Sand Silt Clay Research Articles

Effects of the Properties of Fines on the Pore Water Pressure Generation Characteristics of Sand–Silt–Clay Mixtures during Cyclic Loading

To investigate the effects of the properties of plastic fines on the pore water pressure generation characteristics of fine-grained soils during cyclic loadings, we used 29 sets of test data from the literature and prepared another 21 reconstituted specimens with different types of fines and fine contents (FCs) for cyclic triaxial testing. Two types of undisturbed soil specimens and three types of reconstituted soil specimens were also included for testing. The results indicated that under cyclic loading, the pore water pressure (PWP) ratios of clean sands increased slowly, stagnated, then finally accelerated until initial liquefaction, whereas those of the plastic soils containing fines with a plastic index (PI) value of >5 increased sharply in the initial stage. In addition, the cyclic stress ratio of specimens containing mudstone (PI = 12.4) and kaolinite (PI = 32.0) fines increased by 1.5–3.0 times more than non-plastic fines if the cyclic number chosen was 100. The range of the upper and lower limits of the PWP curves of the specimens with an FC of 30% were smaller that of the limits of the PWP curves of the specimens with an FC of 15%. The above results were further analyzed using a mathematical model. This paper systematically uses both the literature and laboratory test data to demonstrate that plastic fines and non-plastic fines have significantly different effects on water pressure generation under cyclic loading conditions, and a mathematical model also demonstrated the same trends. These findings are able to clarify previous unclear arguments. Thus, the model results developed in this study could also provide the field of engineering with a complete advanced calculation, requiring analysis only via software.

Effect of N Fertilizer Dosage and Base/Topdressing Ratio on Potato Growth Characteristics and Yield

Nitrogen fertilizer is an important kinetic energy for potato production. To study the effect of nitrogen(N) fertilizer application and the topdressing ratio on potato growth and yield, different N application levels: N75 (75 kg ha−1), N150 (150 kg ha−1), N225 (225 kg ha−1) and different N fertilizer base/topdressing ratios: T1 (2:8), T2 (5:5), T3 (8:2), and T4 (10:0) were used to find the best N fertilizer operation. The results showed that higher yields can be obtained when 120–180 kg ha−1 N was applied under the base/topdressing ratio of 8:2 in silt loam (sand–silt–clay: 29-50-21). The base N fertilizer dosage largely determined the root morphology, while topdressing fertilizer mainly affected the leaf photosystem, however, rhizosphere topdressing at the early stages of bud emergence did not immediately affect the leaf soluble protein and the sugar content. Topdressing N increased the tuber crude protein and ascorbic acid content to some extent, but had weak effect on the amylose/amylopectin ratio, for the starch content was mainly influenced by total N application. When base N fertilizer was low, it could be compensated by applying fertilizer during flowering, though when the amount of base fertilizer was sufficient, topdressing would cause a decrease in the average single potato weight and an increase in potato sets per plant, thereby reducing the commercial potato rate. Overall, adopting a suitable base/topdressing ratio can promote plant growth and improve tuber quality and yield. However, the relationship between the specific application amount and the ratio under different soil texture conditions needs further study.

CPTu-based approaches for cyclic liquefaction assessment of alluvial soil profiles

Over the years, methods to assess cyclic liquefaction potential based on piezocone penetration tests (CPTu) have been developed. This paper presents a comparative study between three CPTu-based methodologies, mainly in terms of the normalization procedures of overburden stresses, equivalent clean sand resistance, and magnitude scaling factor (MSF). Four CPTu profiles from a pilot site in southwest Portugal are thoroughly analysed with different methods, in terms of factor of safety against liquefaction, the Liquefaction Potential Index (LPI), and the Liquefaction Severity Number (LSN). The site presents very heterogeneous soil profiles, composed of alluvial deposits. Due to the presence of significant sand-silt–clay interbedded layers, the influence of transition zones and the use of different soil behaviour type index (Ic) cut-off values were also considered. From these analyses, a set of recommendations is presented for CPTu-based liquefaction assessment. Based on the extensive database of CPTu results in the pilot site area, a new classification relating LPI and LSN is proposed to assess liquefaction severity and damage.

