Soil column experiments for iodate and iodide using K-edge XANES and HPLC–ICP-MS

Radioactive iodine is one of the most problematic radionuclides because of its long half life and high mobility. Mobility of iodine depends on the chemical form to a great extent. This paper reports the results of soil column experiments we conducted to evaluate the mobilities of IO₃⁻ and I⁻. In order to determine the mechanisms of adsorption of IO₃⁻ and I⁻ on soil, adsorption isotherms were obtained by batch experiments. Both adsorption isotherms of IO₃⁻ and I⁻ are well explained by Langmuir model. The adsorption maximum of IO₃⁻ is about five times larger than that of I⁻. In the column experiments, iodine distributions between soil and pore water in the soil column were determined at various depths. Chemical forms of iodine in soil and pore water were determined by X-ray absorption near-edge structure (XANES), and high performance liquid chromatography connected to inductively coupled plasma mass spectrometry (HPLC–ICP-MS), respectively. Vertical profiles of iodine in pore water were simulated using Visual MODFLOW. Our results showed, upon I⁻ infiltration through the column, that a small amount of I⁻ adsorbed on soil, and its mobility is mainly controlled by advection and dispersion. The profile of iodine concentration in pore water was well simulated by assuming equilibrium-controlled Langmuir type adsorption without considering any chemical transformations. For the IO₃⁻ addition system into the column, however, IO₃⁻ adsorbed to soil to a larger degree, which causes a much larger retardation effect than I⁻. In addition, reduction of IO₃⁻ to I⁻ was also confirmed in both soil and pore water by XANES and HPLC–ICP-MS, respectively. The fraction of I⁻ increased toward the deeper end in both phases because of its lower affinity for soil than IO₃⁻, where the reduced I⁻ was released to the pore water and transported by the water flow. In this study, such reduction effect was clearly demonstrated by the speciation analyses of iodine in both soil and water phases, which confirmed that the mobility of I⁻ is a dominant factor that controls the fate of iodine in the surface environment.     

Physical and Compaction Behaviour of Clay Soil–Fly Ash Mixtures

At present, nearly 100 million tonnes of fly ash is being generated annually in India posing serious health and environmental problems. To control these problems, the most commonly used method is addition of fly ash as a stabilizing agent usually used in combination with soils. In the present study, high-calcium (ASTM Class C—Neyveli fly) and low-calcium (ASTM Class F—Badarpur fly ash) fly ashes in different proportions by weight (10, 20, 40, 60 and 80 %) were added to a highly expansive soil [known as black cotton (BC) soil] from India. Laboratory tests involved determination of physical properties, compaction characteristics and swell potential. The test results show that the consistency limits, compaction characteristics and swelling potential of expansive soil–fly ash mixtures are significantly modified and improved. It is seen that 40 % fly ash content is the optimum quantity to improve the plasticity characteristics of BC soil. The fly ashes exhibit low dry unit weight compared to BC soil. With the addition of fly ash to BC soil the maximum dry unit weight (γ_dmax) of the soil–fly ash mixtures decreases with increase in optimum moisture content (OMC), which can be mainly attributed to the improvement in gradation of the fly ash. It is also observed that 10 % of Neyveli fly ash is the optimum amount required to minimize the swell potential compared to 40 % of Badarpur fly ash. Therefore, the main objective of the study was to study the effect of fly ashes on the physical, compaction, and swelling potential of BC soils, and bulk utilization of industrial waste by-product without adversely affecting the environment.     

