Fine Quartz Sand Research Articles

An evaluation of arsenic release from monolithic solids using a modified semi-dynamic leaching test

Quicklime and quicklime–fly ash-based stabilization/solidification (S/S) effectiveness was evaluated by performing semi-dynamic leaching tests (American Nuclear Society 16.1). Artificial soil samples, contaminated with arsenic trioxide (As 2O 3) as well as field soil samples contaminated with arsenic (As) were tested. The artificial soils were prepared by mixing amounts of kaolinite or montmorillonite with fine quartz sand. The S/S effectiveness was evaluated by measuring effective diffusion coefficients ( D e) and leachability indices (LX). Treatment was most effective in kaolinite-based artificial soils treated with quicklime and in quicklime–fly ash treated field soils. The experimental results indicate that D e values were lowered as a result of S/S treatment. Upon treatment LX values were higher than 9, suggesting that S/S treated soils are acceptable for “controlled utilization”. Based on a model developed by de Groot and van der Sloot [G.J. de Groot, H.A. van der Sloot, in: T.M. Gilliam, C.C. Wiles (Eds.), Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes, vol. 2, ASTM STP 1123, ASTM, PA, 1992, p. 149], the leaching mechanism for all of the treated soils was found to be controlled by diffusion. The effect of soluble silica (Si) on As leachability was also evaluated. When soluble Si concentration was less than 1 ppm, As leachability was the lowest. The controlling mechanism of As immobilization whether sorption, precipitation, or inclusion was also evaluated. It was determined that precipitation was the dominant mechanism.

Diapause and emergence of Sitodiplosis mosellana (Diptera: Cecidomyiidae) and its parasitoid Macroglenes penetrans (Hymenoptera: Pteromalidae)

AbstractThe requirements for successful diapause of field-collected larvae and emergence of the adult wheat midge, Sitodiplosis mosellana (Géhin), and its egg parasitoid Macroglenes penetrans (Kirby) were investigated in the laboratory. Both species showed little decline in survival for up to 5 weeks at 20 °C in dry wheat spikes and could successfully diapause in wheat spikes at 0 °C for at least 200 d, although larvae usually drop to the soil to diapause. Both species diapaused successfully in clay loam and fine quartz sand, but survival was lower in vermiculite or coarse activated clay. Diapause was completed successfully at soil temperatures of −5 to 2.5 °C, and both species survived for at least 500 d at 2.5 °C with no increase in mortality. Larval survival declined after 120 d at −10 °C. Usually more than 95% of all surviving wheat midges emerged as adults after a single diapause period of 100 d or more, but up to 5% of wheat midges and 12%−57% of parasitoids did not emerge until they were exposed to a second cold period. Postdiapausal larvae pupated and adult wheat midges emerged at constant temperatures of 16, 20, 26, and 28 °C with no differences in mortality, although none emerged at 10 °C. The timing of wheat midge emergence was temperature dependent, requiring 306 degree-days above a threshold of 9 °C. Degree-day requirements and soil temperatures from a nearby weather station accurately predicted the average timing of emergence in the field, but not the year-to-year variation in date of 50% emergence. The wheat midge and its parasitoid are well adapted to the conditions they encounter in their range in western Canada. Methods for rearing both species through diapause and adult emergence are described.

Comparison of different chamber techniques for measuring soil CO 2 efflux

Twenty chambers for measurement of soil CO 2 efflux were compared against known CO 2 fluxes ranging from 0.32 to 10.01 μmol CO 2 m −2 s −1 and generated by a specially developed calibration tank. Chambers were tested on fine and coarse homogeneous quartz sand with particle sizes of 0.05–0.2 and 0.6 mm, respectively. The effect of soil moisture on chamber measurements was tested by wetting the fine quartz sand to about 25% volumetric water content. Non-steady-state through-flow chambers either underestimated or overestimated fluxes from −21 to +33% depending on the type of chamber and the method of mixing air within the chamber’s headspace. However, when results of all systems tested were averaged, fluxes were within 4% of references. Non-steady-state non-through-flow chambers underestimated or overestimated fluxes from –35 to +6%. On average, the underestimation was about 13–14% on fine sand and 4% on coarse sand. When the length of the measurement period was increased, the underestimation increased due to the rising concentration within the chamber headspace, which reduced the diffusion gradient within the soil. Steady-state through-flow chambers worked almost equally well in all sand types used in this study. They overestimated the fluxes on average by 2–4%. Overall, the reliability of the chambers was not related to the measurement principle per se. Even the same chambers, with different collar designs, showed highly variable results. The mixing of air within the chamber can be a major source of error. Excessive turbulence inside the chamber can cause mass flow of CO 2 from the soil into the chamber. The chamber headspace concentration also affects the flux by altering the concentration gradient between the soil and the chamber.

