677 resultados para Sands


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One map on folded leaf in pocket of Vol. 1.

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Mode of access: Internet.

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Mode of access: Internet.

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This study is aimed at determining the spatial distribution, physical properties, and groundwater conditions of the Vashon advance outwash (Qva) in the Mountlake Terrace, WA area. The Qva is correlative with the Esperance Sand, as defined at its type section; however, local variations in the Qva are not well-characterized (Mullineaux, 1965). While the Qva is a dense glacial unit with low compressibility and high frictional shear strength (Gurtowski and Boirum, 1989), the strength of this unit can be reduced when it becomes saturated (Tubbs, 1974). This can lead to caving or flowing in excavations, and on a larger scale, can lead to slope failures and mass-wasting when intersected by steep slopes. By studying the Qva, we can better predict how it will behave under certain conditions, which will be beneficial to geologists, hydrogeologists, engineers, and environmental scientists during site assessments and early phases of project planning. In this study, I use data from 27 geotechnical borings from previous field investigations and C-Tech Corporation’s EnterVol software to create three-dimensional models of the subsurface geology in the study area. These models made it possible to visualize the spatial distribution of the Qva in relation to other geologic units. I also conducted a comparative study between data from the borings and generalized published data on the spatial distribution, relative density, soil classification, grain-size distribution, moisture content, groundwater conditions, and aquifer properties of the Qva. I found that the elevation of the top of the Qva ranges from 247 to 477 ft. I found that the Qva is thickest where the modern topography is high, and is thinnest where the topography is low. The thickness of the Qva ranges from absent to 242 ft. Along the northern, east-west trending transect, the Qva thins to the east as it rises above a ridge composed of Pre- Vashon glacial deposits. Along the southern, east-west trending transect, the Qva pinches out against a ridge composed of pre-Vashon interglacial deposits. Two plausible explanations for this ridge are paleotopography and active faulting associated with the Southern Whidbey Fault Zone. Further investigations should be done using geophysical methods and the modeling methods described in this study to determine the nature of this ridge. The relative density of the Qva in the study area ranges from loose to very dense, with the loose end of the spectrum probably relating to heave in saturated sands. I found subtle correlations between density and depth. Volumetric analysis of the soil groups listed in the boring logs indicate that the Qva in the study area is composed of approximately 9.5% gravel, 89.3% sand, and 1.2% silt and clay. The natural moisture content ranges from 3.0 to 35.4% in select samples from the Qva. The moisture content appears to increase with depth and fines content. The water table in the study area ranges in elevation from 231.9 to 458 ft, based on observations and measurements recorded in the boring logs. The results from rising-head and falling-head slug tests done at a single well in the study area indicate that the geometric mean of hydraulic conductivity is 15.93 ft/d (5.62 x 10-03 cm/s), the storativity is 3.28x10-03, and the estimated transmissivity is 738.58 ft2/d in the vicinity of this observation well. At this location, there was 1.73 ft of seasonal variation in groundwater elevation between August 2014 and March 2015.

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On the morning of March 27th, 2013, a small portion of a much larger landslide complex failed on the western shoreline of central Whidbey Island, Island County, Washington. This landslide, known as the Ledgewood-Bonair Landslide (LB Landslide), mobilized as much as 150,000 cubic meters of unconsolidated glacial sediment onto the coastline of the Puget Sound (Slaughter et al., 2013, Geotechnical Engineering Services, 2013). This study aims to determine how sediment from the Ledgewood-Bonair Landslide has acted on the adjacent beaches 400 meters to the north and south, and specifically to evaluate the volume of sediment contributed by the slide to adjacent beaches, how persistent bluff-derived accretion has been on adjacent beaches, and how intertidal grain sizes changed as a result of the bluff-derived sediment, LiDAR imagery from 2013 and 2014 were differenced and compared to beach profile data and grain size photography. Volume change results indicate that of the 41,850 cubic meters of sediment eroded at the toe of the landslide, 8.9 percent was redeposited on adjacent beaches within 1 year of the landslide. Of this 8.9 percent, 6.3 percent ended up on the north beach and 2.6 percent ended up on the south beach. Because the landslide deposit was primarily sands, silts, and clays, it is reasonable to assume that the remaining 91.1 percent of the sediment eroded from the landslide toe was carried out into the waters of the Puget Sound. Over the course of the two-year study, measurable accretion is apparent up to 150 meters north and 100 meters south of the landslide complex. Profile data also suggests that the most significant elevation changes occurred within the first two and half months since the landslides occurrence. The dominant surficial grain size of the beach soon after the landslide was coarse-sand; in the years following the landslide, 150 meters north of the toe the beach sediment became finer while 100 meters south of the toe the beach sediment became coarser. Overall, the LB Landslide has affected beach profile and grain size only locally, within 150 meters of the landslide toe.

