Literatura académica sobre el tema "Deep soil layers"
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Artículos de revistas sobre el tema "Deep soil layers"
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Fei, Wang, Xu Yilu, Yang Xiaodong, Liu Yanju, Lv Guang-Hui y Yang Shengtian. "Soil water potential determines the presence of hydraulic lift of Populus euphratica Olivier across growing seasons in an arid desert region". Journal of Forest Science 64, No. 7 (1 de agosto de 2018): 319–29. http://dx.doi.org/10.17221/49/2018-jfs.
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Hydraulic lift (HL) of deep-rooted plants is a water adaptation phenomenon to extreme drought conditions which would subsequently improve the survival of shallow-rooted plants in an arid desert area. There is an ongoing debate on whether the difference in water potential between plant roots and soils determine the presence of HL, thus considerable research efforts are needed to improve our understanding. In this study, we used the Ryel model and comparative analysis to determine the changes in soil water potential (SWP), the soil layer of obtaining water from plant roots (SLOW), the amount water released from plant roots into soils, and the total amount of release water of HL (H<sub>T</sub>) of five stratified soil layers at different depths (i.e. 0–10, 10–40, 40–70, 70–100 and 100–150 cm) across plant growing season (i.e. June, August and October). The results showed that SLOW always appeared in the lowest SWP soil layer, and that lowest SWP differed among soil layers. The lowest SWP soil layer and SLOW shifted from shallow to deep soil layers across the growing seasons. Additionally, H<sub>T</sub> decreased across the growing seasons. Fine root biomass decreased in shallow whereas increased in deep soil layers across growing seasons. Our results proved the water potential difference among soil layers determined the presence of HL in an arid desert region. The changes in water potential difference among soil layers might shift the lowest SWP soil layer from shallow to deep soil layers, and as a consequent decrease H<sub>T</sub> across plant growing seasons.
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S. P., Pogorilyy, Prysyazhnyi V. G. y Shkarivskyi G. V. "Research of the reasons of excessing the air and underground soil layers of the deep blocked soils of black earth". Mehanization and electrification of agricultural, n.º 15(114) (2022): 124–30. http://dx.doi.org/10.37204/0131-2189-2022-15-15.
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Purpose. Investigation of the causes of compaction of arable and subsoil soil layers of deep podzolic chernozems. Methods. Experimental studies of the density of arable and subsoil soil layers of deep podzolic chernozems with subsequent processing of the results on a PC. Results. The results of experimental researches of formation of the overcompacted layers of chernozems of deep podzolic depending on ways and means of influence on them are stated. Conclusions. As a result of research it is established that on deep chernozem chernozems the maximum depth of overcompacted layers formed by self-compaction for virgin soil does not exceed 30 cm, and man-made impact on these soils leads to overcompaction of layers up to 40 cm deep. Possible areas of further research on this issue are the study of technical and technological aspects of ensuring acceptable for optimal plant development density. Keywords: overcompaction, arable and subsoil layers of soil, division of chernozems deep podzolic, running systems, soil density.
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Zhang, Shu-Wen, Xubin Zeng, Weidong Zhang y Michael Barlage. "Revising the Ensemble-Based Kalman Filter Covariance for the Retrieval of Deep-Layer Soil Moisture". Journal of Hydrometeorology 11, n.º 1 (1 de febrero de 2010): 219–27. http://dx.doi.org/10.1175/2009jhm1146.1.
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Abstract Previous studies have demonstrated that soil moisture in the top layers (e.g., within the top 1-m depth) can be retrieved by assimilating near-surface soil moisture observations into a land surface model using ensemble-based data assimilation algorithms. However, it remains a challenging issue to provide good estimates of soil moisture in the deep layers, because the error correlation between the surface and deep layers is low and hence is easily influenced by the physically limited range of soil moisture, probably resulting in a large noise-to-signal ratio. Furthermore, the temporally correlated errors between the surface and deep layers and the nonlinearity of the system make the retrieval even more difficult. To tackle these problems, a revised ensemble-based Kalman filter covariance method is proposed by constraining error covariance estimates in deep layers in two ways: 1) explicitly using the error covariance at the previous time step and 2) limiting the increase of the soil moisture error correlation with the increase of the vertical distance between the two layers. This method is then tested at three separate point locations representing different precipitation regimes. It is found that the proposed method can effectively control the abrupt changes of error covariance estimates between the surface layer and two deep layers. It significantly improves the estimates of soil moisture in the two deep layers with daily updating. For example, relative to the initial background error, after 150 daily updates, the error in the deepest layer reduces to 11.4%, 32.3%, and 27.1% at the wet, dry, and medium wetness locations, only reducing to 62.3%, 80.8%, and 47.5% with the original method, respectively. However, the improvement of deep-layer soil moisture retrieval is very slight when the updating frequency is reduced to once every three days.
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Xie, Haixia, Shuai He, Chuanqin Huang y Wenfeng Tan. "Origin of Smectite in Salinized Soil of Junggar Basin in Xinjiang of China". Minerals 9, n.º 2 (10 de febrero de 2019): 100. http://dx.doi.org/10.3390/min9020100.
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In this paper, salinized soils with different degrees of salinity are sampled in Junggar Basin of Xinjiang of China. The X-ray diffraction, transmission electron microscopy, and inductively coupled plasma mass spectrometry are employed to investigate the morphology and distribution characteristics of smectite in salinized soil profiles. In the salinized soil profiles of this region, crystals of smectite are poor where lattice fringes are not parallel. In all soil layers, the content of smectite in the soil increases with the decrease in content of illite, which has demonstrated significant negative correlation (r = 0.79, n = 50, p < 0.01) between illite and smectite. This phenomenon has demonstrated that illite may be transformed into smectite in salinized soils of studied regions. In general, the transformation process of illite to smectite is affected by climate condition. The δ18O values of secondary carbonate in the 0–10 cm soil layers is higher than that in deep soil layers, which indicates that δ18O concentrates in surface soil and reflects temperature rise during soil layer formation. The δ13C values of secondary carbonate and soil organic matter in 0-10cm soil layers are higher than that in deep soil layers. It indicates that C4 plants were the main plants, which reflects that the climate was relatively dry during the formation of the surface soil. Thus, the climate during the surface soil formation is arid, which is not conducive for leaching K+ from illite of the 0–10 cm soil to form smectite. As a result, the content of the smectite becomes lowest in the soil surface. In the relative humid condition of deep soil layers, the K+ of the illite of the soil would be relative easily leached and more smectite may be formed. Furthermore, the presence of salt in the salinized soil would promote the formation of smectite in Junggar Basin of Xinjiang. A lot of Ca2+, Na + and Mg2+ in the soil solution of salinized soils would enter into the illite and occupy K+ positions. The studied result shows that the amount of smectite would increase with the increase of salt below 10cm of the soil layer, where the amount of smectite would be significantly correlated with soil electrical conductivity (r = 0.64, n = 39, p < 0.01). In the Junggar Basin in Xinjiang, therefore, the salinized soil below 10 cm would have the necessary water conditions and chemical components for illite transformation to smectite.