Geomorphological sedimentary characteristics in the coastal area of Ma river delta, Thanh Hoa province

The coastal area of the Ma river delta is formed by the interaction of continental and marine processes, between neo-tectonic activities and exogenous processes, between natural factors and human activities during the Late Holocene. Using remote sensing and geoscience research methods (granulometry, paleontology, geochemistry, clay mineralogy) and geomorphological studies (geneses, morphology, dynamics) combined with field survey, this coastal area, except the denuded mountainous remnants, could be distinguished into 12 morpho-sedimentary units formed and developed by the dynamic interactions of the river, waves and tides. The units formed by fluvial dynamics include: 1) Point bar is composed of clayey silt and sandy silt, 2) Channel bar composed of silty sand, 3) Levee with the composition of silty sand and 4) The flood plain of silty clay. The Late Holocene evolution of the Ma river delta was dominated by wave dynamics, reflected by a wave-formed association of dunes, interdune swamps and current sand beaches. The wave-formed units include 5) Dune’s sand and silty sand, 6) Back-dune depressions composed of sand silt clay, 7) Beach composed of sand, 8) Lagoon plain of silty clay and 9) Strand plain composed of silty sand. The tide-influenced units include 10) Supratidal flat with the composition of silty clay, 11) Intertidal flat characterized by clay or silty clay interbedded with thin fine sand or silty sand layers, 12) Subtidal flat of sand and silty sand.

Índices Físicos do Solo e Alterações Qímicas Decorrentes da Ocupação por Necrópoles em Caçapava do Sul – Rio Grande do Sul

Cemeteries are an environmental and sanitary problem, while at the same time they represent a public need. Many cemeteries were installed in unsuitable areas, resulting in the contamination of soil and water resources. Physical features of soil as infiltration and permeability are very important to deployment or regularization of cemeteries. This study aimed to determine the permeability and chemical quality to compare with resolutions of CONAMA 335/03 and CONAMA 420/09, and determine the coefficient of soil infiltration into soil occupied by the cemetery in the town of Cacapava do Sul-RS. We used the technique of Fluorescence Spectroscopy Energy Dispersive X-ray (ED-XRF) Bruker brand, model S1 Turbo SD to 7 different sites and 4 different depths of soil. For granulometric analysis the technique described by ABNT-NBR/6502/95. Seven tests were conducted using the Guelph permeameter, model 2800. For determining the coefficient of soil infiltration, the technique described by ABNT-NBR/7229/93, in 7 soil samples. The results showed that only cadmium exceeded higher levels than permitted by the legislation. The soil were classified as Sand Silt-Clay. The results pointed the permeability between 5,87.10 -6 cm.s -1 and 1,94.10 -3 , exceeding the limits of legislation, while the results of the infiltration is between 21 and 85 L/m 2 .d, framing as Semi waterproof.

Growth of Pacific White Shrimp Litopenaeus vannamei Cultured on Inland Low‐Salinity Pond Soils

AbstractLow‐salinity inland ponds in west Alabama were used to determine whether soil composition and water ionic profiles influenced shrimp growth. Soils from four farms were collected and placed into individual tanks equipped with airlift biofilters and 2.5‰ reconstituted seawater. Pacific white shrimp Litopenaeus vannamei were cultured for 42 d. Growth, survival, water, and sediment ionic profiles were analyzed at the end of the trial. There were no differences in survival among treatments. Shrimp grown on Farm 1 soil had the highest weight gain (4,244%), while shrimp cultured on Farm 3 soil grew the least (3,127%). Water placed in the tanks with Farm 1 soil had a lower calcium concentration (156 mg/L) and higher potassium (58 mg/L) and magnesium (80 mg/L), respectively, than water in the tanks with Farm 3 and Farm 4 soils. Differences were observed in soil pore water for potassium, sodium, exchangeable cations, sand–silt–clay composition, and organic matter. Sand–silt–clay composition indicated that soil from Farm 1 was characterized as sandy clay loam, while soils from Farms 2, 3, and 4 were clay loam. Shrimp growth was higher on sandy clay loam soil.

