Fine Sand Fraction Research Articles

Interpretation of X‐ray Absorption Spectra by synchrotron radiation of the uranium mineral species transported by the main stream “El Tigre”, in Peña Blanca, Chihuahua, Mexico

The state of Chihuahua, Mexico, has several uranium deposits. The most important is the Peña Blanca deposit at north of the Chihuahua City. After an intensive exploration in the 80’s, the mineral extracted and unprocessed was confined in rock stacks exposed to weathering. To characterize the transport of uranium by surface water in the form of particles or dissolved, a sampling was carried out in the bed of the stream “El Tigre”. Nine sediment samples were collected near the Nopal 1 mine, and separated into coarse sand, fine sand, silt, and fine silt + clay fractions. The activity concentration of the uranium series isotopes was determined by gamma spectrometry, applied to the different fractions of each sample. The fine silt + clay and fine sand fractions were analyzed by X-ray diffraction in the 2 most active samples, Nopal 1 and Nopal 2. The phases are quartz, calcite, montmorillonite, sanidine, orthoclase, albite, kaolinite and magnetite. Particles of d < 100 μm (P1-Bulk) were extracted from the fine sand fraction of Nopal 1 with the help of ultraviolet light fluorescence; uranium and silicates were confirmed in them by SEM-EDS. P1-Bulk sample was subjected to X-ray absorption spectroscopy measurements on the U L3-edge, as well as to the samples fine silt + clay fraction of the Nopal 1 (P1-Clay) and Nopal 2 (P1-Silt). The X-ray absorption near edge (XANES) region analyzed indicates the presence of hexavalent uranium in the three samples. The fit of the Extended X-ray absorption fine structure (EXAFS) spectrum of the P1-Bulk sample indicates that it is α-uranophane. This result is consistent with the reports of the area.

A detailed quartz and feldspar luminescence chronology for the Khonako II loess section (Southern Tajikistan)

Parts of Central Asia have been dominated by high dust flux since the start of the Quaternary. The resulting loess-palaeosol deposits are important archives for landscape and climate changes, but there is a lack of chronological data for the subaerial deposits of Southern Tajikistan. Our study presents a high-resolution luminescence chronology for the Khonako II section in the Khovaling region. Thirty-seven samples were collected from the first ∼8 m of the section, corresponding to the Holocene soil and the upper part of the Loess 1 (L1) unit. We applied quartz OSL dating to the coarse-silt fraction (40–63 μm) and polymineral pIRIR200,290 dating to the very fine sand fraction (63–90 μm). The polymineral pIRIR200,290 signal has satisfactory characteristics. The quartz dose response curve displays a non-single exponential growth above ∼100 Gy, thus, the De values were estimated by fitting a single exponential function plus linear component to the dose response data. To assess the pIRIR200,290 residual dose at deposition, we used the offset between our quartz and polymineral chronologies from Khonako II and equivalent doses measured on modern dust samples from Tajikistan and Uzbekistan. The resulting 9.2 ± 0.4 Gy dose was then subtracted from the pIRIR200,290 doses for final age calculation. The quartz OSL and pIRIR ages are then generally consistent. The obtained high-resolution luminescence chronology shows that the upper part of the L1 unit accumulated during the end of marine isotope stage (MIS) 3 and through MIS 2 (39–20 ka). The average dust accumulation rates (DAR) increased from ∼31 cm ka−1 to 41 cm ka−1 between MIS 3 and MIS 2. The DAR reached a peak of ∼71 cm ka−1 at 21 ka. A hiatus of ∼7–9 ka was then identified between the end of the last glacial maximum (LGM) and the beginning of the Holocene, and the average DAR decreased during the Holocene. Our results indicate a continuous high dust flux in the Khovaling plateau over the last 39 ka, but reworking processes and potential deflation events mark the LGM-Holocene transition. High-resolution luminescence dating studies in Tajikistan are therefore important to detect potential discontinuities in the sequences and provide an independent timescale for interpreting the climate proxies and calculating dust accumulation rates.

