Kinds Of Soil Samples Research Articles

A near-infrared (NIR) organic probe for rapid naked-eye detection of fluoride ions in aqueous medium.

A dihydroxy-substituted tricyanopyrroline-based near-infrared (NIR) colorimetric probe (TCP-34Hy) is developed for the effective detection of fluoride ions in aqueous medium in the presence of Ca2+ ions. The naked-eye detection (drastic color change) selectively makes the NIR colorimetric sensor more efficient. The probe can detect fluoride ions from inorganic sources (NaF/KF) as well as organic sources (TBAF) in water. The water samples from different sources, such as tap, pond, river, and sewage, have been tested successfully for fluoride ion detection using the probe (TCP-34Hy). Investigations of different kinds of soil samples (clay soil, red soil, and river sand) after pre-treatment with NaF are also productive for detection of fluoride ions in water. The probe can also detect fluoride ions in toothpaste in aqueous medium. The role of Ca2+ is discussed and explained on the basis of experimental results. Additionally, the probe (TCP-34Hy) shows high selectivity towards fluoride ion detection with a LOD of 2.3 μM (0.052 ppm) in aqueous medium.

Development of lycopene-based whole-cell biosensors for the visual detection of trace explosives and heavy metals

Residual explosives in conflicting zones have caused irreversible damage to human safety and the environment. Whole-cell biosensors can to detect remnants of buried explosives, such as 2,4-dinitrotoluene (DNT), a stable and highly volatile compound in explosives. However, all the reported whole-cell biosensors utilize fluorescence or luminescence as the biological markers, making their detection difficult in real minefields. Here, we presented a lycopene-based whole-cell biosensor in Escherichia coli to output visible signals in response to DNT, which can help in the visual detection of buried explosives. To construct the whole-cell biosensor, the DNT-responsive promoter yqjF was used as the sensing element, and the lycopene synthetic gene cassette crtEBI was served as the reporting element. Then, the metabolic flux for lycopene production was enhanced to improve the output signal of the whole-cell biosensor, and a terminator was utilized to reduce the background interference. The optimized biosensor LSZ05 could perceive at least 1 mg/L DNT. The DNT-specificity and robust performance of the biosensor under different environmental factors were confirmed. Our results showed that converting the biosensor into a lyophilized powder was an effective storage method. The biosensor LSZ05 could effectively detect DNT in two kinds of soil samples. The lycopene-based whole-cell biosensor could also be used to visually detect heavy metals. Our findings laid the foundation for visually detecting buried explosives in minefields, which was a valuable supplement to the reported biosensors. The methods used for optimizing the lycopene-based whole-cell biosensor, including the improvement of the output signal and reduction of background interference, were quite effective.

Insights into relationships between polycyclic aromatic hydrocarbon concentration, bacterial communities and organic matter composition in coal gangue site

Coal mining usually brought polycyclic aromatic hydrocarbons (PAHs) contamination. Relationships between the concentration of PAHs, bacterial communities and soil environmental factors were important for bioremediation of PAHs in soil. Total 4 kinds of soil samples with different concentrations of PAHs were selected from 7 typical coal gangue（CG） sites in Huainan, Anhui Province. The relationships between microorganisms, dissolved organic matter (DOM) composition and PAHs concentration were systematically analyzed in this work. Total 11 kinds of PAHs were enriched in the soil surface layer. That was attributed to the strong binding of soil organic matter (SOM) to PAHs. PAHs contamination reduced the diversity of soil microbial. The abundance of PAHs-degrading genera such as Arthrobacter decreased with the increasing concentration of PAHs. Mycobacterium increased with the increasing concentration of PAHs in all samples. The microbial activities decreased with increasing concentration of PAHs. The increasing contents of LWM-PAHs and DOM were beneficial to improve the activities of soil microbial. The increasing DOM aromaticity was beneficial to improve the bioavailability of PAHs according to the correlation analysis between PAHs content and DOM structural parameters. The obtained results provide a basis for better understanding the contamination characteristics and microbial communities of coal gangue PAH-contaminated sites.

