Optimal Interpolation and Kriging Mapping of Soil Characters in Glacial Moraine Landscapes

The objective of this research is to analyze optimal interpolation and Kriging mapping of soil characters in Glacial Moraine Landscapes. The research site is located in sloping landscapes, Kuehren, North Germany. The survey method was detailed using maps with scales of 1：5,000. Soil sampling was performed by soil pits and borings and completely analyzed in laboratory. Collected data were evaluated by Geostatistics program for spatial soil variability analyses. All maps （produced by Kriging interpolation） picture redistribution of soil nutrients and soil fractions and all map isolines run in similar directions according to landscape nets. The position in the landscape is responsible for increased soil variability. Soil variability becomes higher with decreasing elevation; this means it increases from hilltops to lower slopes. All observed soil characters show relationships to the soil variability. This variability system is caused by convex depressions and hedgerows （Knicks） function as barriers for the redistribution of transported material and offsite sedimentation. Therefore fluxes can be assessed by soil gain and loss balances.

Variogram Analyses of Soil Characters in Glacial Moraine Landscapes

The objective of this research is to analyze variogram analyses of soil characters in Glacial Moraine Landscapes. The research site is located in sloping landscapes, Kuehren, North Germany. The survey method was detailed using maps with scales of 1：5,000. Soil sampling was performed by soil pits and borings and completely analyzed in laboratory. Collected data were evaluated by geostatistics program for spatial soil variability analyses. The variogram models show that spatial soil variability ranges between 70-120 m （mean： 85 m）. Effective distances of sampling are calculated at around 50 m. The range values of soil characters are proportional with the range of elevation （range： 70 m, effective distance： 40 m）. The relief determines mainly the spatial variability of soil characters.

Thermomechanical Characterization of Three Soils of Abeche in Chad

The study carried out concerns the valorization of agricultural waste for the development of biosourced materials that can be used as insulation in homes. This article is devoted to the influence of gum arabic on the mechanical and thermal properties of clay soils in the town of Abéché. The mechanical tests were carried out using the CBR press equipped with two devices (bending device and compression device). Thermal property such as thermal conductivity was determined by the hot wire method and thermal resistance was derived by calculation. Thus, the tests were carried out on test pieces made from a mixture of clay and gum arabic in solution. The experimental program includes seven formulations (0%, 2%, 4%, 6%, 8%, 10% and 12%). The results obtained showed that the best flexural and compressive strengths are obtained by using gum arabic with a rate of 8% and a maximum stress of 4.3 MPa. In addition, the thermal results also showed that the thermal conductivity decreases when the percentage of gum arabic increases, which makes it possible to increase the thermal resistance, thus confirming the capacity of gum arabic to provide thermal insulation.

HVSR analysis of pumice sands for sediment depth characterization:A case study for Guadalajara,Mexico

The horizontal to vertical spectral ratio(HVSR)methodology is used here to characterize pumice soils and to image the three-dimensional surface geometry of Guadalajara,Mexico.Similar to other Latin American cities,Guadalajara is exposed to high seismic risk,with the particularity of being the largest urban settlement in Latin America built on pumice soils.Methodology has not yet been tested to characterize subsoil depths in pumice sands.Due to the questionable use of traditional geotechnical tests for the analysis of pumice soils,HVSR provides an alternative for its characterization without altering its fragile and porous structure.In this work,resonance frequency(F0)and peak amplitude(A0)are used to constrain the depth of the major impedance contrast that represents the interface between bedrock and pumice soil.Results were compared with borehole depths and other available geotechnical and geophysical data and show good agreement.One of the profiles estimated on the riverbanks that cross the city,reveals different subsoil thickness that could have an impact on different site responses on riverine areas to an eventual earthquake.Government and academic efforts are combined in this work to characterize depth sediments,an important parameter that impacts the regulations for construction in the city.