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Juraev, Fazliddin U., Umeda X. Umedova, Shuxrat B. Shodiyev, Amrillo A. Fayziyev y Abrorjon A. ugli Savriddinov. "Deep tillage using bioselvent preparation before soil washing". BIO Web of Conferences 82 (2024): 01016. http://dx.doi.org/10.1051/bioconf/20248201016.
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The article presents a new tool for deep soil tillage, as well as design, operation principles and parameters of two-tier deep tillage device used in the process of deconsolidation of gypsum and dense soil layers according to a special technology with active rotating working bodies and the technology of its application, while improving the ameliorative state of saline soils using the biosolvent chemical composition with spraying on the soil surface and inner layer, before the autumn washing with salt, and washes out harmful salts from the soil. The developed tools and the parameters of their device for deep tillage of the soil and the technology of its application, the results of theoretical and experimental studies are presented.
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Wang, Shaofei, Xiaodong Gao, Min Yang, Gaopeng Huo, Xiaolin Song, Kadambot H. M. Siddique, Pute Wu y Xining Zhao. "The natural abundance of stable water isotopes method may overestimate deep-layer soil water use by trees". Hydrology and Earth System Sciences 27, n.º 1 (4 de enero de 2023): 123–37. http://dx.doi.org/10.5194/hess-27-123-2023.
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Abstract. Stable water isotopes have been used extensively to study the water use strategy of plants in various ecosystems. In deep vadose zone (DVZ) regions, the rooting depth of trees can reach several meters to tens of meters. However, the existence of roots in deep soils does not necessarily mean the occurrence of root water uptake, which usually occurs at a particular time during the growing season. Therefore, quantifying the contribution of deep-layer soil water (DLSW) in DVZ regions using the natural abundance of stable water isotopes may not be accurate because this method assumes that trees always extract shallow- and deep-layer soil water. We propose a multi-step method for addressing this issue. First, isotopic labeling in deep layers identifies whether trees absorb DLSW and determines the soil layer depths from which trees derive their water source. Next, we calculate water sources based on the natural abundance of stable isotopes in the soil layer determined above to quantify the water use strategy of trees. We also compared the results with the natural abundance of stable water isotopes method. The 11- and 17-year-old apple trees were taken as examples for analyses on China's Loess Plateau. Isotopic labeling showed that the water uptake depth of 11-year-old apple trees reached 300 cm in the blossom and young fruit (BYF) stage and only 100 cm in the fruit swelling (FSW) stage, whereas 17-year-old trees always consumed water from the 0–320 cm soil layer. Overall, apple trees absorbed the most water from deep soils (>140 cm) during the BYF stage, and 17-year-old trees consumed more water in these layers than 11-year-old trees throughout the growing season. In addition, the natural abundance of stable water isotopes method overestimated the contribution of DLSW, especially in the 320–500 cm soil layer. Our findings highlight that determining the occurrence of root water uptake in deep soils helps to quantify the water use strategy of trees in DVZ regions.
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Shi, Ming, Lianjin Tao y Zhigang Wang. "Study on the Influence of Deep Soil Liquefaction on the Seismic Response of Subway Stations". Applied Sciences 14, n.º 6 (9 de marzo de 2024): 2307. http://dx.doi.org/10.3390/app14062307.
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Subway systems are a crucial component of urban public transportation, especially in terms of safety during seismic events. Soil liquefaction triggered by earthquakes is one of the key factors that can lead to underground structural damage. This study investigates the impact of deep soil liquefaction on the response of subway station structures during seismic activity, aiming to provide evidence and suggestions for earthquake-resistant measures in underground constructions. The advanced finite element software PLAXIS was utilized for dynamic numerical simulations. Non-linear dynamic analysis methods were employed to construct models of subway stations and the surrounding soil layers, including soil–structure interactions. The UBC3D-PLM liquefaction constitutive model was applied to describe the liquefaction behavior of soil layers, while the HS constitutive model was used to depict the dynamic characteristics of non-liquefied soil layers. The study examined the influence of deep soil liquefaction on the dynamic response of subway station structures under different seismic waves. The findings indicate that deep soil liquefaction significantly increases the vertical displacement and acceleration responses of subway stations compared to non-liquefied conditions. The liquefaction behavior of deep soil layers leads to increased horizontal effective stress on both sides of the structure, thereby increasing the horizontal deformation of the structure and posing a potential threat to the safety and functionality of subway stations. This research employed detailed numerical simulation methods, incorporating the non-linear characteristics of deep soil layer liquefaction, providing an analytical framework based on regulatory standards for evaluating the impact of deep soil liquefaction on the seismic responses of subway stations. Compared to traditional studies, this paper significantly enhances simulation precision and practical applicability. Results from this research indicate that deep soil layer liquefaction poses a non-negligible risk to the structural safety of subway stations during earthquakes. Therefore, the issue of deep soil liquefaction should receive increased attention in engineering design and construction, with effective prevention and mitigation measures being implemented.
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Na, Li, Risu Na, Yongbin Bao y Jiquan Zhang. "Time-Lagged Correlation between Soil Moisture and Intra-Annual Dynamics of Vegetation on the Mongolian Plateau". Remote Sensing 13, n.º 8 (15 de abril de 2021): 1527. http://dx.doi.org/10.3390/rs13081527.
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Soil moisture is a reliable water resource for plant growth in arid and semi-arid regions. Characterizing the interaction between soil moisture and vegetation is important for assessing the sustainability of terrestrial ecosystems. This study explores the spatiotemporal characteristics of four soil moisture layers (layer 1: 0–7 cm, layer 2: 7–28 cm, layer 3: 28–100 cm, and layer 4: 100–289 cm) and the time-lagged correlation with the normalized difference vegetation index (NDVI) for different vegetation types on an intra-annual scale on the Mongolian Plateau (MP). The most significant results indicated that: (1) the four layers of soil moisture can be roughly divided into rapid change (layers 1 and 2), active (layer 3), and stable (layer 4) layers. The soil moisture content in the different vegetation regions was forest > grassland > desert vegetation. (2) The soil moisture in layer 1 showed the strongest positive correlation with NDVI in the whole area; meanwhile, the soil moisture of layers 2 and 3 showed the strongest negative correlation with the NDVI mainly in grassland and desert, and layer 4 showed the strongest negative correlation with the NDVI in the forest. (3) Mutual responses of NDVI and deep layer soil moisture required a longer time compared with the shallow layer. In the annual time scale, the NDVI was affected by the change in soil moisture in most of the study area, except for coniferous forest and desert vegetation regions. (4) Under the different stages of vegetation change, the soil moisture changes advance than NDVI about 3 months during the greening stage, while the NDVI changes advance than soil moisture by 0.5 months during the browning stage. Regardless of the stage, changes in soil moisture are initiated from the shallow layer and advance to the deep layer. The results of this study provide deep insight into the relationship between soil moisture and vegetation in arid and semi-arid regions.
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Wei, Di, Yang Zhang, Yiwen Li, Yun Zhang y Bo Wang. "Hydrothermal Conditions in Deep Soil Layer Regulate the Interannual Change in Gross Primary Productivity in the Qilian Mountains Area, China". Forests 14, n.º 12 (12 de diciembre de 2023): 2422. http://dx.doi.org/10.3390/f14122422.