Seasonality, soil attributes and root biomass in cerrado, cerradão and forest environments, western Amazon

The Amazon rainforest region presents a phytophysiognomy that ranges from savannas to cerrados, all of them intimately associated to climate and soil characteristics. Evidence has been given that plant growth and development are affected by soil quality and seasonality, thus making it crucial to understand them and how they are related to each other in order to grasp the dynamics of the whole ecosystem. In this context, the goal of this research was to assess how seasonality, soil attributes, and root system biomass are related in natural cerrado, cerradão, and forest areas in southern Amazonas State, in Brazil. Soil samples were collected during dry (June/2018) and rainy (December/2018) seasons from three different layers 0.00–0.05m; 0.05–0.15m, and 0.15–0.30m deep. In each area ten sampling points were randomly chosen. Two kinds of soil samples were collected: the first using 4.0 cm height by 5.1cm internal-diameter soil sample rings; and the second were intact soil lumps. Physical and Chemical soil attributes assessed were macro-porosity (MaP), micro-porosity (MiP), total porosity (TP), soil density (SD), aggregates texture and stability (GMD and WAR), gravimetric humidity (HG), organic carbon (OC), exchangeable aluminum (Al3+), potential acidity (H+Al), sum of bases (SB), cation exchange capacity (CEC), and root biomass (RB). All data were analysed via Tukey t test and student T test to compare results between seasons and areas. Increasing vegetation density (cerrado < cerradão < forest) was followed by an increment in CEC and OC, showing the importance of these attributes to maintaining biodiversity in environments. In amazon cerrado, rainy season as well a sandier soil textures provided favourable conditions to the growth and development of plants’ root system. Soil attributes were little affected by seasonality, that had greater effect on MiP, TP, SD, and OC, leading to lesser values for these variables during rainy season.

Compressive strength characteristics of hybrid fiber-reinforced cemented soil

ABSTRACT Cemented soil commonly faces issues regarding strength, cracking resistance, and water stability when used in airstrip pavements. Three kinds of soil samples (low-liquid limit clay, high-liquid limit clay, and clayey sand), four kinds of fibers (basalt fiber, glass fiber, fine polypropylene fiber, and coarse polypropylene fiber), and one curing agent (cement) were analyzed in a systematic investigation of the compressive strength of fiber-reinforced cemented soil based on unconfined compressive strength (UCS), water stability, and failure mode. When 38 mm coarse polypropylene fiber at 0.3% content was mixed with 12 mm fine polypropylene fiber at 0.3% content, the hybrid fiber-reinforced cemented soil prepared after 7 d of saturated curing achieved UCS values of 4.18 (low-liquid limit clay), 4.36 (high-liquid limit clay), and 4.16 MPa (clayey sand), which satisfied airstrip requirements for the strength of base course. In this study, coarse polypropylene fiber was adopted and mixed with fine fiber to give full play to their respective advantages and effectively enhance the mechanical properties of cemented soil. The research results improved the understanding of the mechanical properties and reinforcement mechanism of coarse and fine fiber reinforced cemented soil in theory, and enriched the materials and methods of airstrip construction in engineering.

In-situ determination of soil water retention curves in heterogeneous soil profiles with a novel dielectric tube sensor for measuring soil matric potential and water content

Techniques of determining soil water retention curve (SWRC) have been developed for several decades, but very few have considered the heterogeneity of SWRC at different depths caused by texture, structure and other constituents. In this study, we designed a novel dielectric tube sensor (DTS) moving in a pair of tubes installed in-situ to measure soil water content (SWC) and soil matric potential (SMP) in heterogeneous soil profiles for determining wetting-path SWRCs. A series of experiments were conducted to test the optimal size of DTS, calibrate the DTS for SWC measurement and SMP measurement, test the water proof function of the impermeable sheet and equilibrium rate of SMP tube and determine SWRCs in a layered and stony soil tank with a relatively slow drip irrigation. Commercial sensors were also employed in comparison with the DTS during the drip irrigation experiment. The results showed that when the distance of the two electrodes of the DTS was 5 mm, the measurement range, volume of sensitivity and coefficient of variation were optimal. The calibration results verified that the DTS was suitable to measure volumetric SWC (R2 > 0.9914) and SMP (R2 = 0.9992). The SMP tube exhibits good water-proof property among different layers, and the average equilibrium rate was 2.1 kPa·s−1 in loamy soil and 7.3 kPa·s−1 in pure sand. The dynamics of SWC and SMP measured by the DTS approximately agreed well with the data measured by the commercial sensors. The relatively reduced agreement between the DTS and TEROS21 for SMP measurements may attribute to their different volume of sensitivity and installed position. Based on these, the wetting-path SWRCs were determined in-situ in a soil tank containing four kinds of soil samples. Furthermore, the determined SWRCs in four soil samples verified that stones decreased soil water holding capacity.

