the total hydrolysable amino acids, its percentage distribution and derived degradation indexes. Prevalent winds exceeding 6 m s−1, the coastline morphology and type of terrestrial vegetation determine the annual dynamics of the seagrass beach-cast. In the most protected beach (Son Real) the seagrass beach-cast remained nearly stationary during the two studied years while it exhibited wide annual fluctuations in the less protected one (Es Trenc). The amounts of P. oceanica wrack washed on Son Real and Es Trenc beaches, respectively, were estimated at 309 kg DW m coastline−1 yr−1 and 1359 kg DW m coastline−1 yr−1. They supplied between 20 kg CaCO3 m coastline−1 yr−1 and 47 kg CaCO3 m coastline−1 yr−1. Between 54% (Son Real) and 70% (Es Trenc) of seagrass beach-cast, respectively accounting for 1.5 kg N m coastline−1 yr−1 and 8.6 kg N m coastline−1 yr−1, were annually exported from the beaches to adjacent dune systems. Our results reveal that Mediterranean seagrass meadows might be an important source of materials, including sand and nutrients, for adjacent terrestrial systems, able to support their functioning.

Immunotoxicological and neurotoxicological profile of health effects following subacute exposure to geogenic dust from sand dunes at the Nellis Dunes Recreation Area, Las Vegas, NV

Energy Technology Data Exchange (ETDEWEB)

Keil, Deborah, E-mail: Deborah.Keil@montana.edu [Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717 (United States); Buck, Brenda [Department of Geoscience, University of Nevada, Las Vegas, NV 89154 (United States); Goossens, Dirk [Department of Geoscience, University of Nevada, Las Vegas, NV 89154 (United States); Geography Research Group, Department of Earth and Environmental Sciences, KU Leuven (Belgium); Teng, Yuanxin [Department of Geoscience, University of Nevada, Las Vegas, NV 89154 (United States); Leetham, Mallory; Murphy, Lacey [Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717 (United States); Pollard, James [Department of Geoscience, University of Nevada, Las Vegas, NV 89154 (United States); Eggers, Margaret [Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717 (United States); McLaurin, Brett [Department of Environmental, Geographical, and Geological Sciences, Bloomsburg University of Pennsylvania, Bloomsburg, PA 17815 (United States); Gerads, Russell [Brooks Rand Labs, LLC, Bothell, WA 98011 (United States); DeWitt, Jamie [Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834 (United States)

2016-01-15

Exposure to geogenic particulate matter (PM) comprised of mineral particles has been linked to human health effects. However, very little data exist on health effects associated with geogenic dust exposure in natural settings. Therefore, we characterized particulate matter size, metal chemistry, and health effects of dust collected from the Nellis Dunes Recreation Area (NDRA), a popular off-road vehicle area located near Las Vegas, NV. Adult female B6C3F1 mice were exposed to several concentrations of mineral dust collected from active and vegetated sand dunes in NDRA. Dust samples (median diameter: 4.4 μm) were suspended in phosphate-buffered saline and delivered at concentrations ranging from 0.01 to 100 mg dust/kg body weight by oropharyngeal aspiration. ICP-MS analyses of total dissolution of the dust resulted in aluminum (55,090 μg/g), vanadium (70 μg/g), chromium (33 μg/g), manganese (511 μg/g), iron (21,600 μg/g), cobalt (9.4 μg/g), copper (69 μg/g), zinc (79 μg/g), arsenic (62 μg/g), strontium (620 μg/g), cesium (13 μg/g), lead 25 μg/g) and uranium (4.7 μg/g). Arsenic was present only as As(V). Mice received four exposures, once/week over 28-days to mimic a month of weekend exposures. Descriptive and functional assays to assess immunotoxicity and neurotoxicity were performed 24 h after the final exposure. The primary observation was that 0.1 to 100 mg/kg of this sand dune derived dust dose-responsively reduced antigen-specific IgM antibody responses, suggesting that dust from this area of NDRA may present a potential health risk. - Graphical abstract: During periods of heavy wind erosion, dense dust clouds of locally emitted geogenic dust enrobe the central Nellis Dune Recreation Area dunes. - Highlights: • Toxicological effects were characterized specific to geogenic dust exposure from a recreational sand dune site in Nevada. • The geogenic dust is a mixture of many metals and crystalline silica. • Exposure to geogenic dust dose

Investigations on organics in the Libyan beach sand and water: extraction, spectroscopy and gas chromatography, Zwarah to East Tripoli coastline

International Nuclear Information System (INIS)

Ali, L.H.; El-Jawashi, S.A.; Ejbali, A.A.; Garbaj, M.J.

1998-01-01

Forty-three samples from fifteen locations extending along 200 kilometers from near the Tunisian borders to 20 kilometers east of Tripoli harbour were examined for their organic contents. Sampling was conducted under the following specifications. 1. Dry beach sand, 3-4 meters away from water (denoted ds). 2. Wet beach sand, obtained from 1 meter depth (denoted ws). 3. Beach water (denoted w). Known amounts of sand (ds or ws) and beach water (w) were extracted with a suitable volume of chloroform. Organics in the extracts were determined gravimetrically by complete evaporation of chloroform, the residue was further examined by gas chromatography, and distribution of carbon numbers in each sample were assessed. Alternatively, a direct determination of organics concentration in CHCl 3 solution was obtained spectrophotometrically from calibration curves of absorptions at 410nm and 260nm. Infrared study on organics isolated from different locations enabled the assessment of the degree of oxidation suffered by each sample. This was obtained by comparing the relative absorption values at 1736 and 1712cm -1 , normalized with respect to 2925 cm -1 ; C-H stretching vibration; to rule out effects due to concentration. Organics concentration in shore water ranged from 0.05 to 9.50 ppm, depending on location and industrial activities, while much higher concentrations, ranging from 50-1500 ppm were detected in dry and wet beach sand samples. (author)

44 CFR 65.11 - Evaluation of sand dunes in mapping coastal flood hazard areas.

Science.gov (United States)

2010-10-01

... mapping coastal flood hazard areas. 65.11 Section 65.11 Emergency Management and Assistance FEDERAL... Insurance Program IDENTIFICATION AND MAPPING OF SPECIAL HAZARD AREAS § 65.11 Evaluation of sand dunes in mapping coastal flood hazard areas. (a) General conditions. For purposes of the NFIP, FEMA will consider...

Origin of the late quaternary dune fields of northeastern Colorado

Science.gov (United States)

Muhs, D.R.; Stafford, T.W.; Cowherd, S.D.; Mahan, S.A.; Kihl, R.; Maat, P.B.; Bush, C.A.; Nehring, J.

1996-01-01

Stabilized eolian deposits, mostly parabolic dunes and sand sheets, cover much of the landscape of northeastern Colorado and adjacent parts of southwestern Nebraska in four geographically distinct dune fields. Stratigraphic and soil-geomorphic relations and accelerator radiocarbon dating indicate that at least three episodes of eolian sand movement occurred between 27 ka and 11 ka, possibly between 11 ka and 4 ka, and within the past 1.5 ka. Thus, eolian sand deposition took place under both glacial and interglacial climatic conditions. In the youngest episodes of eolian sand movement, Holocene parabolic dunes partially buried Pleistocene sand sheet deposits. Late Holocene sands in the Fort Morgan and Wray dune fields, to the south of the South Platte River, have trace element ratios that are indistinguishable from modern South Platte River sands, but different from Ogallala Formation bedrock, which has previously been cited as the main source of dune sand on the Great Plains. Sands in the Greeley dune field, to the north of the South Platte River, have trace element concentrations that indicate a probable Laramie Formation source. Measurements of parabolic dunes indicate paleowinds from the northwest in all dune fields, in good agreement with resultant drift directions calculated for nearby weather stations. Thus, paleowinds were probably not significantly different from present-day winds, and are consistent with a South Platte River source for the Fort Morgan and Wray dune fields, and a Laramie Formation source for the Greeley dune field. Sand accumulated downwind of the South Platte River to form the Fort Morgan dune field. In addition, sand was also transported farther downwind over the upland formed by the calcrete caprock of the Ogallala Formation, and deposited in die lee of the upland on the southeast side. Because of high wind energy, the upland itself served as a zone of sand transport, but little or no sand accumulation took place on this surface. These

Vulnerability of National Park Service beaches to inundation during a direct hurricane landfall: Fire Island National Seashore

Science.gov (United States)

Stockdon, Hilary F.; Thompson, David M.

2007-01-01

Waves and storm surge associated with strong tropical storms are part of the natural process of barrier-island evolution and can cause extensive morphologic changes in coastal parks, leading to reduced visitor accessibility and enjoyment. Even at Fire Island National Seashore, a barrier-island coastal park in New York where extratropical storms (northeasters) dominate storm activity, the beaches are vulnerable to the powerful, sand-moving forces of hurricanes. The vulnerability of park beaches to inundation, and associated extreme coastal change, during a direct hurricane landfall can be assessed by comparing the elevations of storm-induced mean-water levels (storm surge) to the elevations of the crest of the sand dune that defines the beach system. Maps detailing the inundation potential for Category 1-4 hurricanes can be used by park managers to determine the relative vulnerability of various barrier-island parks and to assess which areas of a particular park are more susceptible to inundation and extreme coastal changes.

Testing model parameters for wave‐induced dune erosion using observations from Hurricane Sandy

Science.gov (United States)

Overbeck, Jacquelyn R.; Long, Joseph W.; Stockdon, Hilary F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave‐impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision‐making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Testing model parameters for wave-induced dune erosion using observations from Hurricane Sandy

Science.gov (United States)

Overbeck, J. R.; Long, J. W.; Stockdon, H. F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave-impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision-making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Dune growth under multidirectional wind regimes

Science.gov (United States)

Gadal, C.; Rozier, O.; Claudin, P.; Courrech Du Pont, S.; Narteau, C.

2017-12-01

Under unidirectional wind regimes, flat sand beds become unstable to produce periodic linear dunes, commonly called transverse dunes because their main ridges are oriented perpendicular to the air flow. In areas of low sediment availability, the same interactions between flow, transport and topography produce barchan dunes, isolated sand-pile migrating over long distances with a characteristic crescentic shape. For the last fifteen years, barchan dunes and the instability at the origin of transverse dunes have been the subject of numerous studies that have identified a set of characteristic length and time scales with respect to the physical properties of both grains and fluid. This is not the case for dunes developing under multidirectional wind regimes. Under these conditions, dune orientation is measured with respect to the direction of the resultant sand flux. Depending on the wind regime, dunes do not always line up perpendicularly to the resultant sand flux, but can also be at an oblique angle or even parallel to it. These oblique and longitudinal dunes are ubiquitous in all deserts on Earth and planetary bodies because of the seasonal variability of wind orientation. They are however poorly constrained by observations and there is still no complete theoretical framework providing a description of their orientation and initial wavelength. Here, we extend the linear stability analysis of a flat sand of bed done in two dimensions for a unidirectional flow to three dimensions and multidirectional flow regimes. We are able to recover transitions from transverse to oblique or longitudinal dune patterns according to changes in wind regimes. We besides give a prediction for the initial dune wavelength. Our results compare well to previous theory of dune orientation and to field, experimental and numerical data.

The morphology and morphodynamics of sand-gravel subaquatic dunes: the Raba River estuary, Poland

Directory of Open Access Journals (Sweden)

Artur RADECKI-PAWLIK

2012-08-01

Full Text Available In the outlet of the Raba River to the Vistula, the biggest river in Poland, the morphology and morphodynamics of sand and fine-gravel subaquatic dunes were investigated. The site is situated in highland region just about the entrance to Polish Carpathians. The dunes formed on the Raba River bed estuary are composed of sand and fine gravel (d50 up to 11 mm. Systematic observation (within the 2000-2005 were made of geometry, sediment composition and hydraulic climate under which the dunes grew and decomposed. The investigation focuses here mostly on the geometrical parameters of these bed forms such as height, length, as well as granulometric characteristics of the sediment. Based on in-site measurements different hydraulic parameters were calculated such as shear stresses, resistant coefficient, Froude and Reynolds numbers and roughness coefficient. It was found that the relation between height (H and length (L of the Raba estuary dunes describes the formula: H = 0.05L0.35. Also these dunes are steeper and flatter then classical H/L index is: H/L = 0.0518L0.622. During the field campaign, when the foot access to the estuary was possible and dunes were spotted on the river bed the range of measured water velocity was from v = 0.39 m∙s-1 to v = 0.81 m∙s-1 with the highest velocity over the dune crest. At the same time the measured range of shear stresses within the dune field formation were from t = 0.115 N×m-2 to t = 1.59 N×m-2. On the field investigations the CCHE2D - two-dimensional unsteady flow and sediment transport model for non-equilibrium transport of non-uniform sediment mixtures – was applied. The model was used to simulate the morphodynamic changes along the outlet of the Raba River basing on field observations of the 2005 summer flood as well as calculate hydraulics parameters. It was also used to test and confirm the range of morphodynamic changes, which take place along the research reach where the dunes are being developed

Modeling Megacusps and Dune Erosion

Science.gov (United States)

Orzech, M.; Reniers, A. J.; Thornton, E. B.

2009-12-01

Megacusps are large, concave, erosional features of beaches, of O(200m) alongshore wavelength, which sometimes occur when rip channel bathymetry is present. It is commonly hypothesized that erosion of the dune and back beach will be greater at the alongshore locations of the megacusp embayments, principally because the beach width is narrower there and larger waves can more easily reach the dune toe (e.g., Short, J. Geol., 1979, Thornton, et al., Mar. Geol., 2007). At present, available field data in southern Monterey Bay provide some support for this hypothesis, but not enough to fully confirm or refute it. This analysis utilizes XBeach, a 2DH nearshore sediment transport model, to test the above hypothesis under a range of wave conditions over several idealized rip-megacusp bathymetries backed by dunes. Model results suggest that while specific wave conditions may result in erosional hot spots at megacusp embayments, other factors such as tides, wave direction, and surf zone bathymetry can often play an equal or stronger role.

Sand dunes of the Gaza Strip (southwestern Palestine: morphology, textural characteristics and associated environmental impacts

Directory of Open Access Journals (Sweden)

Khalid Fathi Ubeid

2014-07-01

Full Text Available Sand dunes are wide spread in the Gaza Strip and are present in its northern, central and southern regions. Thirty sand samples were collected at seven locations along the middle region of the Strip. The coordinates for each sampling site were positioned using GPS and processed with ArcGIS software. Mechanical and chemical properties were examined to determine the textural characteristics and carbonate contents of the dune sands. The mean grain size is fine to medium, and the sands range from moderate- to well-sorting. The skewness is fine to very fine, and the kurtosis ranges from mesokurtic to very leptokurtic. Additionally, the results show that the carbonate content ranges from 1.5% to 5%. The high permeability, good porosity, and low carbonate content of the sand dunes in the Gaza Strip have led to more groundwater pollution via leachates percolating from the solid waste landfills and basins from wastewater treatments constructed above the sand dunes. Sand quarries have also changed the natural landscape of the Gaza Strip. These quarries were excavated randomly, used for a short period and then disused. This random and unregulated excavation has led to the destruction of natural habitats for flora and fauna.   Resumen Las dunas de arena se extienden ampliamente en la Franja de Gaza y hacen presencia en las regiones del norte, centro y sur. Para este trabajo se recolectaron treinta muestras de arena en siete puntos a lo largo de la región media de la Franja. Las coordenadas de cada muestra se marcaron con el GPS y se procesaron con el programa ArcGIS. Se examinaron las propiedades químicas y mecánicas para determinar las características de textura y los contenidos de carbonato de las dunas de arena. El tamaño del grano está entre fino y medio y las arenas oscilan entre moderadas y bien definidas. La asimetría estadística va desde fina hasta muy fina y la variedad de la curtosis se ubica entre mesocúrtica y muy leptoc

Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in Southwestern Saudi Arabian Dune Sand

KAUST Repository

Mughal, Iqra

2013-01-01

In arid lands, a major contribution to water loss is by soil water evaporation. Desert sand dunes in arid regions are devoid of runoff and have high rates of infiltration. Rainwater is commonly stored within them because of the low permeability

Sand erosion at the toe of a gabion-protected dune face

OpenAIRE

Chapman, A.

1992-01-01

The purpose of this research project was to study the manner in which erosion takes place the the toe of a dune slope protected by gabions, and to examine the response of the gabions to this erosion. A sand slope overlaid by model gabions was subjected to wave attack in a hydraulic flume, and periodic measurements of the bottom profile were taken. The results showed that the gabions performed well, and continued to provide protection to the slope even after a considerable amount of erosion an...

Assessment of natural radioactivity and gamma-ray dose in monazite rich black Sand Beach of Penang Island, Malaysia.

Science.gov (United States)

Shuaibu, Hauwau Kulu; Khandaker, Mayeen Uddin; Alrefae, Tareq; Bradley, D A

2017-06-15

Activity concentrations of primordial radionuclides in sand samples collected from the coastal beaches surrounding Penang Island have been measured using conventional γ-ray spectrometry, while in-situ γ-ray doses have been measured through use of a portable radiation survey meter. The mean activity concentrations for 226 Ra, 232 Th and 40 K at different locations were found to be less than the world average values, while the Miami Bay values for 226 Ra and 232 Th were found to be greater, at 1023±47 and 2086±96Bqkg ̶ 1 respectively. The main contributor to radionuclide enrichment in Miami Bay is the presence of monazite-rich black sands. The measured data were compared against literature values and also recommended limits set by the relevant international bodies. With the exception of Miami Bay, considered an elevated background radiation area that would benefit from regular monitoring, Penang island beach sands typically pose no significant radiological risk to the local populace and tourists visiting the leisure beaches. Copyright © 2017 Elsevier Ltd. All rights reserved.

The impact of fire on sand dune stability: Surface coverage and biomass recovery after fires on Western Australian coastal dune systems from 1988 to 2016

Science.gov (United States)

Shumack, Samuel; Hesse, Paul; Turner, Liam

2017-12-01

This study aims to determine the common response of coastal sand dunes in Western Australia (WA) to fire on decadal time-scales, in terms of ecological-geomorphic-climatic interactions to test the hypothesis that fire plays a role in coastal dune destabilisation. Fires are commonly suggested to have contributed to widespread dune reactivation in Australia and globally, a hypothesis that is relatively untested. We used data from the Landsat Thematic Mapper, Enhanced Thematic Mapper Plus, and Operational Land Imager missions to monitor changes in surface coverage on coastal sand dunes in south-west WA after fires. We analysed 31 fire scars from 1988 to 2016 in two Landsat scenes on the west and south coast of WA. Recovery ratios derived from the Normalised Difference Vegetation Index (NDVI) were used to monitor patterns in post-fire biomass and surface cover. Recovery ratios are correlated with indices of burn severity, and meteorological data to investigate relationships. We also used Maximum Likelihood Classification to monitor changes in bare sand area. Results suggest that recovery followed a strongly consistent pattern, and is characterised by rapid vegetation cover re-establishment within six to twelve months. Prior to this, some aeolian activity may have occurred but without substantial surface changes. Initial germination and/or resprouting were followed by steady growth up to seven years, where NDVI typically neared pre-fire values. Some variation in early recovery occurred between the west and south coast, possibly owing to relative proportions of reseeding and resprouting plants. A log regression explained 75% of the recovery pattern (79% on the south coast). Precipitation had some ability to explain recovery up to nine months post-fire (r2 = 0.29 to 0.54). No relationships were observed between estimates of burn severity and recovery. After nine months, the biggest cause of spatial variation in recovery was the pre-fire community composition and related

A standardized method for sampling and extraction methods for quantifying microplastics in beach sand.

Science.gov (United States)

Besley, Aiken; Vijver, Martina G; Behrens, Paul; Bosker, Thijs

2017-01-15

Microplastics are ubiquitous in the environment, are frequently ingested by organisms, and may potentially cause harm. A range of studies have found significant levels of microplastics in beach sand. However, there is a considerable amount of methodological variability among these studies. Methodological variation currently limits comparisons as there is no standard procedure for sampling or extraction of microplastics. We identify key sampling and extraction procedures across the literature through a detailed review. We find that sampling depth, sampling location, number of repeat extractions, and settling times are the critical parameters of variation. Next, using a case-study we determine whether and to what extent these differences impact study outcomes. By investigating the common practices identified in the literature with the case-study, we provide a standard operating procedure for sampling and extracting microplastics from beach sand. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reattachment Zone Characterisation Under Offshore Winds With Flow Separation On The Lee Side Of Coastal Dunes

Science.gov (United States)

Delgado-Fernandez, I.; Jackson, D.; Cooper, J. A.; Baas, A. C.; Lynch, K.; Beyers, M.

2010-12-01

Airflow separation, lee-side eddies and secondary flows play an essential role on the formation and maintenance of sand dunes. Downstream from dune crests the flow surface layer detaches from the ground and generates an area characterised by turbulent eddies in the dune lee slope (the wake). At some distance downstream from the dune crest, flow separates into a reversed component directed toward the dune toe and an offshore “re-attached” component. This reattachment zone (RZ) has been documented in fluvial and desert environments, wind tunnel experiments and numerical simulations, but not yet characterised in coastal dunes. This study examines the extent and temporal evolution of the RZ and its implications for beach-dune interaction at Magilligan, Northern Ireland. Wind parameters were measured over a profile extending from an 11 m height dune crest towards the beach, covering a total distance of 65 m cross-shore. Data was collected using an array of nine ultrasonic anemometers (UAs) deployed in April-May 2010, as part of a larger experiment to capture airflow data under a range of incident wind velocities and offshore directions. UAs were located along the profile (5 m tower spacing) over the beach, which allowed a detailed examination of the RZ with empirical data. Numerical modelling using Computational Fluid Dynamics (CFD) software was also conducted with input data from anemometer field measurements, running over a surface mesh generated from LiDAR and DGPS surveys. Results demonstrate that there is a wind threshold of approximately 5-6 ms-1 under which no flow separation exists with offshore winds. As wind speed increases over the threshold, a flow reversal area is quickly formed, with the maximum extent of the RZ at approximately 3.5 dune heights (h). The maximum extent of the RZ increases up to 4.5h with stronger wind speeds of 8-10 ms-1 and remains relatively constant as wind speed further increases. This suggests that the spatial extent of the RZ is

Stability of isolated Barchan dunes

Science.gov (United States)

Fourrière, Antoine; Charru, François

2010-11-01

When sand grains are entrained by an air flow over a non-erodible ground, or with limited sediment supply from the bed, they form isolated dunes showing a remarkable crescentic shape with horns pointing downstream. These dunes, known as Barchan dunes, are commonly observed in deserts, with height of a few meters and velocity of a few meters per year (Bagnold 1941). These dunes also exist under water, at a much smaller, centimetric size (Franklin & Charru 2010). Their striking stability properties are not well understood yet. Two phenomena are likely to be involved in this stability: (i) relaxation effects of the sand flux which increases from the dune foot up to the crest, related to grain inertia or deposition, and (ii) a small transverse sand flux due to slope effects and the divergence of the streamlines of the fluid flow. We reproduced aqueous Barchan dunes in a channel, and studied their geometrical and dynamic properties (in particular their shape, velocity, minimum size, and rate of erosion). Using coloured glass beads (see the figure), we were then able to measure the particle flux over the whole dune surface. We will discuss the stability of these dunes in the light of our measurements.

Seed bank dynamics of blowout penstemon in relation to local patterns of sand movement on the Ferris Dunes, south-central Wyoming

Science.gov (United States)

Kassie L. Tilini; Susan E. Meyer; Phil S. Allen

2017-01-01

Plants restricted to active sand dunes possess traits that enable both survival in a harsh environment and local migration in response to a shifting habitat mosaic. We examined seed bank dynamics of Penstemon haydenii S. Watson (blowout penstemon) in relation to local sand movement. We measured within-year sand movement along a 400 m transect and examined plant density...

Modeling river dune development and dune transition to upper stage plane bed

NARCIS (Netherlands)

Naqshband, Suleyman; van Duin, Olav; Ribberink, Jan S.; Hulscher, Suzanne J.M.H.

2016-01-01

Large asymmetric bedforms known as dunes commonly dominate the bed of sand rivers. Due to the turbulence generation over their stoss and lee sides, dunes are of central importance in predicting hydraulic roughness and water levels. During floods in steep alluvial rivers, dunes are observed to grow

Sand dune movement in the Victoria Valley, Antarctica

Science.gov (United States)

Bourke, Mary C.; Ewing, Ryan C.; Finnegan, David; McGowan, Hamish A.

2009-08-01

We use vertical aerial photographs and LiDAR topographic survey data to estimate dune migration rates in the Victoria Valley dunefield, Antarctica, between 1961 and 2001. Results confirm that the dunes migrated an average of 1.5 m/year. These values are consistent with other estimates of dune migration from cold climate deserts and are significantly lower than estimates from warm deserts. Dune migration rates are retarded by the presence of entrained ice, soil moisture and a reversing wind regime. Dune absorption, merging and limb extension are apparent from the time-series images and account for significant changes in dune form and the field-scale dune pattern. Dune-field pattern analysis shows an overall increase in dune-field organization with an increase in mean dune spacing and a reduction in total crest length and defect density. These data suggest that dunes in other cold desert environments on Earth, Mars or Titan, that may also have inter-bedded frozen laminae, still have the potential to migrate and organize, albeit at lower rates than dunes in warm deserts.

Rip currents, mega-cusps, and eroding dunes

Science.gov (United States)

Thornton, E.B.; MacMahan, J.; Sallenger, A.H.