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The variability in soil hydrothermal conditions generally contributes to the diverse distribution of vegetation cover types and growth characteristics. Previous research primarily focused on soil moisture alone or the average values of soil hydrothermal conditions in the crop root zone (0–100 cm). However, it is still unclear whether changes in gross primary productivity (GPP) depend on the hydrothermal conditions at different depths of soil layers within the root zone. In this study, the soil hydrothermal conditions from three different layers, surface layer 0–7 cm (Level 1, L1), shallow layer 7–28 cm (Level 2, L2), and deep layer 28–100 cm (Level 3, L3) in the Qilian Mountains area, northwestern China, are obtained based on ERA5-Land reanalysis data. The Sen-MK trend test, Pearson correlation analysis, and machine learning algorithm were used to explore the influence of these three soil hydrothermal layers on GPP. The results show that soil moisture values increase with soil depth, while the soil temperature values do not exhibit a stratified pattern. Furthermore, the strong correlation between GPP and deep soil hydrothermal conditions was proved, particularly in terms of soil moisture. The Random Forest feature importance extraction revealed that deep soil moisture (SM-L3) and surface soil temperature (ST-L1) are the most influential variables. It suggests that regulations of soil hydrothermal conditions on GPP may involve both linear and nonlinear effects. This study can obtain the temporal and spatial dynamics of soil hydrothermal conditions across different soil layers and explore their regulations on GPP, providing a basis for clarifying the relationship between soil and vegetation in arid mountain systems.
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Jamshed, Muhammad Ammar. "Analyze Soil Fertility using Deep Learning Convolutional Neural Networks". Shanlax International Journal of Arts, Science and Humanities 10, n.º 3 (1 de enero de 2023): 1–5. http://dx.doi.org/10.34293/sijash.v10i3.5281.
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This research revolves around how plant soil potential can be further discovered and used for farming through detection of relevant nutrients and chemicals within the soil landscapes within areas and even desert climates and how we can improve land soil fertility of the purpose of farming both using Convolutional neural networks which process of imagery in layers and predictive detections of objects within image backgrounds and frontal lobes. When we view layers for farming beneath the surface to understand suitability of farming done on top. The general model applied can be summarized as follows: As shown In Appendix 1a, we can see the various layers soil has to assess the possibility of nutrient provision for farming [2]. The Objective is to examine availability of plant nutrients using convolution of Nueral networks to classify open farmlands through image analysis and layering. Convolution Nueral networks is divided into four steps starting with input of images, drafting a convolution layer, creating a pooling layer and flattening the Nueral network. It can be performed as a machine learning Algorithmic procedure with Python as well as R programming. CNN divides the images into pixels, edges, frontal lobes and shading through the support of power machine learning libraries and packages like Tensorflow and Keras.
Tesis sobre el tema "Deep soil layers"
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Silva, Vinicius Evangelista. "Atributos do solo e desenvolvimento radicular em plantações de eucalipto no Brasil /". Ilha Solteira, 2019. http://hdl.handle.net/11449/182207.
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Orientador: Salatier BuzettiResumo: O desenvolvimento radicular em plantações de eucalipto tem sido apontado como uma das estratégias cruciais para sua adaptação e crescimento, em especial, em condições tropicais, que possuem solos pobres em nutrientes. Neste contexto, torna-se extremamente importante avaliar o perfil do solo nestas plantações, a luz de uma perspectiva de fornecimento de nutrientes e água para as plantações de eucalipto. Tendo isto em vista, especificamente nesta tese, dois trabalhos foram conduzidos para avaliar os atributos do solo e o desenvolvimento radicular em plantações de eucalipto no brasil, a saber: 1) Disponibilidade de Água no Solo em Plantios de Eucalipto em uma Cronossequência, e suas Relações com a Produtividade e Densidade Básica da Madeira e suas Estimativas Através de Redes Neurais Artificiais no Brasil; 2) Padrões e Distribuição Vertical dos Atributos do Solo na Plantação de Eucalipto no Brasil. A rede experimental completa possui 34 experimentos plantados em um gradiente climático no Brasil e 2 locais no Uruguai, com 36 locais experimentais no total. Avaliaram-se sítios desde baixo incremento médio anual (13,7 m³ ha-1 ano-1, 61% abaixo da média nacional de produtividade), até sítios com elevada produtividade com IMA de 67,2 m³ há-1 ano-1 (92% acima da média nacional de produção de madeira). No trabalho 1, avaliaram-se14 experimentos, e no trabalho 2, 4 experimentos, todos eles ao longo de um forte gradiente climático no Brasil. No caso do trabalho 1 foram avaliados atributos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The root development in eucalyptus plantations has been pointed out as one of the crucial strategies for their adaptation and growth, especially in tropical conditions, which have nutrient poor soils. In this context, it is extremely important to evaluate the soil profile in these plantations, considering a nutrient and water supply perspective for eucalyptus plantations. With this in mind, specifically in this thesis, two studies were conducted to evaluate soil attributes and root development in eucalyptus plantations in Brazil, namely: 1) Availability of Soil Water in Eucalyptus Plantations in a Chronosequence, and their Relationships with the Productivity and Basic Density of Madeira and its Estimates through Artificial Neural Networks in Brazil; 2) Patterns and Vertical Distribution of Soil Attributes in Eucalyptus Plantation in Brazil. The complete experimental network has 34 experiments planted in a climatic gradient in Brazil and 2 sites in Uruguay, with 36 experimental sites in total. Sites were evaluated from low average annual increment (13.7 m³ ha-1 year-1, 61% below the national average of productivity), to sites with high productivity with an IMA of 67.2 m³ ha-1 year -1 (92% above the national average of wood production). In work 1, 14 experiments were evaluated, and in the work 2, 4 experiments, all of them along a strong climatic gradient in Brazil. In the case of work 1, physical attributes of the soils (clay, silt, total sand, field capacity, permanent wiltin... (Complete abstract click electronic access below)
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El, Mekdad Fatima. "La rhizodéposition dans les horizons profonds du sol peut-elle permettre de stocker du carbone ?" Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS086.pdf.