Assessment of Water Retention Test by Continuous Pressurization Method

Abstract The water retention test involving the stepwise pressurization method (SPM) and a pressure plate extractor has been mainly used to obtain the soil–water characteristic curve (SWCC) of soils. The disadvantage of this test is that the measurement of the drying and wetting paths of the SWCC is time consuming. Thus, a water retention test involving a continuous pressurization method (CPM) in this paper was proposed, and the experiments for three kinds of soil samples were performed. Unlike the SPM, the pore air pressure in the CPM is continuously given to the specimen at a constant pressurization rate. In particular, for the measurement of the transient pore water pressure inside specimen according to the applied pore air pressure, a microtensiometer (height: 25 mm, diameter: 3 mm) was placed vertically at the center of the specimen. The suction for the specimen was defined as the difference between the applied pore air pressure and the measured pore water pressure. It was confirmed that the testing time for the drying and wetting paths of the SWCC in the test involving the CPM was remarkably shortened. The results of the CPM for its verification were compared with those of the SPM under the same initial condition of the specimen. The two test results showed good agreement regardless of the soil samples. Furthermore, the effect of the pressurization rate of the pore air pressure for the CPM was examined. Finally, the proposed water retention test involving the CPM was found to be highly efficient and accurately measure the drying and wetting paths of the SWCC in a short time.

Numerical Simulation Study on Mechanical Properties of Coarse-Grain Mixed Soil High and Steep Slope at Different Water Contents

In order to study the stability mechanism of coarse-grained mixed soil with high steep slope in different areas of water content in southeast Tibet, this paper takes a high-steep slope of Sejila Mountain in Nyingchi City as the research object, and the undisturbed soil configuration for on-site retrieval includes natural water content. Three kinds of soil samples with a rate of 6%, a water content of 3% and a water content of 9% were obtained by using the ABAQUS numerical analysis using the mechanical parameters obtained by the large-scale triaxial test to obtain the development of the plastic zone of the model. The high-steep slope is used to form the penetrating plastic zone and the calculation non-convergence is used as the safety factor for determining the slope instability. The characteristic point displacement is abruptly changed to the safety factor of the slope instability criterion, and the characteristics of high-steep slope failure are observed. And the sliding surface map and displacement change after numerical calculation to lose stability, analyze the safety factor that forms the through-plastic region as a standard, and the safety factor that does not converge to the force and displacement calculation. The high-steep slope can be known by numerical analysis. The numerical calculation of the natural moisture content gives the highest safety factor, indicating that the high steep slope is the most stable under natural moisture content.

Influence of CT scanning parameters on rock and soil images

Geotechnical mechanical testing machine is an important means to study the characteristics of rock and soil rupture, which is of great significance in shale gas exploitation, nuclear waste disposal and earthquake prediction. For the convenience of research, the complex structure of rock and soil is often neglected, and the geotechnical material is regarded as a macro continuum. On this basis, a new method is used, X-ray CT scale cracks, crack size is larger than the micro-scale cracks, the number of cracks is less, but geotechnical CT images can still show the crack initiation location, propagation path, through the process, cracks and the relationship between aggregate mortar. When CT-scale microcracks can be found, the length of microcracks is equal to the magnitude of aggregate-scale, and can be compared with numerical simulation results. In this paper, four different kinds of soil samples are selected to design relevant tests. The specific effects of CT scanning parameters on CT images of rock and soil samples are studied by direct and indirect methods combined with CT number curves under different scanning conditions. The results show that the scanning voltage and filtering function have great influence on CT images and CT numbers of rock and soil samples. The enhancement or inhibition of the filtering function to the geotechnical CT image depends on the property of the selected filtering function, but has nothing to do with the soil quality of the sample. Finally, the selection principle of the CT scanning parameters is given. With the help of reasonable CT scanning parameters, the quality of the geotechnical CT image can be improved and the relatively accurate geotechnical CT value can be obtained.