An Integrated Geostatistical Approach for Contaminated Site and Soil Characterisation

For several years, abandoned or stopped industrial sites increasingly arouse the interest of politics and investors. Having a high social and economic estate value, these sites generally reveal contaminated soils that must be remediated first before receiving any new use. Due to financial, environmental or human health stakes, heuristic methods appear inappropriate because they do not provide reliable estimations of contaminated soil volumes and ignore spatial uncertainties. Problems at hand may be very complex, involving multiple correlated contaminants for which spatially varying pollutant grades are to be estimated and confronted to various regulatory thresholds, depending on redevelopment target areas. In such conditions, geostatistics provides effective methods to quantify local and global uncertainties about soil contamination and contaminated soil volumes. By quantifying uncertainties, geostatistical models are useful as support for decision-making about redevelopment scenarios or remediation techniques. Specific approaches are required, however, to overcome particular modelling issues as related to the skewness of pollutant grade distributions or change of support. Making use of our practical experience, such an integrated geostatistical approach is proposed for modelling contaminated sites. It is illustrated by application to a recent actual case study.     

Deterministic and Probabilistic Stability Analysis of Soil Slope – A Case Study

This paper deals with the soil slope stability analysis along the road section (National Highway-05) near Luhri area, Himachal Pradesh, India. The area constantly experiences local as well as regional slides which enhances the siltation, reduce carrying capacity of the Sutlej river with time and further increases the water level on the banks of the slope. High traffic congestion puts the area at high risk zone and therefore, stability analysis was done using probabilistic as well as deterministic approach under static conditions through limit equilibrium method (LEM) and finite element method (FEM). FEM was used for stability analysis, mainly to obtain deformational characteristics, under static conditions and compared with LEM results. The results of both the methods help in identifying the zones of vulnerability in the case study. Further, the values of safety factor obtained from both the methods are in close approximation. The study also reveals that the slope is critically stable and a remedial measure has been suggested by modifying the geometry of the slope, which needs proper protection from any external factors like rainfall and earthquakes that may cause unforeseeable circumstances.     

Geochemical Baseline and Trace Metal Pollution of Soil in Panzhihua Mining Area

A total of 31 topsoil samples were systematically collected from the Panzhihuaminingarea including steel smelting,coal mining ,urban and rural districts.A normalization procedure was adopted to establish the environmental geochemical baseline models for this area.By using the above baseline models,the regional geochemical baseline values of As,Cr,Cu,Ni,Pb and Zn were determined.On the basis of the baselines,the enrichment factors were used to analyze the mechanism of trace metal pollution in topsoil from anthropogenic sources,and the results showed that the serious trace metal pollution is caused by human activities in coal mine,iron mine,smelting factory,tailing dam and other industrial districts in the Panzhihua area.     

Laboratory Investigation of the Effect of Initial Dry Density and Grain Size Distribution on Soil–Water Characteristic Curves of Wide-Grading Gravelly Soil

Wide-grading gravelly soils are often encountered in debris flow source areas. To perform stability analyses under rainfall conditions, the soil–water characteristic curves (SWCC) are significant. However, the studies for SWCC of wide-grading gravelly soils are rare. In order to investigate the effects of initial dry density and grain size distribution on the SWCCs of wide-grading gravelly, a large-scale osmotic column, allowing the measurement of both volumetric water content and matric suction at various levels, was fabricated for a series of osmotic column tests. The test data were best-fitted to Van Genuchten equation using a least-squares algorithm and found that both the initial dry density and grain size distribution had a greater effect on the SWCCs. An increase in the initial dry density resulted in an increase in water retention capacity. The air entry value and residual volumetric water content increased linearly with increases in the initial dry density, whereas the maximum slope of SWCC decreased linearly with increases in the initial dry density. The air entry value and residual volumetric water content increased linearly with increases in the fine content (particle diameter <0.075), whereas the maximum slope increases linearly with increases in the effective size, d ₁₀.     