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L'augmentation des émissions anthropiques de CO2 dans l'atmosphère accélère le changement climatique. Les sols contiennent trois fois plus de carbone que l'atmosphère et constituent donc un réservoir d'importance cruciale pour la régulation du climat. Il existe actuellement une réflexion pour stocker le carbone dans les couches profondes du sol, notamment via la rhizodéposition des plantes. Nous avons donc mené une expérience au CEREEP-Ecotron Ile-de-France pour quantifier les apports, et la persistance, du carbone rhizodéposé par les plantes à l'aide d'un marquage continu au 13C-CO2. Pour ce faire, deux variétés de blé aux systèmes racinaires contrastés ont été plantés dans des mésocosmes et cultivés pendant une saison de croissance complète et sous atmosphère enrichie en 13C. Nos objectifs étaient de quantifier le flux de carbone de l'atmosphère vers le sol et de mesurer sa persistance à court terme. Nos résultats suggèrent que la variété ancienne Plantahof rhizodépose une quantité plus élevée de carbone par rapport à la variété récente Nara notamment en profondeur. Cependant, le carbone apporté au sol par ces deux variétés a conduit à des pertes par minéralisation et des priming effects similaires. Ainsi, le bilan total du carbone était plus affecté par la profondeur du sol que les variétés utilisées dans l'étude. Par ailleurs, j'ai étudié, à partir d'une analyse bibliographique, la distribution selon la profondeur des activités enzymatiques hydrolases et oxydoréductases impliquées dans les cycles du carbone, de l'azote et du phosphore en fonction de la profondeur du sol. Les résultats de cette analyse ont montré que les profils d'activité dépendaient très fortement de la façon dont ces activités étaient exprimées, avec des activités qui diminuent avec la profondeur lorsqu'exprimées par masse de sol alors qu'elles sont plutôt stables, voire augmentent, lorsque exprimé par rapport à la biomasse microbienne. Pris dans leur ensemble, ces résultats montrent que la prise en compte du fonctionnement sur l'intégralité de la colonne de sol est indispensable pour comprendre la dynamique du carbone dans les écosystèmes terrestresIncreasing anthropogenic emissions of CO2 to the atmosphere are accelerating climate change. These emissions could be partially compensated by carbon fixation in the oceans, vegetation and soils. In particular, soils contain three times more carbon than the atmosphere, and therefore play a crucial role in climate regulation. It has been suggested that storing carbon in the deep layers of the soil, via rhizodeposition of plants, may be a useful avenue to pursue in order to mitigate climate change. We therefore conducted an experiment at CEREEP-Ecotron Ile-de-France to quantify the input and persistence of rhizodeposited carbon by plants using a continuous 13C-CO2 label. Two wheat varieties with contrasting root systems were planted in mesocosms and grown for a full growing season in a 13C-enriched atmosphere. Our objectives were to quantify the rooting-dependent flux of carbon from the atmosphere to the soil by isotopic tracing with 13C, and to measure its short-term persistence. The results showed that the old variety Plantahof rhizodeposited a larger amount of carbon than the more recent variety Nara, especially at depth. However, the carbon supplied to the soil by these two varieties led to similar amounts of organic C mineralization and priming effects. Thus, the total carbon balance was more related to the effect of soil depth than to the varieties used in the study. Furthermore, I carried out a meta-analysis of the distribution of enzymatic activities as a function of soil depth for hydrolases and oxidoreductases involved in the carbon, nitrogen and phosphorus cycle. The results of this analysis showed that the activity profiles depended very strongly on the way these activities were expressed, with activities mostly decreasing when expressed per soil mass, but remaining rather stable or even increasing with depth when expressed per unit microbial biomass. Taken together, these results show that considering the functioning of the entire soil column is essential to understand the dynamics of carbon in terrestrial ecosystems
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Peiris, Thanuja Pubudini. "Soil-pile interaction of pile embedded in deep layered marine sediment under seismic excitation". Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/75518/1/Thanuja%20Pubudini_Peiris_Thesis.pdf.
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This research provides validated Finite Element techniques to analyse pile foundations under seismic loads. The results show that the capability of the technique to capture the important pile response which includes kinematic and inertial interaction effects, effects of soil stiffness and depth on pile deflection patterns and permanent deformations.
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Khamis, Enad. "Compression of a thin layer overlying deep soil deposit". Thesis, 2003. http://spectrum.library.concordia.ca/2400/1/MQ91057.pdf.
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Roads constitute the largest and most expensive project governments undertake. The deterioration of the infrastructure of these roads represents a major and outstanding problem in transportation engineering. Construction of roads is usually made by stripping the top soil (600 to 1000 mm), which often contains organic materials, and replacing it with a layer of subgrade material (crushed stones, well-graded sand). A thin layer of asphalt or concrete is usually placed on the top of the subgrade layer to provide a durable surface. This thesis examines the role of a deep deposit on the compression of the overlain subgrade layer. The object of this study is to provide a practical method of analysis for the design of airport runways. The cross-anisotropic elastic body that is characterized by three independent elastic constant with a plane of isotropy is suggested as an improved mathematical model of natural soil deposit. The theory of stresses and displacements in a two-layer system is presented in accordance with the theory of elasticity. The theory present herein reveals the controlling influence of two important ratios on the load-settlement characteristics of the "two-layer system," namely; the ratio of the thickness of the upper layer to the radius of the bearing area and the ratio of the modulus of the deposit to that of the upper layer. For practical design purposes, the theoretical results of settlement and compression of the upper layer have been evaluated numerically and expressed in basic influence curves, for rough and smooth interfaces at the center and the edge of the load. These influence curves are made for a various combination of anisotropic and isotropic two-layer system. The influence curves of the compression of a thin layer overlying deep deposit, confirm that the stiffness of the lower layer has a significant influence on the compression of the upper layer.
Capítulos de libros sobre el tema "Deep soil layers"
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Hammam, Adel H. y A. E. Abdel Salam. "Behavior of Bored Piles in Two Soil Layers, Sand Overlaying Compressible Clay (Case Study)". En Advances in Analysis and Design of Deep Foundations, 15–27. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61642-1_2.
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Morimoto, Junko, Susumu Goto, Akito Kuroyanagi, Motoko Toyoshima y Yuichiro Shida. "Natural Succession of Wetland Vegetation in a Flood-Control Pond Constructed on Abandoned Farmland". En Ecological Research Monographs, 209–24. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-6791-6_13.
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AbstractCan a flood-control basin be considered a component of green infrastructure (GI) with not only disaster prevention functions but also biodiversity conservation functions? We studied the succession of wetland vegetation in a flood-control basin constructed in a floodplain. The number of species composing the buried seeds depended on the depth of the soil layer, with shallower (recent) layers having more species. Plants germinated from buried seeds in deep (ancient) soil layers were small and difficult to identify based on morphology alone, but DNA-based analyses made it possible to identify these species. The occurrence of three species of Juncus and Cyperus in the peat layer that developed between 840 and 1215 years ago indicates that it is possible to regenerate wetland plants from the past if the buried seeds are well preserved and in good condition. The excavated section of the experimental site, which was set in part of the flood-control basin, received dispersed seeds from the surrounding agricultural land and contained more species than did the soil layer itself. The shallower the water depth was (the shallower the excavation depth), the greater the number of species that occurred. In addition, species with different life forms occurred depending on the water depth. More species occurred in the entire flood-control basin than in the experimental site. The factors that determined the type of plant community were years since excavation, water depth, and water quality. Finally, we discussed the management practices concerning the supply of propagules and the management of suitable habitats as essential factors for flood-control basins constructed on fallow land to function as GI.
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Zhu, Jiao, Guoxing Chen y Dingfeng Zhao. "The Influence of Bedrock Surface Depth on Seismic Site Response in Deep Sediment Layers". En Proceedings of GeoShanghai 2018 International Conference: Advances in Soil Dynamics and Foundation Engineering, 224–32. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0131-5_25.
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Li, Guowei, Ruyi Liu, Chao Zhao, Yang Zhou y Li Xiong. "Compaction Effect Due to Single Pile Driving in PHC Pile Treated Soft Clayey Deposit". En Lecture Notes in Civil Engineering, 315–25. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2532-2_26.