Measurement of grass root reinforcement for copper slag mixed soil using improved shear test apparatus and calculating formulas

The root permeated copper slag mixed soil is a effective way to reinforce soft soil and dispose the copper slag. In order to better investigate the strength rule of it, firstly, a new shear test apparatus is developed for the purpose of measuring the root reinforcement for copper slag mixed soil. The utilized apparatus has a much larger measurement range compared to the traditional apparatus. Secondly, based on the developed measurement equipment, the formulas for calculating the shear strength of the mixed soil is derived by taking a full consideration on the dynamic changes of the effective shear area. Thirdly, 4 different kinds of soil samples are chosen and tested in a case study to demonstrate the use of the apparatus. The calculation of the shear strength between the traditional formula and the newly proposed method is compared in the measurement results. Finally, the reinforcement effect of Bermuda grass roots on copper slag-soil mixture is studied. The influence of weight percentage of copper slag, roots content, and moisture content on the shear strength of mixed soil are investigated. The authenticates results showed that the soft clay in combination with copper slag and root of grass has promising mechanical properties over the original soil in geotechnical engineering applications.

Application of magnetic nanoparticles coated with sodium dodecyl sulfate and modified with 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol as a novel adsorbent for dispersive-magnetic solid-phase extraction and determination of palladium in soil samples.

A rapid, sensitive, precise, and accurate dispersive-magnetic solid-phase extraction technique combined with flame atomic absorption spectrometry was established for pre-concentration and separation of Pd (II) in soil samples. In the developed system, 5-amine-1,10-phenanthroline was used as synergistic complexant; sodium dodecyl sulfate and 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol ligand coated on magnetic nanoparticles were synthesized by a chemical precipitation method, and then employed as the efficient magnetic adsorbent with good magnetic properties and dispersibility. Various operational parameters affecting the extraction efficiency has been studied and optimized in details. Under the optimum experimental conditions, the detection limit of the mentioned method for palladium ions was 0.12μg/L, while the relative standard deviation was 1.8%. Finally, the developed method was applied for the analysis of palladium ions in three kinds of soil samples and quantitative recoveries were achieved over the range of 96.7-104.0%. It can be a powerful alternative applied to the determination of traces of Pd ions from various real samples in further researches.

Effects of soil properties and biosurfactant on the behavior of PAHs in soil-water systems

The interactions among biosurfactant, soil components and PAHs govern the efficiency of biosurfactant enhanced remediation, which was still poorly studied. In this study, we investigated effects of biosurfactant and soil properties on sorption and desorption of phenanthrene (PHE) and pyrene (PYR) in soil – water systems. Two kinds of soil samples (ditch and under plant) from the same petroleum contaminated site in western Canada were applied. The results indicate that soil organic matter (SOM) was the predominant factor that affects PAHs sorption onto soil. The SOM content in ditch soil was half of that in under plant soil, therefore ditch soil showed less sorption affinity to PAHs than under plant soil. We also examined the combined effects of soil DOM and biosurfactant on desorption of PAHs. The results indicated that more PAHs were desorbed from ditch soil than the under plant soil under the combined conditions. The SOM was still the key factor that determined desorption of PAHs. Besides, competitions among PAHs, DOM and surfactant for sorption sites exist. In high solute concentration system, the competition for sorption site was more severely than low concentration system and more PAHs were sequenced in soil phase in high PAH concentration system. Also in low biosurfactant system, less PAHs were desorbed from soil. The study results should be helpful in broadening knowledge of biosurfactant enhanced bioremediation of PAHs.

Research on the Impact of Moisture Content on the CBR Value of Shanxi Loess

Several typical soil samples in Shanxi Province were selected. Laboratory experiments were adopted to study the CBR of the three kinds of soil samples with different compaction and different water content. Orthogonal experiment was used to analyze the impact of factors including water content, compaction and soil sample category on the CBR value. The result shows that the moisture content has great impact on CBR value and the CBR value is maximize under optimum moisture content and maximum degree of compaction condition, while the not flooded CBR is decrease with the increasing of water content.

Water Content Estimation in Soils Using Novel Planar Electromagnetic Sensor Arrays

Agriculture is one of the important sectors for food supplies. Therefore, a tool for monitoring the agro-environment is important in order to maintain the permanence of agricultural soils. This paper suggests an alternative method for the detection of water content in soils by developing a sensor array with a combination of planar meander and interdigital electromagnetic sensors. The study involved sensor array fabrication using the printed circuit board (PCB) method. The experimental setup consisted of a frequency waveform generator and a signal oscilloscope to collect and analyse the sensors’ output, with VEE Agilent software used to establish the interface. A set of experiments was conducted to determine the relationship between the sensors’ output and the soils’ parameters. The performance of the system was observed where the sensors were tested with the addition of various kinds of soil samples with different concentrations of water content. The sensitivity of the developed sensors was evaluated where the best sensor was selected. Based on the outcomes of the experiments, the Y sensor array placement has the highest sensitivity and can be used to measure the water content in the soils where the data accuracy is compared

