Percentage Of Sand Particles Research Articles

Wind Tunnel Test of Sand Particle Size Distribution along Height in Blown Sand

In aeolian sand movement, the vertical distribution of sand particle size is intricately linked to sand flux, wind–sand flow field and dune development. In the present study, the distribution characteristics of sand grains in four particle size ranges at nine heights were investigated through sand blowing tests at five different reference wind speeds. The correlation between sand particle size and wind speed indicates that when the particle size was ≥0.35 mm, there was a linear variation of mass percentage with wind speed. When the particle size was <0.35 mm, when Z ≤ 0.15 m, a linear variation of mass percentage with wind speed was found; when Z > 0.15 m, an exponential modification in mass percentage with wind velocity was observed for sand grains falling within this specific range of particle sizes. The correlation between sand particle size and height indicates that when the reference wind speed was ≥15 m/s, the mass percentage of sand particles varied linearly with height. When the reference wind speed was ≤13.5 m/s, the mass percentage of sand grains with particle size in the 0.25–0.35 mm range increases first and then decreases with increasing height. The present results can provide a reference for subsequent research on the aerodynamic characteristics of wind–sand flow fields and on the mechanism of dune formation.

Physicochemical characteristics of sediment from odeama creek of the Niger Delta area of Nigeria

The coastal environment of the Niger Delta sub-region of Nigeria has been degraded over the years as a result of anthropogenic activity, particularly oil exploration and exploitation. This study is carried out to investigate if there are human influences on the quality of sediment in Odeama creek. Water samples were obtained from 20 sampling points and four control points during wet and dry season. The samples were analyzed using standard methods and procedures. The physical and chemical parameters analyzed showed no statistical difference (p> 0.05) at 95% confidence limit between sampling points except copper, which was statistically significant (p < 0.05) at 95% confidence interval during the wet season. The particle size analyses are in the order: sand > clay > silt. The percentage composition observed ranged from 52. 90 – 73. 20%, 15.60 – 33.20%, 5.50 - 19.0% for (sand, clay and silt respectively) and 70.6 –83.40%, 5.40 – 13.80%, 9.30 – 19.90% for (sand, clay and silt respectively); pH range of 2.80 – 5.10 and 4.30 – 6.70; TOC, 0.34 – 1.35mg/kg and 0.78 – 3.03 mg/kg; THC, 0.69 – 4.68mg/kg and 0.88 – 106.14 mg/kg; PAH, 0.00 – 3.54 mg/kg and 0.57 – 72.55mg/kg; chloride, 444.86 – 804.50 mg/kg and 924.71 – 1624mg/kg; Iron, 39.31 – 1171 mg/kg and 24.16 – 166.27 mg/kg; Zn, 1.04 – 30.98 mg/kg and 3.44 – 23.14 mg/kg, Cr, 0.01 –0.22 mg/kg and 0.002 – 0.04mg/kg; Pb, 0.00 – 0.06 mg/kg and 0.28-2.16 mg/kg during the wet and dry season respectively. The high values of PAH, THC, Iron, zinc, sulphate, chloride and sodium could be attributable to anthropogenic influence from illegal bunkering, oil spillage and runoff from surrounding farmlands. Low TOC and heavy metals with the exception of Iron; is an indication that most of the heavy metals and organic compounds produced from the observed anthropogenic influence in the study area may be dissolved more in the water column due to high percentage of sand particles in the study area. The level of PAH and THC observed could be detrimental to aquatic life and humans. Environmental monitoring of anthropogenic activities should therefore be conducted to curtail the adverse effect of the exceedances observed in this study.

Simulating Soil Water Status of Irrigated Fields: The Effects of Soil Data and Root Water Uptake Distribution

<b>Highlights</b> <list list-type=bullet><list-item> The effects of variability in two key inputs to irrigation scheduling models were investigated. </list-item><list-item> Commonly used soil textural data underestimated sand particles, resulting in larger errors in simulated water content. </list-item><list-item> Sensor-based root water uptake distribution led to better model performance than constant and linear patterns. </list-item><list-item> Irrigation timing and amount variables were more impacted by variability in soil data than water uptake distributions. </list-item></list> <b>Abstract</b>. With recent advances in web-based irrigation scheduling tools and mobile applications and the possibility of using more complex modeling approaches, it is important to evaluate the effects of variable input data on the output of these tools and models. Two types of input data that are highly variable across irrigated fields and soil profiles are soil textural data and root water uptake distribution (RWUD). In this study, root zone soil textural data from two sources of commonly used, freely available web soil survey (WSS) and time-consuming, labor-intensive in-situ sampling (ISS) were used in combination with three RWUDs (constant, linear, and sensor-based) to simulate volumetric water content (θv) at four soil layers in six irrigated fields, using the HYDRUS model. The percentage of sand particles based on WSS was about half of the measured amount on average, resulting in a considerable difference in estimated hydraulic properties and soil water thresholds. Sensor data revealed that RWUDs were highly nonuniform, with more than 60% of water extraction occurring from the top 30 cm of the root zone. Among the six combinations of two sources of soil data and three RWUDs, ISS-sensor resulted in the smallest errors in simulated θv, and WSS-constant yielded the largest errors. Simulated θv data were translated to actionable end-user variables of irrigation trigger (IT) and soil water depletion (SWD), which determine the timing and the amount of irrigation applications, respectively. Relying on WSS resulted in irrigation trigger being called about four times more than when measured soil data were used. The average SWD based on WSS was 157 mm, about two times larger than the average SWD based on ISS (68 mm).