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AbstractThe compaction effect of extra-long prestressed high-strength concrete (PHC) piles in deep soft soil foundation was studied by field test. The pore water pressure gauge, inclinometer were embedded in different plane positions or different depths of the foundation to monitor the pore pressure and deformation of the foundation when driving pile. The research shows that the magnitude of excess pore water pressure caused by single pile installation is mainly related to buried depth of the measuring point and the linear distance between the pile tip and the measuring point. The shorter the distance or the deeper the depth is, the greater the excess pore pressure caused by pile installation. The horizontal influence radius of pile compacting on the pore water pressure is about 10.7 m. The excess pore pressure induced by pile installation increases with depth, and is obviously affected by stratum properties. In the vicinity of soil with high permeability coefficient, such as thin sand layer or silty fine sand layer, the excess pore pressure cannot be accumulated in a large amount. The existing subgrade obviously restricts the lateral deformation of soil between piles and PHC piles. The pile deformation is small at the top and bottom, and large in the middle. The inflection point of the deformation curve appears at the pile connection position. The relationship the excess pore pressure of the measuring point with the depth and distance of the measuring point is given.
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Huynh, Quoc Thien, Van Qui Lai, Viet Thai Tran y Minh Tam Nguyen. "Back Analysis on Deep Excavation in the Thick Sand Layer by Hardening Soil Small Model". En Lecture Notes in Civil Engineering, 659–68. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5144-4_63.
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Suzuki, Maki. "Responses of Ground-Layer Vegetation and Soil Properties to Increased Population Density of Sika Deer and Environmental Conditions". En Ecological Research Monographs, 415–30. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9554-4_24.
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Qin, Yunzhu, Dayang Nur Sakinah Musa, Shaorun Lin y Xinyan Huang. "Persistent Underground Smouldering Fire in Deep Peat Layer". En Advances in Forest Fire Research 2022, 1274–78. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_192.
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Peatlands are important terrestrial carbon pools. Due to climate change and human activities, peatlands are more prone to large-scale fires than ever before, especially deep underground fires. However, most current smouldering researches focus on small-scale smouldering behaviour in relatively shallow layers, which poses a research gap. This work explores in-depth (up to 60 cm) smouldering behaviour, such as persistence, propagation and emission. Experimental results demonstrate that underground smouldering fires can sustain in deep soil layers for more than a week without any additional oxygen supply. Because of the competition of oxygen supply and heat losses, a critical depth of 55 cm for smouldering propagation was obtained, below which smouldering cannot self-sustained propagate. This work will help better connect lab-scale experiments with real underground smouldering peat fires and understand smouldering dynamics in deep soil layers.
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Evans, M. E. G. "Ground beetles and the soil: their adaptations and environmental effects". En The Environmental Impact of Burrowing Animals and Animal Burrows, 119–33. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198546801.003.0008.
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Abstract Ground beetles form a reservoir of predators in the upper soil levels of most terrestrial habitats. Although best known as surface runners, ground beetles may burrow into the soil to find prey, to store food such as seeds, for concealment (from predators or prey), or to reach deep hibernation sites. The most specialized burrowers are the Scaritini, which have elongate, pedunculate bodies and a range of digging adaptations. Their tunnels may reach over 70 cm, but most carabids penetrate only the more superficial layers of the soil, especially the litter and humus layers. This intrusion is facilitated by a horizontal pushing ability which differs widely between species. All carabid locomotor capabilities are compromises at various levels between the reciprocal abilities of running and pushing. Scaritines have emphasized the force component and tiger beetles the speed component, but most carabids exhibit a medium-speed/medium-force compromise. In all ground beetles the horizontal pushing ability is enhanced by a strong or weak wedge pushing ability. The ground beetle technique of wedge-pushing has been compared to the more sophisticated methods shown by two distinct groups of millipedes. The effect of all these wedge-pushers is to split up matted leaves and slow down the annual compaction of the litter layer. As with deep burrowers, their activities aid soil drainage, aeration and the movement of nutrients.
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Miguel, Pablo, Tiago Schuch Lemos Venzke, Adão Pagani Junior, José Vitor Peroba Rocha, Jeferson Diego Leidemer, Stefan Domingues Nachtigall, Mélory Maria Fernandes de Araujo et al. "Physical Quality of Soils in a Toposequence of a Forest Fragment under Livestock Activity in a Watershed in South Brazil". En Sustainable Development. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106560.
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The conservation of native forests is fundamental to the preservation of hydric resources in the landscape. The use of animals in forest fragments has resulted in degradations in the soil, resulting in the grating of these. Thus, soil classes were studied and physical parameters of forest soils were evaluated in areas without and with cattle grazing in the “Arroio Pelotas” watershed, Pelotas, Rio Grande do Sul, extreme south of Brazil. The results were submitted to statistical analysis with the Kruskal–Wallis nonparametric test with a significance level of 5%. The means of the physical parameters of soil in the same toposequence and layers with and without the presence of livestock were compared. By analyzing soil physical attributes (density, macroporosity, and microporosity) it can be seen that the structural quality of the soil is affected by the access of animals inside the forest fragments, especially in the upper layer of the soil (0–5 cm deep). In forest fragments without access to animals, the physical structure of the soil presented the best conditions of macroporosity and, consequently, greater protection of nutrients, microorganisms, and water resources. Therefore, it is concluded that conservation by the isolation of protective forests in rural property planning benefits the quality of forest soils.
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Keefer, Robert F. "Effective Water Use—Irrigation". En Handbook of Soils for Landscape Architects. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195121025.003.0010.
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Soils that are suitable for irrigation are deep soils that are permeable and have a high available water-holding capacity (usually containing much organic matter). Limitations for irrigation include presence of restrictive layers (pans), erodible soils, sloping land, susceptibility to stream overflow, salinity or alkalinity, stoniness, and hazard of soil blowing. The amount of plant-available water in a soil depends on rooting depth and soil texture. Coarse textured sands hold much less available water than finer textured clayey soils. Available water increases as the texture becomes finer up to a silt loam. Any soil texture finer than that results in no additional increase in available water. In shallow soils, the rooting depth is limited by the soil depth. In deep soils, root depth is determined by the kind of plants present: . . . Trees and large shrubs 48 inches depth Medium shrubs and vines 40 inches depth Small shrubs and ground cover 24 inches depth . . . A number of techniques can be used to determine when water should be applied to soil in which plants are growing. These techniques include observing the plants, especially for wilting; feeling the soil; using tensiometers or electrical resistance meters installed in the soil; and measuring temperatures of plant leaves. Wilting—When plants begin to lose water they droop and wilting results. If plants remain in this condition very long, they soon die. It is better to water plants before they become wilted. Any plant that is wilted will require some time to reestablish its water equilibrium, thereby slowing the growth of that plant. The amount of moisture in a soil can be roughly estimated by the “feel method”. The degree of moisture can be determined by rolling or squeezing the soil into a ball. The soil moisture condition can be divided into six categories from dry to very wet: . . . a. If a ball will not form → soil is too dry for plants. b. If the ball formed will not crumble when rubbed → soil is too wet for plants. . . .
Actas de conferencias sobre el tema "Deep soil layers"
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Toda, Misato, Petar Mandaliev y Raffael Schreiber. "Is microplastic transported into deep soil layers? Analysis of agricultural soil using hyperspectral imaging and artificial neural networks". En Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.20652.
