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Significance of compaction time delay on compaction and strength characteristics of sulfate resistant cement-treated expansive soil

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第5期13卷 1193-1202页

作者： P.Sriram Karthick Raja T.Thyagaraj department of Civil Engineering Indian Institute of Technology MadrasChennai600036India

The addition of cement for stabilization of expansive soils is one of the most commonly used *** with every calcium-based stabilizer,the time delay between the physical mixing of the stabilizer and compaction plays an important role in achieving the desired results after ***,a clear insight on the determination of optimum time delay for achieving the maximum desired compaction properties of cement-stabilized soils is yet to be ***,the recent studies highlighted the use of sulfate to mitigate the negative effect of compaction time *** only drawback with the use of sulfate along with calcium-based stabilizers is the formation of ettringite,which deteriorates the stabilized soil *** view of this,the present study is aimed at using the sulfate resistant cement(SRC)as a stabilizer along with the controlled addition of sulfate solutions to mitigate the negative effect of compaction time delay in stabilizing the expansive *** bring out the above effects,three periods of time delays(0 h,6 h and 24 h)and three sulfate concentrations of 5000 parts per million(ppm),10,000 ppm and 20,000 ppm were *** experimental results showed that the delay in compaction resulted in the formation of clogs and reduction of strength of SRC-stabilized expansive *** sulfate addition to SRC-stabilized expansive soil,the formation clogs was not curtailed and resulted in the formation of ettringite *** formations were captured with the help of scanning electron microscope(SEM)images and validated with electron dispersive X-ray spectroscopy(EDAX)***,an attempt is also made to explain the mechanism of density and strength reduction with the aid of physico-chemical properties and mercury intrusion porosimetry(MIP)studies.

关键词： Compaction time delay Ettringite Sulfate resistant cement(SRC) Mercury intrusive porosimetry(MIP) Sulfate

Daylighting the Role of soil Ecosystem Services (SoESs) for Climate Change Adaptation

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Journal of Geoscience and Environment Protection 2023年第9期11卷 367-385页

作者： Merve Yilmaz Mutlu Azime Tezer department of Urban Planning Istanbul Technical University Istanbul Türkiye

soil plays a critical role in providing various Ecosystem Services (ESs) that are beneficial to humanity. Services such as clean air, water, and food production are directly or indirectly provided through soils. The soil ecosystem is considered as the most important Carbon (C) sink in terrestrial systems, and human activities, particularly land use, impact ESs and increase carbon emissions into the atmosphere. Mapping ESs and assessing the risks associated with climate-related hydro-meteorological hazards and soil degradation can contribute to making spatial decisions for planning more climate-resilient. Indeed, strategies based on soil ecosystem services provide valuable insight for enhancing the resilience of spatial decision-making in adapting to climate change. The aim of this article is to illuminate the significance of SoES in the spatial planning decision-making for better integration and adaptation into climate change adaptation policies as a decision support tool. In this regard, ESs related to climate change were highlighted and mapped, and their suitability for settlement development decisions and relation with ESs’ integrity were assessed through weighted multi-criteria analysis, while discussing the contributions of this process to climate change adaptation. Incorporating Social-Ecological Systems (SoESs) factors into suitability analysis is crucial for comprehensive urban planning, particularly in the context of climate change adaptation and environmental protection. In this study, two settlement suitability analyses were conducted. The first analysis considered various factors, such as land use, soil classification, DEM (Digital Elevation Model), and slope. The second analysis utilized weighted climate-related SoES indicators, including soil depth, soil carbon sequestration capacity, soil loss, flood risk, temperature, and precipitation. The results revealed that the SoES-based suitability analysis was more stringent in identifying suitable areas for

关键词： Spatial Planning Suitability Analysis Environment Ecological Footprints Resillience

Multi-criteria decision making methods to address rural land allocation problems:A systematic review

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International soil and water Conservation Research 2021年第4期9卷 490-501页

作者： Sintayehu Legesse Gebre Dirk Cattrysse Esayas Alemayehu Jos Van Orshoven department of Mechanical Engineering Center for Industrial ManagementTraffic&InfrastructureKU Leuven(University of Leuven)Celestijnenlaan 3003001LeuvenBelgium department of Earth and Environmental Sciences Division of ForestNature and LandscapeKU Leuven(University of Leuven)Celestijnenlaan 200E3001LeuvenBelgium department of Natural Resource Management Jimma UniversityJimmaEthiopia department of Civil and Environmental Engineering JITJimma UniversityJimmaEthiopia