2007-01-01

Dune erosion is shown to occur at the embayment of beach mega-cusps O(200 m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18 km shoreline in southern Monterey Bay, California. This section of the bay consists of a sandy shoreline backed by extensive dunes, rising to heights exceeding 40 m. There is a large increase in wave height going from small wave heights in the shadow of a headland, to the center of the bay where convergence of waves owing to refraction over the Monterey Bay submarine canyon results in larger wave heights. The large alongshore gradient in wave height results in a concomitant alongshore gradient in morphodynamic scale. The strongly refracted waves and narrow bay aperture result in near normal wave incidence, resulting in well-developed, persistent rip currents along the entire shoreline. The alongshore variations of the cuspate shoreline are found significantly correlated with the alongshore variations in rip spacing at 95% confidence. The alongshore variations of the volume of dune erosion are found significantly correlated with alongshore variations of the cuspate shoreline at 95% confidence. Therefore, it is concluded the mega-cusps are associated with rip currents and that the location of dune erosion is associated with the embayment of the mega-cusp.

Late Pleistocene dune activity in the central Great Plains, USA

Science.gov (United States)

Mason, J.A.; Swinehart, J.B.; Hanson, P.R.; Loope, D.B.; Goble, R.J.; Miao, X.; Schmeisser, R.L.

2011-01-01

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of

Difference in the wind speeds required for initiation versus continuation of sand transport on mars: implications for dunes and dust storms.

Science.gov (United States)

Kok, Jasper F

2010-02-19

Much of the surface of Mars is covered by dunes, ripples, and other features formed by the blowing of sand by wind, known as saltation. In addition, saltation loads the atmosphere with dust aerosols, which dominate the Martian climate. We show here that saltation can be maintained on Mars by wind speeds an order of magnitude less than required to initiate it. We further show that this hysteresis effect causes saltation to occur for much lower wind speeds than previously thought. These findings have important implications for the formation of dust storms, sand dunes, and ripples on Mars.

Separation of zircon from the beach sand deposit of Srikurmam area, Srikakulam district, Andhra Pradesh - a case study

International Nuclear Information System (INIS)

Rao, G.V.S.U.; Sharma, A.K.; Seshadrinath, S.T.; Fahmi, Sohail; William Prasad, Ch.; Nagabhushanam, B.

2011-01-01

Beach sand placer deposits occur along the eastern and western coasts of India, which contain heavy minerals, such as ilmenite, rutile, garnet, monazite, zircon and sillimanite. Among these, zircon is used in zircaloys (nuclear industry), ceramics, refractories, abrasives, etc. Separation and chemical characterization of pure zircon is a prelude for understanding the different elements and impurities present and its industrial application. In recent times, several methods are developed for beneficiation and separation of individual heavy minerals from beach sands. In this paper, separation of zircon from beach sand of Srikurmam area, Andhra Pradesh was taken up as a case study. The process flow sheet adopted for separation and isolation of pure zircon from beach sand sample consists of desliming of beach sand, wet tabling of sand fraction, removal of magnetite by low intensity magnetic separation from table concentrate, perm roll magnetic separation and induced roll magnetic separation of table concentrate. The concentrates were further subjected to iso-dynamic magnetic separator after observing impurity present in the sample under binocular stereomicroscope. In the present process, about 95% pure zircon was obtained. Further concentration of zircon was carried out under the binocular stereomicroscope by hand picking of impurity to obtain 99.5% pure zircon concentrate. The pure zircon concentrate was analyzed for major, minor and trace elements by chemical method for characterization of zircon and cross validation of physical processes through which the zircon concentrate was obtained. Chemical analysis of the pure zircon concentrate indicated 63.15 to 64.79% ZrO 2 and 32.2 to 32.8% SiO 2 . These values are nearer to that of pure zircon, which stoichiometrically contains 67.2% ZrO 2 and 32.8 % SiO 2 with little iron. In the present study, ZrO 2 +HfO 2 content varies from 65.27 to 66.17% and hafnium from 1.25 to 1.46% HfO 2 in the zircon concentrate. The variation

Dune mobility in the St. Anthony Dune Field, Idaho, USA: Effects of meteorological variables and lag time

Science.gov (United States)

Hoover, R. H.; Gaylord, D. R.; Cooper, C. M.

2018-05-01

The St. Anthony Dune Field (SADF) is a 300 km2 expanse of active to stabilized transverse, barchan, barchanoid, and parabolic sand dunes located in a semi-arid climate in southeastern Idaho. The northeastern portion of the SADF, 16 km2, was investigated to examine meteorological influences on dune mobility. Understanding meteorological predictors of sand-dune migration for the SADF informs landscape evolution and impacts assessment of eolian activity on sensitive agricultural lands in the western United States, with implications for semi-arid environments globally. Archival aerial photos from 1954 to 2011 were used to calculate dune migration rates which were subsequently compared to regional meteorological data, including temperature, precipitation and wind speed. Observational analyses based on aerial photo imagery and meteorological data indicate that dune migration is influenced by weather for up to 5-10 years and therefore decadal weather patterns should be taken into account when using dune migration rates as proxies from climate fluctuation. Statistical examination of meteorological variables in this study indicates that 24% of the variation of sand dune migration rates is attributed to temperature, precipitation and wind speed, which is increased to 45% when incorporating lag time.

Assessment of natural radioactivity of sands in beaches from Great Vitoria, ES, Brazil

International Nuclear Information System (INIS)

Aquino, Reginaldo Ribeiro de

2010-01-01

In this work the concentrations of natural radionuclides 226 Ra, 232 Th and 40 K were determined in superficial sand samples for 16 locations throughout the coast of the Great Victory, metropolitan region of the state of Espirito Santo, Southeast of Brazil. The assessed beaches were Manguinhos and Jacaraipe in Serra county, Camburi, Praia do Canto and Curva da Jurema in Vitoria county, Praia da Costa and Itapua in Vila Velha county, Setibao, Setibinha, Praia do Morro, Praia das Castanheiras and Areia Preta in Guarapari county and sand of the Paulo Cesar Vinha Reserve also located in Guarapari county. Three sand samples of each beach were sealed in 100 mL high density polyethylene flasks. After approximately 4 weeks in order to reach secular equilibrium in the 238 U and 2 '3 2 Th series, the samples were measured by high resolution gamma spectrometry and the spectra analyzed with the WinnerGamma software. The self absorption correction was performed for all samples. The 226 Ra concentration was determined from the weighted average concentrations of 214 Pb and 21 '4Bi, the 232 Th concentration was determined from the weighted average concentrations of 228 Ac, 2 '1 2 Pb and 212 Bi and the concentration of 40 K is determined by its single gamma transition of 1460 keV. The radium equivalent concentration and the external hazard index where obtained from the concentrations of 226 Ra, 232 Th and 4 '0K. 226 Ra concentrations show values varying from 3 +- 1 Bq.kg-1 to 738 +- 38 Bq.kg -1 , with the highest values for the central locality of the Camburi beach. 232 Th concentrations show values varying from 7 +- 3 Bq.kg -1 to 7422 +- 526 Bq.kg -1 , with the highest values for Areia Preta beach. 40 K concentrations show values varying from 14 +- 6 Bq.kg -1 to 638 +- 232 Bq.kg -1 , with the highest values for Areia Preta beach. Calculation of the radium equivalent and the external hazard index showed two distinct groups. In the first one, for the majority of the beaches, the

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...

Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

Science.gov (United States)

Máguas, C.; Rascher, K. G.; Martins-Loução, A.; Carvalho, P.; Pinho, P.; Ramos, M.; Correia, O.; Werner, C.

2011-12-01

In spite of the relative importance of groundwater in costal dune systems, studies concerning the responses of vegetation to ground water (GW) availability variations, particularly in Mediterranean regions, are scarce. Thus, the main purpose of this study is to compare the responses of co-occurring species possessing different functional traits, to changes in GW levels (i.e. the lowering of GW levels) in a sand dune ecosystem. For that, five sites were established within a 1 km2 area in a meso-mediterranean sand dune ecosystem dominated by a Pinus pinaster forest. Due to natural topographic variability and anthropogenic GW exploitation, substantial variability in depth to GW between sites was found. Under these conditions it was possible to identify the degree of usage and dependence on GW of different plant species (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader) and how GW dependence varied seasonally and between the heterogeneous sites. Results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy). Species comparison revealed that variability in pre-dawn water potential (Ψpre) and bulk leaf δ13C was related to site differences in GW use in the deep-rooted (Pinus pinaster, Myrica faya) and phreatophyte (Salix repens) species. However, such variation was more evident during spring than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understory drought-adapted shrub, seemed to be independent of water availability across seasons and sites. Thus, the susceptibility to lowering of GW due to anthropogenic exploitation, in plant species from sand dunes, is variable, being particularly relevant for deep

Enhanced ex situ bioremediation of crude oil contaminated beach sand by supplementation with nutrients and rhamnolipids.

Science.gov (United States)

Nikolopoulou, M; Pasadakis, N; Norf, H; Kalogerakis, N

2013-12-15

Mediterranean coastal regions are particularly exposed to oil pollution due to extensive industrialization, urbanization and transport of crude and refined oil to and from refineries. Bioremediation of contaminated beach sand through landfarming is both simple and cost-effective to implement compared to other treatment technologies. The purpose of the present study was to investigate the effect of alternative nutrients on biodegradation of crude oil contaminated beach sand in an effort to reduce the time required for bioremediation employing only indigenous hydrocarbon degraders. A natural sandy soil was collected from Agios Onoufrios beach (Chania, Greece) and was contaminated with weathered crude oil. The indigenous microbial population in the contaminated sand was tested alone (control treatment) or in combination with inorganic nutrients (KNO3 and K2HPO4) to investigate their effects on oil biodegradation rates. In addition, the ability of biosurfactants (rhamnolipids), in the presence of organic nutrients (uric acid and lecithin), to further stimulate biodegradation was investigated in laboratory microcosms over a 45-day period. Biodegradation was tracked by GC/MS analysis of aliphatic and polycyclic aromatic hydrocarbons components and the measured concentrations were corrected for abiotic removal by hopane normalizations. It was found that the saturated fraction of the residual oil is degraded more extensively than the aromatic fraction and the bacterial growth after an incubation period of approximately 3 weeks was much greater from the bacterial growth in the control. The results show that the treatments with inorganic or organic nutrients are equally effective over almost 30 days where C12-C35n-alkanes were degraded more than 97% and polyaromatic hydrocarbons with two or three rings were degraded more than 95% within 45 days. The results clearly show that the addition of nutrients to contaminated beach sand significantly enhanced the activity of

Minimal size of a barchan dune

Science.gov (United States)

Parteli, E. J. R.; Durán, O.; Herrmann, H. J.

2007-01-01

Barchans are dunes of high mobility which have a crescent shape and propagate under conditions of unidirectional wind. However, sand dunes only appear above a critical size, which scales with the saturation distance of the sand flux [P. Hersen, S. Douady, and B. Andreotti, Phys. Rev. Lett. 89, 264301 (2002); B. Andreotti, P. Claudin, and S. Douady, Eur. Phys. J. B 28, 321 (2002); G. Sauermann, K. Kroy, and H. J. Herrmann, Phys. Rev. E 64, 31305 (2001)]. It has been suggested by P. Hersen, S. Douady, and B. Andreotti, Phys. Rev. Lett. 89, 264301 (2002)] that this flux fetch distance is itself constant. Indeed, this could not explain the protosize of barchan dunes, which often occur in coastal areas of high litoral drift, and the scale of dunes on Mars. In the present work, we show from three-dimensional calculations of sand transport that the size and the shape of the minimal barchan dune depend on the wind friction speed and the sand flux on the area between dunes in a field. Our results explain the common appearance of barchans a few tens of centimeter high which are observed along coasts. Furthermore, we find that the rate at which grains enter saltation on Mars is one order of magnitude higher than on Earth, and is relevant to correctly obtain the minimal dune size on Mars.

Microbiological quality assessment of sand and water from three selected beaches of South Coast, São Paulo State, Brazil.

Science.gov (United States)

Pinto, K C; Hachich, E M; Sato, M I Z; Di Bari, M; Coelho, M C L S; Matté, M H; Lamparelli, C C; Razzolini, M T P

2012-01-01

This study aimed to assess the sanitary quality of water, and wet and dry sand from three beaches located in the South Coast region of São Paulo State, Brazil, selected taking into account the frequency of tourists and the water quality (good, fair and poor). Thirty-six water samples each of wet and dry sand and seawater were collected monthly over a period of one year and analyzed for fecal indicator bacteria (FIB: thermotolerant coliforms, Escherichia coli, and enterococci), presumptive Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and dermatophytes. The results revealed FIB concentrations more elevated in dry sand followed by wet sand and water. P. aeruginosa and presumptive S. aureus were detected with a similar frequency in water and sand samples, but maximum concentrations and geometric means were higher in dry sand. C. albicans was detected only in water samples whereas the dermatophyte Microsporum sp. was isolated exclusively from dry and wet sand samples. This evaluation showed also that the environment had a significant influence on P. aeruginosa but not on presumptive S. aureus concentrations. According to threshold values proposed in the literature for E. coli and enterococci dry sand densities, none of the beaches would be considered of sufficient quality for recreational activities.

Distribution of natural and anthropogenic radionuclides in beach sand samples from Mediterranean Coast of Turkey

International Nuclear Information System (INIS)

Özmen, S.F.; Cesur, A.; Boztosun, I.; Yavuz, M.

2014-01-01

Following Fukushima Dai-ichi Nuclear Power Plant accident, a huge amount of radionuclides were released in atmosphere and ocean. It's impact on the environment is of great concern to the good of the public at large. In this regard environmental radioactivity monitoring such as external dose rate and radioactivity measurements in environmental samples has been carried out. For this purpose, several beach sand samples were collected from south coast of the Turkey in September 2011 and radioactivity concentrations of 226 Ra ( 238 U), 228 Ac ( 232 Th), 40 K, 134 Cs and 137 Cs were determined by gamma spectrometry using a high-purity Germanium detector. The measured activity concentrations in beach sand samples ranged from 4.0±0.5 to 21.5±1.8 Bq/kg, 1.8±0.4 to 27.9±2.4 Bq/kg, 19.0±2.2 to 590.3±28.6 Bq/kg and 0.1±0.0 to 1.0±0.1 Bq/kg for 226 Ra, 232 Th, 40 K and 137 Cs, respectively. However there was no sign of 134 Cs in the sample spectrum after Fukushima Dai-ichi Nuclear Power Plant accident. Hence we can safely conclude that there was no significant material transfer from Fukushima to Turkey. The other activities are in good agreement with the published results of neighboring areas. The absorbed gamma dose rate (D) and the annual effective dose (AED) of beach sand samples were below the world wide average implying that the radiation hazard is insignificant. The data presented in this study would also be very useful to determine the possible future effects of the nuclear power plant to the environment. - Highlights: • Activity values of all samples are lower than the world wide average values. • Gamma dose rates of beach sand samples are in the range of 10–200 nGy/h. • Ra eq activity and AED values of samples are less than world wide average values. • No significant material transfer from Fukushima to Turkey. • Strong correlations detected in between elemental and radioactivity concentration

Laboratory coupling tests for optimum land streamer design over sand dunes surface

KAUST Repository

Almalki, Hashim

2012-02-26

The cost of data acquisition in land is becoming a major issue as we strive to cover larger areas with seismic surveys at high resolution. Over sand dunes the problem is compounded by the week coupling obtain using geophones, which often forces us to bury the phone. A major challenge is designing such a land streamer system that combines durability, mobility and the required coupling. We share a couple of such designs and discuss the merits behind such designs and test their capability. The testing includes, the level of coupling, mobility and drag over sand surfaces. For specific designs loose sand can accumulate inside the steamer reducing its mobility. On the other hand, poor coupling will attenuate the high frequencies and cause an effective delay in the signal. The weight of the streamer is also an important factor in both mobility and coupling as it adds to the coupling it reduces the mobility of the streamer. We study the impact of weight and base plate surface area on the seismic signal quality, as well as the friction factor of different designs.

Mobilisation of toxic trace elements under various beach nourishments

NARCIS (Netherlands)

Pit, I.R.; Dekker, S.C.; Kanters, T.J.; Wassen, M.J.; Griffioen, J.

2017-01-01

To enhance protection and maintain wide beaches for recreation, beaches are replenished with sand: socalled beach nourishments. We compared four sites: two traditional beach nourishments, a mega beach nourishment and a reference without beach nourishment. Two sites contain calcareous-rich sand,

Enhanced Gravitational Drainage of Crude Oil Through Alabama Beach Sand Caused by the Dispersant Corexit 9500A

Science.gov (United States)

Steffy, D. A.; Nichols, A.; Hobbs, K.

2017-12-01

Oil spill material released by the 2010 Deepwater Horizon accident contaminated a majority of the 60 miles of Alabama coastline. In response to the oil spill, BP sprayed a dispersant, Corexit 9500A, as an initial remediation effort. An unforeseen impact of the saltwater-dispersant mixture includes the mobilization of oil-spilled material into the underlying beach sand. This study investigated the effect of the dispersant to promote gravitational drainage by measuring the physical characteristics of the sand, saltwater, crude oil, and the dispersant solution. The saltwater-dispersant mixture promoted the downward movement of oil mass 20 times greater extent than just saltwater. These tests are meant to simulate spill material on the beach being exposed to a low-energy, 1-meter mixed tide occurring along the Alabama coastline. A separate test simulated oilwet sand exposed to saltwater and a saltwater-dispersant mixture. The oil-wet sand impeded the vertical movement of saltwater, but allowed a saltwater-dispersant solution to mobilize the oil to migrate downward. The mobilization of oil in this three phase system of saltwater, oil, and air is controlled by: the pressure-saturation profile of the sand; interfacial tension with saltwater; and its surface tension with air.

Assessment of offshore New Jersey sources of Beach replenishment sand by diversified application of geologic and geophysical methods

Science.gov (United States)

Waldner, J.S.; Hall, D.W.; Uptegrove, J.; Sheridan, R.E.; Ashley, G.M.; Esker, D.

1999-01-01

Beach replenishment serves the dual purpose of maintaining a source of tourism and recreation while protecting life and property. For New Jersey, sources for beach sand supply are increasingly found offshore. To meet present and future needs, geologic and geophysical techniques can be used to improve the identification, volume estimation, and determination of suitability, thereby making the mining and managing of this resource more effective. Current research has improved both data collection and interpretation of seismic surveys and vibracore analysis for projects investigating sand ridges offshore of New Jersey. The New Jersey Geological Survey in cooperation with Rutgers University is evaluating the capabilities of digital seismic data (in addition to analog data) to analyze sand ridges. The printing density of analog systems limits the dynamic range to about 24 dB. Digital acquisition systems with dynamic ranges above 100 dB can permit enhanced seismic profiles by trace static correction, deconvolution, automatic gain scaling, horizontal stacking and digital filtering. Problems common to analog data, such as wave-motion effects of surface sources, water-bottom reverberation, and bubble-pulse-width can be addressed by processing. More than 160 line miles of digital high-resolution continuous profiling seismic data have been collected at sand ridges off Avalon, Beach Haven, and Barnegat Inlet. Digital multichannel data collection has recently been employed to map sand resources within the Port of New York/New Jersey expanded dredge-spoil site located 3 mi offshore of Sandy Hook, New Jersey. Multichannel data processing can reduce multiples, improve signal-to-noise calculations, enable source deconvolution, and generate sediment acoustic velocities and acoustic impedance analysis. Synthetic seismograms based on empirical relationships among grain size distribution, density, and velocity from vibracores are used to calculate proxy values for density and velocity

Holocene moisture variations over the arid central Asia revealed by a comprehensive sand-dune record from the central Tian Shan, NW China

Science.gov (United States)

Long, Hao; Shen, Ji; Chen, Jianhui; Tsukamoto, Sumiko; Yang, Linhai; Cheng, Hongyi; Frechen, Manfred

2017-10-01

Arid central Asia (ACA) is one of the largest arid (desert) areas in the world, and its climate is dominated by the westerlies. In this study, we examined sand dune evolution from the Bayanbulak Basin in the Tian Shan (Xinjiang, NW China), aiming to infer the Holocene moisture history of the ACA. Combined with stratigraphic observation and environmental proxies analysis (grain size, magnetic susceptibility and total organic content), large numbers of luminescence ages from multiple sites (eight sections, 79 samples) were applied to reconstruct the evolution of the sand dune accumulation in the study basin. The overall results imply very dry conditions characterized by sand dune accumulation at ∼12-6.5 ka, a wet interval between ∼6.5 and 0.8 ka when soil formation occurred, and decreased moisture during the last 0.8 ka. This moisture variation pattern is generally consistent with that inferred from many lacustrine records in the core zone of ACA, suggesting a widespread dry period in the early-to-middle Holocene and relatively wet middle-to-late Holocene. Thus, the moisture history derived from the current sand dune system contrasts with that in Asian monsoon areas, which are characterized by a strong monsoon (high precipitation) in the early and mid-Holocene and a weak monsoon (low precipitation and dry climate) during the late Holocene. Our results strongly suggest that the winter solar insolation and the external boundary conditions such as atmospheric CO2 concentration, ice sheets, and meltwater fluxes, have been major influential factors triggering the Holocene moisture evolution in the core zone of ACA.

77 FR 55224 - Notice of Availability of the Proposed Imperial Sand Dunes Recreation Area Management Plan and...

Science.gov (United States)

2012-09-07

... Availability of the Proposed Imperial Sand Dunes Recreation Area Management Plan and California Desert... California Desert Conservation Area (CDCA) Plan Amendment/Final Environmental Impact Statement (EIS), for the.... District Court in September 2006. Portions of the biological opinion for the Peirson's milkvetch were also...

An experiment to restore coastal sand dunes at Miramar beach, Goa: An appraisal

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas, A.

on the adjacent roads. Driven by highest wind speeds during June -August (36 km/h in 2004 and even 60 km/h in 2007), this episode is most intense during this period every year. A recurring phenomenon, sand deposits on the traffic circle creates nuisance...

Response to storm conditions of two different beaches at the Mediterranean coast of Morocco

Science.gov (United States)

El Mrini, Aldelmounim; Anfuso, Giorgio; Nachite, Driss; Taaouati, Mohamed

2010-05-01

In recent decades the increased demand for the recreational use of beaches has resulted in the uptake of studies on the morphodynamic processes which are acting on beaches. This knowledge is fundamental for appropriate coastal erosion management, suitable tourist use of littoral and for the design and shape of human construction. The Mediterranean sectors of Moroccan littoral investigated in this study, Ksar Rimal and Cabo Negro beaches, are respectively located north and south of Cabo Negro promontory and, over recent years, have been subject to increasing tourist activity. This has consisted mainly of the construction of two tourist ports (Marina Smir and Kabila), residential developments, hotels and a motorway which runs parallel to the coast, affecting the dune ridges and two lagoons which are of great ecological interest. In detail, the dunes located in the backshore at Ksar Rimal beach, are nowadays occupied by summer houses threaten by coastal retreat. A wide, partially urbanized, backshore is observed at Cabo Negro beach. With the intention of characterize the morphodynamic and seasonal behavior and the response of the studied beaches to storm impact, a beach monitoring program was carried out in the period 2006-2008, with special attention to the February-March 2008 stormy period. On analyzing the information obtained, it was possible to characterize the morphology and sedimentology of the studied beaches, and to calculate beach volumetric variations. Ksar Rimal is an open, exposed beach characterized by an intermediate slope (tan β = 0.10) with medium-coarse sands. The beach showed a reflective beach state characterized by plunging breakers. Small morphological seasonal changes were observed, most important morphological and volumetric variations (about 20 m3/m) taking place after winter storms which usually gave rise to a more dissipative beach profile (tan β = 0.05) characterized by spilling breakers. Beach recovery was quite rapid, usually lasting 2

The prevalence and distribution of indicators of fecal contamination in the sand from beaches of Oran coast

Science.gov (United States)

Messaoui, N.; Matallah-Boutiba, A.; Boutiba, Z.