Evaluation of Land Capability for Housing Deveopment at Nachi Built Environment, Enugu State, Nigeria

There are criteria that certify the sustainable potentials of any built environment. Low income housing scheme proposed by Enugu state government for its workers is targeted at Nachi, Udi local government area in Enugu state, Nigeria. To assess the capability of this location for the project, site investigation and experimental design methods were adopted to measure the geo-morphological and hydrologic features and conduct laboratory tests on the basic and strength properties of the formation respectively. Findings explain that Nachi lies on the slope of 700; hence the average runoff is high. Prolific confined aquifer result to underground water potential for consumption since the formation is porous with high elevation at 221 meters. It is also discovered that the area possesses low shear strength which is capable of resisting the high shear stress measured in the soil sample of the formation. Soil plasticity is measured as 10 indicating high erodible potential. The particle size distribution of the formation is poorly sorted with high percentage of sand particles, and very low percentage of gravel, with intercalation of compressible particles in the formation. The rain intensity is measured high with very high rate of runoff potential that is capable of causing erosion on the sloppy terrain with low bearing strength. The study therefore concludes that Nachi as a proposed site for the low housing scheme is not suitable considering the fact that the initial cost involved in preparing standard foundation of the buildings and the surrounding for sustainable housing will make it exorbitant for the low income earners. Any effort to compromise doing the right things from the beginning for a sustainable housing will degenerate the housing to high maintenance culture when in use. In the absence of no other available land the study therefore recommends that edicts and official programmes be enacted and instituted respectively to curb down erosion menace in the area with standard foundation designs that will guarantee safety to the buildings effectively in the area. If the housing scheme must stand for the low income earners the government must as matter of policy subsidize the cost of the houses reasonably such that the workers in the state can easily afford them.

Experimental studies on curling development of artificial soils

Abstract Soil curling is an important phenomenon associated with volume changes induced by increasing soil suction upon desiccation. The study of soil behaviors associated with drying in soils (e.g. soil shrinkage, desiccation cracks and curling) has received increasing attention over the last few years, which has been mainly driven by the forecast climate change that will warm up our planet. There are significant gaps in the current knowledge related to the factors that control the development of curling deformations in soils. For this, the curling phenomenon is investigated through laboratory desiccation tests on different mixtures of artificial soils. The effects of soil grain size distribution, mineralogy, soil microstructure, and soil water content on the curling deformation are analyzed. Digital photos were taken at regular time intervals during the tests to understand the volume changes in the soil samples during drying. It is found that soil fabric and soil water content have significant effects on curling scenario. It is observed that the percentage of sand particles and the initial water content play a critical role in the development of soil curling. Samples of pure clayey minerals experienced shrinkage without or with minor curling during drying.

The effects of the reverse seasonal flooding on soil texture within the hydro-fluctuation belt in the Three Gorges reservoir, China