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This project investigates the correlation between contaminants and the wood waste present in marine sediments off the shore of the Port of Everett in the former Weyerhaeuser Mill-A pulp mill site. The investigation includes the results of two field studies, which tested contaminant levels in 22 boreholes as well as several surface samples. The contaminants include heavy metals and wood waste byproducts. These results, along with 14 other bore logs, provide the framework for a three-dimensional site model, interpolating the full extent of the depositional units and organic and inorganic chemicals found at Mill-A. The sediments of interest are divided into five depositional units defined by the percent wood content and type of wood: native material (<5% wood), intermediate (<30% wood), sawdust (<30% wood), woodchips (<30% wood), and poorly sorted sands with silt (SM-SP) (0% wood). The contaminants include arsenic, 2,4-dimethylphenol, and total organic carbon. Three-dimensional modeling software, RockWorks, interpolated the discrete borehole data of sediment and contaminants assuming horizontal continuity between sampling locations. The sediment distribution was calculated within concentration ranges for each contaminant of concern. The lowest detection limits, the screening levels, and the cleanup levels defined these ranges. Total organic carbon served as a proxy to estimate the quantity of wood waste in the sediment. As a known byproduct of wood decomposition, 2,4-dimethylphenol was expected to be more prevalent in the depositional units with more wood waste. Finally, arsenic was a proxy for other contaminants to determine if contaminants at Mill-A are dominant in sediments with high percentages of wood waste. The volumetric distribution established that high levels of total organic carbon are present in the sediment with higher percentages of wood waste. This correlation was stronger in the decomposing sawdust-rich sediment than the woodchip-rich sediment. The 2,4-dimethylphenol concentrations above cleanup standards were dominant in the sawdust-rich, intermediate and native sediments. Concentrations of 2,4-dimethylphenol below cleanup levels characterized the native sediment. The distribution of arsenic showed no statistically significant correlation to wood content in sediment. These results do not support the hypothesis of contaminant-rich wood waste, as many of the high concentrations of contaminants were not in the wood-rich sediments. This suggests that the contaminants are more distributed among all depositional units at Mill-A rather than focused within sediments with a high percent of wood waste. Understanding the distribution of potentially toxic compounds with wood waste is important for restoring the Puget Sound waterways to a more habitable environment. Future studies should include new data to validate these results and to limit the uncertainty of the extent of contaminants. Future studies may also find motive in looking for a correlation between contaminants and grain size based on previous studies linking these characteristics. These investigations will benefit the current cleanup effort as well as future cleanup efforts at similarly contaminated waterways.

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New data on the settling velocity of artificial sediments and natural sands at high concentrations are presented. The data are compared with a widely used semiempirical Richardson and Zaki equation (Trans. Inst. Chem. Eng. 32 (1954) 35), which gives an accurate measure of the reduction in velocity as a function of concentration and an experimentally determined empirical power n. Here, a simple method of determining n is presented using standard equations for the clear water settling velocity and the seepage flow within fixed sediment beds. The resulting values for n are compared against values derived from new and existing laboratory data for beach and filter sands. For sands, the appropriate values of n are found to differ significantly from those suggested by Richardson and Zaki for spheres, and are typically larger, corresponding to a greater reduction in settling velocity at high concentrations. For fine and medium sands at concentrations of order 0.4, the hindered settling velocity reduces to about 70% of that expected using values of n derived for spheres. At concentrations of order 0.15, the hindered settling velocity reduces to less than half of the settling velocity in clear water. These reduced settling velocities have important implications for sediment transport modelling close to, and within, sheet flow layers and in the swash zone.