2017-02-01

The microbiological quality of water at public bathing beaches is regularly monitored using fecal indicator bacteria (FIB) as a surrogate for the presence of human sewage and pathogens. The common feature of all these routine screening procedures is that the primary analysis is for indicator organisms rather than the pathogens that might cause concern. Indicator organisms are bacteria such as non-specific coliforms, Escherichia coli and Pseudomonas aeruginosa that are very commonly found in the human or animal gut and which, if detected, may suggest the presence of sewage. Indicator organisms are used because even when a person is infected with more pathogenic bacteria, they will still be excreting many millions times more indicator organisms than pathogens. It is therefore reasonable to surmise that if indicator organism levels are low, then pathogen levels will be very much lower or absent. Judgments as to suitability of water for use are based on very extensive precedents and relate to the probability of any sample population of bacteria being able to be infective at a reasonable statistical level of confidence. Exposure to FIB and associated pathogens may also occur through contact with contaminated beach sand, but no standards limiting levels of microbes in sand or required monitoring program has been established. As a result, the factors affecting FIB and pathogen survival/persistence in sand remain largely unstudied. A possible contamination of the sand by bacterial communities could be a source of transmission of certain pathogenic bacteria. The goal of this study was to look for a presence of certain bacteria that could be a source of illness to swimmers and compare the different levels of contamination between beach sand and sea water in four sites along the Western Oranian coast. First analysis were made during the dry season and rainy season from December 2010 to June 2012 to estimate fecal coliforms, Pseudomonas spp and total germs levels. E.coli and

An experiment on a sand-dune environment in Southern Venetian coast based on GPR, VES and documentary evidence

Energy Technology Data Exchange (ETDEWEB)

Galgaro, A.; Finzi, E. [Padua Univ., Padua (Italy). Dipt. di Geologia, Paleontologia e Geofisica; Tosi, L. [Consiglio Nazionale delle Ricerche, Venice (Italy). Ist. per l Studio della Dinamica delle Grandi Masse

2000-04-01

The internal structures of some surviving sand dunes and the ancient shore-lines along the coast south of Venice (Italy) have been investigated integrating ground probing radar (GPR) profiles, vertical electrical soundings (VES) and water conductivity measurements in some boreholes. The GPR penetration depth has been limited (4-5 m, using a 400 MHz antenna) by the high conductivity of salt water saturating pores of the shallow sediments. On the other hand, the excellent spatial resolution of the radar survey provided an estimate of internal dune bedding features, such as cross lamination and forwarding ancient covered coast-lines dated in the Thirties. The interpretation of the data, in particular along one line 360 m long intercepting a sizeable sand-dune bank, seems to offer clues to the evolutional history of the coast line and the depth of transition from fresh-water to brackish-salt water. The water table was detected with electrical measurements and direct observations in boreholes, whereas the transition between fresh and salt water was pointed out indirectly by the high energy absorption and total back-reflection of the electromagnetic waves, encountered at this boundary, and directly by the strong decrease in VES resistivity values.

Galveston Island, Texas, Sand Management Strategies

Science.gov (United States)

2016-07-01

billion m3 of beach quality sand . However, Texas projects to date have not utilized these sources because of transportation costs. The lack of nearby...estimate that the San Luis Pass flood shoal contains approximately 11.8 million yd3 of beach quality sand . However, it is expected that if permits...a source of beach- quality sand . 2. Sand could be intercepted before it reaches the present dry beach. ERDC/CHL TR-16-13 55 3. The volume of

Plant responses to an edaphic gradient across an active sand dune/desert boundary in the great basin desert.

NARCIS (Netherlands)

Rosenthal, D.M.; Ludwig, F.; Donovan, L.A.

2005-01-01

In arid ecosystems, variation in precipitation causes broad-scale spatial heterogeneity in soil moisture, but differences in soil texture, development, and plant cover can also create substantial local soil moisture heterogeneity. The boundary between inland desert sand dunes and adjacent desert

Natural radioactivity measurements in beach sand along the South East coast of Tamil Nadu, India

International Nuclear Information System (INIS)

Selvi, B.S.; Vijayakumar, B.; Ravi, P.M.

2017-01-01

Measurement of natural radioactivity in beach sand was carried out along the south east coast of Tamil Nadu, India, The activity concentrations of "2"3"8U, "2"3"2Th and "4"0K in beach sand ranged from 2 to 2,762 Bqkg"-"1 with a mean value of 236 Bq.kg"-"1, 7 to 30,872 Bqkg"-"1 with a mean value of 2,300 Bqkg"-"1 and 6.0 to 890 Bqkg"-"1 with a mean value of 85 Bqkg"-"1, respectively. The Radium Equivalent Activity, the external hazard index, the absorbed dose rate and the annual effective dose were assessed and compared with world average values. The results indicate that the absorbed dose rates range from 10 to 20506 nGyh"-"1 with mean value of 1545 nGy.h"-"1. The annual effective dose range between 0.01 and 25.15 mSvy"-"1, with the mean value of 1.90 mSvy"-"1. (author)

Isotopes based assessment of groundwater renewal and related anthropogenic effects in water scarce areas: Sand dunes study in Qasim area, Saudi Arabia

International Nuclear Information System (INIS)

Al-Sagaby, A.; Moallim, A.

2001-01-01

The investigation of recharge in the sand dune, Qasim, Saudi Arabia, with the help of chloride concentration and isotope content has revealed inconsistent pattern and less homogeneity. Monotonic chloride concentration and isotope content was the result of seasonal recharge occurrence in the study area. In addition, applying chloride mass-balance method, recharge rate calculation in the sand dune site, Qasim, Saudi Arabia, was made. The results (1.80 and 1.84mmy -1 - dune site) estimated during this project using this method was a long way below the recharge rates (30mmy -1 , 13.4mmy -1 in the dune site and 5mmy -1 in the swale site) obtained with the application of tritium method in the previous years (1994 and 1996). 1.80 and 1.84mmy -1 was for CRP-Saud-9405 project and was calculated 1997 and 1998 respectively. The reason for the lower recharge rate with the application of chloride mass-balance method could be the source of chloride input and high evaporation, which causes accumulation of chloride salts in the area. (author)

Baseline for beached marine debris on Sand Island, Midway Atoll

Science.gov (United States)

Ribic, Christine; Seba B. Sheavly,; John Klavitter,

2012-01-01

Baseline measurements were made of the amount and weight of beached marine debris on Sand Island, Midway Atoll, June 2008–July 2010. On 23 surveys, 32,696 total debris objects (identifiable items and pieces) were collected; total weight was 740.4 kg. Seventy-two percent of the total was pieces; 91% of the pieces were made of plastic materials. Pieces were composed primarily of polyethylene and polypropylene. Identifiable items were 28% of the total; 88% of the identifiable items were in the fishing/aquaculture/shipping-related and beverage/household products-related categories. Identifiable items were lowest during April–August, while pieces were at their lowest during June–August. Sites facing the North Pacific Gyre received the most debris and proportionately more pieces. More debris tended to be found on Sand Island when the Subtropical Convergence Zone was closer to the Atoll. This information can be used for potential mitigation and to understand the impacts of large-scale events such as the 2011 Japanese tsunami.

Natural radioactivity in sand beaches of Guarapari, Espirito Santo state, Brazil: a comparative study

International Nuclear Information System (INIS)

Vasconcelos, Danilo C.; Pereira, Claubia; Oliveira, Arno H.; Santos, Talita O.; Reis, Patricia L.

2011-01-01

Using gamma ray spectrometry, the activity concentration of naturally occurring radionuclides 226 Ra, 232 Th, and 40 K was determined in sand beaches samples from different areas in Guarapari, Espirito Santo state, from Brazil. The absorbed dose rates and annual effective dose were calculated and the results are compared with the internationally accepted values as well as others high background radiation areas (HBRAs).The activity concentration of the 232 Th in Areia Preta as well as the absorbed dose rates and annual effective dose were higher than the others regions compared. The results show that Areia Preta in Guarapari has higher background found in beaches in world. (author)

Latitudinal and altitudinal controls of Titan's dune field morphometry

Science.gov (United States)

Le Gall, A.; Hayes, A. G.; Ewing, R.; Janssen, M. A.; Radebaugh, J.; Savage, C.; Encrenaz, P.; the Cassini Radar Team

2012-01-01

Dune fields dominate ˜13% of Titan's surface and represent an important sink of carbon in the methane cycle. Herein, we discuss correlations in dune morphometry with altitude and latitude. These correlations, which have important implications in terms of geological processes and climate on Titan, are investigated through the microwave electromagnetic signatures of dune fields using Cassini radar and radiometry observations. The backscatter and emissivity from Titan's dune terrains are primarily controlled by the amount of interdune area within the radar footprint and are also expected to vary with the degree of the interdunal sand cover. Using SAR-derived topography, we find that Titan's main dune fields (Shangri-La, Fensal, Belet and Aztlan) tend to occupy the lowest elevation areas in Equatorial regions occurring at mean elevations between ˜-400 and ˜0 m (relative to the geoid). In elevated dune terrains, we show a definite trend towards a smaller dune to interdune ratio and possibly a thinner sand cover in the interdune areas. A similar correlation is observed with latitude, suggesting that the quantity of windblown sand in the dune fields tends to decrease as one moves farther north. The altitudinal trend among Titan's sand seas is consistent with the idea that sediment source zones most probably occur in lowlands, which would reduce the sand supply toward elevated regions. The latitudinal preference could result from a gradual increase in dampness with latitude due to the asymmetric seasonal forcing associated with Titan's current orbital configuration unless it is indicative of a latitudinal preference in the sand source distribution or wind transport capacity.

Limits of Wave Runup and Corresponding Beach-Profile Change from Large-Scale Laboratory Data

Science.gov (United States)

2010-01-01

A nearly vertical scarp developed after 40 min of wave action, with the upper limit of beach change identified at the toe of the dune scarp. and...change UL was found to approximately equal the vertical excursion of total wave runup, Rtw. An exception was runs where beach or dune scarps were...approximately equal the vertical excursion of total wave runup, Rtw. An exception was runs where beach or dune scarps were produced, which substantially limit the

Transient Electromagnetic Soundings Near Great Sand Dunes National Park and Preserve, San Luis Valley, Colorado (2006 Field Season)

Science.gov (United States)

Fitterman, David V.; de Sozua Filho, Oderson A.

2009-01-01

Time-domain electromagnetic (TEM) soundings were made near Great Sand Dunes National Park and Preserve in the San Luis Valley of southern Colorado to obtain subsurface information of use to hydrologic modeling. Seventeen soundings were made to the east and north of the sand dunes. Using a small loop TEM system, maximum exploration depths of about 75 to 150 m were obtained. In general, layered earth interpretations of the data found that resistivity decreases with depth. Comparison of soundings with geologic logs from nearby wells found that zones logged as having increased clay content usually corresponded with a significant resistivity decrease in the TEM determined model. This result supports the use of TEM soundings to map the location of the top of the clay unit deposited at the bottom of the ancient Lake Alamosa that filled the San Luis Valley from Pliocene to middle Pleistocene time.

Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

Directory of Open Access Journals (Sweden)

C. Máguas

2011-12-01

Full Text Available In spite of the relative importance of groundwater in costal dune systems, studies concerning the responses of vegetation to ground water (GW availability variations, particularly in Mediterranean regions, are scarce. Thus, the main purpose of this study is to compare the responses of co-occurring species possessing different functional traits, to changes in GW levels (i.e. the lowering of GW levels in a sand dune ecosystem. For that, five sites were established within a 1 km² area in a meso-mediterranean sand dune ecosystem dominated by a Pinus pinaster forest. Due to natural topographic variability and anthropogenic GW exploitation, substantial variability in depth to GW between sites was found. Under these conditions it was possible to identify the degree of usage and dependence on GW of different plant species (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader and how GW dependence varied seasonally and between the heterogeneous sites. Results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy. Species comparison revealed that variability in pre-dawn water potential (Ψ_pre and bulk leaf δ¹³C was related to site differences in GW use in the deep-rooted (Pinus pinaster, Myrica faya and phreatophyte (Salix repens species. However, such variation was more evident during spring than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψ_pre and bulk leaf δ¹³C. In contrast, the response of Corema album, an endemic understory drought-adapted shrub, seemed to be independent of water availability across seasons and sites. Thus, the susceptibility to lowering of GW due to anthropogenic

Size distribution and structure of Barchan dune fields

Directory of Open Access Journals (Sweden)

O. Durán

2011-07-01

Full Text Available Barchans are isolated mobile dunes often organized in large dune fields. Dune fields seem to present a characteristic dune size and spacing, which suggests a cooperative behavior based on dune interaction. In Duran et al. (2009, we propose that the redistribution of sand by collisions between dunes is a key element for the stability and size selection of barchan dune fields. This approach was based on a mean-field model ignoring the spatial distribution of dune fields. Here, we present a simplified dune field model that includes the spatial evolution of individual dunes as well as their interaction through sand exchange and binary collisions. As a result, the dune field evolves towards a steady state that depends on the boundary conditions. Comparing our results with measurements of Moroccan dune fields, we find that the simulated fields have the same dune size distribution as in real fields but fail to reproduce their homogeneity along the wind direction.

Popham Beach, Maine: An example of engineering activity that saved beach property without harming the beach

Science.gov (United States)

Kelley, Joseph T.

2013-10-01

Beach and property erosion on coasts is a widespread and chronic problem. Historical approaches to this issue, including seawalls and sand replenishment, are often inappropriate or too expensive. In Maine, seawalls were banned in 1983 and replenishment is too costly to employ. Replacement of storm-damaged buildings is also not allowed, and a precedent case on Popham Beach, Maine required that the owner remove an unpermitted building from a site where an earlier structure was damaged. When the most popular park in Maine, Popham Beach State Park, experienced inlet associated erosion that threatened park infrastructure (a bathhouse), temporary measures were all that the law allowed. Because it was clear that the inlet channel causing the erosion would eventually change course, the state opted to erect a temporary seawall with fallen trees at the site. This may or may not have slowed the erosion temporarily, but reassured the public that "something was being done". Once a storm cut a new tidal inlet channel and closed off the old one, tidal water still entered the former channel and continued to threaten the bathhouse. To ultimately save the property, beach scraping was employed. Sand was scraped from the lower beach to construct a sand berm that deflected the tidal current away from the endangered property. This action created enough time for natural processes to drive the remains of the former spit onto the beach and widen it significantly. Whereas many examples of engineering practices exist that endanger instead of saving beaches, this example is one of an appropriate engineering effort to rescue unwisely located beach-front property.

Holocene eolian activity in the Minot dune field, North Dakota

Science.gov (United States)

Muhs, D.R.; Stafford, Thomas W.; Been, J.; Mahan, S.A.; Burdett, J.; Skipp, G.; Rowland, Z.M.

1997-01-01

Stabilized eolian sand is common over much of the Great Plains region of the United States and Canada, including a subhumid area of ??? 1500 km2 near Minot, North Dakota. Eolian landforms consist of sand sheets and northwest-trending parabolic dunes. Dunes and sand sheets in the Minot field are presently stabilized by a cover of prairie grasses or oak woodland. Stratigraphic studies and accelerator mass spectrometry radiocarbon dating of paleosols indicate at least two periods of eolian sand movement in the late Holocene. Pedologic data suggest that all of the dune field has experienced late Holocene dune activity, though not all parts of the dune field may have been active simultaneously. Similar immobile element (Ti, Zr, La, Ce) concentrations support the interpretation that eolian sands are derived from local glaciofluvial and glaciolacustrine sediments. However, glaciolacustrine and glaciofluvial source sediments have high Ca concentrations from carbonate minerals, whereas dune sands are depleted in Ca. Because noneolian-derived soils in the area are calcareous, these data indicate that the Minot dune field may have had extended periods of activity in the Holocene, such that eolian abrasion removed soft carbonate minerals. The southwest-facing parts of some presently stabilized dunes were active during the 1930s drought, but were revegetated during the wetter years of the 1940s. These observations indicate that severe droughts accompanied by high temperatures are the most likely cause of Holocene eolian activity.

Controls on desert dune activity - a geospatial approach

Science.gov (United States)

Lancaster, N.; Hesse, P. P.

2017-12-01

Desert and other inland dunes occur on a wide spectrum of activity (defined loosely as the proportion of the surface area subject to sand movement) from unvegetated to sparsely vegetated "active" dunes through discontinuously vegetated inactive dunes to completely vegetated and degraded dunes. Many of the latter are relicts of past climatic conditions. Although field studies and modeling of the interactions between winds, vegetation cover, and dune activity can provide valuable insights, the response of dune systems to climate change and variability past, present, and future has until now been hampered by the lack of pertinent observational data on geomorphic and climatic boundary conditions and dune activity status for most dune areas. We have developed GIS-based approach that permits analysis of boundary conditions and controls on dune activity at a range of spatial scales from dunefield to global. In this approach, the digital mapping of dune field and sand sea extent has been combined with systematic observations of dune activity at 0.2° intervals from high resolution satellite image data, resulting in four classes of activity. 1 km resolution global gridded datasets for the aridity index (AI); precipitation, satellite-derived percent vegetation cover; and estimates of sand transport potential (DP) were re-sampled for each 0.2° grid cell, and dune activity was compared to vegetation cover, sand transport potential, precipitation, and the aridity index. Results so far indicate that there are broad-scale relationships between dunefield mean activity, climate, and vegetation cover. However, the scatter in the data suggest that other local factors may be at work. Intra-dune field patterns are complex in many cases. Overall, much more work needs to be done to gain a full understanding of controls at different spatial and temporal scales, which can be faciliated by this spatial database.

Does salt stress constrain spatial distribution of dune building grasses Ammophila arenaria and Elytrichia juncea on the beach?

Science.gov (United States)

van Puijenbroek, Marinka E B; Teichmann, Corry; Meijdam, Noortje; Oliveras, Imma; Berendse, Frank; Limpens, Juul

2017-09-01

Rising sea levels threaten coastal safety by increasing the risk of flooding. Coastal dunes provide a natural form of coastal protection. Understanding drivers that constrain early development of dunes is necessary to assess whether dune development may keep pace with sea-level rise. In this study, we explored to what extent salt stress experienced by dune building plant species constrains their spatial distribution at the Dutch sandy coast. We conducted a field transplantation experiment and a glasshouse experiment with two dune building grasses Ammophila arenaria and Elytrigia juncea . In the field, we measured salinity and monitored growth of transplanted grasses in four vegetation zones: (I) nonvegetated beach, (II) E. juncea occurring, (III) both species co-occurring, and (IV) A. arenaria dominant. In the glasshouse, we subjected the two species to six soil salinity treatments, with and without salt spray. We monitored biomass, photosynthesis, leaf sodium, and nutrient concentrations over a growing season. The vegetation zones were weakly associated with summer soil salinity; zone I and II were significantly more saline than zones III and IV. Ammophila arenaria performed equally (zone II) or better (zones III, IV) than E. juncea , suggesting soil salinity did not limit species performance. Both species showed severe winter mortality. In the glasshouse, A. arenaria biomass decreased linearly with soil salinity, presumably as a result of osmotic stress. Elytrigia juncea showed a nonlinear response to soil salinity with an optimum at 0.75% soil salinity. Our findings suggest that soil salinity stress either takes place in winter, or that development of vegetated dunes is less sensitive to soil salinity than hitherto expected.

Changes in vegetation and biological soil crust communities on sand dunes stabilizing after a century of grazing on San Miguel Island, Channel Island National Park, California

Science.gov (United States)

Zellman, Kristine L.

2014-01-01

San Miguel Island is the westernmost of the California Channel Islands and one of the windiest areas on the west coast of North America. The majority of the island is covered by coastal sand dunes, which were stripped of vegetation and subsequently mobilized due to droughts and sheep ranching during the late 19th century and early 20th century. Since the removal of grazing animals, vegetation and biological soil crusts have once again stabilized many of the island's dunes. In this study, historical aerial photographs and field surveys were used to develop a chronosequence of the pattern of change in vegetation communities and biological soil crust levels of development (LOD) along a gradient of dune stabilization. Historical aerial photographs from 1929, 1954, 1977, and 2009 were georeferenced and used to delineate changes in vegetation canopy cover and active (unvegetated) dune extent among 5 historical periods (pre-1929, 1929–1954, 1954–1977, 1977–2009, and 2009–2011). During fieldwork, vegetation and biological soil crust communities were mapped along transects distributed throughout San Miguel Island's central dune field on land forms that had stabilized during the 5 time periods of interest. Analyses in a geographic information system (GIS) quantified the pattern of changes that vegetation and biological soil crust communities have exhibited on the San Miguel Island dunes over the past 80 years. Results revealed that a continuing increase in total vegetation cover and a complex pattern of change in vegetation communities have taken place on the San Miguel Island dunes since the removal of grazing animals. The highly specialized native vascular vegetation (sea rocket, dunedelion, beach-bur, and locoweed) are the pioneer stabilizers of the dunes. This pioneer community is replaced in later stages by communities that are dominated by native shrubs (coastal goldenbush, silver lupine, coyote-brush, and giant coreopsis), with apparently overlapping or

Mineral legislations applicable to beach sand industry

International Nuclear Information System (INIS)

D'Cruz, Eric

2016-01-01

India has got a wealth of natural resources in different geological environs and shoreline placers form an important constituent of the natural resources. Large reserves of beach sand minerals, viz. imenite, rutile, leucoxene, zircon, sillimanite, garnet and monazite are the economic minerals in the coastal and inland placer sands. In the federal structure of India, the State Governments are the owners of minerals located within their respective boundaries. The State Governments grant the mineral concessions for all the minerals located within the boundary of the State, under the provisions of the Acts and Rules framed for the purpose. Though the mineral wealth is under the control of the State, the power for framing the rules for the grant of mineral concessions vastly rest with the Central Government. Since mineral concessions are often granted for a longer duration of thirty to fifty years or more, a historical perspective of these rules are imperative in understanding the issues involved with BSM mining industry. Under the Govt. of India Act, 1935, Regulation of Mines and Oilfields and Mineral Development was kept under Federal control, declared by Federal Law. The word 'Federal' was substituted by the word 'Dominion' by the India (Provincial Constitution) Order, 1947. No legislation was, however, enacted in pursuance of above power until after Independence. However, the Govt. on India made the Mining Concession (Central) Rules, 1939 for regulating grants of prospecting license

Water Use for Cultivation Management of Watermelon in Upland Field on Sand Dune

Science.gov (United States)

Hashimoto, Iwao; Senge, Masateru; Itou, Kengo; Maruyama, Toshisuke

Early-maturing cultivation of watermelon in a plastic tunnel was invetigated in upland field on sand dune on the coast of the Japan Sea to find water use to control blowing sand and to transplant seedlings. This region has low precipitation, low humidity, and strong wind in March and April, when sand is readily blown in the field. Water is used to control blowing sand on days with precipitation below 5 mm, minimum humidity below the meteorological average in April, and maximum wind velocity above the meteorological average in April. For the rooting and growth of watermelon seedlings, soil temperature needs to be raised because it is low in April. Ridges are mulched with transparent, porous polyethylene films 10 or more days before transplanting the seedlings and irrigated with sprinklers on fine days for the thermal storage of solar energy. The stored heat steams the mulched ridges to raise soil temperature to 15°C or higher on the day of transplanting the seedlings. The total amount of irrigation water used for watermelon cultivation was 432.7 mm, of which 23.6 mm was for blowing sand control and 26.6 mm was for transplanting the seedlings. The combined amount, 50.2 mm, is 11.6% of the total amount of water used for cultivation management.

Evaluation of Ra, Th, K and radium equivalent activity in sand samples from Camburi Beach, Vitoria, Espirito Santos, Brazil

International Nuclear Information System (INIS)

Barros, Livia F.; Pecequilo, Brigitte R.S.

2013-01-01

Camburi beach, in the city of Vitoria, Espirito Santo State. Brazil, is a naturally high background region in Brazil. The beach sands contain monazite, ilmenite and other accessory minerals rich in 226 Ra, 23 '2Th and 40 K. As these radionuclides are the main natural contributors to external exposure from gamma rays, the knowledge of the sands radioactivity content plays an important role in radiation protection. In this work, 226 Ra, 232 Th and 40 K activities concentrations, together with the radium equivalent activity, Ra eq. were determined in some selected sand samples from a single location at Camburi beach, known for the high level of radioactivity. The sand samples collected monthly from January to December 2011, were dried and sealed in standard 100 mL HPDE polyethylene flasks and measured by high resolution gamma-spectrometry after a 4 weeks ingrowth period, in order to allow the secular equilibrium in the 238 U and 23 '2Th series. Preliminary results, without considering samples self-attenuation, show activities concentrations in the range from 12 ± 1 Bq kg -1 to 1022 ± 30 Bq kg -1 for 226 Ra, 35 ± 1 Bq kg -1 to 5731 ± 134 Bq kg -1 for 232 Th and 18 ± 4 Bqkg -1 to 430 ± 21 Bq kg -1 for 40 K. The Ra eq , presented values ranging from 63 Bq kg -1 to 9250 Bq kg -1 . (author)

Shifts in the microbial community composition of Gulf Coast beaches following beach oiling.