On soil textural classifications and soil-texture-based estimations

Abstract. The soil texture representation with the standard textural fraction triplet sand–silt–clay is commonly used to estimate soil properties. The objective of this work was to test the hypothesis that other fraction sizes in the triplets may provide a better representation of soil texture for estimating some soil parameters. We estimated the cumulative particle size distribution and bulk density from an entropy-based representation of the textural triplet with experimental data for 6240 soil samples. The results supported the hypothesis. For example, simulated distributions were not significantly different from the original ones in 25 and 85 % of cases when the sand–silt–clay and very coarse+coarse + medium sand − fine + very fine sand − silt+clay were used, respectively. When the same standard and modified triplets were used to estimate the average bulk density, the coefficients of determination were 0.001 and 0.967, respectively. Overall, the textural triplet selection appears to be application and data specific.

Geochemistry, spatial distribution and environmental risk assessment of the surface sediments: Anchar Lake, Kashmir Valley, India

Anchar Lake, a mono-basined freshwater lake in Kashmir Valley, has experienced major sediment deterioration due to changes in the local catchment and anthropogenic inputs during the recent past. The present study was conducted to evaluate the major, trace element concentrations and environment risk assessment in the surface sediments of Anchar Lake. Spatial distribution of organic matter (OM), CaCO3, TOC, sand–silt–clay and C/N ratio was studied to understand their source and accumulation in recent surface sediments. Textural studies indicate that most of the sediment samples are clayey silt to silty clay except one sample being of sandy–clay–silt nature. OM, CaCO3 content and C/N ratio results reveal that the sediments are organically rich and the source of OM is controlled by both; autochthonous and terrestrial sources. The major oxide geochemistry reflects higher concentrations of CaO, MgO and TiO2 compared to the UCC values and the possible dilution effect of CaO on other major oxides. Environmental risk assessment indices (Igeo and EF) reveal that the lake surface sediments are low to moderately enriched with Cu, Ni, Zn and Pb and thus are a direct threat to aquatic life. Pollution load index indicates higher contamination of the sediment samples collected along the agricultural and urban land-cover sites. In the absence of industries and metal mines in the catchment area, the agricultural inputs, domestic effluents and untreated sewage discharges are the probable source for the moderate increase in trace metals in the lake sediments. Based on geochemical and environmental parameters, an assessment of sediment contamination results revealed potential risks ranging from moderate to strong for the lake environment, particularly towards areas proximal to agricultural and land-use sites. The above results from this study thus add to the fundamental knowledge of the present lake processes occurring within the lake and its interactions with the surrounding catchment areas.

Consequences of using different soil texture determination methodologies for soil physical quality and unsaturated zone time lag estimates