Land allocation has been an important issue in land use planning research *** allocation involves different multifunctional activities of maximizing environmental,economic and social ***-criteria decision making(MCDM)method is the most popular tool to optimize land allocation problems by considering decision variables,conflicting objectives,and ***,decision-makers face problems on how to optimize the land allocation while minimizing the conflicting trade-offs existing in the decision *** this review study,we aim at identifying and extracting information on MCDM methods to solve land allocation problems from English language articles published between 2000 and 2019 and indexed by four scientific literature databases(Web of Science,Science Direct,Scopus,Google scholar).To this end,we applied a systematic literature review approach,*** Preferred Reporting Items for Systematic Reviews and Meta-Analysis procedure(Moher et al.,2009),with a structured database search expression.120 articles were selected of which,after careful screening of title,keywords and abstract,69 were retained for detailed *** review study report compiles comprehensive information by classifying the papers into application area,optimization objectives,criteria used,decision techniques,publication year and study *** summary,we found that in the last two decades,the use of the MCDM method has increased,particularly in Europe and ***(analytical hierarchal process)is frequently used for multi-attribute land allocation problems with reference to ecotourism and ecosystem ***(linear programming)and SA(simulating annealing)methods are predominantly used to optimize multi-objectives complex agricultural and forest land allocation problems respectively.

关键词： Database Allocation Decision techniques PRISMA

Utilization of Compost as a soil Amendment to Increase soil Health and to Improve Crop Yields

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Open Journal of soil Science 2022年第6期12卷 216-224页

作者： Jerome Wright Scott Kenner Bret Lingwall department of Civil Engineering South Dakota Mines Rapid City USA

Compost amendments have remarkable potential for improving soil structure, porosity and water holding capacity. soil health is the ability to function as a living system, to sustain plant and animal productivity, to enhance water and air quality, and to promote plant and animal health. soil health can be estimated by measuring the total living microbial biomass, retained carbon, odor, and texture. Poor or deteriorating soil health is threatening food security. The potential for compost to reverse these negative trends is transformative if means and methods for large scale composting and compost amendments can be developed. A field-scale compost soil amendment project was implemented in Rapid City, South Dakota. The compost was added to a soil plot at 5 wt% and 10 wt% and the results were compared with an adjacent untreated plot without any compost addition. Measurements of soil health characteristics indicate that compost amendments improve soil health, crop yields, and soil water content. Treating soils with compost has the potential to reverse global deteriorating soil health.

关键词： Compost Crop Yields soil Health Food Security

Effects of Charcoal Production on soil Physicochemical Properties in Moro Local Government Area of Kwara State, Nigeria

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Journal of Environmental Protection 2022年第2期13卷 220-232页

作者： Abdulrasheed Abidemi Adio Abiola Omolewa Saliu Mariam Abiola Akanbi-Gada Bolaji Abiodun Najeemdeen department of Plant and Environmental Biology Kwara State University Malete Nigeria

Charcoal production is a major economic activity in rural Kwara State, North-Central Nigeria. Given that it generally involves the use of traditional earth kilns, this study was designed to investigate the effects of charcoal production on the physical and chemical properties of soil. Replicate soil core samples were collected within a depth of 0 - 20 cm from 19 charcoal kiln sites (CKS) and 19 adjacent control sites (ACS) across five administrative districts in the study area. These samples were subjected to laboratory analysis to determine their physical and chemical qualities and then t-test was used to statistically compare the CKS and ACS soils. There was no significant difference in soil texture between both sites. However, CKS soil pH and electrical conductivity significantly increased (p 0.05) due to charred biomass introduced to soils by the process of charcoal production. The CKS cation exchange capacity, Ca and Mg increased significantly (p soil physical and chemical properties for agriculture purposes. However, further studies are suggested to understand its effects on vegetation cover and soil biota.

关键词： Charcoal Production Earth Kiln soil Properties Guinea Savanna soil Properties

Discrete element modeling of sand behavior in a biaxial shear test

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第9期9卷 1176-1183页

作者： Zhi-yi HUANG Zhong-xuan YANG Zhen-yu WANG department of Civil Engineering Zhejiang University Hangzhou 310027 China MOE Key Laboratory of Soft soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310027 China department of Civil Engineering The University of Hong Kong Hong Kong China

The mechanical behavior of sand is very complex, and depends on factors including confining pressure, density, and drainage condition. A soil mass can be contractive or dilative when subjected to shear loading, and eventually reaches an ultimate state, referred to as the critical state in soil mechanics. Conventional approach to explore the mechanical behavior of sand mainly relies on the experimental tests in laboratory. This paper gives an alternative view to this subject using discrete element method (DEM), which has attracted much attention in recent years. The implementation of the DEM is carried out by a series of numerical tests on granular assemblies with varying initial densities and confining pressures, under different test configurations. The results demonstrate that such numerical simulations can produce correct responses of the sand behavior in general, including the critical state response, as compared to experimental observations. In addition, the DEM can further provide details of the microstructure evolutions during shearing processes, and the resulting induced anisotropy can be fully captured and quantified in the particle scale.