Directory of Open Access Journals (Sweden)

Ryan J Newton

Full Text Available Microorganisms associated with coastal sands serve as a natural biofilter, providing essential nutrient recycling in nearshore environments and acting to maintain coastal ecosystem health. Anthropogenic stressors often impact these ecosystems, but little is known about whether these disturbances can be identified through microbial community change. The blowout of the Macondo Prospect reservoir on April 20, 2010, which released oil hydrocarbons into the Gulf of Mexico, presented an opportunity to examine whether microbial community composition might provide a sensitive measure of ecosystem disturbance. Samples were collected on four occasions, beginning in mid-June, during initial beach oiling, until mid-November from surface sand and surf zone waters at seven beaches stretching from Bay St. Louis, MS to St. George Island, FL USA. Oil hydrocarbon measurements and NOAA shoreline assessments indicated little to no impact on the two most eastern beaches (controls. Sequence comparisons of bacterial ribosomal RNA gene hypervariable regions isolated from beach sands located to the east and west of Mobile Bay in Alabama demonstrated that regional drivers account for markedly different bacterial communities. Individual beaches had unique community signatures that persisted over time and exhibited spatial relationships, where community similarity decreased as horizontal distance between samples increased from one to hundreds of meters. In contrast, sequence analyses detected larger temporal and less spatial variation among the water samples. Superimposed upon these beach community distance and time relationships, was increased variability in bacterial community composition from oil hydrocarbon contaminated sands. The increased variability was observed among the core, resident, and transient community members, indicating the occurrence of community-wide impacts rather than solely an overprinting of oil hydrocarbon-degrading bacteria onto otherwise

Quantitative And Qualitative Measurement Of Radio- Activity In Sand Samples From Chalet Beach In Songkhla Province

International Nuclear Information System (INIS)

Sukhowattanakit, Jirapa; Kessaratikoon, Prasong; Udomsomporn, Suchin; Thorarit, Wutthidej

2005-10-01

The quantitative and qualitative measurement of radioactivity in 39 sand samples collected from Chalatat beach in Songkhla province are presented. Experimental results were obtained by using a high-purity germanium detector and gamma spectroscopy analysis system and comparing to the standard soil (IAEA SOIL 6) at the Office of Atoms for Peace (OAP). The measuring time of all sand samples is 10,000 seconds. Some radioisotopes such as K-40, Cs-137, Tl-208, Bi-212, Pb-212, Bi-214, Pb- 214, Ra-226 and Ac-228 were found in sand samples. In addition, the radioactivity of Ra-226 and Cs-137 in those samples were found in normal level

An experiment on a sand-dune environment in Southern Venetian coast based on GPR, VES and documentary evidence

Directory of Open Access Journals (Sweden)

L. Tosi

2000-06-01

Full Text Available The internal structures of some surviving sand dunes and the ancient shore-lines along the coast south of Venice have been investigated integrating Ground Probing Radar (GPR profiles, Vertical Electrical Soundings (VES and water conductivity measurements in some boreholes. The GPR penetration depth has been limited (4-5 m,using a 400 MHz antenna by the high conductivity of salt water saturating pores of the shallow sediments. On the other hand, the excellent spatial resolution of the radar survey provided an estimate of internal dune bedding features, such as cross lamination and forwarding ancient covered coast-lines dated in the Thirties. The interpretation of the data, in particular along one line 360 m long intercepting a sizable sand-dune bank, seems to offer clues to the evolutional history of the coast line and the depth of transition from fresh-water to brackish-salt water. The water table was detected with electrical measurements and direct observations in boreholes, whereas the transition between fresh and salt water (brackish water was pointed out indirectly by the high energy absorption and total back-reflection of the EM waves, encountered at this boundary, and directly by the strong decrease in VES resistivity values.

A study of global sand seas

Science.gov (United States)

McKee, Edwin D.

1979-01-01

The birth of the idea that led to this publication on "Global Sand Seas" dates back to the late 1920's. At that time I was engaged in a study of the Coconino Sandstone of Arizona's Grand Canyon. Considerable controversy existed then as to whether this sandstone was a subaqueous deposit or was composed of wind-formed dunes. It became apparent that definitive literature was sparse or lacking on types of dunes, global distribution of these types, the mechanics of their development, the precise nature of their internal structure of cross-stratificiation, and the relation of wind systems to these sand forms. Especially lacking were data on criteria that could confidently be used in the recognition of ancient dunes. The common denominator in this publication is eolian sand bodies. Although the book is concerned primarily with desert sand seas, the subject matter is not restricted to deserts; it includes many references to deposits of coastal sand and to sand bodies in humid climates. Nor does the book deal exclusively with dunes, which, according to most definitions, involve mounds or hills. Many references are made to sand sheets, sand stringers, and other types of sand deposits that have no prominent topographic expression. All sand bodies accumulated by the action of wind are discussed. Chapters A-J of this publication are primarily topical. Chapters cover the grain texture, the color, and the structure of modern dunes and other eolian sands. Special treatment is given to the relation of wind data to dune interpretation, the evolution of form in current-deposited sand bodies as determined from experimental studies, and the discriminant analysis technique for differentiating between coastal and inland desert sands. This topical part of the publication also includes an analysis of criteria used in ancient deposits to interpret their eolian genesis and a consideration of economic application of the principles described, including a discussion of potentials and problems

Coexistence of Dunes and Humid Conditions at Titan's Tropics

Science.gov (United States)

Radebaugh, Jani; Lorenz, R. D.; Lunine, J. I.; Kirk, R. L.; Ori, G. G.; Farr, T. G.; Malaska, M.; Le Gall, A.; Liu, Z. Y. C.; Encrenaz, P. J.; Paillou, P.; Hayes, A.; Lopes, R. M. C.; Turtle, E. P.; Wall, S. D.; Stofan, E. R.; Wood, C. A.; Cassini RADAR Team

2012-10-01

At Titan's equatorial latitudes there are tens of thousands of dunes, a landform typical of desert environments where sand does not become anchored by vegetation or fluids. Model climate simulations predict generally dry conditions at the equator and humid conditions near the poles of Titan, where lakes of methane/ethane are found. However, moderate relative methane humidity was observed at the Huygens landing site, recent rainfall was seen by Cassini ISS near the Belet Sand Sea, and a putative transient lake in Shangri-La was observed by Cassini VIMS, all of which indicate abundant fluids may be present, at least periodically, at Titan's equatorial latitudes. Terrestrial observations and studies demonstrate dunes can exist and migrate in conditions of high humidity. Active dunes are found in humid climates, indicating the movement of sand is not always prohibited by the presence of fluids. Sand mobility is related to precipitation, evaporation and wind speed and direction. If dune surfaces become wetted by rainfall or rising subsurface fluids, they can become immobilized. However, winds can act to dry the uppermost layers, freeing sands for saltation and enabling dune migration in wet conditions. Active dunes are found in tropical NE Brazil and NE Australia, where there are alternating dry and wet periods, a condition possible for Titan's tropics. Rising and falling water levels lead to the alteration of dune forms, mainly from being anchored by vegetation, but also from cementation by carbonates or clays. Studies of Titan's dunes, which could undergo anchoring of organic sediments by hydrocarbon fluids, could inform the relative strength of vegetation vs. cementation at humid dune regions on Earth. Furthermore, a comprehensive survey of dune morphologies near regions deemed low by SARTopo and stereo, where liquids may collect in wet conditions, could reveal if bodies of liquid have recently existed at Titan's tropics.

Compositional variations in sands of the Bagnold Dunes, Gale crater, Mars, from visible-shortwave infrared spectroscopy and comparison with ground truth from the Curiosity rover

Science.gov (United States)

Lapotre, M. G. A.; Ehlmann, B. L.; Minson, S. E.; Arvidson, R. E.; Ayoub, F.; Fraeman, A. A.; Ewing, R. C.; Bridges, N. T.

2017-12-01

During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single-scattering albedo spectra and a Markov chain Monte Carlo implementation of Hapke's radiative transfer theory to fully constrain uncertainties and permitted solutions. These predictions, evaluated against in situ measurements at one site from the Curiosity rover, show that X-ray diffraction-measured mineralogy of the basaltic sands is within the 95% confidence interval of model predictions. However, predictions are relatively insensitive to grain size and are nonunique, especially when modeling the composition of minerals with solid solutions. We find an overall basaltic mineralogy and show subtle spatial variations in composition in and around the Bagnold Dunes, consistent with a mafic enrichment of sands with cumulative aeolian-transport distance by sorting of olivine, pyroxene, and plagioclase grains. Furthermore, the large variations in Fe and Mg abundances ( 20 wt %) at the Bagnold Dunes suggest that compositional variability may be enhanced by local mixing of well-sorted sand with proximal sand sources. Our estimates demonstrate a method for orbital quantification of composition with rigorous uncertainty determination and provide key constraints for interpreting in situ measurements of compositional variability within Martian aeolian sandstones.

Impacts of simulated climate change and fungal symbionts on survival and growth of a foundation species in sand dunes.

Science.gov (United States)

Emery, Sarah M; Rudgers, Jennifer A

2013-12-01

For many ecosystems, one of the primary avenues of climate impact may be through changes to foundation species, which create habitats and sustain ecosystem services. For plants, microbial symbionts can often act as mutualists under abiotic stress and may mediate foundational plant responses to climate change. We manipulated the presence of endophytes in Ammophila breviligulata, a foundational sand dune species, to evaluate their potential to influence plant responses to climate change. We simulated projected climate change scenarios for temperature and precipitation using a growth chamber experiment. A 5 °C increase in temperature relative to current climate in northern Michigan reduced A. breviligulata survival by 45 %. Root biomass of A. breviligulata, which is critical to dune stabilization, was also strongly reduced by temperature. Plants inoculated with the endophyte had 14 % higher survival than endophyte-free plants. Contrary to our prediction, endophyte symbiosis did not alter the magnitude or direction of the effects of climate manipulations on A. breviligulata survival. However, in the absence of the endophyte, an increase in temperature increased the number of sand grains bound by roots by 80 %, while in symbiotic plants sand adherence did not significantly respond to temperature. Thus, plant-endophyte symbiosis actually negated the benefits in ecosystem function gained under a warmer climate. This study suggests that heat stress related to climate change in the Great Lakes may compromise the ability of A. breviligulata to stabilize dune ecosystems and reduce carbon storage and organic matter build-up in these early-successional systems due to reduced plant survival and root growth.

Beach sand mineral industries in India and challenges of value addition

International Nuclear Information System (INIS)

Patra, R.N.

2016-01-01

Beach sand minerals (BSM) are a suite of seven minerals that often occur together in various proportions in the beach sands of coastal India. They are also called heavy minerals as they have densities in the range 3.2 gms/cc to 5.2 gms/cc, which are higher than the sand. Ilmenite, leucoxene and rutile are oxide minerals of titanium metal. Zircon is silicate of zirconium where as silimanite is silicate of aluminum. The titanium, zirconium and thorium bearing minerals are atomic minerals under the atomic energy act 1962 and need no objection from the Department of Atomic Energy (DAE) for their mining. Further authorization is necessary from DAE to handle and process monazite as it contains thorium, as it is a prescribed substance under the notification issued under the atomic energy act. Radioactive nature of monazite also mandates obtaining permission from Atomic Energy Regulatory Board (AERB) with a view to ensure regulatory compliance with radiological safety. Monazite is processed to produce rare earths, trisodium phosphate (TSP) and thorium compounds.Thorium values are stockpiled in engineered trenches for use in nuclear power program of the country where as rare earths are used for manufacture of high power permanent magnets, energy efficient optical phosphors, metal alloys for battery to store electricity and hydrogen, as additives to glass for imparting special optical properties and myriads of applications in defence and strategic sectors. Rare earths of late have assumed importance as high power rare earths based permanent magnets are used in manufacture of wind mills, MRI machines, magnetic levitated bearings etc, having minimal impact on green house gas generation and use in renewable energy sector. The presentation brings out the limitation of value added product industries in India, the efforts taken by Indian Rare Earths Ltd. (IREL) in developing value added products in the face of technology denial regime and hostile market dynamics. The road map for

Natural radioactivity dose assessment in beach sands of the Espírito Santo, Brazil

International Nuclear Information System (INIS)

Fontainha, C.C.P.; Santos, T.O.; Aguilar, V.J.C.; Takahashia, L.C.

2017-01-01

The presence of natural radionuclide contributes significantly to the environmental dose levels that the human being receives, being important to be aware of the distribution, composition and the background of these soils. In this work, the activity concentration of the natural radionuclides was determined by gamma spectrometry from the sands of eight beach from Anchieta e Guarapari, in the Espírito Santo, Brazil. The activity concentration of 226 Ra, 232 Th and 40 K was expressed by radio equivalent activity (R aeq ), which takes into account the associated radiological risk. From these data, the annual effective dose rate for external environment (H eout ) and the radiation risk indexes (H ex ) were calculated. In the sands of Além, Coninhos, Onça, Três Praias, Morcego and Padres beaches the R aeq values ranged from 771.9 to 8743.3 Bq.kg -1 , while H ex ranged from 1.0 to 11.4 Bq.kg -1 and H eout ranged from 0.6 to 6.0 mSv.year -1 , with the lowest values being from Além and the larger ones from Padres. The Areia Vermelha beach presented higher values the others, with R aeq of 152.6 kBq.kg -1 , H ex of 2.1 Bq.kg -1 and H eout 1.0 Sv.year -1 . This evaluation is a favorable tool for radiological protection because it allows to chart the natural radioactivity to the coast of Espírito Santo, Brazil. (author)

Evaluation of Ra, Th, K and radium equivalent activity in sand samples from Camburi Beach, Vitoria, Espirito Santos, Brazil

Energy Technology Data Exchange (ETDEWEB)

Barros, Livia F.; Pecequilo, Brigitte R.S., E-mail: lfbarros@ipen.br, E-mail: brigitte@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2013-07-01

Camburi beach, in the city of Vitoria, Espirito Santo State. Brazil, is a naturally high background region in Brazil. The beach sands contain monazite, ilmenite and other accessory minerals rich in {sup 226}Ra, {sup 23}'2Th and {sup 40}K. As these radionuclides are the main natural contributors to external exposure from gamma rays, the knowledge of the sands radioactivity content plays an important role in radiation protection. In this work, {sup 226}Ra, {sup 232}Th and {sup 40}K activities concentrations, together with the radium equivalent activity, Ra{sub eq.} were determined in some selected sand samples from a single location at Camburi beach, known for the high level of radioactivity. The sand samples collected monthly from January to December 2011, were dried and sealed in standard 100 mL HPDE polyethylene flasks and measured by high resolution gamma-spectrometry after a 4 weeks ingrowth period, in order to allow the secular equilibrium in the {sup 238}U and {sup 23}'2Th series. Preliminary results, without considering samples self-attenuation, show activities concentrations in the range from 12 {+-} 1 Bq kg{sup -1} to 1022 {+-} 30 Bq kg{sup -1} for {sup 226}Ra, 35 {+-} 1 Bq kg{sup -1} to 5731 {+-} 134 Bq kg{sup -1} for {sup 232}Th and 18 {+-} 4 Bqkg{sup -1} to 430 {+-} 21 Bq kg{sup -1} for {sup 40}K. The Ra{sub eq}, presented values ranging from 63 Bq kg{sup -1} to 9250 Bq kg{sup -1}. (author)

A luminescence dating intercomparison based on a Danish beach-ridge sand

DEFF Research Database (Denmark)

Murray, Andrew; Buylaert, Jan-Pieter; Thiel, Christine

2015-01-01

peninsula, northern Jutland (Denmark). About 200 kg of sand was sampled at night from a single beach ridge. The sand was homogenised using a cement mixer and packed in ~700 moisture and light-tight bags for distribution. The quartz luminescence characteristics are satisfactory (e.g. fast-component dominated...... and good dose recovery) and our own equivalent dose determinations and measurements of radionuclide concentrations for twenty of these bags demonstrate the degree of homogenisation. One natural sample and one sample of pre-processed quartz was made available on request; analysis of all the responses gives...... a mean dose (pre-processed quartz) of 4.58 Gy, σ ¼ 0.40 (n ¼ 26), to be compared to the mean dose (self-extracted quartz) of 4.52 Gy, σ ¼ 0.55 (n ¼ 21). The mean age is 3.99 ± 0.14 ka, σ ¼ 0.71 (n ¼ 22), i.e. a relative standard deviation of 18%.We present an analysis of all the important quantitative...

Characteristics of dune-paleosol-sequences in Fuerteventura. - What should be questioned?

Science.gov (United States)

Faust, Dominik; Willkommen, Tobias; Yanes, Yurena; Richter, David; Zöller, Ludwig

2013-04-01

Characteristics of dune-paleosol-sequences in Fuerteventura. - What should be questioned? Dominik Faust, TU Dresden, Germany Tobias Willkommen, TU Dresden, Germany Yurena Yanes, CSIC Granada/Cincinatti, Spain/USA David Richter, TU Dresden, Germany Ludwig Zöller, Uni Bayreuth, Germany The northern part of Fuerteventura is characterized by large dune fields. We investigated dune-paleosol-sequences in four pits to establish a robust stratigraphy and to propose a standard section. An interaction of processes like dune formation, soil formation and redeposition of soils and sand are most important to understand the principles of landscape development in the study area. To our mind a process cycle seem to be important: First climbing-dunes are formed by sand of shelf origin. Then soil formation could have taken place. Soil and/or sand were then eroded and deposited at toe slope position. This material in turn is the source of new sand supply and dune formation. The described cycle may be repeated several times and this ping-pong-process holds on. The results are sections composed of dune layers, paleosols and colluvial material interbedded. Fundamental questions still remain unanswered: Is climate change responsable for changes in process combination (e.g. from dune formation to soil formation)? Or are these features due to divergence phenomenon, where different effects/results (dune and soils) may be linked to similar causes (here: climate)? Assuming that different features (soils and dunes) were formed under one climate, increasing soil forming intensity could be mainly a function of decreasing sand supply. This in turn could be caused by reduced sand production (s. ZECH et al. accepted). However geochemical data and mollusc assemblages point to changing environments in space and even climate modifications in time.

Comparative decay of Catellicoccus marimmalium and enterococci in beach sand and seawater.

Science.gov (United States)

Brown, Kendra I; Boehm, Alexandria B

2015-10-15

Most studies characterize microbial source tracking (MST) target performance using sensitivity and specificity metrics. However, it is important to also consider the temporal stability of MST targets in relation to regulated microbial pollutants. Differences among bacterial target stabilities may lead to erroneous conclusions about sources of contamination. The present study evaluates the relative stability of MST targets and fecal indicator organisms using the gull/pigeon-associated Catellicoccus marimammalium (CAT) marker and enterococci (ENT). The decay rates of CAT and ENT measured by culture (cENT) and QPCR (tENT) were compared in sand and seawater laboratory microcosms under environmentally relevant conditions (subject to tidal wetting versus no wetting in sand, and sunlit versus dark conditions in seawater). Bacterial targets were more persistent in beach sand than in seawater with decay rates on the order of 0.01-0.1 per day and 1 to 10 per day, respectively. Targets were more persistent in unwetted compared to wetted sand, and dark compared to sunlit seawater. During the first 8 days of the sand experiment, the decay rate k of CAT was greater than that of cENT. The decay rates of CAT, tENT, and cENT were similar in sand after day 8 and in dark seawater. In sunlit seawater, the decay rates were different between targets with kcENT > kCAT > ktENT. The decay rates presented here are useful for fate and transport models and also inform the use of MST marker concentrations to infer ENT sources in the environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

STUDY OF THE EFFECT OF ALUMINUM CONTENT AND C / S RATIO ON THE PHYSICO-MECHANICAL AND THERMAL PROPERTIES OF A LIGHTWEIGHT CONCRETE MADE FROM SAND DUNE

Directory of Open Access Journals (Sweden)

Z. Damene

2015-07-01

Full Text Available This research is a contribution to the development of local materials especially in the development of a cellular concrete with dunes sand. This is an experimental study whose objective is to see the influence of the C/S (dosage of cement compared to sand and the dosage of aluminum on the physico- mechanical and thermal performance of lightweight concrete cellular type. The results showed that the cement compared to the sand has a remarkable effect on the reaction and that on expansion the mechanical behavior as well as the dosage of aluminum in the composition of cellular concrete has a certain threshold Aluminium beyond which provides no relief benefits. Based on these results, the cellular concrete made from sand dune can be classified as light structural concrete with insulation suitable for very hot and arid environment of our region power.

Programs to obtain vertical heights from mean sea level and for computing volume of sand/mineral along beaches: A case study with Kalbadevi beach profiling data and results

Digital Repository Service at National Institute of Oceanography (India)

Ganesan, P.

Two programs have been developed to process profile data, for obtaining vertical heights with respect to mean sea level (M.S.L.) and for computation of volume of heavy mineral / sand accumulation or erosion along the beaches. The final output...

The Carolina Sandhills: Quaternary eolian sand sheets and dunes along the updip margin of the Atlantic Coastal Plain province, southeastern United States

Science.gov (United States)

Swezey, Christopher; Fitzwater, Bradley A.; Whittecar, G. Richard; Mahan, Shannon; Garrity, Christopher P.; Aleman Gonzalez, Wilma B.; Dobbs, Kerby M.

2016-01-01

The Carolina Sandhills is a physiographic region of the Atlantic Coastal Plain province in the southeastern United States. In Chesterfield County (South Carolina), the surficial sand of this region is the Pinehurst Formation, which is interpreted as eolian sand derived from the underlying Cretaceous Middendorf Formation. This sand has yielded three clusters of optically stimulated luminescence ages: (1) 75 to 37 thousand years ago (ka), coincident with growth of the Laurentide Ice Sheet; (2) 28 to 18 ka, coincident with the last glacial maximum (LGM); and (3) 12 to 6 ka, mostly coincident with the Younger Dryas through final collapse of the Laurentide Ice Sheet. Relict dune morphologies are consistent with winds from the west or northwest, coincident with modern and inferred LGM January wind directions. Sand sheets are more common than dunes because of effects of coarse grain size (mean range: 0.35–0.59 mm) and vegetation. The coarse grain size would have required LGM wind velocities of at least 4–6 m/sec, accounting for effects of colder air temperatures on eolian sand transport. The eolian interpretation of the Carolina Sandhills is consistent with other evidence for eolian activity in the southeastern United States during the last glaciation.

Scheme study of separation and concentration of heavy minerals from the black sand in Aguas dulces beach - Rocha

International Nuclear Information System (INIS)

Mujica, H.; Marotta, L.

1968-12-01

This work is about a study of separation and concentration of heavy minerals from the black sand in Aguas dulces beach - Rocha. The beneficial minerals in that prospected zone are: ilmenite, zircon, rutile and monazite, associated with gangue minerals

Antioxidant activity of raw, cooked and Rhizopus oligosporus fermented beans of Canavalia of coastal sand dunes of Southwest India.

Science.gov (United States)

Niveditha, Vedavyas R; Sridhar, Kandikere R

2014-11-01

The raw and processed (cooked and cooked + solid-state fermented with Rhizopus oligosporus) split beans of two landraces of coastal sand dune wild legumes (Canavalia cathartica and Canavalia maritima) of the southwest coast of India were examined for bioactive compounds (total phenolics, tannins and vitamin C) and antioxidant potential (total antioxidant activity, ferrous-ion chelating capacity, DPPH free radical-scavenging activity and reducing activity). One-way ANOVA revealed significant elevation of bioactive compounds as well as antioxidant activities in fermented beans compared to raw and cooked beans in both legumes (p beans of both legumes were significantly lowest compared to raw and cooked beans (p beans of C. cathartica, while total antioxidant and free radical-scavenging activities of fermented beans of C. maritima were clustered. The present study demonstrated that split beans of coastal sand dune Canavalia fermented by R. oligosporus endowed with high bioactive principles as well as antioxidant potential and thus serve as future nutraceutical source.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Winds pick up and transport grains from nearby beach sands and alluvial deposits into a wide Red Sea coastal plain at the border of the beach. The mineralogical (Qt–Ft–Lt) and geochemical composition of the sands, indicate that SF and QS coastal dune sands are mature and influenced by quartz-rich sands. The average ...

An evaluation of flora from coastal sand dunes of India: Rationale for conservation and management

Digital Repository Service at National Institute of Oceanography (India)

Rodrigues, R.S.; Mascarenhas, A.; Jagtap, T.G.

stream_size 37100 stream_content_type text/plain stream_name Ocean_Coast_Manage_54_181a.pdf.txt stream_source_info Ocean_Coast_Manage_54_181a.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 1... Author version: Ocean & Coastal Management, vol.54(2); 2011; 181-188 An evaluation of flora from coastal sand dunes of India: Rationale for conservation and management Rouchelle S. Rodrigues, Antonio Mascarenhas, Tanaji G. Jagtap * National...

Environmental isotopes in North African groundwaters; and the Dahna sand-dune study, Saudi Arabia

International Nuclear Information System (INIS)

Sonntag, C.; Thoma, G.; Muennich, K.O.; Dincer, T.; Klitzsch, E.

1980-01-01

I. North Saharian palaeowaters were mainly formed during a long humid period between 50,000 and 20,000 years BP., which was followed by a cool dry period from 20,000 to 14,000 years BP. These palaeowaters show a significant west-east decrease in deuterium and 18 O because of past groundwater formation by local rainfall from the western drift. Sahel zone groundwaters seem to show meridional variation of deuterium and 18 O due to a tropical convective influence. II. A computer model estimate of the alternate play between rainwater infiltration and evaporation in the Dahna sand-dune (near Riyadh, Saudi Arabia) yields a mean annual groundwater recharge of 20 mm annually which agrees with that obtained from bomb tritium vertical profiles of the sand moisture. The model also describes the deuterium and 18 O profiles. (author)

Importance of Antecedent Beach and Surf-Zone Morphology to Wave Runup Predictions

Science.gov (United States)

2016-10-01

mounted at a 30° angle toward the ocean to enable viewing of the dune toe . Though angles of incidence to the water are relatively low from the laser’s...automated terrestrial laser scanner was mounted above the dune (Figure 1A) to continuously measure the free surface profile of the beach and water...maximum and mean water levels reached during storms with variations in beach and dune morphology will therefore be a good predictor of areas of the coast

Effects of beach cast cleaning on beach quality, microbial food web, and littoral macrofaunal biodiversity

Science.gov (United States)

Malm, Torleif; Råberg, Sonja; Fell, Sabine; Carlsson, Per

2004-06-01

At the end of the summer, drifting filamentous red algae cover shallow bottoms and accumulate in huge cast walls on the open shores of the non-tidal central Baltic Sea. The hypotheses that beach cleaning increases water clarity, decreases the organic content of the sand, and increases the species diversity in the shallow zone closest to the shore, were tested through field investigations and experiments. Cleaned shorelines were compared with un-cleaned shorelines at two sites with different intensity of beach cleaning in a rural area of SE Sweden. The results show that water clarity was significantly increased off the intensively cleaned beach but not off the moderately cleaned one. Similarly, the total leakage of nitrogenous compounds decreased off the intensively cleaned beach, but not off the moderately cleaned. The organic content of the sand was lower on both cleaned beaches compared with nearby un-cleaned beaches. The total animal biomass was significantly lower on the intensively cleaned beach compared with the un-cleaned beach, but the moderately cleaned beach gave no such effect. The difference in biodiversity and community structure between cleaned and un-cleaned beaches was insignificant. The most obvious difference in species composition was a much higher number of planktivore opossum shrimps of the genus Mysis and Praunus on the un-cleaned beaches. The bacterial production and the amount of ciliates larger than 20 mm were also higher on un-cleaned beaches, indicating that the microbial food web off the un-cleaned beaches is stimulated by the discharge of decomposing algal material. The conclusion of the study is that mechanical cleaning reduces the organic content of the beach sand and may change the water quality and microbial production, but the effect on the macrofaunal biodiversity is insignificant.