Thermophysical Characterization of Local Materials from a Locality in Chad for Use in Eco-Building

With the aim of enhancing the value of local building materials, the subject of this paper is a thermophysical study of natural Chadian clay from the eastern region of Chad, “Abeche”. Samples were taken from a brickwork in Abeche from a depth of 1 m, then using a clay brick-making press, 4 × 5 × 8 cm3 clay test tubes were made with 2%, 4%, 6% and 8% cow dung, and a 100% clay sample was used as a control. These samples underwent thermophysical characterization using the hot-wire method with a hot-plane option, yielding results that could improve thermophysical performance. The thermal conductivity of the test sample is in the order of 0.715 to 0.420 W/m. K, at 8% for cow dung, so the addition of cow dung as a percentage in the clay matrix enabled us to obtain various satisfactory thermal parameters.

Clay Materials for Ceramics Application from N’Djamena in the Chad Republic: Mineralogical, Physicochemical and Microstructural Characterization

Herein, we report some characteristics of the clayey materials (CMs) collected from Kaliwa (C1), Kabé (C2) and Malo (C3) district in N’Djamena (Chad). Three samples were characterized applying XRF, XRD, FTIR, SEM. In addition, TGA/DSC were performed to control decomposition/mass loss and show phase transitions respectively of CMs. Geochemical analysis by XRF reveals the following minerals composition: SiO2 (~57% - 66%), Al2O3 (~13% - 15%), Fe2O3 (~6% - 10%), TiO2 (~1% - 2%) were the predominant oxides with a reduced proportion in C1, and (~7%) of fluxing agents (K2O, CaO, Na2O). Negligible and trace of MgO (~1%) and P2O5 was noted. The mineralogical composition by XRD shows that, C1, C2 and C3 display close mineralogy with: Quartz (~50%), feldspar (~20%) as non-clay minerals, whereas clays minerals were mostly kaolinite (~15%), illite (~5%) and smectite (~10%). FTIR analysis exhibits almost seemingly similar absorption bands characteristic of hydroxyls elongation, OH valence vibration of Kaolinite and stretching vibration of some Metal-Oxygen bond. SEM micrographs of the samples exhibit microstructureformed by inter-aggregates particles with porous cavities. TGA/DSCconfirm the existence of quartz (570˚C to 870˚C), carbonates (600˚C - 760˚C), kaolinite (569˚C - 988˚C), illite (566˚C - 966˚C), MgO (410˚C - 720˚C) and smectite (650˚C - 900˚C). The overall characterization indicates that, these clayey soils exhibit good properties for ceramic application.

Perception of the Mechanization of Rice Cultivation and Its Effects on the Soil in the Senegal River Valley

In Senegal, particularly in the Senegal River valley, agricultural mechanization remains limited, mainly due to a lack of agricultural equipment, a lack of expertise in agricultural machinery and an apprehension of the consequences on soil quality. To better understand agricultural mechanization of rice cultivation, this survey study has been carried out in the Senegal river valley. Precisely, this work aimed to characterize farm machinery and its effects on soil and rice cultivation. A questionnaire was administered to 304 out of 1270 farmers, spread over 8 rice-growing areas, 4 of which are located in the Podor department, three in Dagana and one in Saint-Louis. The results showed that 99.3% of farmers used motorized equipment, with 95.7% using tractor and 3.6% a power tiller. Offset tillage, which is a shallow cultivation practice carried out to break up hard soil without turning it over, was most widespread among growers (95.4%). 78.3% of the valley’s farmers felt that the machinery used to carry out tillage operations was inefficient. According to the farmers, the main constraints on the use of agricultural machinery in the valley were: the upkeep and maintenance of equipment (57%), the lack of expertise in mechanization (31%), and issues adapting machinery to local conditions (12%). Those constraints have contributed to a drop in yields in recent years, the spread of weeds on cultivated plots and the gradual degradation of the soil in the area according to 78% of farmers.