Societal Responsibility and Development Trends of Global Soil Studies and the Provisions for China: Lessons from the Status of the 《World’s Soil Resources Report》

2015 is the International Year of Soil (IYS) adopted by the 378th Congress of the United Nations. The Status of the World’s Soil Resources was released by the Food and Agriculture Organization of the United Nations, which was the policy report about the status of the world soil resources for the first time. The universal values of the global community were strengthened by the challenges for the global society from the risk and safety of the change of soil quality, functions, services and soil health. One third of the world soil resources were suffering serious degradation, which could affect the food security in the future, regional development and local conflicts in the report. The major task of the global monitoring, regulation and management of the world soil resources and the social responsibility of supporting the sustainable soil management by education, research and technology development were highlighted. The social responsibility and global development trends of soil science and management strategies were discussed by the keywords, the distribution of contributing authors and the citation of the references, as well as the main contents of the report. The keywords distribution of the report showed that the focus of the soil research included the change of soil quality, processes, functions and services induced by the natural driving forces, human’s activity and soil degradation, as well as the hotspots covered soil carbon/nitrogen-water-biological pool and distribution related with the biogeochemistry, global climate change and ecosystem functions and human health. The number and structure of the cited papers showed that the integration research based on the mega-data analysis were the prominent development trend of the soil science. The geographic distribution of all the contributing authors showed that dominant discourse of the global soil science were grasped by the developed countries including Europe and the United States, China had just limited effects on the global soil science. It is urgent to promote China’s soil science research and the services for global society.     

Effect of Soil–Water Characteristic Parameters on Saturation Line and Stability of Slope

Rainfall infiltration is the main factor that causes slope instability. To study the effect of hydraulic parameters on the final saturation line and stability of slopes, a numerical slope model is established with a saturated–unsaturated seepage analysis method. Analysis results show the following, (1) When parameter a increases, the effective rainfall duration decreases linearly, and the ultimate safety factor increases gradually; when parameter m increases, the effective rainfall duration increases linearly, and the ultimate safety factor decreases linearly; when parameter n increases, both the effective rainfall duration and the ultimate safety factor decrease first and then remain stable. (2) When the saturated permeability coefficient decreases, the effective rainfall duration presents a crescent trend, and the ultimate safety factor decreases first and then remains the same after rainfall intensity exceeds the saturated permeability coefficient of soil. (3) When rainfall intensity is less than the saturated permeability coefficient of soil, the location of the final saturation line rises as the saturated permeability coefficient decreases and is thus independent of parameters a, m, and n.     

“Ecohydrology of Water controlled Ecosystems—Soil Moisture and Plant Dynamics”评介

水文学是众多地学分支中发展最快的学科之一，约40年前水文学开始成为一门研究流域水流运动物理规律的专门学科，30年前人类开始认识到水是控制全球气候的主要因素之一，三态水之间的转化和循环成为研究热点，在近10年内，人类进一步认识到：水循环强烈影响着氮、碳等元素的循环，陆地生物圈内水资源的可获得性控制着植物的生长、氮元素的提升以及碳蓄积速率，植被因素和水文循环开始同时受到气候、水文以及生态学研究组织的高度重视，水文学发展到了生态水文学阶段。生态水文学自诞生之日起就在朝着两个不同的方向发展：一类是由生态学家发起的集中于植被对微气候响应的研究，另一类是由水文学家发起的不同复杂程度的水文模型与植物模型耦合研究。如此看来生态水文学进一步的发展必将是：前者会不断增加观测试验的分类程度，而后者则会逐渐提高模型的复杂程度，两个方向交叉的可能性将很小。但Ignacio Rodriguez-hurbe与Amilcare Porporato吸收了成熟的非线性科学思想以及早期发展的降水模型随机理念，提出了一种在解释各种生物物理过程时既能保证其简单性又不失系统非线性本质的低维模型，为生态水文学的两个发展方向找到了一个交叉点，也为该学科创造了一个全新的学科增长点。     

Studyon Soil and Water Loss Characteristic of the Railway Construction in Mountain Area

The factor of human projectactivity is often the immediate cause resulting in soil and water loss． The Baoji-Lanzhou second railway inconstruction is an example．The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern China is studied systematically and that caused possibly by the road bed project，the road moat project，the field project，the tunnel project and the service road project inconstruction is probed．At the same time，the type，the intensity and influencing factor of soil and water loss in the northwest mountain railway construction are also studied．     

Study on Soil and Water Loss Characteristic of the Railway Construction in Mountain Area

The factor of human project activity is often the immediate cause resulting in soil and water loss. The Baoji-Lanzhou second railway in construction is an example. The soil and water loss law caused by earth and stone mountain railway engineering construction in the northwestern China is studied systematically and that caused possibly by the road bed project, the road moat project, the field project, the tunnel project and the service road project in construction is probed. At the same time, the type, the intensity and influencing factor of soil and water loss in the northwest mountain railway construction are also studied.     