Mars Global Digital Dune Database (MGD3): Global dune distribution and wind pattern observations

Science.gov (United States)

Hayward, Rosalyn K.; Fenton, Lori; Titus, Timothy N.

2014-01-01

The Mars Global Digital Dune Database (MGD3) is complete and now extends from 90°N to 90°S latitude. The recently released south pole (SP) portion (MC-30) of MGD3 adds ∼60,000 km2 of medium to large-size dark dune fields and ∼15,000 km2 of sand deposits and smaller dune fields to the previously released equatorial (EQ, ∼70,000 km2), and north pole (NP, ∼845,000 km2) portions of the database, bringing the global total to ∼975,000 km2. Nearly all NP dunes are part of large sand seas, while the majority of EQ and SP dune fields are individual dune fields located in craters. Despite the differences between Mars and Earth, their dune and dune field morphologies are strikingly similar. Bullseye dune fields, named for their concentric ring pattern, are the exception, possibly owing their distinctive appearance to winds that are unique to the crater environment. Ground-based wind directions are derived from slipface (SF) orientation and dune centroid azimuth (DCA), a measure of the relative location of a dune field inside a crater. SF and DCA often preserve evidence of different wind directions, suggesting the importance of local, topographically influenced winds. In general however, ground-based wind directions are broadly consistent with expected global patterns, such as polar easterlies. Intriguingly, between 40°S and 80°S latitude both SF and DCA preserve their strongest, though different, dominant wind direction, with transport toward the west and east for SF-derived winds and toward the north and west for DCA-derived winds.

Natural radioactivity dose assessment in beach sands of the Espírito Santo, Brazil

Energy Technology Data Exchange (ETDEWEB)

Fontainha, C.C.P.; Santos, T.O.; Aguilar, V.J.C.; Takahashia, L.C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem; Rocha, Z., E-mail: crissia@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

The presence of natural radionuclide contributes significantly to the environmental dose levels that the human being receives, being important to be aware of the distribution, composition and the background of these soils. In this work, the activity concentration of the natural radionuclides was determined by gamma spectrometry from the sands of eight beach from Anchieta e Guarapari, in the Espírito Santo, Brazil. The activity concentration of {sup 226}Ra, {sup 232}Th and {sup 40}K was expressed by radio equivalent activity (R{sub aeq}), which takes into account the associated radiological risk. From these data, the annual effective dose rate for external environment (H{sub eout}) and the radiation risk indexes (H{sub ex}) were calculated. In the sands of Além, Coninhos, Onça, Três Praias, Morcego and Padres beaches the R{sub aeq} values ranged from 771.9 to 8743.3 Bq.kg{sup -1}, while H{sub ex} ranged from 1.0 to 11.4 Bq.kg{sup -1} and H{sub eout} ranged from 0.6 to 6.0 mSv.year{sup -1}, with the lowest values being from Além and the larger ones from Padres. The Areia Vermelha beach presented higher values the others, with R{sub aeq} of 152.6 kBq.kg{sup -1}, H{sub ex} of 2.1 Bq.kg{sup -1} and H{sub eout} 1.0 Sv.year{sup -1}. This evaluation is a favorable tool for radiological protection because it allows to chart the natural radioactivity to the coast of Espírito Santo, Brazil. (author)

Coastal Dunes of the Baltic Sea Shores: A Review

Directory of Open Access Journals (Sweden)

Łabuz Tomasz Arkadiusz

2018-03-01

Full Text Available The article summarises results of studies conducted along the Baltic Sea sandy coasts by scientists involved in coastal dune research, and presents an attempt to describe the types and distribution of dune coasts. The Baltic Sea coasts feature lower and higher foredunes. The lowland behind the coastal dune belt is covered by wandering or stabilised inland dunes – transgressive forms, mainly parabolic or barchans. The source of sediment for dune development includes fluvioglacial sands from eroded coasts, river-discharged sand, and older eroded dunes. Due to the ongoing erosion and coastal retreat, many dunes have been eroded, and some are withdrawing onto the adjacent land. There are visible differences between the south-eastern, western, and northern parts of the Baltic Sea coast with respect to dune development. The entire southern and eastern coast abounds in sand, so the coastal dunes are large, formerly or currently wandering formations. The only shifting dunes are found at the Polish and the Russian–Lithuanian coasts on the Łebsko Lake Sandbar as well as on the Vistula and Curonian Spits. The very diverse shoreline of the south-western coast experiences a scarcity of larger sandy formations. Substantial parts of the Baltic Sea sandy coasts have been eroded or transformed by humans. The northern part of the Baltic Sea coast features mainly narrow and low sandy coasts (e.g. in Estonia. Further north, sandy dunes are virtually absent.

Barrier island morphology and sediment characteristics affect the recovery of dune building grasses following storm-induced overwash.

Science.gov (United States)

Brantley, Steven T; Bissett, Spencer N; Young, Donald R; Wolner, Catherine W V; Moore, Laura J

2014-01-01

Barrier islands are complex and dynamic systems that provide critical ecosystem services to coastal populations. Stability of these systems is threatened by rising sea level and the potential for coastal storms to increase in frequency and intensity. Recovery of dune-building grasses following storms is an important process that promotes topographic heterogeneity and long-term stability of barrier islands, yet factors that drive dune recovery are poorly understood. We examined vegetation recovery in overwash zones on two geomorphically distinct (undisturbed vs. frequently overwashed) barrier islands on the Virginia coast, USA. We hypothesized that vegetation recovery in overwash zones would be driven primarily by environmental characteristics, especially elevation and beach width. We sampled species composition and environmental characteristics along a continuum of disturbance from active overwash zones to relict overwash zones and in adjacent undisturbed environments. We compared species assemblages along the disturbance chronosequence and between islands and we analyzed species composition data and environmental measurements with Canonical Correspondence Analysis to link community composition with environmental characteristics. Recovering and geomorphically stable dunes were dominated by Ammophila breviligulata Fernaud (Poaceae) on both islands while active overwash zones were dominated by Spartina patens (Aiton) Muhl. (Poaceae) on the frequently disturbed island and bare sand on the less disturbed island. Species composition was associated with environmental characteristics only on the frequently disturbed island (p = 0.005) where A. breviligulata was associated with higher elevation and greater beach width. Spartina patens, the second most abundant species, was associated with larger sediment grain size and greater sediment size distribution. On the less frequently disturbed island, time since disturbance was the only factor that affected community

Barrier island morphology and sediment characteristics affect the recovery of dune building grasses following storm-induced overwash.

Directory of Open Access Journals (Sweden)

Steven T Brantley

Full Text Available Barrier islands are complex and dynamic systems that provide critical ecosystem services to coastal populations. Stability of these systems is threatened by rising sea level and the potential for coastal storms to increase in frequency and intensity. Recovery of dune-building grasses following storms is an important process that promotes topographic heterogeneity and long-term stability of barrier islands, yet factors that drive dune recovery are poorly understood. We examined vegetation recovery in overwash zones on two geomorphically distinct (undisturbed vs. frequently overwashed barrier islands on the Virginia coast, USA. We hypothesized that vegetation recovery in overwash zones would be driven primarily by environmental characteristics, especially elevation and beach width. We sampled species composition and environmental characteristics along a continuum of disturbance from active overwash zones to relict overwash zones and in adjacent undisturbed environments. We compared species assemblages along the disturbance chronosequence and between islands and we analyzed species composition data and environmental measurements with Canonical Correspondence Analysis to link community composition with environmental characteristics. Recovering and geomorphically stable dunes were dominated by Ammophila breviligulata Fernaud (Poaceae on both islands while active overwash zones were dominated by Spartina patens (Aiton Muhl. (Poaceae on the frequently disturbed island and bare sand on the less disturbed island. Species composition was associated with environmental characteristics only on the frequently disturbed island (p = 0.005 where A. breviligulata was associated with higher elevation and greater beach width. Spartina patens, the second most abundant species, was associated with larger sediment grain size and greater sediment size distribution. On the less frequently disturbed island, time since disturbance was the only factor that affected

Iron oxides and monazite from sands of two beaches in Espirito Santo, Brazil

International Nuclear Information System (INIS)

Coelho, Flavia dos Santos; Couceiro, Paulo Rogerio da Costa; Lopes, Ana Lucia; Fabris, Jose Domingos

2005-01-01

Sand samples collected from two sampling sites on Guarapari and Iriri beaches, state of Espirito Santo, Brazil, were studied in an attempt to better describe their chemical and mineralogical compositions and radioactive behaviors. The sands were found to contain about 6 (Guarapari) and 2 dag kg -1 (Iriri) of rare earth and thorium that, if allocated to the monazite-(Ce) structure, lead to the averaged formulae Ce 3+ 0,494G d 3+ 0,012 La 3+ 0,209 Nd 3+ 0,177 Pr 3+ 0,040 Sm 3+ 0,024 Th 4+ 0,033 (PO 4 ) and Ce 3+ 0,474 La 3+ 0,227 Nd 3+ 0,190 Pr 3+ 0,044 Sm 3+ 0,032 Th 4+ 0,024 (PO 4 ). From Moessbauer spectroscopy data, the magnetic fractions of these sands were found to contain stoichiometric hematite (47.4 dag kg -1 , from Guarapari, and 25.1 dag kg -1 , from Iriri) and magnetite (44.1 and 58.8 dag kg -1 ). The specific α and β radiation activities were also measured for both samples. (author)

Compositional variations in sands of the Bagnold Dunes, Gale Crater, Mars, from visible-shortwave infrared spectroscopy and comparison with ground truth from the Curiosity Rover

Science.gov (United States)

Lapotre, Mathieu G.A.; Ehlmann, B. L.; Minson, Sarah E.; Arvidson, R. E.; Ayoub, F.; Fraeman, A. A.; Ewing, R. C.; Bridges, N. T.

2017-01-01

During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single scattering albedo spectra and a Markov-Chain Monte Carlo implementation of Hapke's radiative transfer theory to fully constrain uncertainties and permitted solutions. These predictions, evaluated against in situ measurements at one site from the Curiosity rover, show that XRD-measured mineralogy of the basaltic sands is within the 95% confidence interval of model predictions. However, predictions are relatively insensitive to grain size and are non-unique, especially when modeling the composition of minerals with solid solutions. We find an overall basaltic mineralogy and show subtle spatial variations in composition in and around the Bagnold dunes, consistent with a mafic enrichment of sands with cumulative transport distance by sorting of olivine, pyroxene, and plagioclase grains during aeolian saltation. Furthermore, the large variations in Fe and Mg abundances (~20 wt%) at the Bagnold Dunes suggest that compositional variability induced by wind sorting may be enhanced by local mixing with proximal sand sources. Our estimates demonstrate a method for orbital quantification of composition with rigorous uncertainty determination and provide key constraints for interpreting in situ measurements of compositional variability within martian aeolian sandstones.

Burrowing inhibition by fine textured beach fill: Implications for recovery of beach ecosystems

Science.gov (United States)

Viola, Sloane M.; Hubbard, David M.; Dugan, Jenifer E.; Schooler, Nicholas K.

2014-10-01

Beach nourishment is often considered the most environmentally sound method of maintaining eroding shorelines. However, the ecological consequences are poorly understood. Fill activities cause intense disturbance and high mortality and have the potential to alter the diversity, abundance, and distribution of intertidal macroinvertebrates for months to years. Ecological recovery following fill activities depends on successful recolonization and recruitment of the entire sandy intertidal community. The use of incompatible sediments as fill material can strongly affect ecosystem recovery. We hypothesized that burrowing inhibition of intertidal animals by incompatible fine fill sediments contributes to ecological impacts and limits recovery in beach ecosystems. We experimentally investigated the influence of intertidal zone and burrowing mode on responses of beach invertebrates to altered sediment texture (28-38% fines), and ultimately the potential for colonization and recovery of beaches disturbed by beach filling. Using experimental trials in fill material and natural beach sand, we found that the mismatched fine fill sediments significantly inhibited burrowing of characteristic species from all intertidal zones, including sand crabs, clams, polychaetes, isopods, and talitrid amphipods. Burrowing performance of all five species we tested was consistently reduced in the fill material and burrowing was completely inhibited for several species. The threshold for burrowing inhibition by fine sediment content in middle and lower beach macroinvertebrates varied by species, with highest sensitivity for the polychaete (4% fines, below the USA regulatory limit of 10% fines), followed by sand crabs and clams (20% fines). These results suggest broader investigation of thresholds for burrowing inhibition in fine fill material is needed for beach animals. Burrowing inhibition caused by mismatched fill sediments exposes beach macroinvertebrates to stresses, which could depress

Post tsunami rebuilding of beaches and the texture of sediments

Digital Repository Service at National Institute of Oceanography (India)

Loveson, V.J.; Gujar, A.R.; Rajamanickam, G.V.; Chandrasekar, N.; Manickaraj, D.S.; Chandrasekaran, R.; Chaturvedi, S.K.; Mahesh, R.; Josephine, P.J.; Deepa, V.; Sudha, V.; Sunderasen, D.

and textural statistic studies. In view of the presence tsunami in between, the beach sand composition and texture have been drastically changed, the studies on beach re-building effort has been initiated in continuing the beach sand sample collection to 2006...

A Wireless Sensor Network Framework for Real-Time Monitoring of Height and Volume Variations on Sandy Beaches and Dunes

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Alessandro Pozzebon

2018-04-01

Full Text Available In this paper, the authors describe the realization and testing of a Wireless Sensor Network (WSN framework aiming at measuring, remotely and in real time, the level variations of the sand layer of sandy beaches or dunes. The proposed framework is based on an innovative low cost sensing structure, able to measure the level variations with a 5-cm degree of precision and to locally transfer the acquired data through the ZigBee protocol. The described sensor is integrated in a wider ZigBee wireless sensor network architecture composed of an array of sensors that, arranged according to a grid layout, can acquire the same data at different points, allowing the definition of a dynamic map of the area under study. The WSN is connected to a local Global System for Mobile Communications (GSM gateway that is in charge of data processing and transmission to a cloud infrastructure through a General Packet Radio Service (GPRS connection. Data are then stored in a MySQL database and made available any time and anywhere through the Internet. The proposed architecture has been tested in a laboratory, to analyze data acquisition, processing timing and power consumption and then in situ to prove the effectiveness of the system. The described infrastructure is expected to be integrated in a wider IoT architecture including different typologies of sensors, in order to create a multi-purpose tool for the study of coastal erosive processes.

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.

The physics of wind-blown sand and dust.

Science.gov (United States)

Kok, Jasper F; Parteli, Eric J R; Michaels, Timothy I; Karam, Diana Bou

2012-10-01

The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.

Sediment volume in the north polar sand seas of Mars

International Nuclear Information System (INIS)

Lancaster, N.; Greeley, R.

1990-01-01

Data from studies of the cross-sectional area of terrestrial transverse dunes have been combined with maps of dune morphometry derived from Viking orbiter images to generate new estimates of sediment thickness and dune sediment volume in the north polar sand seas of Mars. A relationship between dune spacing and equivalent sediment thickness (EST) was developed from field data on Namibian and North American dunes and was applied to data on dune spacing and dune cover measured on Viking orbiter images to generate maps of dune sediment thickness for Martian north polar sand seas. There are four major sand seas in the north polar region of Mars, covering an area of 6.8 x 10 5 km 2 . Equivalent sediment thickness ranges between 0.5 and 6.1 m with a mean of 1.8 m. The sand seas contain a total of 1158 km 3 of dune sediment, which may have been derived by erosion of polar layered deposits and concentrated in its present location by winds that change direction seasonally

Environmental geochemistry: radiometry and radiology of the monazitic sand in the Areia Preta Beach, Guarapari - Espirito Santo State, Brazil

International Nuclear Information System (INIS)

Moura, Jorge Costa de; Wiedemann, Cristina Maria; Ludka, Isabel Pereira; Mendes, Julio Cezar; Nascimento, Ricardo de Campos Costa; Wallfass, Carin Margarete; Westrenen, Wim van

1998-01-01

The Areia Preta Beach, in Guarapari, is famous for its natural radiation and important for the tourism of this region. Thousands of people visit this area in order to be cured from illnesses like arthritis, rheumatism, and cancer by exposing themselves to the radiation. This work presents the gamma radiation dose rate values measured in the sand of this beach since April 1996. These values punctually exceed nearly 800 times the maximum values compared with the national and international legislation concerning artificial ionizing radiation. The data collected during seven field campaigns of monitoring shows seasonal variations of exposure rates. The minimum values were obtained in winter, and the maximum values in summer, which is the high season for tourism. The results indicates that this beach represents a serious health hazard for those that visit the beach intensively. (author)

78 FR 40128 - Notice of Intent to Prepare a Draft Environmental Impact Statement (EIS) for the Reaches 8, 9...

Science.gov (United States)

2013-07-03

... to R-134+135. The Town proposes to place approximately 74,300 cubic yards of beach quality sand in... beach quality sand is proposed to be placed between R-134+135 and R-135+551 to elevate the existing berm... and dune restoration projects between R-128+955 and R-138+551 with sand placement and the construction...

Development and optimization of a solid-phase microextraction gas chromatography-tandem mass spectrometry methodology to analyse ultraviolet filters in beach sand.

Science.gov (United States)

Vila, Marlene; Llompart, Maria; Garcia-Jares, Carmen; Homem, Vera; Dagnac, Thierry

2018-06-06

A methodology based on solid-phase microextraction (SPME) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous analysis of eleven multiclass ultraviolet (UV) filters in beach sand. To the best of our knowledge, this is the first time that this extraction technique is applied to the analysis of UV filters in sand samples, and in other kind of environmental solid samples. Main extraction parameters such as the fibre coating, the amount of sample, the addition of salt, the volume of water added to the sand, and the temperature were optimized. An experimental design approach was implemented in order to find out the most favourable conditions. The final conditions consisted of adding 1 mL of water to 1 g of sample followed by the headspace SPME for 20 min at 100 °C, using PDMS/DVB as fibre coating. The SPME-GC-MS/MS method was validated in terms of linearity, accuracy, limits of detection and quantification, and precision. Recovery studies were also performed at three concentration levels in real Atlantic and Mediterranean sand samples. The recoveries were generally above 85% and relative standard deviations below 11%. The limits of detection were in the pg g -1 level. The validated methodology was successfully applied to the analysis of real sand samples collected from Atlantic Ocean beaches in the Northwest coast of Spain and Portugal, Canary Islands (Spain), and from Mediterranean Sea beaches in Mallorca Island (Spain). The most frequently found UV filters were ethylhexyl salicylate (EHS), homosalate (HMS), 4-methylbenzylidene camphor (4MBC), 2-ethylhexyl methoxycinnamate (2EHMC) and octocrylene (OCR), with concentrations up to 670 ng g -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

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

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.

Breeding system and its consequence on fruit set of a rare sand dune shrub Eremosparton songoricum (Fabaceae: Papilionoideae): implications for conservation

Science.gov (United States)

The breeding system and its consequence on fruit set of Eremosparton songoricum (Litv.) Vass., a rare shrubby legume occurring in moving or semi-fixed sand dunes of Central Asian deserts, were examined by manipulative experiments and observational studies in natural populations during the period of ...

Geomorphology and drift potential of major aeolian sand deposits in Egypt

Science.gov (United States)

Hereher, Mohamed E.

2018-03-01

Aeolian sand deposits cover a significant area of the Egyptian deserts. They are mostly found in the Western Desert and Northern Sinai. In order to understand the distribution, pattern and forms of sand dunes in these dune fields it is crucial to analyze the wind regimes throughout the sandy deserts of the country. Therefore, a set of wind data acquired from twelve meteorological stations were processed in order to determine the drift potential (DP), the resultant drift potential (RDP) and the resultant drift direction (RDD) of sand in each dune field. The study showed that the significant aeolian sand deposits occur in low-energy wind environments with the dominance of linear and transverse dunes. Regions of high-energy wind environments occur in the south of the country and exhibit evidence of deflation rather than accumulation with the occurrence of migratory crescentic dunes. Analysis of the sand drift potentials and their directions help us to interpret the formation of major sand seas in Egypt. The pattern of sand drift potential/direction suggests that the sands in these seas might be inherited from exogenous sources.

Dynamics of a cliff top dune

Science.gov (United States)

Rasmussen, K. R.

2012-12-01

Morphological changes during more than 100 years have been investigated for a cliff-top dune complex at Rubjerg at the Danish North Sea coast. Here the lower 50 m of the cliff front is composed of Pleistocene steeply inclined floes of silt and clay with coarse sand in between which gives it a saw-tooth appearance. On top of this the dunes are found for several kilometres along the coastline. Due to erosion by the North Sea the cliff has retreated about 120 m between approximately 1880 and 1970 as indicated from two national surveys, and recent GPS-surveys indicate that erosion is continuing at a similar rate. Nevertheless the cliff top dune complex has survived, but its morphology has undergone some changed. The old maps indicate that around 1880 the dune complex was composed of several up to about 20 m high dunes streamlined in the East-West direction which is parallel to the prevailing wind direction. When protective planting started during the first half of the 20th Century the cliff top dunes gradually merged together forming a narrow, tall ridge parallel to the shore line with the highest part reaching about 90 m near 1970. In 1993 the highest points along the ridge was almost 95 m high, but then the protective planting was considerably reduced and recent annual GPS-surveys indicate that the dunes respond quickly to this by changing their morphology towards the original appearance. It is remarkable that despite the mass wasting caused by the constant erosion of the cliff front the dunes have remained more or less intact. Theoretical studies of hill flow indicate given the proper geometry of the cliff then suspension of even coarse grains can be a very effective agent for carrying sand from the exposed parts of the cliff front to and beyond the cliff-top. Mostly the sand grains are deposited within some hundred meters downwind of the cliff dune while silt is often carried more than 10 km inland. Field observations indicate that where the dislodged floes and

Aeolian sedimentary processes at the Bagnold Dunes, Mars: Implications for modern dune dynamics and sedimentary structures in the aeolian stratigraphic record of Mars

Science.gov (United States)

Ewing, Ryan C.; Bridges, Nathan T.; Sullivan, Rob; Lapotre, Mathieu G. A.; Fischer, Woodward W.; Lamb, Mike P.; Rubin, David M.; Lewis, Kevin W.; Gupta, Sanjeev

2016-04-01

Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under Martian conditions. In-situ observations of sand dunes (informally called the Bagnold Dunes) by Curiosity Rover in Gale Crater, Mars provide the first opportunity to make observations of dunes from the grain-to-dune scale thereby filling the gap in knowledge between theory and orbital observations and refining our understanding of the martian aeolian stratigraphic record. We use the suite of cameras on Curiosity, including Navigation Camera (Navcam), Mast Camera (Mastcam) and Mars Hand Lens Imager (MAHLI), to make observations of the Bagnold Dunes. Measurements of sedimentary structures are made where stereo images are available. Observations indicate that structures generated by gravity-driven processes on the dune lee slopes, such as grainflow and grainfall, are similar to the suite of aeolian sedimentary structures observed on Earth and should be present and recognizable in Mars' aeolian stratigraphic record. Structures formed by traction-driven processes deviate significantly from those found on Earth. The dune hosts centimeter-scale wind ripples and large, meter-scale ripples, which are not found on Earth. The large ripples migrate across the depositional, lee slopes of the dune, which implies that these structures should be present in Mars' stratigraphic record and may appear similar to compound-dune stratification.The Mars Science Laboratory Curiosity Rover Team is acknowledged for their support of this work.

Bali beach conservation project and issues related to beach maintenance after completion of project

OpenAIRE

Onaka, S.; Endo, S.; Uda, T.

2013-01-01

Bali Island in Indonesia is a world-famous resort area, and the beaches composed of coral sand are one of the most important resources for tourism. However, serious beach erosion has occurred since the 1970s owing to the tourism development along the coastal areas. To recover previous natural sandy beaches, Bali Beach Conservation Project was undertaken by the Indonesian Government as the ODA project financed by Japan. Three seriously eroded beaches (Sanur, Nusa Dua and Kuta) with a total len...

Detection of Salmonella enterica Serovar Montevideo and Newport in Free-ranging Sea Turtles and Beach Sand in the Caribbean and Persistence in Sand and Seawater Microcosms.