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Харчук, Олег, Светлана Баштовая y А. Кириллов. "Динамика влажности почвы в агрофитоценозах сои в годы, предшествовавшие засухе-2020". En International Scientific Symposium "Plant Protection – Achievements and Prospects". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2020. http://dx.doi.org/10.53040/9789975347204.85.
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In the soybean cenosis (mainly the Aura variety) with a characteristic density (400-500 × 103 plants/ha), the dynamics of soil moisture in the years preceding the drought-2020 was studied. The main factor of drought-2020 is the low (about 100 mm lower than the average annual value) moisture accumulation in the soil before sowing for the autumn-spring 2019/2020, mainly due to low precipitation. An additional prerequisite for drought-2020 is a decrease in soil moisture (including deep soil layers) during harvesting in recent years, which is the reason for an additional deficit in a soil layer 0-100 cm of approximately 25 mm of water.
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Al-Masri, M. S., A. Aba, A. Al-Hamwi y H. Mukallati. "Characterization of NORM Contaminated Sites at the Syrian Oilfield: Depth Profiles and Leaching Processes". En ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4772.
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Production water containing naturally occurring radioactive materials (NORM) has been collected in unlined artificial lagoons for evaporation in some Syrian oilfields. These lagoons have become highly contaminated with NORM and the situation has urged the operating oil companies in Syria to initiate a remediation program in cooperation with the Atomic Energy Commission of Syria. Part of this national remediation program is to characterize the contaminated soil as a preliminary step for disposal of this waste. Depth profiles of radioactivity have been established and found to be variable from one field to another. Factors that influence this distribution have been evaluated and are presented. Laboratory leaching experiments were performed using six 60-cm cores collected from highly contaminated areas in the oil fields. Results show that 226Ra is transferred to deep layers via erosion caused by disposal of production water and some heavy rain water that occurred in the past. This erosion process is mainly affected by the mineralogical compositions of the contaminated soil and the particle size distribution. Gypsum present in the soil has increased transfer of 226Ra from surface layers to deeper layers; water has caused some sink holes (caves) in those soils containing high amount of gypsum. In addition, 226Ra was also determined in different particle size soil samples before and after leaching experiments where small soil particles sizes were found to be moved downwards by water. Radium was only more concentrated in smaller particle sizes than larger ones in those samples containing low concentration of gypsum. In addition, halite content in the upper soil layers has increased the radium specific activity after leaching since it dissolved in water and moved to deeper layers.
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Malii, Aliona y Oleg Harciuc. "Water use by soybean varieties of different maturity groups". En Scientific International Symposium "Plant Protection – Achievements and Perspectives". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2023. http://dx.doi.org/10.53040/ppap2023.51.
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The seasonal change in soil moisture reserves in dependence on the genetic form of soybeans was studied. It has been established that the deep layers of the soil (40-150 cm) more consistently reflect the influence of the plant component than the surface ones. In 2021, water reserves decreased in the 0-150 cm layer: for the Pentata variety - by 103 mm, and for the Onika variety- by 53 mm. Thus, Onika variety (MG I) retained 50 mm more water in the field for the next season compared to variety Pentata (MG III).
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Tsurumaki, Shizuo, Hiroyuki Watanabe, Akira Tateishi, Kenichi Horikoshi y Shunichi Suzuki. "Evaluation of Dynamic Behavior of Pile Foundations for Interim Storage Facilities Through Geotechnical Centrifuge Tests". En 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22505.
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In Japan, there is a possibility that interim storage facilities for recycled nuclear fuel resources may be constructed on quaternary layers, rather than on hard rock. In such a case, the storage facilities need to be supported by pile foundations or spread foundations to meet the required safety level. The authors have conducted a series of experimental studies on the dynamic behavior of storage facilities supported by pile foundations. A centrifuge modeling technique was used to satisfy the required similitude between the reduced size model and the prototype. The centrifuge allows a high confining stress level equivalent to prototype deep soils to be generated (which is considered necessary for examining complex pile-soil interactions) as the soil strength and the deformation are highly dependent on the confining stress. The soil conditions were set at as experimental variables, and the results are compared. Since 2000, the Nuclear Power Engineering Corporation (NUPEC) has been conducting these research tests under the auspices on the Ministry of Economy, Trade and Industry of Japan.
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Mallants, Dirk, Doncho Karastanev, Dimitar Antonov y Janez Perko. "Innovative In-Situ Determination of Unsaturated Hydraulic Properties in Deep Loess Sediments in North-West Bulgaria". En The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7202.
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In the framework of selecting a suitable site for final disposal of low- and intermediate level short-lived radioactive waste (LILW-SL) in Bulgaria, site characterization is ongoing at the Marichin Valog site, North-West Bulgaria. The site is characterized by a complex sequence of loess, clayey gravel, and clay layers, of which the first 30–40 m are unsaturated. Proper knowledge about unsaturated water flow and concomittant radionuclide transport is key input to safety assessment calculations. Constant-head infiltrometer tests were carried out at several meters below ground surface to determine the unsaturated hydraulic properties of silty loess, clayey loess, and clayey gravel layers. Individual infiltrometers were equipped with 0.5-m-long filter sections; the shallowest filter was from 2 to 2.5 m depth, whereas the deepest was from 9.5 to 10 m depth. Infiltration tests provided data on cumulative infiltration and progression of the wetting front in the initially unsaturated sediments surrounding the infiltrometer. A cylindrical time-domain reflectometry TRIME probe was used to measure water content variations with time during progression of the wetting front. Access tubes for the TRIME probe were installed at 0.3 to 0.5 m from the infiltrometer tubes. By means of an inverse optimization routine implemented in the finite element code HYDRUS-2D, field-scale soil hydraulic parameters were derived for all layers. Results show a great consistency in the optimized parameter values, although the test sites were several meters apart. Apparently the size of the affected volume of soil was large enough to reduce the effect of spatial variability and to produce average field-scale hydraulic parameters that are relevant for large-scale predictions of flow patterns and radionuclide migration pathways.
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Torgovnikov, Grigory y Graham Brodie. "G. Brodieand, G. Torgovnikov. EXPERIMENTAL STUDY OF MICROWAVE SLOW WAVE COMB AND CERAMIC APPLICATORS FOR SOIL TREATMENT AT FREQUENCY 2.45 GHZ". En Ampere 2019. Valencia: Universitat Politècnica de València, 2019. http://dx.doi.org/10.4995/ampere2019.2019.9651.