Elucidation of when the loss of pollutants, below the rooting zone in agricultural landscapes, affects water quality is important when assessing the efficacy of mitigation measures. Investigation of this inherent time lag (tT) is divided into unsaturated (tu) and saturated (ts) components. The duration of these components relative to each other differs depending on soil characteristics and the landscape position. The present field study focuses on tu estimation in a scenario where the saturated zone is likely to constitute a higher proportion of tT. In such instances, or where only initial breakthrough (IBT) or centre of mass (COM) is of interest, utilisation of site and depth specific “simple” textural class or actual sand–silt–clay percentages to generate soil water characteristic curves with associated soil hydraulic parameters is acceptable. With the same data it is also possible to estimate a soil physical quality (S) parameter for each soil layer which can be used to infer many other physical, chemical and biological quality indicators. In this study, hand texturing in the field was used to determine textural classes of a soil profile. Laboratory methods, including hydrometer, pipette and laser diffraction methods were used to determine actual sand–silt–clay percentages of sections of the same soil profile. Results showed that in terms of S, hand texturing resulted in a lower index value (inferring a degraded soil) than that of pipette, hydrometer and laser equivalents. There was no difference between S index values determined using the pipette, hydrometer and laser diffraction methods. The difference between the three laboratory methods on both the IBT and COM stages of tu were negligible, and in this instance were unlikely to affect either groundwater monitoring decisions, or to be of consequence from a policy perspective. When tu estimates are made over the full depth of the vadose zone, which may extend to several metres, errors resulting from the use of hydraulic parameters generated from hand texture data will be resultantly greater, and may lead to flawed predictions regarding the achievability of water policy targets. For this reason laboratory analysis, regardless of method, should be preferred to simple field assessments.

A spectral soil quality index (SSQI) for characterizing soil function in areas of changed land use

During the last several decades, a large proportion of the planet's terrestrial surface has transformed from natural ecosystems to human-dominated systems. These land-use dynamics affect ecosystems' soil quality. The current study was conducted at the fringe of the northern Negev Desert, Israel, and strived to assess and compare the soil quality in three different land-use types (afforestation, traditional grazing, and agro-pastoral) that were changed from managed to unmanaged or vice versa (e.g., shrubland was transformed to a planted forest; pastoral grazing to natural shrubland with no grazing; and agro-pastoral to abandoned agricultural). The overall aim of this research is twofold: (1) to evaluate by reflectance spectroscopy the changes in 14 soil physical, biological, and chemical properties and their derived soil quality index (SQI) in the changed land uses; and (2) to develop a spectral soil quality index (SSQI) toward applying the technique of reflectance spectroscopy as a diagnostic tool of soil quality. To achieve these objectives, several mathematical/statistical procedures, consisting of a series of operations, were implemented, including a principal component analysis (PCA), a partial least squares-regression (PLS-R), and a partial least squares-discriminate analysis (PLS-DA). The PLS-R's most suitable models successfully predicted soil properties (R2>0.80; ratio of performance to deviation (RPD)>2.0), including sand–silt–clay content, NH4, NO3−, and pH. Moderately well-predicted soil properties (0.50<R2<0.80; RPD>2) were residual water, soil organic matter, electric conductivity, and potassium. Poor validation (R2<0.50; RPD<2) results were obtained for potential active carbon, phosphorus, and hydraulic conductivity. In addition, the PLS-R model predicted the SQI in the changed land uses. The correlations between the predicted spectral values of the calculated SQI ranged 0.65<R2<0.81 with RPD>2. The PLS-DA model was used to develop the SSQI model. The correlations between the SSQI and the SQI ranged 0.66<R2<0.74 in the different land uses. This study underscores the potential application of reflectance spectroscopy as a reliable diagnostic screening tool for assessing soil quality. The classification of soils into spectral definitions provides a basis for a spatially explicit and quantitative approach for developing the SSQI. The SSQI can be used to assess hot spots of change in areas of land-use changes and to identify soil degradation.

A sedimentary-based history of hurricane strikes on the southern Caribbean coast of Nicaragua

Multi-millennial hurricane landfall records from the western North Atlantic indicate that landfall frequency has varied dramatically over time, punctuated by multi-centennial to millennial scale periods of hyperactivity. We extend the record geographically by presenting a paleostrike record inferred from a four-core transect from a marsh on the Caribbean coast of Nicaragua. Fossil pollen indicates that the site was a highly organic wetland from ~5400–4900calyr BP, at which time it became a shallow marine lagoon until ~2800calyr BP when it transitioned back into swamp/marsh, freshening over time, with the present fresh-to-brackish Typha marsh developing over the very recent past. Hurricane Joan, 1988, is recorded as a distinctive light-colored sand–silt–clay layer across the top of the transect, identifiable by abrupt shifts in color from the dark marsh deposits, increased grain size, and two upward-fining sequences, which are interpreted as representing the storm's traction and suspension loads. The six layers identified as hurricane-generated display temporal clustering, featuring a marked increase in landfall frequency ~800calyr BP. This pattern is anti-phase with the activity pattern previously identified from the northern Caribbean and the Atlantic coast of North America, thereby opposing the view that hyperactivity occurs simultaneously across the entire basin.