Science.gov (United States)

Ives, A-K; Antaki, E; Stewart, K; Francis, S; Jay-Russell, M T; Sithole, F; Kearney, M T; Griffin, M J; Soto, E

2017-09-01

Salmonellae are Gram-negative zoonotic bacteria that are frequently part of the normal reptilian gastrointestinal flora. The main objective of this project was to estimate the prevalence of non-typhoidal Salmonella enterica in the nesting and foraging populations of sea turtles on St. Kitts and in sand from known nesting beaches. Results suggest a higher prevalence of Salmonella in nesting leatherback sea turtles compared with foraging green and hawksbill sea turtles. Salmonella was cultured from 2/9 and identified by molecular diagnostic methods in 3/9 leatherback sea turtle samples. Salmonella DNA was detected in one hawksbill turtle, but viable isolates were not recovered from any hawksbill sea turtles. No Salmonella was detected in green sea turtles. In samples collected from nesting beaches, Salmonella was only recovered from a single dry sand sample. All recovered isolates were positive for the wzx gene, consistent with the O:7 serogroup. Further serotyping characterized serovars Montevideo and Newport present in cloacal and sand samples. Repetitive-element palindromic PCR (rep-PCR) fingerprint analysis and pulsed-field gel electrophoresis of the 2014 isolates from turtles and sand as well as archived Salmonella isolates recovered from leatherback sea turtles in 2012 and 2013, identified two distinct genotypes and four different pulsotypes, respectively. The genotyping and serotyping were directly correlated. To determine the persistence of representative strains of each serotype/genotype in these environments, laboratory-controlled microcosm studies were performed in water and sand (dry and wet) incubated at 25 or 35°C. Isolates persisted for at least 32 days in most microcosms, although there were significant decreases in culturable bacteria in several microcosms, with the greatest reduction in dry sand incubated at 35°C. This information provides a better understanding of the epizootiology of Salmonella in free-ranging marine reptiles and the potential

Parabolic dune development modes according to shape at the southern fringes of the Hobq Desert, Inner Mongolia, China

Science.gov (United States)

Guan, Chao; Hasi, Eerdun; Zhang, Ping; Tao, Binbin; Liu, Dan; Zhou, Yanguang

2017-10-01

Since the 1970s, parabolic dunes at the southern fringe of the Hobq Desert, Inner Mongolia, China have exhibited many different shapes (V-shaped, U-shaped, and palmate) each with a unique mode of development. In the study area, parabolic dunes are mainly distributed in Regions A, B, and C with an intermittent river running from the south to the north. We used high-resolution remote-sensing images from 1970 to 2014 and RTK-GPS measurements to study the development modes of different dune shapes; the modes are characterized by the relationship between the intermittent river and dunes, formation of the incipient dune patterns, the predominant source supply of dunes, and the primary formation of different shapes (V-shaped, U-shaped, and palmate). Most parabolic dunes in Region A are V-shaped and closer to the bank of the river. The original barchans in this region exhibit "disconnected arms" behavior. With the sand blown out of the riverbed through gullies, the nebkhas on the disconnected arms acquire the external sand source through the "fertile island effect", thereby developing into triangular sand patches and further developing into V-shaped parabolic dunes. Most parabolic dunes in Regions B and C are palmate. The residual dunes cut by the re-channelization of river from transverse dune fields on the west bank are the main sand source of Region B. The parabolic dunes in Region C are the original barchans having then been transformed. The stoss slopes of V-shaped parabolic dunes along the riverbank are gradual and the dunes are flat in shape. The dune crest of V-shaped parabolic dune is the deposition area, which forms the "arc-shaped sand ridge". Their two arms are non-parallel; the lateral airflow of the arms jointly transport sand to the middle part of dunes, resulting in a narrower triangle that gradually becomes V-shaped. Palmate parabolic dunes have a steeper stoss slope and height. The dune crest of the palmate parabolic dune is the erosion area, which forms

Method of Relating Grain Size Distribution to Hydraulic Conductivity in Dune Sands to Assist in Assessing Managed Aquifer Recharge Projects: Wadi Khulays Dune Field, Western Saudi Arabia

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Oliver M. Lopez

2015-11-01

Full Text Available Planning for use of a dune field aquifer for managed aquifer recharge (MAR requires that hydraulic properties need to be estimated over a large geographic area. Saturated hydraulic conductivity of dune sands is commonly estimated from grain size distribution data by employing some type of empirical equation. Over 50 samples from the Wadi Khulays dune field in Western Saudi Arabia were collected and the grain size distribution, porosity, and hydraulic conductivity were measured. An evaluation of 20 existing empirical equations showed a generally high degree of error in the predicted compared to the measured hydraulic conductivity values of these samples. Statistical analyses comparing estimated versus measured hydraulic conductivity demonstrated that there is a significant relationship between hydraulic conductivity and mud percentage (and skewness. The modified Beyer equation, which showed a generally low prediction error, was modified by adding a second term fitting parameter related to the mud concentration based on 25 of the 50 samples analyzed. An inverse optimization process was conducted to quantify the fitting parameter and a new empirical equation was developed. This equation was tested against the remaining 25 samples analyzed and produced an estimated saturated hydraulic conductivity with the lowest error of any empirical equation. This methodology can be used for large dune field hydraulic conductivity estimation and reduce planning costs for MAR systems.

Method of Relating Grain Size Distribution to Hydraulic Conductivity in Dune Sands to Assist in Assessing Managed Aquifer Recharge Projects: Wadi Khulays Dune Field, Western Saudi Arabia

KAUST Repository

Lopez Valencia, Oliver Miguel

2015-11-12

Planning for use of a dune field aquifer for managed aquifer recharge (MAR) requires that hydraulic properties need to be estimated over a large geographic area. Saturated hydraulic conductivity of dune sands is commonly estimated from grain size distribution data by employing some type of empirical equation. Over 50 samples from the Wadi Khulays dune field in Western Saudi Arabia were collected and the grain size distribution, porosity, and hydraulic conductivity were measured. An evaluation of 20 existing empirical equations showed a generally high degree of error in the predicted compared to the measured hydraulic conductivity values of these samples. Statistical analyses comparing estimated versus measured hydraulic conductivity demonstrated that there is a significant relationship between hydraulic conductivity and mud percentage (and skewness). The modified Beyer equation, which showed a generally low prediction error, was modified by adding a second term fitting parameter related to the mud concentration based on 25 of the 50 samples analyzed. An inverse optimization process was conducted to quantify the fitting parameter and a new empirical equation was developed. This equation was tested against the remaining 25 samples analyzed and produced an estimated saturated hydraulic conductivity with the lowest error of any empirical equation. This methodology can be used for large dune field hydraulic conductivity estimation and reduce planning costs for MAR systems.

Improvement of Dune Sands by Residual Oil in Order to Use in Construction of Lagoons

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Alborz Hajian nia

2011-10-01

Full Text Available This research which is based on experimental work, devoted to study the improvement and stabilization of dune sands in order to create strong layer and stabilize slope and floor construction of sewage Lagoons. Materials used stabilizing these soils are residual oil from the refinery. To confirm the effectiveness of the use of residual oil to improve the mechanical properties of the sand, various samples with different percentages were tested. In besides, the geotechnical and environmental tests were done. Results demonstrate that samples made with 5% oil have highest shear and unconfined compaction strength. It revealed that in compare with natural samples, cohesion and loading capacity highly increased and permeability decrease well. Percentage of fine aggregate, minerals and durability of oil in soil material were also investigated. Finally, effects of sewage on the samples were analyzed, and performance the oils were evaluated in order to use in lagoons.

Exploring the contributions of vegetation and dune size to early dune development using unmanned aerial vehicle (UAV) imaging

Science.gov (United States)

van Puijenbroek, Marinka E. B.; Nolet, Corjan; de Groot, Alma V.; Suomalainen, Juha M.; Riksen, Michel J. P. M.; Berendse, Frank; Limpens, Juul

2017-12-01

Dune development along highly dynamic land-sea boundaries is the result of interaction between vegetation and dune size with sedimentation and erosion processes. Disentangling the contribution of vegetation characteristics from that of dune size would improve predictions of nebkha dune development under a changing climate, but has proven difficult due to the scarcity of spatially continuous monitoring data. This study explored the contributions of vegetation and dune size to dune development for locations differing in shelter from the sea. We monitored a natural nebkha dune field of 8 ha, along the coast of the island Texel, the Netherlands, for 1 year using an unmanned aerial vehicle (UAV) with camera. After constructing a digital surface model and orthomosaic we derived for each dune (1) vegetation characteristics (species composition, vegetation density, and maximum vegetation height), (2) dune size (dune volume, area, and maximum height), (3) degree of shelter (proximity to other nebkha dunes and the sheltering by the foredune). Changes in dune volume over summer and winter were related to vegetation, dune size and degree of shelter. We found that a positive change in dune volume (dune growth) was linearly related to initial dune volume over summer but not over winter. Big dunes accumulated more sand than small dunes due to their larger surface area. Exposed dunes increased more in volume (0.81 % per dune per week) than sheltered dunes (0.2 % per dune per week) over summer, while the opposite occurred over winter. Vegetation characteristics did not significantly affect dune growth in summer, but did significantly affect dune growth in winter. Over winter, dunes dominated by Ammophila arenaria, a grass species with high vegetation density throughout the year, increased more in volume than dunes dominated by Elytrigia juncea, a grass species with lower vegetation density (0.43 vs. 0.42 (m3 m-3) week-1). The effect of species was irrespective of dune size or

Modern sedimentary facies, depositional environments, and major controlling processes on an arid siliciclastic coast, Al qahmah, SE Red Sea, Saudi Arabia

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Nabhan, Abdullah I.; Yang, Wan

2018-04-01

The facies and environments along the arid siliciclastic coast of Red Sea in Al Qahmah, Saudi Arabia are studied to establish a depositional model for interpretation of ancient rocks deposited in rift settings. Field and petrographic studies of 151 sediment samples in an area of 20 km2 define seven main facies types: beach, washover fan, tidal channel, dune, sabkha, delta, and wadi (seasonal stream). The wadi and delta facies are composed of poorly to moderately well-sorted, gravelly, medium-to-fine sands. Delta-front sands are redistributed by southward longshore currents to form a beach. Beach facies is composed of well-to-moderately sorted fine sands with minor gravels, which contain high concentrations of magnetite, ilmenite, garnet, pyroxene, amphibole, epidote, titanite, and apatite grains, indicating strong winnowing. Crabs and other burrowers destroy primary sedimentary structures and mix sediments in foreshore and backshore of the beaches. Wind and storm surge rework foreshore and backshore sediments to form washover fans. Sabkha facies occurs extensively in supratidal depressions behind beach, are flooded by rainstorms and spring tide, and capped by a 5-cm-thick crust composed of interlaminated halite, quartz, albite, minor gypsum and biotite, and rarely calcium carbonate. Halite occurs as thin sheets and gypsum as nodules with a chicken-wire structure. Clastic fraction in sabkha sediments ranges from coarse silt to coarse sand with moderate sorting, and is transported by currents and wind. Tidal inlets and tidal creeks assume abandoned wadis and are filled by muddy sand. Sand dunes and sand sheets are 1-7 m high and widely distributed due to variable wind directions. Fine-grained dune sands are moderately well sorted, whereas sheet sands are coarser and poorly sorted due to vegetation baffling. Most eolian sands are sourced from beach deposits. This suite of complex riverine, wave, tidal, wind, chemical, and biological processes form the facies mosaic

Evaluation of potential sources and transport mechanisms of fecal indicator bacteria to beach water, Murphy Park Beach, Door County, Wisconsin

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Juckem, Paul F.; Corsi, Steven R.; McDermott, Colleen; Kleinheinz, Gregory; Fogarty, Lisa R.; Haack, Sheridan K.; Johnson, Heather E.

2013-01-01

Fecal Indicator Bacteria (FIB) concentrations in beach water have been used for many years as a criterion for closing beaches due to potential health concerns. Yet, current understanding of sources and transport mechanisms that drive FIB occurrence remains insufficient for accurate prediction of closures at many beaches. Murphy Park Beach, a relatively pristine beach on Green Bay in Door County, Wis., was selected for a study to evaluate FIB sources and transport mechanisms. Although the relatively pristine nature of the beach yielded no detection of pathogenic bacterial genes and relatively low FIB concentrations during the study period compared with other Great Lakes Beaches, its selection limited the number of confounding FIB sources and associated transport mechanisms. The primary sources of FIB appear to be internal to the beach rather than external sources such as rivers, storm sewer outfalls, and industrial discharges. Three potential FIB sources were identified: sand, swash-zone groundwater, and Cladophora mats. Modest correlations between FIB concentrations in these potential source reservoirs and FIB concentrations at the beach from the same day illustrate the importance of understanding transport mechanisms between FIB sources and the water column. One likely mechanism for transport and dispersion of FIB from sand and Cladophora sources appears to be agitation of Cladophora mats and erosion of beach sand due to storm activity, as inferred from storm indicators including turbidity, wave height, current speed, wind speed, sky visibility, 24-hour precipitation, and suspended particulate concentration. FIB concentrations in beach water had a statistically significant relation (p-value ‹0.05) with the magnitude of these storm indicators. In addition, transport of FIB in swash-zone groundwater into beach water appears to be driven by groundwater recharge associated with multiday precipitation and corresponding increased swash-zone groundwater discharge at

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)

Lizard assemblage from a sand dune habitat from southeastern Brazil: a niche overlap analysis.

Science.gov (United States)

Winck, Gisele R; Hatano, Fabio; Vrcibradic, Davor; VAN Sluys, Monique; Rocha, Carlos F D

2016-01-01

Communities are structured by interactions of historical and ecological factors, which influence the use of different resources in time and space. We acquired data on time of activity, microhabitat use and diet of a lizard assemblage from a sand dune habitat in a coastal area, southeastern Brazil (Restinga de Jurubatiba). We analyzed the data of niche overlap among species in these three axes (temporal, spatial and trophic) using null models. We found a significant overlap within the trophic niche, whereas the overlap for the other axes did not differ from the expected. Based on this result, we discuss the factors acting on the structure of the local lizard community.

Biological control of infective larvae of Ancylostoma spp. in beach sand.

Science.gov (United States)

De Mello, Ingrid Ney Kramer; Braga, Fabio R; Monteiro, Thalita S Avelar; Freitas, Leandro G; Araujo, Juliana M; Soares, Filippe E Freitas; Araújo, Jackson V

2014-01-01

Geohelminths are parasites that stand out for their prevalence and wide distribution, depending on the soil for their transmission. The aim of this work was to evaluate the predatory capacity of the fungal isolate of the genus Duddingtonia (CG768) on third stage larvae (L3) of Ancylostoma spp. in beach sand under laboratory conditions. In the assay A five treatment groups and 1 control group were formed. The treatment groups contained 5000, 10,000, 15,000, 20,000 or 25,000 chlamydospores of the fungal isolate and 1000 Ancylostoma spp. L3 in pots containing 30g of sand. The control group (without fungus) contained only 1000 Ancylostoma spp. L3 and distilled water in pots with 30g of sand. Evidence of predatory activity was observed at the end of 15 days, where we observed the following percentages of reduction of L3: Group 1 (4.5%); Group 2 (24.5%); Group 3 (59.2%); Group 4 (58.8%); Group 5 (63%). However, difference was noted (p<0.01) only at concentrations 15,000, 20,000 and 25,000 in relation to control group. In the assay B two groups were formed in Petri dishes of 9cm in diameter containing agar water 2% medium. In the treated group, each Petri dish contained 500 Ancylostoma spp. L3 and 5g of sand containing the isolate CG 768 at a concentration of 25,000 chlamydospores/g of sand, and the control group (without fungus) contained only 500 L3. At the end of 7 days the non-predation L3 of Petri dishes using the method of Baermann were recovered. Difference (p<0.01) between groups on reducing the average number of Ancylostoma spp. L3 (percent reduction of 84%) was observed. The results of this study confirm earlier work on the efficiency of the Duddingtonia genus in the control of Ancylostoma spp. infective larvae. Copyright © 2013 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

Dune-slope activity due to frost and wind throughout the north polar erg, Mars.

Science.gov (United States)

Diniega, Serina; Hansen, Candice J; Allen, Amanda; Grigsby, Nathan; Li, Zheyu; Perez, Tyler; Chojnacki, Matthew

2017-01-01

Repeat, high-resolution imaging of dunes within the Martian north polar erg have shown that these dune slopes are very active, with alcoves forming along the dune brink each Mars year. In some areas, a few hundred cubic metres of downslope sand movement have been observed, sometimes moving the dune brink 'backwards'. Based on morphological and activity-timing similarities of these north polar features to southern dune gullies, identifying the processes forming these features is likely to have relevance for understanding the general evolution/modification of dune gullies. To determine alcove-formation model constraints, we have surveyed seven dune fields, each over 1-4 Mars winters. Consistent with earlier reports, we found that alcove-formation activity occurs during the autumn-winter seasons, before or while the stable seasonal frost layer is deposited. We propose a new model in which alcove formation occurs during the autumn, and springtime sublimation activity then enhances the feature. Summertime winds blow sand into the new alcoves, erasing small alcoves over a few Mars years. Based on the observed rate of alcove erasure, we estimated the effective aeolian sand transport flux. From this, we proposed that alcove formation may account for 2-20% of the total sand movement within these dune fields.

Occurrence of microplastics in the beach sand of the Chinese inner sea: the Bohai Sea.

Science.gov (United States)

Yu, Xubiao; Peng, Jinping; Wang, Jundong; Wang, Kan; Bao, Shaowu

2016-07-01

The occurrence of microplastics in the beach sand of the Bohai Sea was investigated for the first time. The Bohai Sea is the largest Chinese inner sea and its coastal region is one of the most densely urbanized and industrialized zones of China. Samples from three costal sites (i.e., Bijianshan, Xingcheng and Dongdaihe) were collected, quantified and identified for microplastic analysis. Effects of sample depth and tourism activity were investigated. Surface samples (2 cm) contained higher microplastic concentrations than deep samples (20 cm). Samples from the bathing beach exhibited higher microplastic concentrations than the non-bathing beach, suggesting the direct contribution of microplastics from tourism activity. Of eight types of microplastics that were found, PEVA (polyethylene vinyl acetate), LDPE (light density polyethylene) and PS (polystyrene) were the largest in abundances. Moreover, the non-plastic items from samples were analyzed and results revealed that the majority abundance of the observed non-plastics were viscose cellulose fibers. Further studies are required to evaluate the environmental hazards of microplastics, especially as they may "act as a contaminant transporter" to the Bohai Sea ecosystem. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dunes with Frost

Science.gov (United States)

2004-01-01

31 May 2004 Springtime for the martian northern hemisphere brings defrosting spots and patterns to the north polar dune fields. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 76.7oN, 250.4oW. In summer, these dunes would be darker than their surroundings. However, while they are still covered by frost, they are not any darker than the substrate across which the sand is slowly traveling. Dune movement in this case is dominated by winds that blow from the southwest (lower left) toward the northeast (upper right). The picure covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.

Investigation of Water Holding Capacity of Sugarcane Mulch for Sand Dune Stabilization in Ahvaz

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T. Jamili

2017-01-01

Full Text Available Introduction: Wind erosion is one of the most serious problems in southwest Iran. Fine-grained structure of sand dunes with not enough strong composition and their low moisture retention property make them susceptible to wind erosion. They lack organic matter and are considered inherently of low fertility (Ahmadi, 2002. Studies have shown that non-erodible materials which include bentonite clay (Diouf et al., 1990, ureamelamine formaldehyde and urea–formaldehyde with 0.25% sodium chloride (Lahalih and Ahmed, 1998, acids, enzymes, lignosulfonates, polymers, tree resins (Santoni et al., 2001, waterborne polymer emulsion (Al-Khanbashi and Abdalla, 2006, polyvinyl alcohol and a polyvinyl acetate emulsion (Newman et al., 2005; Han et al., 2007, ash and polyacrylamide (Yang and Zejun, 2012.have significant potential in reducing wind erosion The area under farming of sugarcane in Khuzestan, Iran, is more than 130,000, ha. Vinasse and Filter Kike are two organic ingredients of sugarcane residues which are generated as byproduct materials insugarcane processing. In recent years these residues have been released into the environment and cause it regarded as water pollutant. Over 800,000 m3 of Vinasse is annually stored in each agro-industry. Vinasse also is rich in K, Ca, and Mg with moderate amounts of P and N,and non toxic complexes or heavy metals. Filter Kike is another residue produced in huge amounts by the agro-industry that is composed of cellulosic substances, CaCO3, N, P, K, organic matter, and clay. Therefore, the objective of this research is to investigate the effect of sugarcane mulch on water holding capacity in soil. This study is performed to evaluate the feasibility of using sugarcane residues inproduce of ecofriendly mulches for environmental use. In order of achieving these goals, Vinase, Filter Cake, and clay soil from near the sand dunes were used as sugarcane mulches. Further comparison between traditional oil mulches and

Gamma radiation measurement in select sand samples from Camburi beach - Vitoria, Espirito Santo, Brazil: preliminary results

International Nuclear Information System (INIS)

Barros, Livia F.; Pecequilo, Brigitte R.S.; Aquino, Reginaldo R.

2011-01-01

The variation of natural radioactivity along the surface of the beach sands of Camburi, located in Vitoria, capital of Espirito Santo, southeastern Brazil, was determined from the contents of 226 Ra, 232 Th and 40 K. Eleven collecting points was selected along all the 6 km extension of the Camburi beach. Sand samples collected from all established points on January 2011 were dried and sealed in standard 100 mL polyethylene flasks and measured by high resolution gamma spectrometry after a 4 weeks ingrowth period, in order to allow the secular equilibrium in the 238 U and 232 Th series. The 226 Ra concentration was determined from the weighted average concentrations of 214 Pb and 214 Bi. The 232 Th concentration was determined from the weighted average concentrations of 228 Ac, 212 Pb and 212 Bi and the 40 K from its single gamma transition. Preliminary results show activity concentrations varying from 5 Bq.kg -1 to 222 Bq.kg -1 for 226 Ra and from 14 Bq.kg -1 to 1074 Bq.kg -' 1 for 232 Th, both with the highest values for Camburi South and Central. For 40 K, the activity concentrations ranged from 14 Bq.kg -1 to 179 Bq.kg -1 and the highest values were obtained for Camburi South. (author)

Feeding habits of the frog Pleurodema diplolistris (Anura, Leptodactylidae in Quaternary sand dunes of the Middle Rio São Francisco, Bahia, Brazil

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José Wellington Alves dos Santos

2003-12-01

Full Text Available In this work, we investigate the feeding habits of Pleurodema diplolistris, the most abundant anuran species of the São Francisco sand dunes, during a period of slightly over one year. The fieldwork was undertaken during four excursions to a sand dune in the semiarid Caatinga, Brazil, and the analyses were based on stomach contents. Pleurodema diplolistris were not active during the dry season. The important food categories in diet were Isoptera (winged forms, Coleoptera, and Formicidae. Small and large animals had different food comsumption patterns: small frogs showed positive electivity for termites and large frogs, for ants. The pattern was strongly influenced by large male food electivity. High levels of termite comsumption ocurred during the days of greater capture success. The pattern of high comsumption of termites detected here is different from that described in another study on lizards from the same locality and sampled in the same periods. We discuss alternative hypotheses that could explain the observed patterns.

Frost-covered dunes

Science.gov (United States)

1999-01-01

MOC image of dunes in Chasma Boreale, a giant trough in the north polar cap. This September 1998 view shows dark sand emergent from beneath a veneer of bright frost left over from the northern winter that ended in July 1998.

Predaceous ants, beach replenishment, and nest placement by sea turtles.

Science.gov (United States)

Wetterer, James K; Wood, Lawrence D; Johnson, Chris; Krahe, Holly; Fitchett, Stephanie

2007-10-01

Ants known for attacking and killing hatchling birds and reptiles include the red imported fire ant (Solenopsis invicta Buren), tropical fire ant [Solenopsis geminata (Fabr.)], and little fire ant [Wasmannia auropunctata (Roger)]. We tested whether sea turtle nest placement influenced exposure to predaceous ants. In 2000 and 2001, we surveyed ants along a Florida beach where green turtles (Chelonia mydas L.), leatherbacks (Dermochelys coriacea Vandelli), and loggerheads (Caretta caretta L.) nest. Part of the beach was artificially replenished between our two surveys. As a result, mean beach width experienced by nesting turtles differed greatly between the two nesting seasons. We surveyed 1,548 sea turtle nests (2000: 909 nests; 2001: 639 nests) and found 22 ant species. S. invicta was by far the most common species (on 431 nests); S. geminata and W. auropunctata were uncommon (on 3 and 16 nests, respectively). In 2000, 62.5% of nests had ants present (35.9% with S. invicta), but in 2001, only 30.5% of the nests had ants present (16.4% with S. invicta). Turtle nests closer to dune vegetation had significantly greater exposure to ants. Differences in ant presence on turtle nests between years and among turtle species were closely related to differences in nest placement relative to dune vegetation. Beach replenishment significantly lowered exposure of nests to ants because on the wider beaches turtles nested farther from the dune vegetation. Selective pressures on nesting sea turtles are altered both by the presence of predaceous ants and the practice of beach replenishment.