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EXPERIMENTAL STUDY OF MICROWAVE SLOW WAVE COMB AND CERAMIC APPLICATORS FOR SOIL TREATMENT AT FREQUENCY 2.45 GHZ. G. Brodie and G. Torgovnikov University of Melbourne, 4 Water St, Creswick, Victoria 3363, Australia; e-mail: grigori@unimelb.edu.au Keywords: ceramic applicator, comb applicator, microwave, slow wave, soil microwave treatment In many cases in industry it is required to heat or treat surface layers of different material (soil, timber, concrete, plastics and so on) with microwaves (MW). Traditional MW irradiators (antennas) cannot provide heating only in the surface areas and energy penetrates deep into the material, where it decays exponentially due to normal attenuation. Therefore, energy losses, if a heating depth of 20 - 40 mm (for example to heat soil for killing weed seeds) is all that is required, are very significant. Therefore, it is required to develop special MW applicators for surface treatment to increase process efficiency. To address this problem, a slow wave (which is sometimes called a "surface wave" applicator) comb and ceramic structures, was studied. The main property of slow waves is that the energy concentration is very near impedance electrode – comb or ceramic plate surface. Previously, slow wave structures were used mostly as delay lines and as interaction circuits in MW vacuum devices, and their properties were explored only for these specific applications. The work objectives of this study were: design slow wave, ceramic and comb structure applicators for soil treatment at frequency 2.45 GHz;experimentally study the energy distribution from slow wave applicators in the soil;study of opportunities to use slow wave structures for surface soil layer heating; andrecommendations for practical use of new slow wave applicators. Comb and ceramic slab applicators for frequency 2.45 GHz operation were designed for the soil treatment on the bases of theoretical studies and computer modelling. The comb applicator was made from aluminium and the ceramic slab applicator was made from alumina (DC=9.8, loss tangent=0.0002). A 30 kW (2.45 GHz) microwave generator was used for experiments. Containers with soil were placed on the applicator surface. An auto tuner was used in MW system to provided good impedance matching of the generator and applicators (with soil on top). This resulted in practically no power reflection. The soil “Potting Mix Hortico”, with moisture content range 32-174% and density range 590-1070 kg/m3, was used for the experiments. Energy distribution in the soil was determined by temperature measuring in the soil using thermocouples, after MW heating. Distribution of temperature measuring points covered the whole volume of the soil along and across the applicator. Results of the experiments showed that the comb applicator provides maximum energy release in soil in the central vertical plane. The ceramic alumina applicator forms two temperature maximums in two vertical planes at a distance of about 40 mm from the central applicator plane and a minimum in the applicator central plane. The ceramic applicator provides better uniformity of energy distribution across the width of the applicator due to the two temperature maximums. It reduces overheating of the soil surface and energy losses. The depth of energy penetration provided by ceramic applicator is lower compared with the comb applicator. It means that the ceramic applicator provides better energy localization and more energy absorption in the soil surface layers compared with the comb applicator. To provide better uniformity of energy distribution across the ceramic applicator it is recommended to use ceramics with higher dielectric constants, such as in the range of 15-25, which will allow more energy to be released closer to the applicator surface. It will increase efficiency of MW energy use. The ceramic applicator is more effective for MW treatment of the soil surface areas and is recommended for practical use in machines for thermal treatment and sterilization of surface layers of the soil and other materials.
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Gregersen, Kathrine, Guttorm Grytøyr, Jerome De Sordi y Kristoffer H. Aronsen. "Validation of Soil Models for Wellhead Fatigue Analysis". En ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61644.
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The focus on wellhead fatigue has increased over the last decade, both in terms of consequences of failure and methods for prediction. Wellhead Fatigue is a well integrity concern when drilling subsea wells, especially with exposure to harsh environments and extreme environmental loads. The concern increases with the use of deep water drilling rigs in shallow water. As a result, full-scale measurement has been employed in several projects to document the actual load levels experienced by the subsea wellheads during drilling. Input data uncertainty has always been a challenge when using global analysis to estimate wellhead fatigue. Instrumentation opens new possibilities to validate the global analysis results. In several measurement campaigns, it is observed that the response below the lower flex joint of the drilling riser is overestimated in global analyses. It has been suggested by some that this is an indication that global riser analyses are highly conservative. However, as suggested in previous papers (i.e. Russo et.al, ref.[11]), this discrepancy could also be explained by non-appropriate modelling of the conductor lateral soil resistance for small displacements, leading to underestimation of the soil stiffness. The soil spring model also called p-y curves are usually built following the API recommended methods that are established for foundation piles. Piles are designed for ultimate limit state focusing on displacement conditions that are not optimal for fatigue analyses, as a large part of the total fatigue damage actually occurs for small displacements. A literature review is conducted, to review the basis for the API springs, and alternative p-y-curves with increased initial stiffness have been suggested. Based on the available information four alternative soil models have been proposed. The work performed by BP on p-y curves modelling for laterally loaded conductors (ref. [2]) has been an important input for this paper. In order to illustrate the effect of initial soil stiffness in the global analysis, the present study focuses on conductors installed in homogenous and normally consolidated to slightly overconsolidated clays. This limits somewhat the number of available sites with relevant conditions for full-scale measurements, at least on the Norwegian Continental Shelf, where it is common to find layers of sand interspersed between the clay layers. However, Statoil have conducted one campaign with full-scale measurements at a location with corresponding clay conditions. In this paper, the API formula for “soft clay” and four alternative soil models, have been used as input to a global riser analysis, and the results are validated against measurements. It is the response of the lower stack, in terms of rotations and displacements of BOP, LMRP and LRS, that has been investigated. In addition, the load, in terms of wellhead bending moment has been compared. Results shows that for this given case, the Matlock-API formulation overestimates the lower stack response, compared with full-scale measurements. Comparing the proposed soil models shows that the global response is affected by selection of soil model. The soil formulations outlined by Jeanjean (2009) and Zakeri et.al (2015) give the best match with full-scale measurements for this case.
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Purvina, Dana, Ieva Licite, Aldis Butlers, Andis Lazdins, Guntis Saule, Andris Turks y Larysa Prysiazhniuk. "Evaluation of peat layer thickness effect on soil GHG fluxes". En 22nd International Scientific Conference Engineering for Rural Development. Latvia University of Life Sciences and Technologies, Faculty of Engineering, 2023. http://dx.doi.org/10.22616/erdev.2023.22.tf096.
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Organic soils are the largest source of GHG emissions in Latvia producing the amount of emissions comparable with the whole energy sector. Organic soils in cropland and grassland alone release about 4.5 mill. tonnes of CO2 eq. annually, which is nearly twice as big as the total emissions from the agriculture sector in Latvia. The reduction of the emissions from the organic soils is the primary target to implement the climate neutrality target in the post-2050 period in LULUCF sector. One of the issues in reporting of GHG emissions from organic soils is different definitions of organic soils, e.g. Latvia is using the Intergovernmental Panel on Climate Change (IPCC) definition (at least 10 cm deep peat layer and at least 12% of carbon content in upper 20 cm of the topsoil), while other countries use different criteria, e.g., at least 30 cm or 40 cm deep peat layer. The scope of this study is evaluating the effect of the peat layer thickness on GHG fluxes in grasslands. The study results proved that increase of the peat layer depth is associated with a trend of increase of CO2 and CH4 emissions. There is also strong correlation between CH4 emissions and the groundwater depth and soil temperature and CO2 emissions. N2O emissions are correlating with nitrogen content in soil. In the study sites soil turns into net source of CH4 emissions if the depth of peat layer exceeds 40 cm. The study results point that the peat depth should be considered as one of the parameters in accounting of GHG emissions.