Patterns and controls of surface sediment distribution: west-central Florida inner shelf

The west-central Florida inner shelf represents a transition between the quartz-dominated barrier-island system and the carbonate-dominated mid-outer shelf. Surface sediments exhibit a complex distribution pattern that can be attributed to multiple sediment sources and the ineffectiveness of physical processes for large-scale sediment redistribution. The west Florida shelf is the submerged extension of the Florida carbonate platform, consisting of a limestone karst surface veneered with a thin unconsolidated sediment cover. A total of 498 surface sediment samples were collected on the inner shelf and analyzed for texture and composition. Results show that sediment consists of a combination of fine quartz sand and coarse, biogenic carbonate sand and gravel, with variable but subordinate amounts of black, phosphorite-rich sand. The carbonate component consists primarily of molluskan fragments. The distribution is patchy and discontinuous with no discernible pattern, and the transition between sediment types is generally abrupt. Quartz-rich sediment dominates the inner 15 km north of the entrance into Tampa Bay, but south of the Bay is common only along the inner 3 km. Elsewhere, carbonate-rich sediment is the predominate sediment type, except where there is little sediment cover, in which cases black, phosphorite-rich sand dominates. Sediment sources are likely within, or around the periphery of the basin. Fine quartz sand is likely reworked from coastal units deposited during Pleistocene sea-level high stands. Carbonate sand and gravel is produced by marine organisms within the depositional basin. The black, phosphorite-rich sand likely originates from the bioerosion and reworking of the underlying strata that irregularly crop out within the study area. The distribution pattern contains elements of both storm- and tide-dominated siliciclastic shelves, but it is dictated primarily by the sediment source, similar to some carbonate systems. Other systems with similar sediment attributes include cool-water carbonate, sediment-starved, and mixed carbonate/siliciclastic systems. This study suggests a possible genetic link among the three systems.

The morphology and migration of transverse bars off the west-central Florida coast

A series of migrating shore-normal sandbars with wavelengths of 75–120 m and heights up to 2 m have been identified off the northern tip of Anna Maria Island, a barrier island on the west-central Florida coast. Similar features have been described elsewhere since the 1930s and termed ‘transverse bars’. The transverse bars identified off Anna Maria Island are found for about 3 km along the coast and extend 4 km offshore, well outside the normal surf-zone width. No cusps or any other associated beach expression is evident despite the fact that the bars come to within about 75 m of the beach. Sediments on the crests of the bars are a well-sorted fine quartz sand, whereas sediments in the troughs are a poorly sorted coarse carbonate shell hash. Historical aerial photographs and repeated high-resolution bathymetric surveys provide a means of quantifying the migration of the transverse bars. Analyses of orthorectified aerial photographs from the early 1940s through the mid 1990s clearly show movement or migration taking place in the bar field. In the 40-yr period from 1951 to 1991, the southern edge of the bar field moved 200–350 m to the south, with an average long-term migration rate of 8 m/yr. Repeated bathymetric surveys over an 8-month period give an average short-term migration rate of 21 m/yr to the south. Wave and current measurements suggest that southerly winds associated with the passage of cold fronts drive near-bed currents to the south that are strong enough to initiate sediment transport and cause the southerly migration of the transverse bars.