Development of algebra algorithms for automated generation of grain‐size distribution maps

AbstractThe grain‐size distribution of sediments is a fundamental characteristic in understanding the earth's surface environments and an essential tool in classifying sedimentary environments. Grain‐size data provide important information on the energy and dynamics of depositional environments and aid our understanding of sediment transport. Ternary diagrams (TDs) are useful and conventional tools to classify sediments on the basis of relative grain size (i.e. gravel, sand, mud or sand, silt, clay). The development of spatial modelling in a geographical information system (GIS) can assist in treating, computing and displaying sedimentological data, such as grain‐sizes. In this work, four map algebra (MA) algorithms are written in a GIS environment to automatically produce maps depicting the spatial distribution of sediment texture classes based on the most frequently used grain‐size TDs: the Shepard classification and Flemming classification for sand–silt–clay components, and the Folk et al. classification and Blair and McPherson classification for sand‐gravel‐mud components. The proposed method allows rapid assessments by producing map distributions of the parameters most widely used in sedimentology. Copyright © 2007 John Wiley &amp; Sons, Ltd.

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

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

Fine-scale sedimentary structure: implications for acoustic remote sensing

Detailed measurements of sediment properties and acoustic scattering were made at a carbonate sand–silt–clay site off Dry Tortugas in the Florida Keys. The sediment is characterized by varying scales of biologically controlled random roughness and heterogeneity as well as surficial stratification on centimeter scales. The interface roughness was determined from stereo photogrammetric digitization and parameterized by a power spectrum, whereas sediment volume heterogeneity was determined from core measurements and parameterized by first-order autoregressive models for sound speed and density fluctuations. In contrast to previous investigations, fine-scale sediment bulk density fluctuations were examined in sediment cores with computerized tomography in addition to the standard gravimetric technique. Furthermore, the strongly delineated sediment density and sound velocity transition layer was parameterized by piecewise linear fits. These characterizations of the random and deterministic properties were used in acoustic scattering models in an effort to determine the feasibility of remotely measuring fine-scale features of the seafloor. The result was negative: older, low-resolution models gave moderately good fits to the acoustic data, but the fit did not improve for newer, higher-resolution models. It is suggested that scattering due to shell fragments must be included to account for all features observed in the scattering data at this site.

Late Quaternary evolution of the sub-aqueous Yangtze Delta, China: sedimentation, stratigraphy, palynology, and deformation

Four sediment belts (A–D) of the Yangtze sub-aqueous delta are defined from the sea-bottom sediment distribution. Belt A, delta front fine sand and silt, with trough cross stratification; Belt B, prodelta silty clay and clayey silt, with abundant burrowing and rich in organic matter; Belt C, prodelta to continental shelf sand–silt–clay, with thin layers of sand and clay interbedded; and Belt D, late Pleistocene relict sands (medium to fine grained), mixed with shell fragments. The late Quaternary stratigraphy of the delta consists from bottom upward of: late Pleistocene terrigenous (fluvial and lacustrine) sand and mud; Holocene transgressive silt, prodelta clay and delta front fine sand and silt. In addition, four pollen-spore zones (a–d) derived from these sediment sequences reveal a general trend of climate warming from early to late Holocene. The Zone c, distributed primarily within the prodelta muds, provides evidence for a temperature maximum starting at ca. 7000 years B.P. (Atlantic period). This indicates that the delta initiation was essentially coeval with the climate optimum in early Holocene. Sub-bottom seismic surveys reveal three (I–III) acoustic facies. Facies I and II are characterized by seaward remobilization of water-saturated Holocene prodelta muds; facies III is composed of highly-contorted late Pleistocene strata and mud diapirs that erupted from deep-seated late Pleistocene sediments in front of the estuarine depocenter. Gravity subsidence due to Holocene sediment loading within the depocenter is the major factor in causing the deformation of underlying unconsolidated strata. Furthermore, the sub-aqueous Yangtze Delta proper is now obviously diverting to southeast owing to the long-term, tectonically induced southward shift of the river mouth, and to the marine currents associated with the Coriolis effect. We thus predict that the large Chongming island in river mouth area will have been coalesced with the northern Yangtze coast in the recent future.