Mineralogical compositions of soils under three geological formations in some parts of Ogun state, Nigeria and their agricultural potentials

Investigating the mineralogical compositions of soils under different geological formations becomes imperative for maximizing agricultural productivity and ensuring the long-term viability of agricultural practices. Therefore, studies were carried out on mineral compositions and diversities of soils developed over the Basement complex rock, Coastal plain sands and Ewekoro formations in Ogun state Nigeria. A total of nine profile pits (three per location) of 2 m × 1 m × 2 m size were dug in all the three locations. Soil samples were collected from the pedogenic horizons of each profile pits in replicates into a well labeled polyethylene bag. Using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) the mineral contents and their relative abundance, elemental compositions and morphologies of the fine sand, coarse silt and clay fractions of the soils at different topographic positions were identified, described and compared. Results obtained from XRD and SEM analyses exhibited similarities. The most abundant elements in the basement complex and Ewekoro pedon were oxygen, carbon and silicon whereas in the coastal plain sand pedon, oxygen, carbon and aluminum were the most abundant element. The presence of mixed-layer illite, mica, kaolinite, quartz, hematite, anatase, goethite, and chlorite at varying degrees was observed in the pedons developed on these geological formations, although kaolinite and quartz dominated the soil matrix. The mineralogical complexity of the pedons followed the order of basement complex > coastal plain sand > Ewekoro formation. Profiles developed on the Ewekoro formation exhibited the highest degree of weathering, as evidenced by their chemical properties and mineralogical compositions. The petrographic evaluation of the three geological formations revealed that all pedons were rich in quartz and exhibited varying degrees of mineral complexity and maturation. The overlapping and distinct characteristics among the geologies indicated different stages of weathering. By using the mineral maturity index, profiles developed over the basement complex rock and the coastal plain sand could be regarded as sub-matured and this could have contributed significantly to the native fertility of these soils and profiles from the Ewekoro formation were the most weathered. The use of Ewekoro formation for agriculture would necessitate significant investments in agro-inputs and sound principles of soil management through integrated soil fertility management.

Advances in making Mn oxide‐coated sands

AbstractManganese (Mn) oxide‐coated sand has been suggested as an amendment for scrubbing metals in water filtration beds and also as a less concentrated medium for uniformly amending soils with Mn oxides in mesocosm scale studies. Earlier work at the lab bench scale, using potassium permanganate (KMnO4) solutions that were reduced with sodium (Na) lactate, resulted in sands coated with about 0.13% Mn. The goal of this project was to increase the amount of Mn oxide that could be coated on sand to make it a more useful amendment and also to attempt to scale up the procedure to produce larger (kg) quantities of coated sand. Titration experiments examined the effects of (1) varying the molar ratio of Na lactate to KMnO4, (2) varying the rate at which the titration was accomplished, and (3) varying the concentration (molarity) of the original KMnO4 solution. The results of this work led to an optimal approach utilizing 0.32 M KMnO4 solution that was titrated to a final lactate:permanganate ratio of ∼1.1 with 10% of the lactate being added every 10 min while the suspension was being stirred. The proportion of sand to an initial solution was also increased 5–20 fold to between 50 and 200 g per 100 mL of solution. Applying this method and using a large 20‐ to 30‐L reaction vessel yields sands coated with up to 0.7% Mn in batches 5–10 kg is size, which could be useful as an amendment in mesocosm scale studies, or as a component of treatment filter beds. The examination of various size fractions of the coated sands demonstrated that more Mn was coated on finer sand fractions, which appears to be a function of the particle surface area available for the coating of Mn oxides, and at a rate of 0.3–0.5 µg Mn mm−2 of the particle surface.