PurposeThe formation of the large hydro-fluctuation belt at the altitude of 145–175 m, following the construction of the Three Gorges Dam, developed from the terrestrial system in the Three Gorges reservoir. This research mainly concerned the effects of the resultant reverse seasonal flooding on soil texture.Materials and methodsFour field experimental plots were designed with sample belts and quadrats at the head, middle, and tail sections of the reservoir area. Stratified soil samples were collected, followed by analysis of soil structure and soil grain size of the collected samples.Results and discussionThe reverse seasonal flooding significantly changes texture and nutrient of riparian soil. The percentages of silt and clay formations were greatest at the lower hydro-fluctuation belt, followed by the middle and upper hydro-fluctuation belt, respectively. The percentage of silt and clay particles at 150 m was greater than that of 170 m by 18.12%. Conversely, the percentage of sand particles at the upper hydro-fluctuation belt ranked the highest, and followed by the middle and lower hydro-fluctuation belt, respectively. The percentage of sand particles at 170 m was higher than that at 150 m by 19.72%. Soil texture type changed with increasing altitude gradient, from silt loam, loam, then to sandy loam. Reverse seasonal flooding also promotes silt and clay permeation, and deposition from surface soil to subsurface soil, increasing homogeneity in grain structure between soil layers. This change in soil texture is associated with changes in soil nutrients. The content of soil organic matter, total nitrogen, total phosphorus, and total potassium varied significantly among soil texture types, with loam having the highest soil nutrient concentration and sandy loam having the lowest.ConclusionsThe reverse seasonal flooding promotes the deposition of clay and silt within the hydro-fluctuation belt, inducing the total texture change of loam to silt loam. However, the structures and attributes of soil texture varied along the altitude gradient, as the exposed and submersed season and time span of riparian soil changed with the increase of altitude.

Current status and historical variations of phthalate ester (PAE) contamination in the sediments from a large Chinese lake (Lake Chaohu).

The residual levels of phthalate esters (PAEs) in the surface and two core sediments from Lake Chaohu were measured with a gas chromatograph-mass spectrometer (GC-MS). The temporal-spatial distributions, compositions of PAEs, and their effecting factors were investigated. The results indicated that di-n-butyl phthalate (DnBP), diisobutyl phthalate (DIBP), and di(2-ethylhexyl) phthalate (DEHP) were three dominant PAE components in both the surface and core sediments. The residual level of total detected PAEs (∑PAEs) in the surface sediments (2.146 ± 2.255μg/g dw) was lower than that in the western core sediments (10.615 ± 9.733μg/g) and in the eastern core sediments (5.109 ± 4.741μg/g). The average content of ∑PAEs in the surface sediments from the inflow rivers (4.128 ± 1.738μg/g dw) was an order of magnitude higher than those from the lake (0.323 ± 0.093μg/g dw), and there were similar PAE compositions between the lake and inflow rivers. This finding means that there were important effects of PAE input from the inflow rivers on the compositions and distributions of PAEs in the surface sediments. An increasing trend was found for the residual levels of ΣPAEs, DnBP, and DIBP from the bottom to the surface in both the western and eastern core sediments. Increasing PAE usage with the population growth, urbanization, and industrial and agricultural development in Lake Chaohu watershed would result in the increasing production of PAEs and their resulting presence in the sediments. The significant positive relationships were also found between the PAE contents and the percentage of sand particles, as well as TOC contents in the sediment cores.

Soil Surface and Leave Plantain (Platanus Orientalis)Contamination to Pb and Cd Mapping in Rasht City

Any change in the characteristics of air, soil, water and food that adversely affect the health of the ecosystem, activities of human and other organismsis called contamination. Heavy metal uptake by plants depends on the type and concentration of metalin soil, its bioavailability, and plant species. The use of new sciences such as geostatistics is useful for fast and simple determination of soil and leaf contamination risk. This study studied the amount of soil and leaves of Platanus orientalis contamination in order to map the lead (Pb) and cadmium (Cd) concentration in Rasht city using a geostatistic method. To achieve the goal, 126 samples of surface soil (0-30 cm) and 76 leaf samples (Platanus orientalis) were collected from city streets. Total concentrations of lead and cadmium in the soils and leaves were determined, and clay, silt and sand particle percentage, organic matters, and soil pH were measured. Average concentrations of elements in terms of mg/kg were as follows: soil’s Lead: 86.62, soil’s Cadmium: 0.6, leaf’s Lead: 8.99. For soil Pb and Cd and leaf Pb, spherical model yielded a better fit in the experimental variogram in GS program by using trial and error method. According to the spatial structure, Kriging and IDW estimators were used for interpolation. Kriging estimation was mapped using Arc GIS 9.2 software.

Laboratory Experiments on Phosphorous Release from the Sediments of 9 Lakes in the Middle and Lower Reaches of Yangtze River Region, China