Stratigraphic models for microtidal tidal deltas; examples from the Florida Gulf coast

Extensive vibracoring of both flood- and ebb-tidal deltas along the central Gulf Coast of the Florida peninsula reveals a strong overall similarity with subtle distinctions between flood and ebb varieties. Although the coast in question is microtidal, the inlets range from tide-dominated to distinctly wave-dominated. Both types of tidal deltas overlie a muddy sand interpreted to have been deposited in a back-barrier environment. The sharp contact at the base of the tidal delta sequence is typically overlain by a thin shell gravel layer. The ebb-tidal delta sequence is characterized by fine quartz sand with shell gravel in various concentrations; coarse and massive at the margins of the main ebb channel, and finer and imbricated at the marginal flood channels. The flood-tidal deltas are characterized by the same facies but with a small amount of mud. Shelly facies on the channels on flood deltas are not as well developed as on the ebb deltas. The combination of the stratigraphic sequence and the lithofacies make tidal deltas readily identifiable in the ancient record. The differences between flood and ebb varieties are subtle but consistent.

Soil Water Retention and Conductivity When Vapor Flow Is Important

Models of soil water transport often calculate conductivity K from the water retention curve ~WRC!. Residual water content (u r) has been defined asu where K50. When nonisothermal, coupled vapor and liquid water transport are considered, u r.0 fails because vapor transport often reduces u to near zero. The author's objective was to test a model that used unsaturated K(u) with u dependence typical of u r.0, while a WRC with u r50 was used elsewhere in the model. The system was a closed column of steady state, unsaturated, nonisothermal fine quartz sand with temperature ~T! ranging from 5 to 40°C. Soil parameters were adjusted to simulate replicated experimental data from one initial u condition. The model predicted u and T within the range of the experimental data and reproduced the sharp drying front. It also satisfactorily modeled experiments with several different initial u. Model heat flux predictions averaged 11% more than measured values. Experiments performed with two soil column lengths were not substantially different.

Transport and retention of clay particles in saturated porous media. Influence of ionic strength and pore velocity

The aim of this work was to experimentally evaluate the role of ionic strength and pore velocity on clay suspension transport and retention through a saturated porous medium. A smectite suspension was injected into columns filled with a very fine quartz sand. Experiments were carried out at constant pore velocity with increasing ionic strength adjusted with a divalent electrolyte (CaCl 2) and at constant ionic strength (using three chemical conditions) with decreasing pore velocity. Typical colloid breakthrough curves show two important behaviors: a constant outlet concentration value after a transient phase, and a pronounced tailing effect at the end of the injection step. No differences were observed between the mean travel time of a solute tracer and that of the clay suspension. The classical advection–dispersion equation coupled with a first-order two-site kinetics model was used to reproduce the experimental breakthrough curves. The kinetic model consisted in a site with irreversible deposition and a reversible site used to reproduce the transient phase preceding the plateau of the experimental breakthrough curves. The particle fraction kept by the porous medium increases with ionic strength; consequently the kinetic parameters of the numerical model vary with chemistry. The irreversible sorption rate ( K irr: equivalent to a clean-bed filter coefficient) increases with ionic strength and was directly determined from experimental data. With increasing ionic strength, the deposition rate ( K d) for the reversible sorption increases whereas the release rate ( K r) decreases. The kinetic parameters of the reversible site show an evolution with pore velocity similar to that observed in kinetics model used for modeling solute transport in double porosity media. With decreasing pore velocities, the retention of clay particles increases but the kinetic deposition coefficient of the irreversible site decreases. Particle deposition can also be described and reinterpreted in terms of collector efficiency using the concept of the sphere-in-cell model. The collector efficiency, which adds a correction to the kinetic parameter with the residence time, is a more consistent way to represent particle retention. Its value increases with increasing ionic strength and decreasing pore velocity.

Siliciclastic Facies Belt Formation and the Late Oligocene to Middle Miocene Partial Drowning of the Southern Florida Platform

ABSTRACT A series of siliciclastic shoreline deposits began to prograde onto the southern Florida Platform during deposition of the early Oligocene-age Suwannee Limestone. These sediments were fine to very fine quartz sands deposited in belts parallel to the margin of the platform. The influx and mixing of these siliciclastic sediments did not affect the continued deposition of carbonate sediments on the platform because the sediments did not contain significant quantities of mud. Major siliciclastic sediment influxes occurred during minor regressive, eustatic sea level events affecting primarily the platform margins. Beginning in late Oligocene time, the frequency and volume of siliciclastic sediment influx onto the southern Florida Platform began to cause the drowning of the eastern margin of the platform. The eastern margin of the platform receded from the current geographic margin position westward a distance of about 65 miles. In the central part of the platform about 600 ft of mixed carbonate and siliciclastic sediment was deposited from the late Oligocene to the middle Miocene (Chattian to Serravallian) compared to a maximum of about 65 ft on the eastern margin. Subsequent influx of predominantly siliciclastic sediment with some carbonates in the late Miocene and early Pliocene terminated the growth of the platform and infilled the drowned part of the platform to produce the approximate geometry observed today.