Variasi Spasial Kepadatan Cacing Kacang di Pantai Toronipa Sulawesi Tenggara

The density of peanut worms is concentrated in the subtidal zone and is closely related to the substrate where they live. This research aims to determine spatial variations in peanut worm density. This research was carried out at Toronipa Beach, Southeast Sulawesi from June 2020 to February 2021. Peanut worms were collected using a hand scoop to a depth of ±10 cm in a 10x10 m2 quadrat transect at each station. Data were analyzed using standard formulas and tested using Mann-Whitney and linear regression. The results showed that the highest density of peanut worms was found at station II with a mean value of 12±104 ind/10m2 which was significantly different from stations I and III with densities of 9±52 ind/10m2 and 7±124 ind/10m2 respectively. Five types of seagrass were identified, namely Cymodocea rotundata, Enhalus acoroides, Halodule uninervis, Halophila minor, and Thalassia hemprichii. The number of seagrass species found at stations I, II, and III were 1, 2, and 5, respectively. Peanut worm density was positively correlated with seagrass density with a coefficient of determination of 86.45%. Water quality tends to be the same at all stations, except that organic matter is higher than at stations I and II. The dominant fine sand fraction was found at stations I and III, while very coarse sand was dominantly found at station II. The density of peanut worms on Toronipa Beach is determined by a combination of seagrass density, high levels of organic matter, and the dominant texture of the coarse sand substrate.
 
 Keywords: peanut worm, spatial density, Sulawesi, water quality

Interdisciplinary research of ash heap sediment near Stepnoye settlement (Chelyabinsk Oblast)

An ash heap is defined as a specific object at an archaeological site, usually in the form of a separate hillock containing a layer of finely-dispersed greyish-yellow or ash-coloured soil. The existing assumptions about the formation and functional pur-pose of ash heaps, as special archaeological objects found near the Bronze Age pastoral settlements, have so far been poorly supported by scientific data. At the ash heap near the Sintashta fortified settlement of Stepnoye, Chelyabinsk Oblast, for the first time, large-scale and comprehensive studies were carried out on the structure of these deposits, their granulometric and geo-chemical composition, in combination with the analysis of plant macroremains, paleoparasites, microbiomorphic and palynologi-cal complexes, indicative bacterial groups, and keratinophilic fungi. Judging by the archaeological materials, it is patently obvi-ous that this was a multifunctional object that developed over many centuries and played different roles at different stages. The results of the conducted analyses showed that the 45 cm thick “ash” horizon in the Stepnoye ash heap contains a significant proportion of a fine sand fraction, and not a silty fraction. An increase in the biophilic elements (predominantly calcium, as well as phosphorus and sulphur), accumulated mainly in the organic matter of faunal origin, was noted in the upper bench of the ash layer. However, the high concentration of phytoliths in the “ashy” deposits indicates that the layer was formed mainly as a result of the accumulation of a large amount of plant organic matter. The absence of charcoal and the scarcity of charred macro-remains indicate that the deposited organic material was not burnt but decomposed naturally. The increased content of sapro-trophic bacteria in the “ashy” layer also supports the natural decomposition of an organic matter. The composition of the phyto-lithic and pollen spectrum of the “ashy” horizon is not typical for the steppe of the south of Western Siberia, since it is dominated by a group of mixed herbs with elements of a ruderal flora, and not by cereals. All the data supports the hypothesis that the ash heap is the result of regular practice of cleaning of the floor and interiors of the buildings of the fortified settlement of Stepnoye. This is evidenced by the increase in the number of keratinophilic fungi, which decompose wool and hair and therefore accumu-late in the occupational layer of the structures. Based on the results of the study, the hypotheses that the Stepnoye ash heap is a place of consolidated ash removal or composting of stable manure were rejected.