Experimental Study on Shear Strength of West Sichuan Unsaturated Mixed-Soil

By controlling moisture content to control matrix suction indirectly, three typical unsaturated remolded mixed-soil from west Sichuan are studied by the consolidated untrained triaxial shear test .The test data show that for different kinds of soil samples, the sample with less amount of clay and high content of quartz has bigger internal friction angle relatively, and the sample with hydrophilic mineral and high content of clay has bigger cohesive force. Meanwhile, for the sample without or less hydrophilic mineral, cohesive force is affected mainly by water content, and for the sample with large content of hydrophilic mineral, water content and dry density affect cohesive force together. For a certain sample, the variation of moisture content and dry density affects internal friction angle less, while affects cohesive force more. In addition, the change of internal friction angle resulting from the variation of matrix suction is less, and cohesive force increases as matrix suction increases.

The evaluation of forest fire severity and effect on soil organic matter based on the L*, a*, b* color reading system

The evaluation of forest fire severity and effect on soil is very important when discussing the damage to the environment. The purpose of this study is to evaluate the effect forest fires have on the soil color using the CIE Lab system. The color changes in four kinds of soil samples caused by heating at different temperatures were investigated. It was found that the Δa* and Δb* values drastically decrease when samples were heated over the temperature range from 200 to 250 °C, that is above the ignition temperature of volatile matter. The Δa* and Δb* values show a good linear negative correlation with the atomic ratios of H/C and O/C. The results obtained from this study indicate that the proposed method is able to evaluate the dehydration and decarboxylation of soil caused by forest fires. We demonstrated this method using soil samples collected from unburned and burned areas in Kalimantan, Indonesia.

Effect of land use patterns on stability and distributions of organic carbon in the hilly region of Western Sichuan, China

Soil aggregation is important for the resistance of land surfaces to erosion, and it influences the ability of soils to remain productive. At the same time, it is also an important process of carbon sequestration. The objectives of this study were to elucidate the effects of different land use patterns on soil aggregate stability and the distribution of organic carbon in different aggregate fractions in order to prove that the different land use patterns enhance soil aggregate stability. Five kinds of soil samples were collected from the hilly area of western Sichuan under different land use patterns, such as abandoned farmlands, eucalyptus plantations, Chinese fir plantations, tea plantations and loquat orchards. The results demonstrated that the five land use patterns had high proportions of aggregates at the size of >2 mm after dry sieving, and had high proportions of aggregates at the size of < 0.5 mm after wet sieving. The aggregation abilities of the soils were significantly different depending on land use patterns. Waterstable aggregate stability was highest in the Chinese fir plantations, followed by eucalyptus plantations and tea plantations. Water-stable aggregate stability was the lowest in loquat orchards and abandoned farmlands. Except for coarse particle, soil particle contents of the same size were affected according to the different land use patterns. As the size of aggregates decreased, the organic carbon content of the soil aggregates in tea plantations increased after a decrease, and then reduced again. However, the organic carbon contents of soil aggregates in other land uses increased continuously with the decreasing size of aggregates. Organic carbon content of the soil aggregates was strongly increased in land areas that had been converted from abandoned farmland to Chinese fir plantations, tea plantations and loquat orchards, while it was decreased when abandoned farmland was converted to eucalyptus plantations. The results provided the basis of implementation of returning farmland to forest and the process of carbon sequestration in the study areas.

Soil aggregation, aggregate stability, organic carbon and nitrogen in different soil aggregate fractions under forest and shrub vegetation on the Loess Plateau, China