Evolution of Sand Microstructure during Shear

Quantitative measurements of the local void ratio distribution are used to demonstrate how the microstructure throughout dilatant triaxial specimens of uniform fine quartz sand evolves during drained axial compression loading. Shear-induced increases in the mean of the local void ratio distribution initiate at the center of the specimen and migrate toward the ends of the specimen as axial strain increases. At any given strain, the mean of the local void ratio distribution is largest near the center of the specimen, reflecting the influence of end platen and membrane restraining effects. The results provide direct quantitative microstructure-based evidence that global or macro response, as conventionally used in interpreting specimen behavior, can be misleading as to the true material response. Implications of the test results on practical issues such as the location of local strain measurement systems are noted.

Spatial heterogeneity of acoustic bottom backscattering model parameters and predicted results

Sediment geoacoustic and roughness measurements were made during a mine burial experiment in the North Sea in November 1997. The experiment site was a sand ridge (20.5–32-m water depth) influenced by strong tidal currents and wave action. Stereo photographs indicated that the sediment roughness was characterized by cross-rippled fine sand that transitioned to straight- and sinuous-rippled mixtures of fine quartz sand and mollusk shell fragments. Box core samples were subsampled with core tubes from which measurements of sediment compressional wave velocity and attenuation, density, and grain size distribution were made. Values for sediment velocity ratio, density ratio, slope of the roughness power spectrum, roughness spectral strength, and other measured and calculated parameters were used as input parameters for the composite roughness model to predict bottom backscattering strengths from various regions within the experiment site. Horizontal and vertical variability in sediment properties is high relative to other shallow sites under the influence of strong hydrodynamic forcing. There is a marked interdependence among sediment geoacoustic properties, water depth and bottom roughness features. The influence of hydrodynamic conditions and sediment type on the acoustic model predictions is demonstrated by the spatial variability in predicted scattering of high-frequency sound from the site.

Small-scale laboratory flowslides

Loose cohesionless slopes are susceptible to liquefaction and subsequent flowsliding. Small scale sub-aerial laboratory flowslides have been obtained by inducing the collapse of loose deposits of saturated fine quartz sand. Failure mechanisms resembled field cases and other laboratory experiments. A detailed set of results is presented, illustrating the temporal and longitudinal variation of both surface velocity and the elevations of flowing and static material. Initially, the flowside accelerated under the influence of gravity. Movement was not arrested ‘en masse’, but unsteady deposition of sand and pore fluid occurred, being dependent on deceleration of the flowslide that propagated downstream. As a result, the slope over which the flowing material was moving increased with time. Excess pore water pressures were measured during flowslide motion, the magnitudes of which were reasonably predicted using the Coulomb failure criterion and assuming equilibrium of driving and resisting forces. This was despite the observance of unsteady flow and the limitations of experimental measurement.

Measurement of the radioactivity of238U,232Th,226Ra,137Cs and40K in soil using direct Ge(Li) γ-ray spectrometry

Radioactivity of the nuclides238U(235U),232Th,226Ra,137Cs and40K was measured in soil by direct γ-ray spectrometry using Ge(Li) detector. Relative laboratory method was used. Soil was dired, powdered, sieved and put into hemetically sealed container. CCRMP certified reference materials and compounds of the above nuclides mixed with fine quartz sand were used as references. Five and four γ-lines were used for the determination of232Th and226Ra, respectively, to obtain more accurate results. The most significant interferences, caused by the limited energy resolution of the detector, were resolved. In the case of ordinary soils, using one day duration of measurement and 1 kg mass of soil,232Th,226Ra and40K can be determined with less than 10% relative random error. Elevated concentrations of238U(235U) and226Ra were observed in soil samples collected around a coal-fired power plant in Ajka town, Hungary.