Morphometric Changes between Peroba and Redonda Beaches, Icapuí-Ceará Region, Brazil, Applying High Resolution Remotely Piloted Aircraft Images from 2020 to 2021

Beaches are regions of the coastal zone where the effects of interaction between marine, terrestrial and atmospheric ecosystems are often seen. Natural and anthropic agents act together in coastal processes, which may result in erosion or accretion. If the erosion is intense and continuous, it will represent a severe problem, especially in densely occupied and economically significant beaches, such as the beaches of Peroba and Redonda that have registered erosive events. Thus, this work aimed to analyze the variation of the coastline and the volume of beach sediments through a historical series of one year employing a remotely piloted aircraft, conjugated with the analysis of sediments collected in fields. At Peroba beach, the shoreline was stable, having varied by about 0,87 m/year, and the volume indicated a positive sediment balance of about 18.815 m3. At Redonda beach, the coastline degraded by about 1,27 m/year. The volume indicated a negative sediment balance of -1.230 m3. The beaches were mainly characterized by sediments of very fine and fine sand fractions. The volume variation indicated similar trends to the shoreline, with more significant deposition in the west and erosion in the east.

Granulometry, carbonate and glauconite content as stratigraphic tools to distinguish the Kiel Member and lower Antwerpen Member (Berchem Formation) in the City of Antwerp area (Belgium)

Granulometric, carbonate and glauconite analyses were performed on samples of the Kiel and Antwerpen members (Berchem Formation) in temporary exposures and boreholes in the area of the City of Antwerp. Since the upper part of the Antwerpen Member is only locally preserved from post-depositional erosion, this study focuses on the much more frequently sampled lower part of the Antwerpen Member. The granulometric results show that the Kiel Member and lower part of the Antwerpen Member are both dominated by the fine sand fraction, with an overall finer grain size for the lower Antwerpen Member compared to the Kiel Member. The Kiel Member is relatively enriched in the fine and medium sand fractions, whereas the lower Antwerpen Member is relatively enriched in the very fine sand to silt fraction. Both members show a similar, low clay content. Measurements of clay content are higher in boreholes (on average 3.9–5.2%) than in temporary exposures (less than 1%), which might be explained by the crushing of the glauconite into the clay fraction during drilling. In borehole samples, especially those analysed by sieving, the Antwerpen Member often shows a higher amount of coarse grains than the Kiel Member, which represent shell fragments present in the Antwerpen Member and nearly absent in the Kiel Member. Like the amounts of shells, also the measured carbonate content—measured outside the shell beds—is lower for the Kiel Member than for the lower Antwerpen Member (3% vs 4.2%). The average glauconite content—based on the >63 µm fraction—displays similar, strong fluctuations between 35% and 60% for both members. On top of these fluctuations, a general downward decrease in glauconite content is noticed in the Kiel Member.

Sediment Record of the Earliest Stage of the Evolution of Lake Kanozero (Sw Kola Peninsula): New Data for Regional Deglaciation Reconstructions and Relative Sea-Level Studies

The multi-proxy study of the lowermost part of the sediment sequence of Lake Kanozero (south-western part of the Kola Peninsula, ca. 53 m a.s.l.) revealed the evidences for marine waters penetration into the basin during the earliest stage of its evolution. The diatom analysis inferred the conditions of a large brackish-water basin. Sediments composition and very low organic content also supported large-basin and low-productivity environments. Based on the pollen study, this stage covers a cooling period preceding the Allerød (tentatively assigned to the Older Dryas) and the onset of the Allerød. Periglacial vegetation typical of the cold and dry climate prevailed in the area for the most of the period. The subsequent transition to the freshwater conditions inferred from the diatom study took place in the Allerød, according to the pollen data. Except for a minor decrease in the fine sand fraction, no other corresponding changes were observed in the sediment record suggesting no major shifts in sedimentary environments. In the late Allerød and throughout the Younger Dryas, Lake Kanozero remained a large, low-productive freshwater basin. Our results indicate that ice-free conditions with aquatic sedimentation in the Kanozero depression had already existed in the Older Dryas. This assumes earlier deglaciation of the study area than it was previously thought. The study also suggests that brackish conditions in the White Sea basin established earlier than reported before. While the previous studies found no signals of marine transgression above ca. 41 m a.s.l., our results indicate that the local marine limit in the study area exceeds ca. 53 m a.s.l.