Revegetation has been reported as one of the most effective counter measures to reduce soil and water erosion on the Loess plateau in China. Soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions would be affected by different plant communities. The objectives of this study were to elucidate the effects of different plant communities on soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions in order to prove that the different plant covers enhance soil aggregate stability. Six kinds of soil samples under forest (Quercus liaotungensis, Populus davidiana, Pinus tabulaeformis, Bothriochloa, a 14 year abandoned land, and a 19 year bare fallow soil. Four kinds of soil samples under shrub land (the 24 year old Caragana Korshinskii Kom.; the 14 year old C. Korshinskii Kom., 3 year old abandoned grazing land and traditional slope cropland which is claimed by the farmers for production with very low fertilizers) were collected from the hilly–gully area on the Loess Plateau, which was divided into 0–10 cm and 10–20 cm. We investigated soil aggregate stability and soil aggregate fractions by ultrasonic fractionation (USAS), and the distribution of organic carbon and nitrogen in different fractions under forest and afforested land, as key indicators for soil remediation through revegetation. The results showed that soil organic carbon (Corg) and total nitrogen (Nt) were strongly increased under forest and artificial shrub land compared to cropland and bare fallow land and were higher in the surface layers (0–10 cm) than in the subsurface (10–20 cm). Soil aggregate stability (SAS) was quite low under bare fallow land and cropping land soils, in comparison with the 4 forest communities. The three main fractions of soil aggregates, obtained by ultrasonic fractionation, were < 63 μm, 63–100 μm and 100–250 μm, which represented approximately 60%, 10% and 10%, respectively. In all land uses, macro-aggregates, 1000–630 μm > 630–250 μm had a higher Corg content than micro-aggregates, 250–100 μm > 100–63 μm ≫ 63 μm. In comparison to cropland and bare fallow land, forest and artificial shrub can protect and enhance the Corg, Nt and soil aggregate stability. The higher C:N ratio of macro-aggregate fractions indicates a rapid turnover of soil organic carbon in the top soil of forest sites and even on bare fallow and crop land. The narrow range of C:N ratio in micro-aggregates indicates that soil organic carbon in micro-aggregates is more stable than that in the macro-aggregates. We concluded that revegetation of eroded soils accelerates soil remediation and rehabilitation.

Evaluation of multi-walled carbon nanotubes as solid-phase extraction adsorbents of pesticides from agricultural, ornamental and forestal soils

A new, simple and cost-effective method based on the use of multi-walled carbon nanotubes (MWCNTs) as solid-phase extraction stationary phases is proposed for the determination of a group of seven organophosphorus pesticides (i.e. ethoprophos, diazinon, chlorpyriphos-methyl, fenitrothion, malathion, chlorpyriphos and phosmet) and one thiadiazine (buprofezin) in different kinds of soil samples (forestal, ornamental and agricultural) using gas chromatography with nitrogen phosphorus detection. Soils were first ultrasound extracted with 10 mL 1:1 methanol/acetonitrile (v/v) and the evaporated extract redissolved in 20 mL water (pH 6.0) was passed through 100 mg of MWCNTs of 10–15 nm o.d., 2–6 nm i.d. and 0.1–10 μm length. Elution was carried out with 20 mL dichloromethane. The method was validated in terms of linearity, precision, recovery, accuracy and selectivity. Matrix-matched calibration was carried out for each type of soil since statistical differences between the calibration curves constructed in pure solvent and in the reconstituted soil extract were found for most of the pesticides under study. Recovery values of spiked samples ranged between 54 and 91% for the three types of soils (limits of detection (LODs) between 2.97 and 9.49 ng g −1), except for chlorpyrifos, chlorpyrifos-methyl and buprofezin which ranged between 12 and 54% (LODs between 3.14 and 72.4 ng g −1), which are the pesticides with the highest soil organic carbon sorption coefficient ( K OC) values. Using a one-sample test (Student's t-test) with fortified samples at two concentration levels in each type of soil, no significant differences were observed between the real and the experimental values (accuracy percentages ranged between 87 and 117%). It is the first time that the adsorptive potential of MWCNTs for the extraction of organophosphorus pesticides from soils is investigated.

A Method for Received Waveform Reconstruction Based on Bender Element Test Using Frequency-swept Signal

ABSTRACT An experimental technique for reconstructing the received wave of bender element tests based on linear system theory is shown in this paper. In order to identify the frequency response of testing apparatus, bender element tests using frequency-swept signals are performed. Received waves for one-period sine pulse transmitting with various frequencies are calculated and compared with observed waves in several kinds of soil samples and testing apparatuses. The linearity of the testing system is also confirmed by coherence function. It is shown that calculated data are less affected by random noise and show good agreement with observed data in regards to not only waveform itself but also resulting shear wave velocity. It is mentioned that this technique can provide simulations for arbitrary transmitted waveform with high signal/noise ratio after laboratory tests are performed. It is also mentioned that this technique is advantageous when sufficient amplitude of received wave cannot be ensured or shear wave velocity must be verified, for example, due to uncertainty of arrival time by near-field effect.