Sedimentation and pedogenesis in a Central Amazonian Black water basin

Sedimentation rates were estimated in a Central Amazonian Black-water inundation forest. Sediment deposition on the forest ground, remote from the river bed, during an annual flood period, is of the order of 1 to 10 tons per hectare, depending on water depth and duration of flooding. The sediments consisted of fine organic matter, kaolinite, quartz sands and biogenic particles of silica. Their genesis and deposition depend on the interplay between pedogenic, limnological and biological processes. Sediments derive primarily from the materials leached from the soils. Clay soils are the main source of dissolved silica, and the sandy soils are the main sources of organic coumpounds and mineral particles. The physical sedimentation of particles as quartz sand grains only occurs in the upper reaches of the studied river. In the flood plain, the sedimentation is due to the coagulation and deposition of combined mineral particles and humic substances, and to the biological precipitation of the silica leached from the soil by sponges.

Analysis of fading characteristics of quartz sand as a dosimeter and in irradiation identification applications

Fading characteristics of the thermoluminescent (TL) signal from laboratory fine quartz sand was studied in the temperature range from ambient to 150 °C. Glow curves were unfolded by an iterative, non-linear regression of superimposed Gaussian distributions. The activation energy for the fading of the first peak was estimated at 6 kJ/mol; the temperature range studied was not sufficient to estimate activation energies of the other two peaks. These peaks appearing at higher glow-curve temperatures are relatively stable during prior storage at room temperature (for several weeks) and are suitable for dosimetric purposes as well as for certain identification applications.

An Investigation of Saturation‐Capillary Pressure Relations in Two‐ and Three‐Fluid Systems for Several NAPLS in Different Porous Media

AbstractLack of constitutive data has impeded efforts to model the subsurface transport of organic‐liquid contaminants. To help fill this need, functional relationships between fluid saturations and capillary pressures were obtained using a unique fluid‐retention cell. The functional relationships between water saturations and NAPL‐water capillary pressures, and between total‐liquid saturations and air‐NAPL capillary presures in two‐ and three‐fluid phase systems were measured directly during monotonic drainage of a fine quartz sand and a nonswelling loam soil. Additionally, measurements were made between water saturations and air‐water capillary pressures for an air‐water fluid system in both porous media. The NAPLs investigated were Soltrol 170®, toluene, and trichloroethylene (TCE). Following the measurements, the two‐ and three‐fluid retention relations were compared to test the validity of extending two‐phase saturation‐pressure (S‐P) relations to three‐fluid systems. Good agreement was observed between the two‐ and three‐fluid data for Soltrol 170®, toluene, and TCE in both porous media. An S‐P scaling format for two‐ and three‐phase systems was also evaluated. Results indicate that a single multiphase retention function is suitable for describing two‐ and three‐phase S‐P relations in similar porous media; however, it is unclear whether the scaling factors can be predicted a priori from ratios of interfacial tensions.

Archeological and Geomorphological Investigations at Prehistoric Sites 41WY50 and 41WY60, Willacy County, Texas

In January through March 1993, archeological and geomorphological investigations were conducted at two clay dune sites, 41WY50 and 41WY60, in the outfall area of the Hidalgo-Willacy Drainage Ditch system. This work represents the final investigations of a cultural resource management program conducted for the U.S. Army Corps of Engineers and the local sponsors, Hidalgo County Drainage District No. 1 and Willacy County Drainage District No. I, by Prewitt and Associates, Inc. The results of the archeological investigations were poor. Neither site yielded materials of unquestionable cultural origin, although several small basin-shaped hearth features were encountered. Based on radiocarbon assays from soil humates and the stratigraphic provenience of the features, it is speculated that the occupation(s) at 41WY50 is late Archaic and the occupation(s) at 41WY60 is Late Prehistoric to Historic. Both sites represent very short term occupations and most likely do not represent repetitive use on a seasonal or yearly basis. These investigations suggest that, since the development of the modem coastal environments approximately 3,000 to 4,000 years ago, the south Texas coast between Baffin Bay and the Holocene delta of the Rio Grande has been a resource-poor and inhospitable area that probably was utilized only sparsely or intermittently. The geomorphological investigations were more successful, adding valuable data ahout paleoenvironments and the formation of the modem coastal environments of the Lower Rio Grande Valley. The clay dunes formed through the eolian transport of fine to very fine quartz sand and fine to very fine sand-sized aggregates of clay from adjacent wind-tidal flats during the late Holocene. Stable carbon isotope studies of soil humates suggest that the clay dune plant community was and still is dominated by C, and/or CAM plants. These investigations also disclosed fluctuations in sea level during the late Holocene. An abandoned wind-tidal flat, encountered at 41WY50, indicates that sea level was at least I m higher than present mean sea level between 2300-1100 B.P.