Effects of Plastic Film Mulching on Physical Characters of Soil and Yield and Yield Components of Sweet Potato

Field experiments were carried out to study the effects of plastic film mulching on soil physical characters, including soil temperature, soil moisture content and soil bulk density, and yield and yield components of sweet potato. The results showed that plastic filming mulching increased soil temperature. Considering the soil temperature-increasing effect, the treatments ranked as black plastic film treatment 〉 white plastic film treatment 〉 control. However, with the deepening of soil layer, the warming effect of plastic film mulching was weakened. Black or white plastic film mulching was conducive to low T/R value, especially in the early growth stage of sweet potato. Plastic film mulching significantly improved the storage root yield of sweet potato. In terms of yield-improving effect, the treatments ranked as black plastic film treatment 〉 white plastic film treatment 〉 control. The storage root num- ber per plant showed a downward trend, but the weight of single storage root was increased.

Characterization of Urban Soil with SEM-EDX

The coal is largely used for generation of energy in the India, and their huge exploitations cause contamination of the soil. In the present work, the inorganic contamination of surface soil in the coal basin of the country, Korba is described. The concentration of elements i.e. C, O, S, Cl, Na, Mg, Al, Si, P, K, Ca, Ti, Fe, Mn and Ni in the surface soils (n = 30) was analysed by technique i.e. scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), ranged from 6.6% - 36.4%, 37.8% - 54.3%, 0.07% - 0.39%, 0.03% - 0.25%, 0.10% - 0.39%, 0.12% - 0.49%, 3.7% - 10.3%, 12.2% - 24.4%, 0.11% - 0.60%, 0.68% - 3.22%, 0.8% - 2.7%, 0.25% - 0.61%, 2.3% - 6.4%, 0.08% - 0.22% and 0.04% - 0.16% with mean value (p = 0.05) of 18.8% ± 2.7%, 49.0% ± 1.5%, 0.18% ± 0.03%, 0.11% ± 0.02%, 0.23% ± 0.03%, 0.32% ± 0.03%, 6.1% ± 0.5%, 16.9% ± 0.9%, 0.27% ± 0.04%, 1.6% ± 0.2%, 1.5% ± 0.2%, 0.41% ± 0.03%, 4.3% ± 0.4%, 0.14% ± 0.02% and 0.08% ± 0.01%, respectively. The surface soil morphology, concentration variation of elements, pollution indices and contaminant sources in the soil are discussed.

Instrumental Characterization of Pretoria Clay Soil by XRF, XRD and SEM

The products of refractory materials are used for lining furnace, incinerators and kilns among other uses and they have the potential of withstanding high temperature without deformation. The objective of the research was to charac-terize the clay soil sample collected from Tshwane University of Technology in Pretoria. The sample, collected from a location Latitude 25.0969°S and Longi-tude 28.1624°E, was oven-dried, pulverized and sieved in the laboratory. Min-eralogical and elemental compositions of the sample were determined by using X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) analytical methods. The XRF analysis revealed Fe2O3, Al2O3 and SiO2 as the major constituents, while the other elements occur in minor quantities. Mineralogically, the three samples contain Montmorillonite, Kaolinite and Bentonite, while Samples A contained Quartz in addition to ear-lier mentioned minerals, samples B and C contained Albite.

Contribution to the Characterization of Lateritic Soils for the Manufacture of Compressed Stabilized Earth Bricks