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Charnaux, P., I. A. Perez, C. A. B. Silveira y V. P. C. Braga. "Geotechnical Site Investigation Over 3500 Meters Depth". En Offshore Technology Conference. OTC, 2024. http://dx.doi.org/10.4043/35269-ms.
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Abstract This paper aims to present a survey executed in 3000 meters depth, to support the design of subsea structures in exploration blocks located in Sergipe/Alagoas basin, Brazil, with geotechnical work made over 3500 meters depth, using a Piston Corer for sampling and a gravity CPT for testing. The vessel used for this project was R/V Seward Johnson, a Research/Survey vessel. The Piston Corer used for the survey, to work in depths above 3000 meters, was configured with a core head weighing 1,500 kg, with a maximum length of the sampling tube of 12 m and a 3.5 meters free fall. The samples were recovered in a 102 mm inner diameter plastic PVC (liner) coating within the 112 mm outer diameter steel tube. In addition to being stationary, the Piston Corer have a piston immobilizer, that protects the sample from disruptive forces during pull-out. The gravity CPT that was used in this campaign was coupled on Piston Corer structure, to function in the pressure of deep water. For this Project, gCPT tests was conducted to verify the soil resistance and Piston Corer samples collected, to analyze tactile-visual Classification, determination of moisture content, determination of apparent specific weight, evaluation of the content of Calcium carbonate (CaCO3) and determination of Undrained Shear Strength (Su) by pocket penetometer test, torvane test and laboratory mini vane test. Through the piston core sampling and tactile visual classification, it was possible to define the soil content in the area, consisted of normally consolidated clays. This geotechnical survey has few locations to make a more accurate assessment of what may have occurred geologically in this area. Despite few evidence, analyzing the Piston Core samples onshore, along with gCPT results, the layers of deposition of the sediment were identified, with the general soil composition of the area being described as light brown clayed SILT with fine sand and shell fragments in the superficial sediments and dark gray silty CLAY with fine sand in the deeper sediments. The data produced from this campaign shows the possibility of geotechnical studies in areas of deep water, over 3500 meters depth, with reliable results. In order to work in a deep area, there were some alterations needed in the equipment, such as assembling the CPT in Piston Corer structure, and using a Piston immobilizer on the piston corer sampler. The improved equipment provided good quality data of the region.
Informes sobre el tema "Deep soil layers"
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Løvschal, Mette, Havananda Ombashi, Marianne Høyem Andreasen, Bo Ejstrud, Renée Enevikd, Astrid Jensen, Mette Klingenberg, Søren Munch Kristiansen y Nina Helt Nielsen. The Protected Burial Mound ‘Store Vejlhøj’, Vinderup, Denmark: First Results. Det Kgl. Bibliotek, 2023. http://dx.doi.org/10.7146/aulsps-e.479.
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An archaeological excavation of the protected burial mound Store Vejlhøj in northwestern Denmark was carried out in October-November 2021. The excavation formed part of the ERC-funded research project called ANTHEA, focusing on the deep history of anthropogenic heathlands. It was conducted by Aarhus University in collaboration with Holstebro Museum and Moesgaard Museum. The aim was to test a new method of sampling pollen data from different construction stages in a burial mound and comparing them with pollen data from nearby lake sediments with a view to improving our understanding of prehistoric anthropogenic heathland dynamics. Prior to the excavation, soil cores were collected from two nearby peat sediments as well as six burial mounds (including Store Vejlhøj) within a 1 km range of Lake Skånsø, where previous pollen analyses had been carried out. Based on these preliminary corings, Store Vejlhøj was selected for further archaeological investigation. A dispensation for excavating the protected mound was granted by the Danish Palaces and Culture Agency. The excavation was based on a 5 m long trench through the barrow, moving from its foot inwards. The surface vegetation and 40 cm topsoil were removed by an excavator, after which the remainder of the trench was manually dug in horizontal layers. Observation conditions were good. The excavation revealed a series of well-defined barrow construction stages, as well as unusually wellpreserved turf structures. Only two archaeological finds could be related to the barrow, both of which were later than its initial construction: a secondary urn in the top layer, and the base of a second urn at the foot of the mound. The burial mound was constructed using a minimum of three shells, which could be observed in the trench profile. Turfs were most probably collected locally in a landscape dominated by grass pastures, where no previous turf cutting had taken place. A total of 34 soil samples were collected for paleoecological analyses (pollen, Non-Pollen Polymorphs (NPPs), macrofossils) and geoarchaeological analyses (micromorphology, bulk samples). Preliminary pollen and macrofossil results from the burial mound revealed poor preservation conditions, which prompted a trench extension of 0.5 m by 0.2 m to find better preservation conditions. This extension resulted in the collection of a single final macrofossil sample, although there was no identifiable change in the in-situ preservation conditions. The dating results of the mound have not yet been completed and will be included as appendix 4-6 in 2023.
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Eshel, Amram, Jonathan P. Lynch y Kathleen M. Brown. Physiological Regulation of Root System Architecture: The Role of Ethylene and Phosphorus. United States Department of Agriculture, diciembre de 2001. http://dx.doi.org/10.32747/2001.7585195.bard.
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Specific Objectives and Related Results: 1) Determine the effect of phosphorus availability on ethylene production by roots. Test the hypothesis that phosphorus availability regulates ethylene production Clear differences were found between the two plants that were studied. In beans ethylene production is affected by P nutrition, tissue type, and stage of development. There are genotypic differences in the rate of ethylene production by various root types and in the differential in ethylene production when P treatments are compared. The acceleration in ethylene production with P deficiency increases with time. These findings support the hypothesis that ethylene production may be enhanced by phosphorus deficiency, and that the degree of enhancement varies with genotype. In tomatoes the low-P level did not enhance significantly ethylene production by the roots. Wildtype cultivars and ethylene insensitive mutants behaved similarly in that respect. 2) Characterize the effects of phosphorus availability and ethylene on the architecture of whole root systems. Test the hypothesis that both ethylene and low phosphorus availability modify root architecture. In common bean, the basal roots give rise to a major fraction of the whole root system. Unlike other laterals these roots respond to gravitropic stimulation. Their growth angle determines the proportion of the root length in the shallow layers of the soil. A correlation between ethylene production and basal root angle was found in shallow rooted but not deep-rooted genotypes, indicating that acceleration of ethylene synthesis may account for the change in basal root angle in genotypes demonstrating a plastic response to P availability. Short-time gravitropic response of the tap roots of young bean seedlings was not affected by P level in the nutrient solution. Low phosphorus specifically increases root hair length and root hair density in Arabidopsis. We tested 7 different mutants in ethylene perception and response and in each case, the response to low P was lower than that of the wild-type. The extent of reduction in P response varied among the mutants, but every mutant retained some responsiveness to changes in P concentration. The increase in root hair density was due to the increase in the number of trichoblast cell files under low P and was not mediated by ethylene. Low P did not increase the number of root hairs forming from atrichoblasts. This is in contrast to ethylene treatment, which increased the number of root hairs partly by causing root hairs to form on atrichoblasts. 3) Assess the adaptive value of root architectural plasticity in response to phosphorus availability. A simulation study indicated that genetic variation for root architecture in common bean may be related to adaptation to diverse competitive environments. The fractal dimension of tomato root system was directly correlated with P level.