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The sedimentation rate of sand grains in the hindered settling regime has been considered to assess particle shape effects. The behaviour of various particulate systems involving sand has been compared with the widely used Richardson-Zaki expression. The general form of the expression is found to hold, in as much as remaining as a suitable means to describe the hindered settling of irregular particles. The sedimentation exponent n in the Richardson-Zaki expression is found to be significantly larger for natural sand grains than for regular particles. The hindered settling effect is therefore greater, leading to lower concentration gradients than expected. The effect becomes more pronounced with increasing particle irregularity. At concentrations around 0.4, the hindered settling velocity of fine and medium natural sands reduces to about 70% of the value predicted using existing empirical expressions for n. Using appropriate expressions for the fluidization velocity and the clear water settling velocity, a simple method is discussed to evaluate the sedimentation exponent and to determine the hindered settling effect for sands of various shapes.

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Endothelial dysfunction in ischemic acute renal failure (IARF) has been attributed to both direct endothelial injury and to altered endothelial nitric oxide synthase ( eNOS) activity, with either maximal upregulation of eNOS or inhibition of eNOS by excess nitric oxide ( NO) derived from iNOS. We investigated renal endothelial dysfunction in kidneys from Sprague-Dawley rats by assessing autoregulation and endothelium-dependent vasorelaxation 24 h after unilateral ( U) or bilateral ( B) renal artery occlusion for 30 (U30, B30) or 60 min (U60, B60) and in sham-operated controls. Although renal failure was induced in all degrees of ischemia, neither endothelial dysfunction nor altered facilitation of autoregulation by 75 pM angiotensin II was detected in U30, U60, or B30 kidneys. Baseline and angiotensin II-facilitated autoregulation were impaired, methacholine EC50 was increased, and endothelium-derived hyperpolarizing factor ( EDHF) activity was preserved in B60 kidneys. Increasing angiotensin II concentration restored autoregulation and increased renal vascular resistance ( RVR) in B60 kidneys; this facilitated autoregulation, and the increase in RVR was abolished by 100 mu M furosemide. Autoregulation was enhanced by N-omega-nitro-L-arginine methyl ester. Peri-ischemic inhibition of inducible NOS ameliorated renal failure but did not prevent endothelial dysfunction or impaired autoregulation. There was no significant structural injury to the afferent arterioles with ischemia. These results suggest that tubuloglomerular feedback is preserved in IARF but that excess NO and probably EDHF produce endothelial dysfunction and antagonize autoregulation. The threshold for injury-producing, detectable endothelial dysfunction was higher than for the loss of glomerular filtration rate. Arteriolar endothelial dysfunction after prolonged IARF is predominantly functional rather than structural.

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The efficiency of numerous mineral processing operations can be determined by measuring the magnetic properties of the process streams. This measurement, if done at all, is currently performed by laboratory testing of spot samples. This is an inherently slow process and, where feed grades are variable, optimum performance is generally not achieved. This paper describes the rapid measurement of the magnetic properties of minerals. AC measurement techniques, including the analysis of the phase component of the magnetic vector; frequency dependent magnetic susceptibility and the effect of applied magnetic field strength will be discussed. Industrial applications in mineral sands, copper smelting, ferrosilicon testing and drill core scanning will be reported. (C) 2006 Elsevier Ltd. All rights reserved.