Urban Soil Microbial Features and Their Environmental Significance as Exemplified by Aberdeen City,UK

Urban soil research has invoked great interest in recent years.Previous studies were mainly focused on urban soil physics and chemistry,and soil geography to constrain the source,distribution,transport and deposition of pollutants such as heavy metals and health-hazardous organic matter,bu t litte has been done on soil microbiology.In this paper,the authors reported the variation of microbial features in urban soils compared with those from adjacent rual areas.The results show great changes in basal respiration rates microbial biomass and ecophysiological parameters have taken place in urban environment because of the anthropogenic stress, thus activating the microorganisms.As a result,much more energy,carbon is consumed at a low utilization efficiency.So microbial biosensors can be used to indicate urban environmental pollution effectively.     

Dispersivity Identification and Modification with Lime of Soil in Huaaopao’s Water Conservancy Project

Geotechnical and Geological Engineering - Water-retaining structures built with or on dispersive soil may easily be destroyed then after dangerous accidents associated with dispersive soil...     

Environmental Geochemistry of Heavy Metal Contaminants in Soil and Stream Sediment in Panzhihua Mining and Smelting Area,Southwestern China

Mining and smelting activities are the main causes for the increasing pollution of heavy metals in soil, Water body and stream sediment. An environmental geochemical investiga-tion was carried out in and around the Panzhihua mining and smelting area to determine the ex-tent of chemical contamination in soil and sediment. The main objective of this study was to in-vestigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil andsediment and to assess the degree of pollution in the study area. The data of heavy metal con-centrations reveal that soils and sediments in the area have been slightly contaminated. Geo-chemical maps of Igeo of each heavy metal show that the contaminated sites are located in V-Ti-magnetite sloping and smelting, gangues dam. The pollution sources of the selected elementscome mainly from dusts resultant from mining activities and other three-waste-effluents. The areaneeds to be monitored regularly for trace metal, especially heavy metal enrichment.     

Investigation on Soil–Water Characteristic Curves of Untreated and Stabilized Highly Clayey Expansive Soils

The examination of hydromechanical behavior of expansive soil lies mostly within the unsaturated soil mechanics framework, which renders the study of its soil water characteristic curve (SWCC) a necessity. This paper evaluates the correlations of two physicochemical properties, pH and surface conductance, with the behavior of the SWCCs of four natural expansive soils and four stabilized soils. The effects of chemical stabilization and curing time on the SWCCs are also analyzed. The SWCCs and the corresponding parameters were obtained from pressure plate tests and a fitting model. It was found that pH and surface conductance together showed a good correlation with the air-entry related parameter, α, because they determine the formation of the diffuse double layer around fine particles or aggregates. The macroscopic behavior, in terms of unconfined compressive strength, free swell and swell pressure at optimum moisture content (OMC), was also evaluated and good correlations of these property values with the matric suction values at OMC were observed for the four natural untreated soils, while no correlation existed for the stabilized soils. The results and the discussion provide new insight to address physicochemical mechanisms that determine the macroscopic behavior of expansive soil.     

Distribution of Selenium in Corn and Its Relationship With Soil Selenium in Yutangba Mini—Landscape

Within the range of 0.01 km mini-landscape in Yutangba, Enshi, Hubei Province, the content of Se in corn is very high. The average Se contents in root, stem, leaf and seed of corn were estimated to be 4.36±3. 27mg/kg, 3.08±2.24 mg/kg, 9.74±7.62mg/kg, and 8.07±5.02mg/kg, respectively. The research results show that there is a significantly positive correlation between corn selenium and soil selenium, and thus according to the distribution of Se in corn, three subregions can be divided in Yutangba. The content of selenium in corn is controlled by that of soil. A little variation in selenium content in soil will lead to a considerable corresponding variation in corn. So it is deduced that the organs that contain relatively high Se in plants may be used as a sensitive selenium indicator of Se levels in the environment.     