A wind of change for soft-sediment infauna within operational offshore windfarms

In this study, “artificial reef” (AR) impacts of offshore windfarms (OWFs) on the surrounding soft-sediments were investigated. Benthic grab samples were collected at nearby (37.5 m) and distant (500 or 350 m) positions from turbines of two Belgian OWFs (Belwind: monopiles and C-Power: jackets). Higher macrobenthos abundance and species richness were found nearby jacket foundations of C-Power compared to distant positions and differences were most pronounced within deeper sediments (i.e., gullies between sandbanks) at intermediate levels of fine sand fractions (10–20%) and total organic matter (0.5–0.9%). Strong benthic enrichment (>1000 ind. m−2, >20 spp. sample−1) was also linked with higher fine sand fractions (>20%) near the jackets. Moreover, nearby sediments showed higher occurrences of coastal species and habitat diversification was promoted by Mytilus edulis shell debris and alive organisms (“biofouling drop-offs”). The lack of similar results around monopiles (Belwind) confirms that the extent of detectable AR-effects depends on site- and turbine specific factors.

GEYSERNAYA RIVER ALLUVIUM (KAMCHATKA): COMPOSITION AND FEATURES OF FORMATION<a href="#FN2"><sup>2</sup></a>

A comprehensive compositional analysis of the alluvium from the river with active gas-hydrothermal manifestations was carried out for the first time. Geysernaya river alluvium is characterized by: poor roundness of boulders and pebbles (grades 1–2), poorly sorted fine-clastic component, abundance of rock fragments and intergrown minerals even in the fine sand fraction. All these indicate the sediment weak disintegration with significant amount of slope material in it, including redeposited by mudflows. The high content of smectite-zeolite and other newly formed (secondary) minerals aggregates (up to 70% of the light fraction 0.1–0.25 mm in size) and altered rock fragments (up to 70–80% in the pebble fraction of alluvium) indicate that a gas-hydrothermal activity significantly impact the bedrock and alluvium weathering within the thermal fields. The material accumulates predominant in the areas of: (1) active delivery of slope material (temporary dams), (2) the longitudinal profile flattening in dammed reservoirs, and (3) mudflow material removal. Formation of two dammed reservoirs over the past 15 years, as well as layers of fine sand found in the low terrace’s sediments, indicate that such short-lived basins form periodically in the Geysernaya river valley. The conditions of the fine sand deposition in sections of a single-branch channel and within dammed reservoirs are differ, which affects the heavy fraction leading minerals ratio. The well-rounded gravel and abundance of coarse sand, and their decrepit appearance indicates that, along with the processing of incoming slope and mudflow material large volumes the Geyzernaya river continues to cut in and erodes the ancient fluvial sediments.

A New Porous Nozzle for Aluminum Melts Purification—Preparation and Mathematical–Physical Model

Aluminum and its alloy castings are used more and more widely, and it is particularly important to remove impurities in the alloy. According to the principle of bubble floatation for degassing aluminum melt, a new porous nozzle with controllable pores was developed, and a hydraulic simulation experimental device was studied with the nozzle. The effects of the particle size ratio of the coarse sand to fine sand and volume fraction of fine sand on the porosity of the porous nozzle were studied by orthogonal experiment, and permeability and compressive strength of the porous nozzle were used as test indicators to determine the optimal parameters of preparation for the porous nozzle. The optimal parameters are fine sand of 100 mesh, and fine sand of 50 wt.%, binder of 17.5 wt.%, pore-forming agent of 6 wt.%, and pressure of making sample of 5 MPa. The nozzle with optimal parameters was prepared and tested, and the permeability is 112.2 × 10−12 m2 and the compressive strength is 2.3 MPa. In addition, a physical model of gas transmission in the porous nozzle was proposed. With the increase in the proportion of fine sand, the permeability of the porous nozzle decreases, the compressive strength increases, and the calculated porosity increases. The hydraulic simulation of melt injection was carried out, and the mathematical model for calculating the bubble diameter of bubble floatation was formulated. The model shows that the bubble diameter increases with the increase in gas flow rate. The experiment shows that the prepared porous nozzle has the merits of a simple preparation process and low-cost, which is expected to degas aluminum melts.