Through the sands of time: Beach litter trends from nine cleaned north cornish beaches

International Nuclear Information System (INIS)

Watts, Andrew J.R.; Porter, Adam; Hembrow, Neil; Sharpe, Jolyon; Galloway, Tamara S.; Lewis, Ceri

2017-01-01

Marine litter and its accumulation on beaches is an issue of major current concern due to its significant environmental and economic impacts. Yet our understanding of spatio-temporal trends in beach litter and the drivers of these trends are currently limited by the availability of robust long term data sets. Here we present a unique data set collected systematically once a month, every month over a six year period for nine beaches along the North Coast of Cornwall, U.K. to investigate the key drivers of beach litter in the Bude, Padstow and Porthcothan areas. Overall, an average of 0.02 litter items m −2 per month were collected during the six year study, with Bude beaches (Summerleaze, Crooklets and Widemouth) the most impacted (0.03 ± 0.004 litter items m −2 per month). The amount of litter collected each month decreased by 18% and 71% respectively for Padstow (Polzeath, Trevone and Harlyn) and Bude areas over the 6 years, possibly related to the regular cleaning, however litter increased by 120% despite this monthly cleaning effort on the Padstow area beaches. Importantly, at all nine beaches the litter was dominated by small, fragmented plastic pieces and rope fibres, which account for 32% and 17% of all litter items collected, respectively. The weathered nature of these plastics indicates they have been in the marine environment for an extended period of time. So, whilst classifying the original source of these plastics is not possible, it can be concluded they are not the result of recent public littering. This data highlights both the extent of the marine litter problem and that current efforts to reduce littering by beach users will only tackle a fraction of this litter. Such information is vital for developing effective management strategies for beach and marine litter at both regional and global levels. - Highlights: • Unique and systemically collected beach clean data set from 9 beaches over 6 years. • The most abundant litter items were

Temporal characteristics of coherent flow structures generated over alluvial sand dunes, Mississippi River, revealed by acoustic doppler current profiling and multibeam echo sounding

Science.gov (United States)

Czuba, John A.; Oberg, Kevin A.; Best, Jim L.; Parsons, Daniel R.; Simmons, S. M.; Johnson, K.K.; Malzone, C.

2009-01-01

This paper investigates the flow in the lee of a large sand dune located at the confluence of the Mississippi and Missouri Rivers, USA. Stationary profiles collected from an anchored boat using an acoustic Doppler current profiler (ADCP) were georeferenced with data from a real-time kinematic differential global positioning system. A multibeam echo sounder was used to map the bathymetry of the confluence and provided a morphological context for the ADCP measurements. The flow in the lee of a low-angle dune shows good correspondence with current conceptual models of flow over dunes. As expected, quadrant 2 events (upwellings of low-momentum fluid) are associated with high backscatter intensity. Turbulent events generated in the lower lee of a dune near the bed are associated with periods of vortex shedding and wake flapping. Remnant coherent structures that advect over the lower lee of the dune in the upper portion of the water column, have mostly dissipated and contribute little to turbulence intensities. The turbulent events that occupy most of the water column in the upper lee of the dune are associated with periods of wake flapping.

Lizard assemblage from a sand dune habitat from southeastern Brazil: a niche overlap analysis

Directory of Open Access Journals (Sweden)

GISELE R. WINCK

2016-01-01

Full Text Available ABSTRACT Communities are structured by interactions of historical and ecological factors, which influence the use of different resources in time and space. We acquired data on time of activity, microhabitat use and diet of a lizard assemblage from a sand dune habitat in a coastal area, southeastern Brazil (Restinga de Jurubatiba. We analyzed the data of niche overlap among species in these three axes (temporal, spatial and trophic using null models. We found a significant overlap within the trophic niche, whereas the overlap for the other axes did not differ from the expected. Based on this result, we discuss the factors acting on the structure of the local lizard community.

Measurement and Analysis of Specific Activities of Natural Radionuclides (40K, 226Ra and 232Th) in Beach Sand Samples from Talo Kapo Beach of Yaring District in Pattani Province using Gamma Ray Spectrometry

Science.gov (United States)

Daoh, M.; Masae, R. N.; Po-oh, S.; Boonkrongcheep; Kessaratikoon, P.

2017-09-01

The Specific Activities of 40K, 226Ra and 232Th were studied and determinate for 30 beach sand samples collected from Talo Kapo beach of Yaring district in Pattani province. Experimental results were obtained by using a high-purity germanium (HPGe) detector and gamma spectrometry analysis system. The IAEA-SOIL-6 reference materials obtained from the International Atomic Energy Agency were also used to analyze and compute the 40K, 226Ra and 232Th specific activity in all 30 beach sand samples. The measuring time of each sample is 10,000 seconds. It was found that specific activity range from 1805.37 - 3323.05, 40.96 - 2137.36 38.63 - 4329.28 Bq/kg for with mean values of 2242.79 ± 117.40, 250.18 ± 8.21 and 458.42 ± 7.68 Bq/kg for 40K, 226Ra and 232Th, respectively. Moreover, the results were also compared with research data in the south of Thailand, the Office of Atoms for Peace (OAP) annual report data and the recommended values which were proposed by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR,)

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.

Assessing radiation impact at a protected coastal sand dune site: an intercomparison of models for estimating the radiological exposure of non-human biota

Energy Technology Data Exchange (ETDEWEB)

Wood, Michael D., E-mail: mwood@liv.ac.u [Institute for Sustainable Water Integrated Management and Ecosystem Research (SWIMMER), Nicholson Building, University of Liverpool, Liverpool, Merseyside L69 3GP (United Kingdom); School of Biological Sciences, Nicholson Building, University of Liverpool, Liverpool, Merseyside L69 3GP (United Kingdom); Beresford, Nicholas A.; Barnett, Catherine L. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, Lancashire LA1 4AP (United Kingdom); Copplestone, David [Environment Agency, PO Box 12, Richard Fairclough House, Knutsford Road, Latchford, Warrington, Cheshire WA4 1HG (United Kingdom); Leah, Richard T. [Institute for Sustainable Water Integrated Management and Ecosystem Research (SWIMMER), Nicholson Building, University of Liverpool, Liverpool, Merseyside L69 3GP (United Kingdom); School of Biological Sciences, Nicholson Building, University of Liverpool, Liverpool, Merseyside L69 3GP (United Kingdom)

2009-12-15

This paper presents the application of three publicly available biota dose assessment models (the ERICA Tool, R and D128/SP1a and RESRAD-BIOTA) to an assessment of the Drigg coastal sand dunes. Using measured {sup 90}Sr, {sup 99}Tc, {sup 137}Cs, {sup 238}Pu, {sup 239+240}Pu and {sup 241}Am activity concentrations in sand dune soil, activity concentration and dose rate predictions are made for a range of organisms including amphibians, birds, invertebrates, mammals, reptiles, plants and fungi. Predicted biota activity concentrations are compared to measured data where available. The main source of variability in the model predictions is the transfer parameters used and it is concluded that developing the available transfer databases should be a focus of future research effort. The value of taking an informed user approach to investigate the way in which models may be expected to be applied in practice is highlighted and a strategy for the future development of intercomparison exercises is presented.

Assessing radiation impact at a protected coastal sand dune site: an intercomparison of models for estimating the radiological exposure of non-human biota

International Nuclear Information System (INIS)

Wood, Michael D.; Beresford, Nicholas A.; Barnett, Catherine L.; Copplestone, David; Leah, Richard T.

2009-01-01

This paper presents the application of three publicly available biota dose assessment models (the ERICA Tool, R and D128/SP1a and RESRAD-BIOTA) to an assessment of the Drigg coastal sand dunes. Using measured 90 Sr, 99 Tc, 137 Cs, 238 Pu, 239+240 Pu and 241 Am activity concentrations in sand dune soil, activity concentration and dose rate predictions are made for a range of organisms including amphibians, birds, invertebrates, mammals, reptiles, plants and fungi. Predicted biota activity concentrations are compared to measured data where available. The main source of variability in the model predictions is the transfer parameters used and it is concluded that developing the available transfer databases should be a focus of future research effort. The value of taking an informed user approach to investigate the way in which models may be expected to be applied in practice is highlighted and a strategy for the future development of intercomparison exercises is presented.

Possibility of star (pyramid) dune development in the area of bimodal wind regime

Science.gov (United States)

Biejat, K.

2012-04-01

Star (pyramid) dunes are the largest aeolian landforms. They can occur in three types - simple, complex and compound. Development of this type of dunes is usually connected with multidirectional or complex wind regimes. The aim of this study was to verify a hypothesis that the star dunes can also develop by a bimodal wind regime and by local modifications of nearsurface wind flow directions. Field study was performed on Erg Chebbi, in southern Morocco. Several star and transverse dunes were selected for the study of their shape. The star dunes were analysed concerning their type and position in the dune field. This erg contains all of three types of star dunes together with transverse dunes. The regional wind data show that there are two dominant wind directions - NE (Chergui) and SW (Saheli). To determine the difference in shape of star dunes, we performed topographic surveying by GPS RTK. The results allowed to create 3D models of star dunes. The models were used to determine metric characteristics of star dunes, including area of dune basis, volume, and slope angles. On the basis of 3D models, primary, secondary and, on the compound dunes, tertiary arms were determined. Primary arms on each type of star dunes, as well as crestlines of transverse dunes, have dominant orientation NW-SE, perpendicular to two dominant wind directions. This clearly confirms that star dunes of Erg Chebbi develop by a bimodal wind regime In contrast to primary arms, subsidiary (secondary and tertiary) arms are not connected to general wind regime. The secondary arms of star dunes occur to be differentially developer. There are more subsidiary arms on SW sides in comparison to the E sides of the dunes where inclination of slopes is constant. It can be therefore inferred that sand has been supplied predominantly from SW direction. This is supported by distribution of the dunes on the erg. Most compound star dunes compose a chain along the E margin of the erg. Comparison of compound star

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

Through the sands of time: Beach litter trends from nine cleaned north cornish beaches.

Science.gov (United States)

Watts, Andrew J R; Porter, Adam; Hembrow, Neil; Sharpe, Jolyon; Galloway, Tamara S; Lewis, Ceri

2017-09-01

Marine litter and its accumulation on beaches is an issue of major current concern due to its significant environmental and economic impacts. Yet our understanding of spatio-temporal trends in beach litter and the drivers of these trends are currently limited by the availability of robust long term data sets. Here we present a unique data set collected systematically once a month, every month over a six year period for nine beaches along the North Coast of Cornwall, U.K. to investigate the key drivers of beach litter in the Bude, Padstow and Porthcothan areas. Overall, an average of 0.02 litter items m -2 per month were collected during the six year study, with Bude beaches (Summerleaze, Crooklets and Widemouth) the most impacted (0.03 ± 0.004 litter items m -2 per month). The amount of litter collected each month decreased by 18% and 71% respectively for Padstow (Polzeath, Trevone and Harlyn) and Bude areas over the 6 years, possibly related to the regular cleaning, however litter increased by 120% despite this monthly cleaning effort on the Padstow area beaches. Importantly, at all nine beaches the litter was dominated by small, fragmented plastic pieces and rope fibres, which account for 32% and 17% of all litter items collected, respectively. The weathered nature of these plastics indicates they have been in the marine environment for an extended period of time. So, whilst classifying the original source of these plastics is not possible, it can be concluded they are not the result of recent public littering. This data highlights both the extent of the marine litter problem and that current efforts to reduce littering by beach users will only tackle a fraction of this litter. Such information is vital for developing effective management strategies for beach and marine litter at both regional and global levels. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Environmental Controls and Eco-geomorphic Interactions of the Barchan-to-parabolic Dune Stabilisation and the Parabolic-to-barchan Dune Reactivation

Science.gov (United States)

Yan, Na; Baas, Andreas

2015-04-01

Parabolic dunes are one of a few common aeolian landforms which are highly controlled by eco-geomorphic interactions. Parabolic dunes, on the one hand, can be developed from highly mobile dune landforms, barchans for instance, in an ameliorated vegetation condition; or on the other hand, they can be reactivated and transformed back into mobile dunes due to vegetation deterioration. The fundamental mechanisms and eco-geomorphic interactions controlling both dune transformations remain poorly understood. To bridge the gap between complex processes involved in dune transformations on a relatively long temporal scale and real world monitoring records on a very limited temporal scale, this research has extended the DECAL model to incorporate 'dynamic' growth functions and the different 'growth' of perennial shrubs between growing and non-growing seasons, informed by field measurements and remote sensing analysis, to explore environmental controls and eco-geomorphic interactions of both types of dune transformation. A non-dimensional 'dune stabilising index' is proposed to capture the interactions between environmental controls (i.e. the capabilities of vegetation to withstand wind erosion and sand burial, the sandy substratum thickness, the height of the initial dune, and the sand transport potential), and establish the linkage between these controls and the geometry of a stabilising dune. An example demonstrates how to use the power-law relationship between the dune stabilising index and the normalised migration distance to assist in extrapolating the historical trajectories of transforming dunes. The modelling results also show that a slight increase in vegetation cover of an initial parabolic dune can significantly increase the reactivation threshold of climatic impact (both drought stress and wind strength) required to reactivate a stabilising parabolic dune into a barchan. Four eco-geomorphic interaction zones that govern a barchan-to-parabolic dune transformation

What is a Dune: Developing AN Automated Approach to Extracting Dunes from Digital Elevation Models

Science.gov (United States)

Taylor, H.; DeCuir, C.; Wernette, P. A.; Taube, C.; Eyler, R.; Thopson, S.

2016-12-01

Coastal dunes can absorb storm surge and mitigate inland erosion caused by elevated water levels during a storm. In order to understand how a dune responds to and recovers from a storm, it is important that we can first identify and differentiate the beach and dune from the rest of the landscape. Current literature does not provide a consistent definition of what the dune features (e.g. dune toe, dune crest) are or how they can be extracted. The purpose of this research is to develop enhanced approaches to extracting dunes from a digital elevation model (DEM). Manual delineation, convergence index, least-cost path, relative relief, and vegetation abundance were compared and contrasted on a small area of Padre Island National Seashore (PAIS), Preliminary results indicate that the method used to extract the dune greatly affects our interpretation of how the dune changes. The manual delineation method was time intensive and subjective, while the convergence index approach was useful to easily identify the dune crest through maximum and minimum values. The least-cost path method proved to be time intensive due to data clipping; however, this approach resulted in continuous geomorphic landscape features (e.g. dune toe, dune crest). While the relative relief approach shows the most features in multi resolution, it is difficult to assess the accuracy of the extracted features because extracted features appear as points that can vary widely in their location from one meter to the next. The vegetation approach was greatly impacted by the seasonal and annual fluctuations of growth but is advantageous in historical change studies because it can be used to extract consistent dune formation from historical aerial imagery. Improving our ability to more accurately assess dune response and recovery to a storm will enable coastal managers to more accurately predict how dunes may respond to future climate change scenarios.

Spatial and temporal patterns of airflow across a foredune and beach surface under offshore winds: implications for aeolian sediment transport

Science.gov (United States)

Jackson, D.; Delgado-Fernandez, I.; Lynch, K.; Baas, A. C.; Cooper, J. A.; Beyers, M.

2010-12-01

The input of aeolian sediment into foredune systems from beaches represents a key component of sediment budget analysis along many soft sedimentary coastlines. Where there are significant offshore wind components in local wind regimes this is normally excluded from analysis. However, recent work has shown that if the topography of the foredune is favourable then this offshore component is steered or undergoes flow reversal through leeside eddying to give onshore transport events at the back beach under offshore flow conditions. At particular distances from the foredune crest flow reattaches to the surface to continue its incident offshore direction. The location of this reattachment point has important implications for aeolian transport of sand on the back beach and foredune toe locations. This study reports initial results where the positioning of the reattachment point is mobile and is driven by incident wind velocity (at the foredune crest) and the actual undulations of the foredune crest’s topography, dictating heterogeneous flow behaviour at the beach. Using detailed field measurements (25 Hz, three-dimensional sonic anemometry) and computational fluid dynamic modelling, a temporal and spatial pattern of reattachment positions are described. Implications for aeolian transport and dune evolution are also examined.

The ecology of sandy beaches in Transkei

African Journals Online (AJOL)

Data from an ecological survey of three sandy beaches in. Transkei and from Gulu beach on the eastern Cape coast,. South Africa, are presented. Physical parameters such as beach profile, sand particle size, Eh and carbonate content, as well as abundance, composition, biomass and distribution of the macrofauna and ...

Distribution of natural radionuclides in soils and beach sands of Abana-Çatalzeytin (Kastamonu)

Energy Technology Data Exchange (ETDEWEB)

Kurnaz, Aslı, E-mail: akurnaz@kastamonu.edu.tr; Özcan, Murat, E-mail: murat-ozcan@kastamonu.edu.tr; Çetiner, M. Atıf, E-mail: macetiner@kastamonu.edu.tr [Kastamonu University, Arts and Sciences Faculty, Department of Physics, Kastamonu (Turkey)

2016-03-25

A gamma spectrometric study of distribution of natural radionuclides in soil and beach sand samples collected from the terrestrial and coastal environment of Abana and Çatalzeytin counties of Kastamonu Province in Turkey was performed with the aim of estimating the radiation hazard of the tourist area and the concentrations of {sup 238}U, {sup 232}Th and {sup 40}K were determined. The activity concentrations of {sup 238}U, {sup 232}Th and {sup 40}K were determined in the ranges 14.95–56.0, 46.5–99.4 and 357.5–871.3 Bqkg{sup −1} for soil samples and the mean concentrations were ascertained as 42.34, 71.24 and 624.18 Bqkg{sup −1}, respectively. In sand samples, {sup 238}U, {sup 232}Th and {sup 40}K contents were varied in the ranges of 13.35-41.6, 30.9-53.4 and 275.5-601.3 Bqkg{sup −1} and the mean concentrations were ascertained as 20.57, 45.05 and 411.71 Bqkg{sup −1}, respectively. The mean annual effective doses were calculated as 113.08 and 69.16 µSvy{sup −1} for the soil and sand samples, respectively.

Aeolian sediment transport on a beach: Surface moisture, wind fetch, and mean transport

Science.gov (United States)

Bauer, B. O.; Davidson-Arnott, R. G. D.; Hesp, P. A.; Namikas, S. L.; Ollerhead, J.; Walker, I. J.

2009-04-01

Temporal and spatial changes in wind speed, wind direction, and moisture content are ubiquitous across sandy coastal beaches. Often these factors interact in unknown ways to create complexity that confounds our ability to model sediment transport at any point across the beach as well as our capacity to predict sediment delivery into the adjacent foredunes. This study was designed to measure wind flow and sediment transport over a beach and foredune at Greenwich Dunes, Prince Edward Island National Park, with the express purpose of addressing these complex interactions. Detailed measurements are reported for one stormy day, October 11, 2004, during which meteorological conditions were highly variable. Wind speed ranged from 4 ms - 1 to over 20 ms - 1 , wind direction was highly oblique varying between 60° and 85° from shore perpendicular, and moisture content of the sand surface ranged from a minimum of about 3% (by mass) to complete saturation depending on precipitation, tidal excursion, and storm surge that progressively inundated the beach. The data indicate that short-term variations (i.e., minutes to hours) in sediment transport across this beach arise predominantly because of short-term changes in wind speed, as is expected, but also because of variations in wind direction, precipitation intensity, and tide level. Even slight increases in wind speed are capable of driving more intense saltation events, but this relationship is mediated by other factors on this characteristically narrow beach. As the angle of wind approach becomes more oblique, the fetch distance increases and allows greater opportunity for the saltation system to evolve toward an equilibrium transport state before reaching the foredunes. Whether the theoretically-predicted maximum rate of transport is ever achieved depends on the character of the sand surface (e.g., grain size, slope, roughness, vegetation, moisture content) and on various attributes of the wind field (e.g., average wind

Experimental Investigations of Effect of Sulphur on Beach Sand–Fly Ash–Asphalt (S-F-A) Paving Mixes

OpenAIRE

Satyakumar, M.; Satheeshchandran, R.

2013-01-01

The main components of the flexible pavements are asphalt and aggregates. But in most of the places in India there is shortage of the good quality aggregates (especially coarse aggregates), at the same time beach sand is available in plenty in many regions. Due to relative abundance of beach sand, the studies on the utilities of the beach sand in paving mixes are worth taking up. But beach Sand-Asphalt mix alone is not suitable for pavement construction, because of its low stability and high ...

Morphologic Response and Sediment Redistribution of the Beach and Nearshore Sand Bars due to Extratropical and Tropical Storm Forcing: a Spatial and Temporal Analysis

Science.gov (United States)

Miselis, J. L.; McNinch, J. E.

2005-05-01

Shore-oblique bars and associated exposures of an underlying geologic stratum in the nearshore have been documented along the US East Coast and have been linked to shoreline erosional hotspots. While earlier studies acknowledged that the bedforms responded to extratropical and tropical storms, neither quantified the extent of sediment redistribution after the events. An approach that encompasses actual volume measurements across the nearshore-beach down to a non-sandy stratum and quantifies the response of the beach and the nearshore to the same hydrodynamic forcing will enable a better understanding of the exchange of sediment between the two regions. Total nearshore sediment volume has been shown to be a first-order contributor to the behavior of the shoreline. This volumetric approach is employed in the analysis of morphological changes and the redistribution of sediment in the nearshore and beach following storms. A regional survey from 2002 provides the initial, fair-weather morphologic state of the nearshore (1.5-15m water depth) spanning 40 km of the North Carolina Outer Banks. Four small-scale surveys were conducted in subsequent years, focusing on four 1-km2 regions within the initial 2002 survey area. The smaller regions were selected on the basis of the morphological state observed during the 2002 survey and historical shoreline behavior. Data were collected in March 2003 following a Northeaster; in May 2003 following an extended period of fair weather conditions; in November 2003 following Hurricane Isabel; and finally, in June 2004 after another period of fair weather. A swath bathymetry system was used to collect bathymetry and side scan sonar (acoustic backscatter) and a high-resolution chirp sub-bottom profiler imaged the shallow sub-surface geology of the nearshore. In addition, RTK-GPS was used to map the sub-aerial beach at each 1-km2 site from the toe of the dune to the water line for the May 2003, November 2003, and June 2004 sampling periods

Intertidal Sandbar Welding as a Primary Source of Sediment for Dune Growth: Evidence from a Large Scale Field Experiment

Science.gov (United States)

Cohn, N.; Ruggiero, P.; de Vries, S.

2016-12-01

Dunes provide the first line of defense from elevated water levels in low-lying coastal systems, limiting potentially major flooding, economic damages, and loss of livelihood. Despite the well documented importance of healthy dunes, our predictive ability of dune growth, particularly following erosive storm events, remains poor - resulting in part from traditionally studying the wet and dry beach as separate entities. In fact, however, dune recovery and growth is closely tied to the subtidal morphology and the nearshore hydrodynamic conditions, necessitating treating the entire coastal zone from the shoreface to the backshore as an integrated system. In this context, to further improve our understanding of the physical processes allowing for beach and dune growth during fair weather conditions, a large field experiment, the Sandbar-aEolian Dune EXchange EXperiment, was performed in summer 2016 in southwestern Washington, USA. Measurements of nearshore and atmospheric hydrodynamics, in-situ sediment transport, and morphology change provide insight into the time and space scales of nearshore-beach-dune exchanges along a rapidly prograding stretch of coast over a 6 week period. As part of this experiment, the hypothesis that dune growth is limited by the welding of intertidal sandbars to the shoreline (Houser, 2009) was tested. Using laser particle counters, bed elevation sensors (sonar altimeters and Microsoft Kinect), continuously logging sediment traps, RGB and IR cameras, and repeat morphology surveys (terrestrial lidar, kite based structure from motion, and RTK GPS), spatial and temporal trends in aeolian sediment transport were assessed in relation to the synoptic onshore migration and welding of intertidal sandbars. Observations from this experiment demonstrate that (1) the intertidal zone is the primary source of sediment to the dunes during non-storm conditions, (2) rates of saltation increase during later stages of bar welding but equivalent wind conditions

Aeolian dune sediment flux heterogeneity in Meridiani Planum, Mars.

Science.gov (United States)

Chojnacki, Matthew; Urso, Anna; Fenton, Lori K; Michaels, Timothy I

2017-06-01

It is now known unambiguously that wind-driven bedform activity is occurring on the surface of Mars today, including early detections of active sand dunes in Meridiani Planum's Endeavour crater. Many of these reports are only based on a few sets of observations of relatively isolated bedforms and lack regional context. Here, we investigate aeolian activity across central Meridiani Planum and test the hypothesis that dune sites surrounding Endeavour crater are also active and part of region-wide sediment migration driven by northwesterly winds. All 13 dune fields investigated clearly showed evidence for activity and the majority exhibited dune migration (average rates of 0.6 m/Earth-year). Observations indicate substantial geographic and temporal heterogeneity of dune crest fluxes across the area and per site. Locations with multiple time steps indicate dune sand fluxes can vary by a factor of five, providing evidence for short periods of rapid migration followed by near-stagnation. In contrast, measurements at other sites are nearly identical, indicating that some dunes are in a steady-state as they migrate. The observed sediment transport direction was consistent with a regional northeasterly-to-northwesterly wind regime, revealing more variations than were appreciated from earlier, more localized studies. Craters containing shallow, degraded, flat-floored interiors tended to have dunes with high sediment fluxes/activity, whereas local kilometer-scale topographic obstructions (e.g., central peaks, yardangs) were found to be inversely correlated with dune mobility. Finally, the previous, more limited detections of dune activity in Endeavour crater have been shown to be representative of a broader, region-wide pattern of dune motion.

Impact of shipwrecks on the morphology of world coasts: A review

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas, A; ManiMurali, R.

Role of the grounded ship MV River Princess in activating erosion along the Candolim to Sinquerim coast of Goa, India, is evaluated Beach and dune system was severely affected, as over a kilometre long strip of coastal sand dunes were destroyed...

Hurricane Sandy beach response and recovery at Fire Island, New York: Shoreline and beach profile data, October 2012 to October 2014

Science.gov (United States)

Hehre Henderson, Rachel E.; Hapke, Cheryl J.; Brenner, Owen T.; Reynolds, Billy J.