Influence of Relative Density on Static Soil–Structure Frictional Resistance of Dry and Saturated Sand

Soil–structure frictional resistance is required while designing foundation systems and retaining walls. Although much more attention has been paid in recent years regarding soil–structure interaction for dynamic loading, highly conservative values of the static frictional resistance between soil and structure are used in design. Not much emphasis has been given lately to evaluate static frictional resistance between soil and structure. In this study, a well graded sand, as per USCS classification system, was prepared in the laboratory at different relative densities and moisture contents i.e. dry and saturated, and frictional resistances of those soils were measured. Those soil samples were also sheared against wood, concrete, and steel blocks and corresponding soil–structure frictional resistances were measured. Moreover, similar experiments were performed for saturated and loose poorly graded sand (SP), silty sand (SM) and poorly graded sand with silt (SP–SM). The study result shows that the difference between frictional resistance of soil and skin friction depends on the type of soil, relative density and the moisture content. Interestingly, shear envelopes for soil–soil and soil–structure shearing resistance exhibited curvature. The traditionally adopted soil–structure frictional resistance values adopted by various geotechnical manuals were found to be highly conservative.     

Using Remote Sensing and GIS Techniques to Study Soil Degradation Processes in North Shaanxi Province, China

Satellite image data and thematic map data were used to provide comprehensive views of surface-bound conditions such as soil and vegetation degradation. The current work applies a computerized parametric methodology, developed by FAO, UNEP and UNESCO to assess and evaluate soil degradation at 1 : 250 000 mapping scale. The study area is located in the arid and semi-arid zone of the northern part of Shaanxi Province in China, a region with considerable agricultural potential; Landsat TM images were utilized to provide recent data on land cover and use of the area. ARC/INFO and Arc-View softwares were used to manage and manipulate thematic data, to process satellite images, and tabular data source. ER mapper software is utilized to derive the normalized difference vegetation index (ND VI) values while field data to estimate soil erodibility (SE) factor. A system is established for rating soil parameters, slope, climate factor and human factor activity. The rating values serve as inputs into a modified universal soil loss equation (USLE) to calculate the present state and risk for soil degradation processes, namely soil wind erosion. The produced maps and tabular data show the risk and the present status of different soil degradation processes. The study area, in general, is exposed to high risk of wind erosion and high hazards of water erosion. Several desertification maps were produced, which reflect the desertification types persisting in the study area. Wind erosion, water erosion, vegetation degradation,physical degradation and salinization are the basic desertification maps, and others are combinations of these basic maps. In terms of statistic analysis, 33.75 % of the total land area (120. 330 0 ha) is considered as sand or sand dune, and not included in our analysis of desertification. About 29. 41% of the total land area has slight or moderate desertification and 37. 465 % is facing severe desertification.     

Discussion of ‘Soil creep effects on ground lateral deformation and pore water pressure under embankments’

Settlement analysis of field cases is normally studied based on parameters interpreted from laboratory samples influenced by varying degrees of sample disturbance. Such disturbance is more pronounced in natural soft clays and could significantly affect the engineering properties of the soil, e.g. the over consolidation ratio (OCR) and compressibility index (C_c). Hence, it is vital to understand the role of sample quality in relation to soil characterisation for long-term settlement analyses. In this work, this is numerically illustrated by use of a simple creep model along with realistic parameter selection. This work takes its starting point on critical discussion of the work presented by Fatahi et al. (2013) and uses the opportunity to further clarify some important aspects of settlement/creep analyses in light of sample quality and parameter interpretation valid for the corresponding constitutive model.