Soils of lake environments in the Brazilian Pantanal

The Pantanal comprehends a set of heterogeneous and biodiverse landscapes of esteemed environmental, economic and social value. The study of soils is effective to stratify and to understanding the operation of these environments. The purpose of this study was to characterize and compare soils of lake landscapes of the Pantanal: baías (freshwater lakes), salinas (alkaline lakes) and their respective levees (sandy ridges originally with forest vegetation). For this purpose, we carried out field work with sampling, in triplicate, of superficial soil layers in 12 representative areas of low and high Nhecolândia; analytical determinations of 26 soil attributes were performed, totaling 936 response variables and statistical analyses were performed in order to synthesize the data and present the results. In both landscapes, the fine sand fraction predominates in the soil granulometry. The textural class of the soils varied from very sandy, medium sandy and medium sandy for the baías; very sandy for the levees, with particle density related to the presence of quartz; and very sandy, medium sandy, medium clayey and clayey for the salinas. In the chemical attributes and organic matter, the baías stand out for higher potential acidity (H+Al), slightly high organic matter contents and availability of metal ions, especially Fe; in the levees, higher average remaining phosphorus (Prem) are more evident; while the saline lake soils are related to more alkaline pH values, high base saturation and high Sodium Saturation Indices (ISNa). Salinas landscapes presented the highest data variability and have soil attributes that refer to the action of different environmental processes.

Density of Meretrix meretrix Clamps Under Ecological Pressure on Different Substrate Texture at the Kambu River of Kendari Bay, Southeast Sulawesi

White clams at the mouth of the Kambu River in Kendari Bay have a preference for different substrate textures and are under ecological pressure. This study aims to determine the density of tofu shells at the mouth of the Kambu River, Kendari Bay, Southeast Sulawesi. This research was conducted at the estuary of the Wanggu River, Kendari Bay, Southeast Sulawesi from August 2021 to January 2022. White clams were taken manually using a 1x1 m squared transect. These shellfish samples were taken 6 times in repetition/station in each month of observation. Samples found in the field were counted. Taking the texture of the aquatic substrate together with the sampling of shellfish. The results showed that the maximum density of white clams at the mouth of the Kambu River, Kendari Bay, was 7.3 ind/m2. The highest density of white clams was found at stations I and II, while the lowest density was found at station III. The highest density of shellfish was found in the type of substrate which was dominated by the fine sand fraction, while the lowest density was found in the type of substrate which was dominated by the silt fraction.

The current state of the soil cover of the Southern Balkhash region

The article considered the current state of the soil cover of the Southern Balkhash region. Morphological features of soil images are described, mechanical and chemical composition is determined. According to the morphological characteristics of the soil, it was found that the first image soil is gray soil, the second image soil is grayish yellow sandy soil, and the third image soil belongs to the Sandy orange soil type. The composition of all soil images was dominated by fine sand and coarse dust fractions. Since the chemical composition of the soil is one of its main agrochemical properties, the content of nutrient elements has been determined. As a result, it was found that nitrogen – low, phosphorus – medium, potassium – was sufficiently contained. The content of nutrient elements was higher in the surface layers of the soil than in the lower layers. The humus content is very low. It was found that the reaction of the soil medium is alkaline. The alkalinity of soils increased with the depth of the soil. Soil images on absorbed bases were characterized by a set of absorbed bases of low size (5 - 10 ml- eqv/100 g of soil). The water filtration of the soil was dominated by bicarbonate (NSO3-) ions and CA cation. In terms of the set of salt content, all soil images belong to the category of unsalted, that is, the set of salts was below 0.2%. Keywords: humus, nutrient elements, soil morphology, absorbed bases, soil environment reaction, soil salinization, water filtration.