2015-04-30

In response to the forecasted impact of Hurricane Sandy, which made landfall on October 29, 2012, the U.S. Geological Survey (USGS) began a substantial data-collection effort to assess the morphological impacts to the beach and dune system at Fire Island, New York. Global positioning system (GPS) field surveys of the beach and dunes were conducted just prior to and after landfall and these data were used to quantify change in several focus areas. In order to quantify morphologic change along the entire length of the island, pre-storm (May 2012) and post-storm (November 2012) lidar and aerial photography were used to assess changes to the shoreline and beach.As part of the USGS Hurricane Sandy Supplemental Fire Island Study, the beach is monitored periodically to enable better understanding of post-Sandy recovery. The alongshore state of the beach is recorded using a differential global positioning system (DGPS) to collect data around the mean high water (MHW; 0.46 meter North American Vertical Datum of 1988) to derive a shoreline, and the cross-shore response and recovery are measured along a series of 10 profiles.Overall, Hurricane Sandy substantially altered the morphology of Fire Island. However, the coastal system rapidly began to recover after the 2012­–13 winter storm season and continues to recover in the form of volume gains and shoreline adjustment.

INLAND DUNE VEGETATION OF THE NETHERLANDS

Directory of Open Access Journals (Sweden)

R. HAVEMAN

2003-01-01

Full Text Available Drifting sands in the Netherlands are the result of human over-exploitation (sod-cutting, over-grazing of woodlands and heathlands. The most important association of inland sand dune areas is the Spergulo-Corynephoretum (Corynephorion canescentis, which is poor in vascular plants, but in it older stager rich in mosses and especially lichens. In the Netherlands, the area of drifting sand is reduced dramatically in the last 70 years. mainly by afforestation and spontaneous succession.

Protective role of coastal ecosystems in the context of the tsunami in Tamil Nadu coast, India: Implications for hazard preparedness

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas, A.; Jayakumar, S.

of society bears the recurring loss of humans, livestock and property. Prudent development of coasts is the obvious solution. The inherent benefits offered by a functional sea front have to be considered for a sustainable management of hazard-prone coasts... and high dunes act as efficient dissipaters of wave energy. Sand dunes therefore serve as stores that strong waves draw on during extreme events. Society at large is immensely benefitted. The role played by sand dunes and beach gradients during the tsunami...

Observations and predictions of wave runup, extreme water levels, and medium-term dune erosion during storm conditions

OpenAIRE

Suanez , Serge ,; Cancouët , Romain; Floc'h , France; Blaise , Emmanuel; Ardhuin , Fabrice; Filipot , Jean-François; Cariolet , Jean-Marie; Delacourt , Christophe

2015-01-01

Monitoring of dune erosion and accretion on the high-energy macrotidal Vougot beach in North Brittany (France) over the past decade (2004–2014) has revealed significant morphological changes. Dune toe erosion/accretion records have been compared with extreme water level measurements, defined as the sum of (i) astronomic tide; (ii) storm surge; and (iii) vertical wave runup. Runup parameterization was conducted using swash limits, beach profiles, and hydrodynamic (Hm0, Tm0,–1, and high tide wa...

Frequency distribution of specific activities and radiological hazard assessment in surface beach sand samples collected in Bangsaen beach in Chonburi province, Thailand

Science.gov (United States)

Changkit, N.; Boonkrongcheep, R.; Youngchauy, U.; Polthum, S.; Kessaratikoon, P.

2017-09-01

The specific activities of natural radionuclides (40K, 226Ra and 232Th) in 50 surface beach sand samples collected from Bangsaen beach in Chonburi province in the easthern region of Thailand, were measured and evaluated. Experimental results were obtained by using a high-purity germanium (HPGe) detector and gamma spectrometry analysis system in the special laboratory at Thailand Institute of Nuclear Technology (Public Organization). The IAEA-SOIL-375 reference material was used to analyze the concentration of 40K, 226Ra and 232Th in all samples. It was found that the specific activities of 40K, 226Ra and 232Th were ranged from 510.85 - 771.35, 8.17 - 17.06 and 4.25 - 15.68 Bq/kg. Furthermore, frequency distribution of the specific activities were studied, analyzed and found to be the asymmetrical distribution by using a statistical computer program. Moreover, four radiological hazard indices for the investigated area were also calculated by using the median values of specific activities of 40K, 226Ra and 232Th. The results were also compared with the Office of Atoms for Peace (OAP) annual report data, Thailand and global radioactivity measurement and evaluations.

Gamma radiation measurement in select sand samples from Camburi beach - Vitoria, Espirito Santo, Brazil: preliminary results

Energy Technology Data Exchange (ETDEWEB)

Barros, Livia F.; Pecequilo, Brigitte R.S.; Aquino, Reginaldo R., E-mail: lfbarros@ipen.b, E-mail: brigitte@ipen.b, E-mail: raquino@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The variation of natural radioactivity along the surface of the beach sands of Camburi, located in Vitoria, capital of Espirito Santo, southeastern Brazil, was determined from the contents of {sup 226}Ra, {sup 232}Th and {sup 40}K. Eleven collecting points was selected along all the 6 km extension of the Camburi beach. Sand samples collected from all established points on January 2011 were dried and sealed in standard 100 mL polyethylene flasks and measured by high resolution gamma spectrometry after a 4 weeks ingrowth period, in order to allow the secular equilibrium in the {sup 238}U and {sup 232}Th series. The {sup 226}Ra concentration was determined from the weighted average concentrations of {sup 214}Pb and {sup 214}Bi. The {sup 232}Th concentration was determined from the weighted average concentrations of {sup 228}Ac, {sup 212}Pb and {sup 212}Bi and the {sup 40}K from its single gamma transition. Preliminary results show activity concentrations varying from 5 Bq.kg{sup -1} to {sup 222} Bq.kg{sup -1} for {sup 226}Ra and from 14 Bq.kg{sup -1} to 1074 Bq.kg{sup -'}1 for {sup 232}Th, both with the highest values for Camburi South and Central. For {sup 40}K, the activity concentrations ranged from 14 Bq.kg{sup -1} to 179 Bq.kg{sup -1} and the highest values were obtained for Camburi South. (author)

Effects of disturbance on vegetation by sand accretion and erosion across coastal dune habitats on a barrier island.

Science.gov (United States)

Miller, Thomas E

2015-01-12

Coastal geomorphology and vegetation are expected to be particularly sensitive to climate change, because of disturbances caused by sea-level rise and increased storm frequency. Dunes have critical reciprocal interactions with vegetation; dunes create habitats for plants, while plants help to build dunes and promote geomorphological stability. These interactions are also greatly affected by disturbances associated with sand movement, either in accretion (dune building) or in erosion. The magnitude and intensity of disturbances are expected to vary with habitat, from the more exposed and less stable foredunes, to low-lying and flood-prone interdunes, to the protected and older backdunes. Permanent plots were established at three different spatial scales on St George Island, FL, USA, where the vegetation and dune elevation were quantified annually from 2011 to 2013. Change in elevation, either through accretion or erosion, was used as a measure of year-to-year disturbance over the 2 years of the study. At the scale of different dune habitats, foredunes were found to have the greatest disturbance, while interdunes had the least. Elevation and habitat (i.e. foredune, interdune, backdune) were significantly correlated with plant community composition. Generalized linear models conducted within each habitat show that the change in elevation (disturbance) is also significantly correlated with the plant community, but only within foredunes and interdunes. The importance of disturbance in exposed foredunes was expected and was found to be related to an increasing abundance of a dominant species (Uniola paniculata) in eroding areas. The significant effect of disturbance in the relatively stable interdunes was surprising, and may be due to the importance of flooding associated with small changes in elevation in these low-lying areas. Overall, this study documents changes in the plant community associated with elevation, and demonstrates that the foredune and interdune

APXS-derived chemistry of the Bagnold dune sands: Comparisons with Gale Crater soils and the global Martian average

Science.gov (United States)

O'Connell-Cooper, C. D.; Spray, J. G.; Thompson, L. M.; Gellert, R.; Berger, J. A.; Boyd, N. I.; Desouza, E. D.; Perrett, G. M.; Schmidt, M.; VanBommel, S. J.

2017-12-01

We present Alpha-Particle X-ray Spectrometer (APXS) data for the active Bagnold dune field within the Gale impact crater (Mars Science Laboratory (MSL) mission). We derive an APXS-based average basaltic soil (ABS) composition for Mars based on past and recent data from the MSL and Mars Exploration Rover (MER) missions. This represents an update to the Taylor and McLennan (2009) average Martian soil and facilitates comparison across Martian data sets. The active Bagnold dune field is compositionally distinct from the ABS, with elevated Mg, Ni, and Fe, suggesting mafic mineral enrichment and uniformly low levels of S, Cl, and Zn, indicating only a minimal dust component. A relationship between decreasing grain size and increasing felsic content is revealed. The Bagnold sands possess the lowest S/Cl of all Martian unconsolidated materials. Gale soils exhibit relatively uniform major element compositions, similar to Meridiani Planum and Gusev Crater basaltic soils (MER missions). However, they show minor enrichments in K, Cr, Mn, and Fe, which may signify a local contribution. The lithified eolian Stimson Formation within the Gale impact crater is compositionally similar to the ABS and Bagnold sands, which provide a modern analogue for these ancient eolian deposits. Compilation of APXS-derived soil data reveals a generally homogenous global composition for Martian soils but one that can be locally modified due to past or extant geologic processes that are limited in both space and time.

Barrier island response to an elevated sea-level anomaly: Onslow Beach, North Carolina, USA

Science.gov (United States)

Theuerkauf, E. J.; Rodriguez, A. B.; Fegley, S. R.; Luettich, R.

2012-12-01

Variations in sea level over time scales ranging from hours to millennia influence coastal processes and evolution. At annual time scales, elevated sea-level anomalies produce coastal flooding and promote beach erosion. This study examines the coastal response of Onslow Beach, North Carolina to the summer 2009 East Coast sea-level anomaly. Onslow Beach is a 12-km-long wave-dominated barrier island with highly variable along-barrier morphology. The transgressive southern portion of the island is characterized by a narrow beach, low dunes, and multiple washover fans, while the regressive northern portion is characterized by a wide beach and continuous tall dunes. Hourly tide gauge data from adjacent NOAA stations (Beaufort and Wrightsville Beach) are used to determine the timing and extent of elevated water levels. The seasonal and longer term trends (relative sea level rise) are removed from both of the water level series and the sea-level anomaly is represented by a large residual between the observed and predicted water levels. Beach response is quantified using terrestrial laser scanning for morphology and from geoprobe cores to determine the maximum depth of erosion (MDOE). The mean high water (MHW) shoreline and dune toe are digitized from digital elevation models derived from the laser scans and analyzed using the Digital Shoreline Analysis System (DSAS). Landward (negative) movement of these contacts indicates erosion. Wave data collected from an Acoustic Wave and Current Meter (AWAC) located offshore of the southern end of Onslow Beach is used to characterize the wave regime throughout the study. Water level is elevated in the tide gauge data from June 2009 to March 2010. This sea-level anomaly corresponds with an increase in the maximum depth of erosion between 2009 and 2010. Landward movement of the MHW shoreline and the dunetoe increased during the period between September 2009 and May 2010 indicating an increase in beach erosion during the sea

Responses of three-dimensional flow to variations in the angle of incident wind and profile form of dunes: Greenwich Dunes, Prince Edward Island, Canada

Science.gov (United States)

Walker, Ian J.; Hesp, Patrick A.; Davidson-Arnott, Robin G. D.; Bauer, Bernard O.; Namikas, Steven L.; Ollerhead, Jeff

2009-04-01

This study reports the responses of three-dimensional near-surface airflow over a vegetated foredune to variations in the conditions of incident flow during an 8-h experiment. Two parallel measurement transects were established on morphologically different dune profiles: i) a taller, concave-convex West foredune transect with 0.5-m high, densely vegetated (45%), seaward incipient foredune, and ii) a shorter, concave-straight East foredune transect with lower, sparsely vegetated (14%) seaward incipient foredune. Five stations on each transect from the incipient dune to the crest were equipped with ultrasonic anemometers at 0.6 and 1.65 m height and logged at 1 Hz. Incident conditions were recorded from a 4-m tower over a flat beach. Winds increased from 6 m s - 1 to > 20 m s - 1 and were generally obliquely onshore (ENE, 73°). Three sub-events and the population of 10-minute averages of key properties of flow ( U, W, S, CV U) from all sample locations on the East transect ( n = 235) are examined to identify location- and profile-specific responses over 52° of the incident direction of flow (from 11 to 63° onshore). Topographic steering and forcing cause major deviations in the properties and vectors of near-surface flow from the regional wind. Topographic forcing on the concave-straight dune profile increases wind speed and steadiness toward the crest, with speed-up values to 65% in the backshore. Wind speed and steadiness of flow are least responsive to changes in incident angle in the backshore because of stagnation of flow and are most responsive at the lower stoss under pronounced streamline compression. On the steeper concave-convex profile, speed and steadiness decrease toward the crest because of stagnation of flow at the toe and flow expansion at the slope inflection point on the lower stoss. Net downward vertical velocity occurs over both profiles, increases toward the crest, and reflects enhanced turbulent momentum conveyance toward the surface. All of

Basaltic lava flows covering active aeolian dunes in the Paraná Basin in southern Brazil: Features and emplacement aspects

Science.gov (United States)

Waichel, Breno L.; Scherer, Claiton M. S.; Frank, Heinrich T.

2008-03-01

Burial of active aeolian dunes by lava flows can preserve the morphology of the dunes and generate diverse features related to interaction between unconsolidated sediments and lavas. In the study area, located in southern Brazil, burial of aeolian deposits by Cretaceous basaltic lava flows completely preserved dunes, and generate sand-deformation features, sand diapirs and peperite-like breccia. The preserved dunes are crescentic and linear at the main contact with basalts, and smaller crescentic where interlayered with lavas. The various feature types formed on sediment surfaces by the advance of the flows reflect the emplacement style of the lavas which are compound pahoehoe type. Four feature types can be recognized: (a) type 1 features are related to the advance of sheet flows in dune-interdune areas with slopes > 5°, (b) type 2 is formed where the lava flows advance in lobes and climb the stoss slope of crescentic dunes (slopes 8-12°), (c) type 3 is generated by toes that descend the face of linear dunes (slopes 17-23°) and (d) type 4 occurs when lava lobes descend the stoss slope of crescentic dunes (slopes 10-15°). The direction of the flows, the disposition and morphology of the dunes and the ground slope are the main factors controlling formation of the features. The injection of unconsolidated sand in lava lobes forms diapirs and peperite-like breccias. Sand diapirs occur at the basal portion of lobes where the lava was more solidified. Peperite-like breccias occur in the inner portion where lava was more plastic, favoring the mingling of the components. The generation of both features is related to a mechanical process: the weight of the lava causes the injection of sand into the lava and the warming of the air in the pores of the sand facilitates this process. The lava-sediment interaction features presented here are consistent with previous reports of basalt lavas with unconsolidated arid sediments, and additional new sand-deformation features

Studies of the terrestrial O₂ and carbon cycles in sand dune gases and in biosphere 2

Energy Technology Data Exchange (ETDEWEB)

Severinghaus, Jeffrey Peck [Columbia Univ., New York, NY (United States)

1995-01-01

Molecular oxygen in the atmosphere is coupled tightly to the terrestrial carbon cycle by the processes of photosynthesis, respiration, and burning. This dissertation examines different aspects of this coupling in four chapters. Chapter 1 explores the feasibility of using air from sand dunes to reconstruct atmospheric O₂ composition centuries ago. Such a record would reveal changes in the mass of the terrestrial biosphere, after correction for known fossil fuel combustion, and constrain the fate of anthropogenic CO₂.

Recreational impacts on Colorado River beaches in Glen Canyon, Arizona

Science.gov (United States)

Carothers, Steven W.; Johnson, Robert A.; Dolan, Robert

1984-07-01

Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches.

226Ra, 232Th and 40K analysis in sand samples from some beaches of Great Vitoria, Espirito Santo, Brazil: preliminary results

International Nuclear Information System (INIS)

Aquino, Reginaldo R.; Pecequilo, Brigitte R.S.

2009-01-01

The natural radioactivity in superficial beach sand samples of 7 beaches of Great Vitoria, metropolitan region of the State of Espirito Santo, southeast Brazil, was determined from the 226 Ra, 232 Th and 4 0 K contents. The assessed beaches were Manguinhos, Camburi, Praia do Canto, Curva da Jurema, Itapua, Setibao and Areia Preta. Three samples of each beach were sealed in standard 100 mL polyethylene flasks and stored in order to obtain secular equilibrium in the 238 U and 232 Th series. All samples were measured by high resolution gamma spectrometry and the spectra were analyzed with the WinnerGamma software. The 232 Th concentration was determined from the average concentrations of 228 Ac, 212 Pb and 212 Bi and the 226 Ra concentration was determined from the average concentrations of 214 Pb and 214 Bi. Preliminary results show concentrations varying from 9 Bq.kg -1 to 6035 Bq.kg -1 for 232 Th, from 4 Bq.kg -1 to 575 Bq.kg -1 for 226 Ra and from 13 Bq.kg -1 to 142 Bq.kg -1 for 40 K. Areia Preta beach shows the highest values for 232 Th, while the highest value for 226 Ra was observed for Camburi beach. High values of 40 K were observed for Curva da Jurema beach. (author)

Desalination impacts on the coastal environment: Ash Shuqayq, Saudi Arabia

International Nuclear Information System (INIS)

Alharbi, O.A.; Phillips, M.R.; Williams, A.T.; Gheith, A.M.; Bantan, R.A.; Rasul, N.M.

2012-01-01

Ash Shuqayq (Saudi Red Sea coast) is approximately 28 km long and characterised by narrow rocky headlands with intermittent pocket beaches. Fifty-two sediment samples from six different environments (beach, dune, sabkha, tidal/lagoon, offshore and wadi) were analysed. Testing showed that beach and dune sands are mainly medium to fine grained, with some very coarse sand (MZ = − 0.59ø). Both beach and dune sands are moderately well to moderately sorted, although some are poorly sorted due to an influx of wadi sediments. Sediment source together with littoral reworking contributed to grain size variation. Carbonate content varied between 1.5% and 23%, whilst the organic content varied between 1.1% and 13%. Spatial analysis showed increasing southward carbonate and organic content, with both correlated (r = 0.57). Sabkha sediments had significantly higher carbonate percentages (t = 2.898; df = 18; p < 0.01) and results suggested origins are similar for both UAE Arabian Sea and Saudi Arabian Red Sea coasts. X-ray diffractions show beach and dune sediments are mainly composed of detrital quartz and plagioclase feldspar with uncommon amounts of chlorites. Analysis of sediment characteristics, composition and shoreline distribution alongside coastal processes, indicate that high chlorite levels are probably caused by desalination processes. Due to human and ecosystem health consequences and the likely increased demand for desalination plants, similar analyses should be undertaken elsewhere, e.g. the Mediterranean. - Highlights: ► New and previously unpublished Red Sea sediment information. ► Sediment chemical and spatial variations established. ► Sabkha origins are similar for both UAE Arabian Sea and Saudi Arabian Red Sea coasts. ► Desalination plant shown as cause of increased marine sediment chlorite levels.

Variability of grain sizes in a beach nourishment programme for the Danish West Caost

DEFF Research Database (Denmark)

Frigaard, Peter; Wahl, Niels Arne

2007-01-01

of naturally shaped beaches while at the same time the risk for erosion is reduced. For this reason beach nourishment is used widely along the Danish North Sea coast (called West Coast) and this method is preferred in preference to put up solid constructions. Beach nourishment is the primary method used...... is shaped. The aim of the present investigation was to examine how to extract sand samples of an actual beach nourishment to obtain a satisfactory description of the sedimentary composition. In specific the goal was a description of the variation of the sand characteristics in space. The reason...... for this is that the compositions of sand affect the erosion and the shaping of the beach. The results show that by collecting 13-15 sand samples it is possible to obtain a description of d50 with a precision of 0.1 mm within a confidence interval of 95-99 %. If a precision of 0.05 mm is wanted, it is necessary to collect 67...

Environmental forcing metrics to quantify short-term foredune morphodynamics

Science.gov (United States)

Spore, N.; Conery, I.; Brodie, K. L.; Palmsten, M.

2016-12-01

Coastal foredunes evolve continuously due to competing aeolian and hydrodynamic processes. Onshore to shore-parallel winds transport sand to the dune while storm-driven surge and wave runup remove sand from the dune. Dune-growth requires periods of time when the wind exceeds a threshold velocity to initiate transport and the relative geometry of the dry beach to the wind direction to create large fetches. This study aims to derive an aeolian transport potential (ATP) metric from the precipitation, available fetch (a function of wind angle and dry-beach width), and a threshold wind speed to initiate transport. ATP is then combined with a hydrodynamic transport potential (HTP) metric, defined as the number of hours of wave impact to the foredune or upper beach, to assess the time-dependent magnitude of the forcing factors affecting morphological evolution of the foredune between monthly terrestrial lidar surveys.This study focuses on two distinctly different dune fields and their frontal or incipient dune ridges in Duck, NC at the USACE Field Research Facility (FRF): (1) an undisturbed, tall and narrow recently impacted dune with a near vertical face; and (2) an undisturbed, shorter and wider dune with gentler and more hummocky slopes. The two sites are separated by dune toe position were extracted from the DEMs and compared to the ATP and HTP values between the surveys to evaluate the dominant factors affecting sediment flux to the system.

Migrations of sandy beach meiofauna

African Journals Online (AJOL)

The meiofauna at higher tide levels on a sheltered beach has been found to .... temperature of the sea water was also measured in the shallows (about 0,5 m deep). For the ... Movement was monitored over a five-hour period on the rising tide (08h30-13h30) and a ...... Distribution of sand fauna in beaches at Miami, Florida.

Hawaii Regional Sediment Management Needs Assessment

Science.gov (United States)

2014-07-01

The revet- ment has a crest elevation of +12 ft, 1–4 ton armor stone (two layers thick), ERDC/CHL TR-14-4 8 revetment toe (three stones wide...with calcareous pocket beaches and fringing reef. The Mahaulepu sub-region contains lithified sand dunes ...extensive sand dune system.1 The Polihale, Majors Bay, Oomano, and Kikiaola Shallow Draft Harbor sub- regions comprise the West Kauai region (Figure 7

Swashed away? Storm impacts on sandy beach macrofaunal communities

Science.gov (United States)

Harris, Linda; Nel, Ronel; Smale, Malcolm; Schoeman, David

2011-09-01

Storms can have a large impact on sandy shores, with powerful waves eroding large volumes of sand off the beach. Resulting damage to the physical environment has been well-studied but the ecological implications of these natural phenomena are less known. Since climate change predictions suggest an increase in storminess in the near future, understanding these ecological implications is vital if sandy shores are to be proactively managed for resilience. Here, we report on an opportunistic experiment that tests the a priori expectation that storms impact beach macrofaunal communities by modifying natural patterns of beach morphodynamics. Two sites at Sardinia Bay, South Africa, were sampled for macrofauna and physical descriptors following standard sampling methods. This sampling took place five times at three- to four-month intervals between April 2008 and August 2009. The second and last sampling events were undertaken after unusually large storms, the first of which was sufficiently large to transform one site from a sandy beach into a mixed shore for the first time in living memory. A range of univariate (linear mixed-effects models) and multivariate (e.g. non-metric multidimensional scaling, PERMANOVA) methods were employed to describe trends in the time series, and to explore the likelihood of possible explanatory mechanisms. Macrofaunal communities at the dune-backed beach (Site 2) withstood the effects of the first storm but were altered significantly by the second storm. In contrast, macrofauna communities at Site 1, where the supralittoral had been anthropogenically modified so that exchange of sediments with the beach was limited, were strongly affected by the first storm and showed little recovery over the study period. In line with predictions from ecological theory, beach morphodynamics was found to be a strong driver of temporal patterns in the macrofaunal community structure, with the storm events also identified as a significant factor, likely

Determination of uranium and thorium activity concentrations using activation analysis in beach sands from extreme south Bahia, Brazil

International Nuclear Information System (INIS)

Vasconcelos, Danilo C.; Oliveira, Arno H.; Silva, Mario R.S.; Penna, Rodrigo; Santos, Talita O.; Pereira, Claubia; Rocha, Zildete; Menezes, Maria Angela B.C.

2009-01-01

Levels of natural radioactivity are the major cause of external exposure to gamma radiation. Thus, the determination of activity concentration of primordial radionuclides, such as 238 U and 232 Th, in soils, sand and rock is of basic importance to estimate the radiation levels to which man is directly or indirectly exposed. In order to study the process of specific activity of 238 U and 232 Th, beaches sands samples were collected from eight different locations in extreme south of Bahia state from Brazil. The samples have been analyzed by instrumental neutron activation analyses and for determination of thorium concentrations and delayed neutrons analysis for determination of uranium. The mean specific activity for 238 U and 232 Th was higher in Cumuruxatiba than in others locations studied. Alcobaca and Caraiva also presented high values. The concentrations of these radionuclides were compared with typical world values and Cumuruxatiba have specific activity higher than the others locations, 2,984 Bq/kg maximum value for 238 U and 1,8450 Bq/kg maximum value for 232 Th and activity concentrations in Cumuruxatiba are higher in black sand than in no black sand, suggesting presence of monazite.(author)

Tidal flow separation at protruding beach nourishments

NARCIS (Netherlands)