The aim of this study is to contribute to the mastery of the physical characteristics of lateritic soils in order to improve their use for the manufacture of Compressed Stabilized Earth Bricks (CSEB) in the province of North Kivu in the Democratic Republic of Congo (DRC). The study of the physical characteristics of lateritic soils was carried out. Samples were subjected to experimental identification tests on the physical characteristics (water content, density characteristics, particle size distribution and consistency). The results of the laboratory analysis of soil samples show that the water content varies between 5.4% and 36.99%. The density of the solid grains has an arithmetic mean of 2.5 g/cm3. The apparent density varies from 0.83 to 1.35 g/cm3. As for the dry density, it is in the range of 0.61 to 1.25 g/cm3. These relatively low densities indicate that the material studied has a significant degree of deformability. From the particle size analysis, it appears that the material studied contains an important fraction of fine particles. According to the consistency study, the soils studied are plastic clay as Ap class according to the Central Laboratory for Roads and Bridges (CLRB) geotechnical classification system. The particle size curves of the studied samples are within the preferential range of good soils for the manufacture of CSEB. The points representing the studied samples are within the preferential plasticity range of good soils for the manufacture of CSEB. From the above parameters, it appears that the studied material is well adapted for the manufacture of the Compressed Stabilized Earth Bricks.

The characterization of soil profile distribution for nitrate leached in the paddy soil

Experiment was conducted for five successiveyears under large undisturbed monolith lysime-ters(2m×2m in square,l m in depth).Thesoil was silty clay loam texture and had a con-tent of total N 1.55 g/kg.The soil was flood-ed with penetration rate controlled at approxi-mate 3 mm per day in duration of double-riceseason and laid fallow and natural in winterand spring.Results showed that nitrate was the mainform of nitrogen in percolates.The change of

东北地区白浆土耕层地力特点分析与改良技术

自20世纪70年代我国陆续开展白浆土改良科研与技术实践工作以来,历经50多年的努力,白浆土改良已经初见成效,东北地区的白浆土改良作为黑土地资源保护的重要工作之一,对于恢复耕地地力、提升农业产量意义重大。该文重点论述了东北地区白浆土分布情况、耕地土层结构及理化特征以及对农业生产产生的不利影响,并提出了白浆土改良专项技术策略。

潟湖污泥改性土工程特性与环境风险研究

为实现典型潟湖污泥的无害化处理与资源化利用,文章以海南万宁市小海潟湖污泥为研究对象,利用高炉矿渣、钢渣、工业石膏等大宗工业固废为原料制备的软土固化剂对污泥土进行固化处理。结果显示,软土固化剂改善了潟湖污泥的抗压强度、抗剪强度以及液塑限等工程性能,降低了污泥土中的重金属浸出浓度与迁移释放能力,同时增加了种子发芽指数,使改性污泥土能够满足建设用地回填土强度要求与园林绿化用土的安全指标。通过SEM、XRD表征分析发现,潟湖污泥原样中的硅、铝成分,在碱性激发剂、钢渣粉、矿粉等提供的碱性环境下参与了水化反应,使改性污泥土表面出现大量孔洞以及棒状、片状等稳定的结晶物和以凝胶态存在的水化产物,进一步使污泥土内部结构密实紧凑,颗粒间联结增强。经过软土固化剂固化后的潟湖污泥土工程特性得到显著提升,并使污泥中重金属得到固化稳定化,其环境生态毒害性也得到有效减弱。

不同连作年限设施农用地土壤有机碳与细菌群落功能特征

为探明不同连作年限设施农用地土壤有机碳(Soil organic carbon,SOC)与细菌群落功能变化及其动态响应关系,以北京市南郊设施农业集中地为研究区,采用时空替代法系统分析了未种植(CK)、连作年限0~5年(0~5 a)、5~10年(5~10 a)、10~20年(10~20 a)和20年以上(20 a+)SOC、细菌群落结构及其代谢功能的变化。结合冗余分析(RDA)、典型相关分析(CCA)、PICRUSt2功能预测及Mantel test探究了SOC及其活性组分与细菌优势菌群的动态响应,以及与细菌代谢功能的相互关系。结果表明:连作使研究区微生物生物量碳(Microbial biomass carbon,MBC)、易氧化有机碳(Easily oxidizes organic carbon,EOC)、SOC含量及土壤有机碳密度(Soil organic carbon density,SOCD)均随种植年限先增后减,可溶性有机碳(Dissolved organic carbon,DOC)含量在20 a+时最高,微生物熵(Q)随连作年限增加而减小。连作降低了土壤细菌的多样性,但提高了细菌种群间差异,PICRUSt2预测不同连作年限土壤细菌功能均以新陈代谢为主,5~20 a土壤细菌二级代谢功能丰度明显高于0~5 a、20 a+、CK。相对丰度前10的细菌群中Acidobacteriota与SOC及其活性组分含量均呈负相关,主导和参与SOC累积循环的关键菌群在连作20 a+后出现由富营养型菌群向寡营养和致病类菌群转变的趋势;Mantel分析显示,第3层级有53类与土壤有机碳含量呈显著相关的代谢功能(p<0.05),其中23类隶属于第1层级的新陈代谢,与EOC呈显著相关的代谢功能高达51类。本研究结果可为优化碳循环相关细菌功能群,提升小尺度设施农用地土壤碳汇功能提供参考。