Heavy metal contamination levels, source distribution, and risk assessment in fine sand of urban surface deposited sediments of Ekaterinburg, Russia.

Urban surface deposited sediments (USDS) are unique indicators of local pollution that pose a potential threat to the living environment and human health. Ekaterinburg is a highly populated metropolitan area in Russia with rapid urbanization and industrialization activities. In Ekaterinburg's residential areas, about 35, 12, and 16 samples are represented by green zones, roads, driveways, and sidewalks, respectively. The total concentrations of heavy metals was detected using a chemical analyzer inductively coupled plasma mass spectrometry (ICP-MS). Zn, Sn, Sb, and Pb have the highest concentrations in the green zone, while V, Fe, Co, and Cu represent the utmost values on roads. Moreover, Mn and Ni are the prevailing metals in the fine sand fraction of driveways along with sidewalks. Broadly, the high pollution in the studied zones is generated by anthropogenic activities and traffic emissions. The potential ecological risk (RI) was observed in high risk (IR > 600), even though the results of all heavy metals reveal no adverse health effects from the considered noncarcinogenic metal for adults and children by different exposure pathways except the children's exposure to Co in case of the dermal contact, where the HI values of Co for children in the studied zones are higher than the proposed level (> 1). In all urban zones, the total carcinogenic risk (TLCR) values are predicted as a high potential inhalation exposure.

Heavy metals distribution and mineralogy of saprolite Of southeastern soils developed nigeria on coastal plain sands in southeastern nigeria

The distribution of heavy metals as well as minerals in the fine sand and clay fractions in saprolite derived from coastal plain sands in Southeastern Nigeria were investigated. Heavy metal levels were generally low, when compared to existing permissible standard limits. Ranges for Iron, Manganese, Copper and Zinc were 400-1750 mgkg-1, 51.75-223.75mgkg-1, 12.01-92.75 mgkg-1 and 55-122.1mgkg-1 respectively. Chromium ranged from 1.15-2.53mgkg", Nickel and lead ranged from 0.02-0.08mgkg and0.02-0.25 mgkg-1 respectively. Mineralogical results from the XRD revealed the dominance of quartz, followed by kaolinite with occasional occurrence of illite and wiserite. Trace amounts of Al-Si-Oxide(0.8%) was also found in the fine sand fraction at 18.2-18.9m depth at Uyoafaha. Infrared spectroscopy of the clay fraction also revealed the presence of quartz, kaolinite and lite as well as gibbsite and halloysite.

QUANTITATIVE AND QUALITATIVE CHARACTERIZATION OF THE GRANULOMETRY OF AN INCEPTISOL

Granulometry is an initial factor to be considered in soil research as it plays a fundamental role in physical and chemical properties. The objective of this study was to characterize the granulometric fractions of soil, obtained using the screening and sedimentation method. The Dynamic Light Scattering (DLS), Mid-Infrared (MIR), and Scanning Electron Microscopy with Field Emission Gun (SEM-FEG) techniques were used for this purpose. The quantitative results showed that this soil presents high percentage of clay, followed by fine sand fraction, silt fraction and, finally, the coarse sand fraction. The results obtained by DLS qualify this technique as a procedure to evaluate the quality of the granulometric fractionation of the clay fraction. The MIR analyzes detected characteristic vibrational states of minerals such as kaolinite, halloysite, gibbsite, and quartz. Few works in the literature characterize the clay fraction of the soil without chemical treatment using the SEM-FEG technique. Thus, in this work, pseudo-hexagonal structures were identified, typical of the kaolinite mineral and, to a lesser extent, structures with a filamentous needle-like morphology, which can be ascribed to illite and/or halloysite, whose inorganic functional groups were identified by MIR in the clay fraction of the soil.