In Situ Electromigration as a Method for Removing Sulfate, Metals, and Other Contaminants from Ground Water

AbstractElectromigration is proposed as an in situ method for preconcentrating contaminants in ground water prior to pumping and treating. In earlier investigations by the senior author and co‐workers, it was found that Cu in synthetic ground water migrated strongly to a Pt cathode and plated out as metallic copper. In the present study, carbon electrodes were inserted into a laboratory column of fine quartz sand that was saturated with a lower concentration of CuSO4 solution. A fixed potential of 2.5 V was applied, causing dissolved Cu and SO4 to accumulate strongly at the cathode and anode, respectively. Only minor plating‐out of Cu took place on the carbon electrodes. In addition to the use of carbon electrodes, the present research also investigated the effects of a lower concentration of metal, accumulation of SO4 adjacent to the anodes, adsorption of Cu on the sand, and competition by moving ground water.At an imposed voltage of 2.5 V and in the presence of 65 mg/L of dissolved Cu and 96 mg/L of SO4 (0.001 M CuSO4 solution), electrolysis of water caused large changes in the pH and speciation of the aqueous components, as well as precipitation of solid Cu‐hydroxides. Significant retardation of Cu occurred in the presence of ground water flowing at an average intergranular velocity of 0.2 m/day, but only minor retardation at water velocities of 1.9 and 2.9 m/day.Sulfate tends to migrate strongly to the anodes, suggesting that in situ electromigration may offer a useful new method for preconcentrating such highly soluble ions as SO4, NO3, and CI that are difficult to remove by conventional pump‐and‐treat methods. A number of potential problems exist that should be addressed in a field test.

Siliciclastic-to-carbonate transition on the inner shelf embayment, southwest Florida

The inner shelf embayment adjacent to southwest Florida is a low energy system which displays a distinct and demonstrable transition from dominantly siliciclastic sediments in the north to virtually pure biogenic carbonates in the south. Sediment sources are littoral transport from the north, autochthonous biogenic debris, a modest input from land-derived runoff and a small amount from reworking of older strata. Siliciclastic sediments are well-sorted, fine quartz sand and terrigenous and biogenic mud which is concentrated along the coast of the southern half of the 90 km coast where it accumulates from adjacent terrigenous sources. Biogenic carbonate ranges from mud to gravel in size and is dominated by sand and gravel. The transition zone between the siliciclastic and carbonate sediments covers only about 10 km and trends NNW-SSE with a south-extending lobe of siliciclastic material along the coast. This detailed documentation of regional change in sediment texture and composition along with the geographic distribution provides data for application to the stratigraphic record. Such siliciclastic-carbonate transitions are quite important for example in the Cambro-Ordovician of the Upper Mississippi Valley and the Cretaceous of Central Texas.

Effects of bacterial exopolymer adhesion on the entrainment of sand

Abstract Flow velocity required to erode a bed of acid‐washed sand is increased by intergranular adhesion resulting from growth of the benthic marine bacterium Al‐teromonas atlantica. In general, we find that either pure exopolymer alone or exopolymer generated during in situ growth increases erosion resistance of fine quartz sand. Moreover, the degree of erosion resistance increases in proportion to the concentration of exopolymer‐component uronic acids, which in turn is dependent on relative nitrogen content of peptone‐based growth media. Specifically, we observe that approximately 100 nmol of exopolymer or 1.5 nmol of component uronic acids generated by in situ bacterial growth under nitrogen‐rich conditions per gram of dry sediment can effectively double seawater‐flume flow velocity required for initiation of transport of otherwise noncohesive, 125–177 μm quartz grains. This maximal effect corresponds to an estimated adhesive force that exceeds submerged particle weight by an order of magnitude and ex...