低频电阻率测试技术在特殊土场地中的应用研究进展

定量表征特殊土场地的复杂介质及其工程参数,是工程地质原位测试的重要需求。电阻率测试技术因其快速、无损、精确和经济的特点,常作为低频条件下电法测试的首选。本文综述了电阻率测试技术在导电介质复杂(如污染土、盐渍土、冻土)和高黏粒含量(如膨胀土、软土、黄土)的特殊土场地中的应用情况,系统总结了相关测试方法的综合应用及评价体系研究进展,并论述了低频电阻率测试技术与现有原位测试技术的耦合评价方法及其前景。分析显示,电阻率测试技术在特殊土场地的调查评价中表现出良好效果,具有巨大发展潜力,尤其在区域划分和物理属性监测方面表现突出。然而,其在原位膨胀土和污染土场地的工程应用尚需进一步探索与验证;在黄土、软土和冻土中的定量评价机理及应用研究也需加强。此外,场地电阻率参数的解译及影响因素的消除研究还需深化。有必要开展电学测试与原位测试相结合的联合测试方法研究,以增强对场地工程特性的解译和评价能力。预期成果将为我国特殊土场地调查评价提供发展方向,并提升我国在特殊土场地电阻率测试及原位测试的技术水平。

不同类型纳米生物炭特征及对土壤镉污染修复效果的影响

【目的】生物炭在重金属污染土壤上有一定修复效果,然而未改性生物炭的修复潜力往往较低,生物炭改性可有效提高生物炭表面官能团的种类和数量,增加与重金属相互作用的位点数量,进而提高重金属的修复效率。【方法】对木炭、竹炭、秸秆炭3种类型生物炭进行纳米改性并用扫描电镜、傅里叶变换红外进行表征,采用培养试验,设置不添加生物炭对照、3种不同类型生物炭处理、3种纳米改性生物炭处理共7个处理。【结果】(1)不同类型生物炭纳米改性后表现出孔隙增多、孔径增大、粒径减小,丰富了官能团结构,使含氧官能团强度增加;(2)纳米生物炭可以提高土壤pH、有机碳(SOC)、可溶性有机碳(DOC)、易氧化有机碳(EOC)、颗粒有机碳(POC)含量,其中纳米竹炭相较于未改性竹炭处理SOC提高了20.77%,纳米秸秆炭对土壤DOC、LOC、POC提升效果最好,相较于未改性秸秆炭分别提高了17.05、10.88%、63.36%;添加生物炭也增加了土壤蔗糖酶和纤维素酶活性。(3)添加生物炭使土壤重金属镉有效性降低,改性后增强了对土壤有效态镉的转化,促使可交换态镉和可还原态镉向可氧化态镉和残渣态镉转化迁移,其有效性与土壤pH和有机碳相关。【结论】生物炭纳米改性后其含氧官能团增加,在提高土壤有机碳及降解重金属镉有效性上具有很大潜力,且不同类型纳米生物炭对土壤有机碳及镉形态的影响不同,纳米秸秆炭效果最佳。