Phosphorus (P) has been recognized as the most critical nutrient limiting lake productivity. In addition, P release from sediments may have a significant effect on the water quality and may result in continuous eutrophication in eutrophic lakes. In this study, P release kinetics from sediments and their relationship with sediment composition were investigated, eutrophication risk index (ERI) and degree of phosphorus saturation (DPS) were used to evaluate the eutrophication risk of the studied sediments, and their influencing factors were also discussed. The results show that total P (TP), organic matter (OM), Al2O3+Fe2O3 and the percentage of sand particles were the most important factors affecting the ability of P sorption. P release process was similar for all studied sediments, consisting of the quick and slow reaction processes. The quick reaction mainly occurred within 0.5 h, and slow reaction after 0.5 h. P release occurred within 20 h and then reached the dynamic equilibrium. P release process was slower than P sorption process. Three models (Power function model, Parabolic diffusion model and Simple Elovich model) can satisfactorily describe the P release kinetics. P release was mainly affected by TP, OM, sorbed total phosphorus (STP), DPS and sand particles, and quick P release was mainly a physical process. For the slightly polluted sediments, Al2O3+Fe2O3 mainly restrained P release. But for the heavily polluted sediment both OM and Al2O3+Fe2O3 promoted P release. Both DPS and ERI can be used to evaluate the P-induced lake eutrophication risk, and their threshold values were 6.6% and 25%, respectively. Based on the assessment by DPS and ERI, most of the studied sediments were in eutrophication risk for the studied sediments. For the heavily polluted sediments, Al2O3+Fe2O3 was significantly correlated with DPS. But for the slightly polluted sediments it was significantly negatively correlated with DPS and OM, and the sand particle percentage was negatively related to ERI.

QUALITATIVE METHODS FOR DETECTING THE SEDIMENT SOURCES BY GRAIN SIZE DISTRIBUTION AND X-RAY DIFFRACTION

The sources of sediment deposited in Sengguruh and Sutami reservoirs are detected by qualitative analysis of grain size distribution and mineral composition resulted from x-ray powder diffraction (XRD). Grain size distribution of sediment in Sengguruh reservoir shows that Lesti sub-basin contributes higher percentage of sand particles than Brantas sub-basin. The most dominant minerals in Sengguruh reservoir are Feldspar and Carbonate (Calcite). In Sutami reservoir, the most dominant minerals are Feldspar, Mica and Chlorite. The difference of mineral composition both of reservoirs indicates the increasing of sedimentation from Metro-sub-basin. Now, it should be considered while it was neglected in the past.Finally, the proposed method is applicable to assess sub-basins contribution of sediment origin and to evaluate the existing sedimentation countermeasures.

Wood variation in Laguncularia racemosa and its effect on fibre quality

Laguncularia racemosa wood is commonly used in north-western Mexico and harvested without the knowledge of whether environmental conditions affect wood quality. Laguncularia racemosa anatomy variation was evaluated to identify which cell features, mainly fibre features, are related to an environmental gradient and how this variation affects wood quality. Trees were sampled in six sites along the river where different flooding periods and levels occur. Analyses revealed that in sites with high salinity and flooding levels, there are more abundant vessels and axial parenchyma although the fibres and vessel elements are shorter, suggesting a water stress effect. Correlation analysis confirmed that the higher the percentage of gelatinous fibres, the longer the fibres. This occurred in L. racemosa trees growing in those sites with a high sand particle percentage and a lower flooding level. Anova (analysis of variance) revealed non-significant differences among sites for flexibility, rigidity and Peteri coefficients as well as for Runkel ratio, however the rigidity coefficient is affected by occurrence of gelatinous fibres. L. racemosa wood harvesting should avoid those sites with high flooding level, high sand particle percentage and high salinity that may modify wood quality.

Stepwise advance of the Mu Us Desert since late Pliocene: Evidence from a red clay-loess record

Analyses of paleomagnetic polanty reversals, magnetic susceptibility and grain size on the red clay-loess sequence, about 280 m thick, at Jingbian show that this sequence contains most of the stratigraphic units recorded in the standard red clay-loess sections of the Loess Plateau over the past 3.5 Ma. Using sand particle percentage (> 63 μm%) of the eolian sequence as a proxy indicator of desert extent and aridity in the dust source regions, it is found that during the past 3.5 Ma, there are three important climatic events indicating the advance of the Mu Us Desert. The events occurred at about 2.6, 1.1 and 0.6 MaBP, respectively. The stepwise advance of the Mu Us Desert may be linked closely to increase in global ice volume and uplift of the Tibetan Plateau in the late Cenozoic.

A sedimentological proxy indicator linking changes in loess and deserts in the Quaternary

From Yulin, which is located in the transitional zone between the Loess Plateau and the Mu Us desert, to Weinan in the southernmost part of the Loess Plateau, 9 loess sections were studied. Grain size analyses show that the advance-retreat changes of the deserts in northern China may be the most important factor controlling changes in the sand particle percentage of the loess-soil sequences during the last glacial-interglacial period. It is thus suggegted to use the sand grain content of loess deposits as a proxy indicator of desert variations. Applying this indicator to the last glacial loess deposits in the northwestern part of the Loess Plateau reveals that there were many millennial-scale cycles of the desert environments.