关键词：土壤性质土力学临界状态显微结构

Effect of chlorpyrifos on soil microbial populations and enzyme activities

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Journal of Environmental Sciences 2006年第1期18卷 4-5页

作者： SHAN Min FANG Hua WANG Xiao FENG Bo CHU Xiao-qiang YU Yun-long department of Plant Protection College of Agriculture and Biotechnology Zhejiang University Hangzhou 310029 China

Chlorpyrifos is an organophosphate pesticide that acts as an insecticide-acaricide by ingestion, contact, and inhalation, and is now widely used in greenhouse for the control of pests. The dissipation of chlorpyrifos in crops such as orange fruit （Martinez-Vidal et al., 1998）, tomatoes（Aysal et al., 1999）, soil and its effects on soil microbial characteristics （Singh et al., 2002） has been reported frequently. However, little information is available to describe impacts of chlorpyrifos on soil microbial population and enzyme activity in greenhouse. In this study, the effect of chlorpyrifos on soil bacteria, fungi, actinomycetes, and soil enzyme activity was investigated.

关键词： chlorpyrifos microorganism soil enzyme

Glacial-Interglacial Atmospheric CO_2 Change——The Glacial Burial Hypothesis

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Advances in Atmospheric Sciences 2003年第5期20卷 677-693页

作者： Ning ZENG department of Meteorology and Earth System Science Interdisciplinary Center, University of Maryland, USA department of Meteorology and Earth System Science Interdisciplinary Center University of Maryland USA

Organic carbon buried under the great ice sheets of the Northern Hemisphere is suggested to be the missing link in the atmospheric CO2 change over the glacial-interglacial cycles. At glaciation, the advancement of continental ice sheets buries vegetation and soil carbon accumulated during warmer periods. At deglaciation, this burial carbon is released back into the atmosphere. In a simulation over two glacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean carbon model forced by reconstructed climate change, it is found that there is a 547-Gt terrestrial carbon release from glacial maximum to interglacial, resulting in a 60-Gt (about 30-ppmv) increase in the atmospheric CO2, with the remainder absorbed by the ocean in a scenario in which ocean acts as a passive buffer. This is in contrast to previous estimates of a land uptake at deglaciation. This carbon source originates from glacial burial, continental shelf, and other land areas in response to changes in ice cover, sea level, and climate. The input of light isotope enriched terrestrial carbon causes atmospheric δ13C to drop by about 0.3‰ at deglaciation, followed by a rapid rise towards a high interglacial value in response to oceanic warming and regrowth on land. Together with other ocean based mechanisms such as change in ocean temperature, the glacial burial hypothesis may offer a full explanation of the observed 80–100-ppmv atmospheric CO2 change.

关键词： atmospheric CO2 ice age glacial burial hypothesis climate

Regulation of Phosphate Starvation Responses in Plants： Signaling Players and Cross-Talks

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Molecular Plant 2010年第2期3卷 288-299页

作者： Hatem Rouached A. Bulak Arpat Yves Poirier department of Plant Molecular Biology University of Lausanne CH-1015 Lausanne Switzerland

Phosphate （Pi） availability is a major factor limiting growth, development, and productivity of plants. In both ecological and agricultural contexts, plants often grow in soils with low soluble phosphate content. Plants respond to this situation by a series of developmental and metabolic adaptations that are aimed at increasing the acquisition of this vital nutrient from the soil, as well as to sustain plant growth and survival. The development of a comprehensive understanding of how plants sense phosphate deficiency and coordinate the responses via signaling pathways has become of major interest, and a number of signaling players and networks have begun to surface for the regulation of the phosphate- deficiency response. In practice, application of such knowledge to improve plant Pi nutrition is hindered by complex cross-talks, which are emerging in the face of new data, such as the coordination of the phosphate-deficiency signaling networks with those involved with hormones, photo-assimilates （sugar）, as well as with the homeostasis of other ions, such as iron. In this review, we focus on these cross-talks and on recent progress in discovering new signaling players involved in the Pi-starvation responses, such as proteins having SPX domains.

关键词： Phosphate signaling SPX iron phytohormones.