铀矿污染土壤γ剂量率与核素活度的表征关系

为了对铀矿冶退役治理源项调查作出快速、准确的判定,解决调查过程中存在的测量周期长、检测手段繁琐等问题。以某铀矿污染土壤为研究对象,通过分析铀系核素不平衡条件下的衰变特点,采用半无限大体源估算模式计算了不同垂深污染土壤所致表层关注点的γ剂量率,根据铀系核素的剂量率贡献及对不同垂深的影响,推导出土壤表层γ剂量率与核素活度的表征关系。结果表明:铀系核素所致关注点γ剂量率主要由^(234m)Pa、^(214)Bi和^(214)Pb三个子体贡献,占比为96%;土壤表层(20 cm)污染核素所致关注点剂量率占比约为94%;根据铀系核素分段平衡理论及铀镭平衡系数,推导出以^(238)U和^(226)Ra为代表核素,与土壤表面γ剂量率的表征关系,经与实际监测结果进行对比,偏差在±5%以内。以此为依据可快速识别土壤的污染范围,提高源项调查监测布点的效率,为科学客观的开展污染土壤源项调查提供了新思路。

苏打盐碱土壤黏粒分散特征研究进展

本文系统总结了黏粒分散特征表征方法,归纳可用于表征黏粒分散程度的主要指标;概述了黏粒分散对土壤物理性质的影响;重点阐述影响黏粒分散的因素,包括:土壤酸碱性、离子浓度、土壤有机质、农业管理措施、外源物质施用等;提出了黏粒分散控制方法。根据Na^(+)、K^(+)、Ca^(2+)和Mg^(2+)不同分散和絮凝能力得出,离子性指数、电荷稀疏性、净分散量、土壤结构稳定性的阳离子比和阳离子交换量等是表征黏粒分散特征的常用指标;电动电位势和浊度与黏粒分散存在密切联系,有待进一步应用于苏打盐碱土壤黏粒分散研究。黏粒分散破坏土壤结构,导致土壤水力传导率下降,严重阻碍土壤正常功能。黏粒分散机理:不同阳离子价态不同和不同土壤溶液浓度不同导致黏粒表面正电荷层厚度不同,引起黏粒之间范德华吸引力和静电排斥力作用效果差异,正电荷层较厚导致黏粒分散。通过明晰黏粒分散机理,有助于掌握影响黏粒分散的主要因素,抑制苏打盐碱土壤黏粒分散,改善土壤结构,以期为苏打盐碱土治理提供理论参考和技术指导。

蜀山城市森林公园主要林分的土壤细菌群落特征及其影响因素

基于暖温带-亚热带过渡带且人为活动频繁的城市森林生态系统,从数量生态学角度出发,系统分析蜀山城市森林公园“植被-土壤-细菌”之间的相互作用机制。采用高通量测序技术,全面分析近郊城市森林绿地土壤细菌群落多样性,明确城市森林土壤细菌群落结构的主导影响因素。结果显示,与次生林相比,人工林普遍表现出较低的土壤pH值、含水量、有机碳和营养物质含量,表明人工造林和人类活动会加速土壤酸化。次生林土壤铵态氮(AN)、可溶性有机碳(DOC)含量与人工林差异性显著。人工林土壤细菌OTUs总数较低,马尾松林、麻栎林土壤细菌α多样性指数(S_1指数、H′指数)和次生林差异显著。酸杆菌门、变形杆菌门和放线菌门是主要菌群;次生林土壤酸杆菌门、变形杆菌门相对丰度高于人工林,放线菌门相对丰度低于马尾松林和麻栎林,绿弯菌门相对丰度低于人工林,麻栎林土壤芽单胞菌门相对丰度高于其他林分。土壤pH、AN和DOC是影响细菌群落分布模式的主要理化因子。本研究揭示了地上植被指标与地下土壤理化特性、细菌多样性指标的相关性。