Effect of Volume Fraction of Fine Sand on Magnetorheological Response and Blocking Mechanisms of Cementitious Mixtures Containing Fe3O4 Nanoparticles

Active rheology control (ARC) or active stiffening control (ASC) is a concept with which the conflicting rheological requirements during different stages of concrete casting can be reconciled. For instance, formwork leakage could be reduced by actively controlling structuration at the formwork joints, without having the negative impact of increased structuration during pumping and form filling. Using the concepts of magnetorheology, an active control methodology was thus recently developed by the authors to study the control of formwork leakages under pressure. This was performed using a small-scale laboratory test setup, using cementitious pastes containing magnetisable particles. To upscale from paste to mortar, the effect of volume fraction of sand on the magnetorheological (MR) response and blocking mechanisms of mixtures containing Fe3O4 nanoparticles is thus investigated in the current study. The MR response is determined using storage modulus tests, and the impact of ASC for leakage reduction is investigated by measuring the flow rate. Experimental results show that increasing the sand volume beyond a threshold causes a reduction in mobility of the magnetic particles, and thus lowers the MR effect. Despite this reduction in the MR effect at high sand volume, the increased particle interactions induce clogging and filtration effects, drastically lowering the flow rate. Applying the ASC method refines the voids in the clog, thereby eliminating the filtration effect. It is concluded that ASC can be used on mortar, with the expectation that there would be a reduction in the magnetorheological effect with increasing volume of fine aggregates.

Identification of sediment provenance in the South Yellow Sea using detrital amphibole geochemistry

Marginal seas are major sinks of fluvial sediments. Identifying the sources and quantifying the contributions of different sources are essential to studying the transport and distribution of terrestrial sediments on the shelves of marginal seas. The South Yellow Sea (SYS) to the east of the Asian continent receives sediment discharged by the Huanghe (Yellow) and Changjiang (Yangtze) rivers, and it is a favorable location for studying the provenance of marginal sea deposits. In this study, we tested the geochemistry of amphibole in different grain-size fractions (very fine sand and coarse silt) of the SYS sediments, and compared this geochemistry with those of fractions in the Huanghe River (HH) and the Changjiang River (CJ) to quantify the terrestrial provenance of the sea. The results show that for the very fine sand fraction, Zr, Be, Ga, Ge, Nb, Cd, and Hf in amphibole can be used as indicators to discriminate between the HH and CJ sediments. For the coarse silt fraction, the trace elements of Ba, Zr, Li, Rb, and Hf in amphibole can be used to distinguish the sediment of the two rivers. The mean contribution of the HH sediment to the very fine sand and coarse silt fractions of SYS is 45.0% ± 6.7% and 57.6% ± 5.9%, respectively, compared with 54.8% ± 6.7% and 42.4% ± 5.9% for the CJ, respectively. Provenance analysis of amphibole reveals spatial variation in the supply of terrigenous sediment to different parts of the SYS: the nearshore area of the Shandong Peninsula and the sea areas adjacent to the abandoned Huanghe River (FHH) estuary are supplied mainly by the HH, whereas the South and eastern parts of the SYS are supplied predominantly by the CJ. In the SYS sediment of very fine sand, a line extending from 34°N, 121°E to 35°N, 123°E demarcates the boundary between areas supplied by the HH (north) and the CJ (south), while coarse silt has a longer transport distance and higher mixing degree compared with very fine sand. This study demonstrates that quantitative analysis of the trace-element geochemistry of detrital amphibole can discriminate terrigenous sediment provenance in the mixed area of the marginal sea.