Small-scale fluctuations in acoustic and physical properties in surficial carbonate sediments and their relationship to bioturbation

Measurements of physical and acoustic properties within the top 40 cm of sediment indicate that there are three classes of parameter variability relevant to acoustic bottom scattering at the Marquesas Keys and Dry Tortugas sites. The three classes of variability, spatially and temporally different in terms of scale, are generated by biological and physical processes acting on sediments. Interplay of bioturbation, trawling and storm events create fine laminations of sand–silt–clay and high gravel-size mollusk shell content at the Marquesas Keys site; the predominance of biological processes creates strong surficial gradients and lateral variability in sediment properties at the Dry Tortugas site.

Low‐frequency acoustic transmission at a shallow water site in the Gulf of Mexico

During Area Characterization Test I (ACT I), conducted in September 1992 in 100‐fathom water on the West Florida Shelf, acoustic transmission measurements were made covering the band 50 Hz to 1 kHz using explosive charges detonated at 90‐m depth. The test site had a sand–silt–clay bottom with a gentle slope of 0.135°, and up, down, and cross‐slope transmission data to ranges of 40 km were collected on collocated 25‐element vertical and horizontal hydrophone line arrays. The low sea states and downward refracting acoustic conditions prevalent during ACT I ensured that transmission loss was controlled by geometric spreading and bottom interactions. Transmission loss as a function of range, frequency, and receiver depth has been determined and compared favorably with predictions for both the flat and sloping bottom cases. In addition, the multipath temporal structure and the vertical arrival structure of the received signals have been analyzed and have indicated the role of bottom and subbottom characteristics to the properties of the received signal. These analyses of the signal structure have highlighted transmission mechanisms not readily apparent in transmission loss data and have emphasized the importance of knowing subbottom structure to a detailed understanding of shallow water transmission over sand bottoms. [Work supported by the ARPA Adverse Environments Program.]

Hydraulic properties of a major alluvial aquifer: An isotropic, inhomogeneous system

Field observations, pump test analyses, and three-dimensional digital simulations of a portion of the Missouri River Valley floodplain provided insights about the hydraulic properties of this alluvial aquifer. Three distinct facies can be recognized in the alluvial sediments: a lower cobble facies; a middle gravel—sand facies; and an upper sand—silt—clay facies. Type-curve solutions and two-dimensional finite-difference models must be used with caution for such strongly inhomogeneous aquifers. Three-dimensional digital model analyses suggest the alluvium is best simulated as an isotropic, but inhomogeneous system. Ratios of vertical to horizontal hydraulic conductivity obtained from analyses such as delayed-yield theory are created by aquifer inhomogeneity and not anisotropy per se. Empirical power relations showing an increase of hydraulic conductivity with depth provide valid estimates in the absence of field data. However, these relations do not hold for the beds and banks of the major rivers or their tributaries. Finally, riverstage and observation-well data show that groundwater levels are controlled primarily by river-stage fluctuations and pumping; recharge from precipitation, seepage into and out of smaller streams, and, probably, bedrock recharge are all minor influences.

Susceptibility of Selected Woody Plants to Pelleted Picloram

Susceptibility of Selected Woody Plants to Pelleted Picloram