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Oxygen consumption rates (OCR), aerobic mineralization and sulfate reduction rates (SRR) were studied in the permeable carbonate reef sediments of Heron Reef, Australia. We selected 4 stations with different hydrodynamic regimes for this study. In situ oxygen penetration into the sediments was measured with an autonomous microsensor profiler. Areal OCR were quantified from the measured oxygen penetration depth and volumetric OCR. Oxygen penetration and dynamics (median penetration depths at the 4 stations ranged between 0.3 and 2.2 cm), OCR (median 57 to 196 mmol C m(-2) d(-1)), aerobic mineralization (median 24 to 176 mmol C m(-2) d(-1)) and SRR (median 9 to 42 mmol C m(-2) d(-1)) were highly variable between sites. The supply of oxygen by pore water advection was a major cause for high mineralization rates by stimulating aerobic mineralization at all sites. However, estimated bottom water filtration rates could not explain the differences in volumetric OCR and SRR between the 4 stations. This suggests that local mineralization rates are additionally controlled by factors other than current driven pore water advection, e.g. by the distribution of the benthic fauna or by local differences in labile organic carbon supply from sources such as benthic photosynthesis. Carbon mineralization rates were among the highest reported for coral reef sediments, stressing the role of these sediments in the functioning of the reef ecosystem.

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'I'he accurate rreasurement of bed shear stress has been extremely difficult due to its changing values until white propunded a theory which would give constant shear along the bed of a flume. In this investigation a flume has been designed according to White's theory and by two separate methods proven to give constant shearing force along the bed. The first method applied the Hydrogen Bubble Technique to obtain accurate values of velocity thus allowing the velocity profile to be plotted and the momentum at the various test sections to be calculated. The use of a 16 mm Beaulieu movie camera allowed the exact velocity profiles created by the hydrogen bubbles to be recorded whilst an analysing projector gave the means of calculating the exact velocities at the various test sections. Simultaneously Preston's technique of measuring skin friction using Pitot tubes was applied. Twc banks of open ended water manometer were used for recording the static and velocity head pressure drop along the flume. This tvpe of manometer eliminated air locks in the tubes and was found to be sufficiently accurate. Readings of pressure and velocity were taken for various types and diameters of bed material both natural sands and glass spheres and the results tabulated. Graphs of particle Reynolds Number against bed shear stress were plotted and gave a linear relationship which dropped off at high values of Reynolds number. It was found that bed movement occurred instantaneously along the bed of the flume once critical velocity had been reached. On completion of this test a roof curve inappropriate to the bed material was used and then the test repeated. The bed shearing stress was now no longer constant and yet bed movement started instantaneously along the bed of the flume, showing that there are more parameters than critical shear stress to bed movement. It is concluded from the two separate methods applied that the bed shear stress is constant along the bed of the flume.

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This thesis reports on the development of a technique to evaluate hydraulic conductivities in a soil (Snowcal) subject to freezing conditions. The technique draws on three distinctly different disciplines, Nuclear Physics, Soil Physics and Remote Sensing to provide a non-destructive and reliable evaluation of hydraulic conductivity throughout a freezing test. Thermal neutron radiography is used to provide information on local water/ice contents at anytime throughout the test. The experimental test rig is designed so that the soil matrix can be radiated by a neutron beam, from a nuclear reactor, to obtain radiographs. The radiographs can then be interpreted, following a process of remote sensing image enhancement, to yield information on relative water/ice contents. Interpretation of the radiographs is accommodated using image analysis equipment capable of distinguishing between 256 shades of grey. Remote sensing image enhancing techniques are then employed to develop false colour images which show the movement of water and development of ice lenses in the soil. Instrumentation is incorporated in the soil in the form of psychrometer/thermocouples, to record water potential, electrical resistance probes to enable ice and water to be differentiated on the radiographs and thermocouples to record the temperature gradient. Water content determinations are made from the enhanced images and plotted against potential measurements to provide the moisture characteristic for the soil. With relevant mathematical theory pore water distributions are obtained and combined with water content data to give hydraulic conductivities. The values for hydraulic conductivity in the saturated soil and at the frozen fringe are compared with established values for silts and silty-sands. The values are in general agreement and, with refinement, this non-destructive technique could afford useful information on a whole range of soils. The technique is of value over other methods because ice lenses are actually seen forming in the soil, supporting the accepted theories of frost action. There are economic and experimental restraints to the work which are associated with the use of a nuclear facility, however, the technique is versatile and has been applied to the study of moisture transfer in porous building materials and could be further developed into other research areas.