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  • English  (23)
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  • 1
    Language: English
    In: Vadose Zone Journal, 2015, Vol.14(8)
    Description: Water in soil is known to be a key factor for controlling N2O emissionsbecause N2O is mainly produced by denitrification in anoxic environments.In this study, we proposed a methodology to image the water and soil structureof a soil sample...
    Keywords: Sciences of the Universe ; Sciences of the Universe ; Continental Interfaces, Environment ; Soil ; Nitrous Oxide ; X-Ray Computed Tomography ; Gas Diffusivity ; Pore Connectivity ; Agriculture
    E-ISSN: 1539-1663
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  • 2
    Language: English
    In: Applied Physics A, 2016, Vol.122(11), pp.1-9
    Description: Building stones are frequently subjected to very intense degradation due to salt crystallization, often responsible for strong modifications of their pore network. These effects have a great influence on the mechanical properties and durability of the materials, and on the penetration of water. Therefore, the quantification and visualization of water absorption into the pore network of degraded stones could provide useful information to better understand the weathering process. In this study, neutron radiography has been used (1) to monitor and visualize in two dimensions the capillary water uptake in a Sicilian calcarenite widely used as building and replace stone (namely Sabucina stone) and (2) to quantify the water content distribution, as a function of time and weathering degree. Additionally, traditional experiments based on gravimetric methods have been performed, following the standard recommendations. Results demonstrated a change in the physical properties of Sabucina stones with the intensification of the degradation process, with severe effects on the capillary imbibition dynamics. The water penetration depth at the end of the experiment was substantially higher in the fresh than in the weathered stones. The water absorption kinetics was faster in the weathered samples, and the amount of water absorbed increased with the number of weathering cycles. Good agreement between classical and neutron imaging data has also been evidenced. However, neutron radiography has allowed retrieving additional spatial information on the water absorption process, and to better understand how salt weathering affects the petrophysical properties of the studied stone and how it influences then the stone response against water.
    Keywords: Green Buildings ; Diagnostic Imaging;
    ISSN: 0947-8396
    E-ISSN: 1432-0630
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  • 3
    Language: English
    In: Vadose Zone Journal 8 , ., 2015
    Description: Water in soil is known to be a key factor for controlling N2O emissions because N2O is mainly produced by denitrification in anoxic environments. In this study, we proposed a methodology to image the water and soil structure of a soil sample with X-ray computed tomography while controlling the hydric state and monitoring N2O fluxes. We used a multistep outflow system to apply two wetting–drying cycles to an undisturbed soil. The soil core was scanned with coarse-resolution X-ray computed tomography, one time during wetting and several times during drying, to measure quantitative and qualitative indicators of the pore network. Nitrous oxide emissions were higher during the first (C1) than during the second (C2) wetting–drying cycle for both the wetting and the drying phases. Fluxes increased quickly after the beginning of the drying phase to reach a peak after 5 h. Differences in the intensity of N2O emissions between the two cycles were attributed to differences in the water saturation, air-phase connectivity, and relative gas diffusion coefficient, which led to more or less N2O production, consumption, and entrapment in the soil. The speed of the N2O emissions at the beginning of the drying phase depended on the rate of increase of the air-filled pore volume and connectivity, and was especially well described by the estimated relative gas diffusion coefficient. Parameters of the soil structure were not able to explain completely the intensity of N2O emissions during drying; N2O production and consumption factors were also involved.
    Keywords: N2o ; Earth Sciences ; Flux Hydrique ; Structure Du Sol ; Émission De Gaz ; Modélisation ; Eau Du Sol ; Flux De Gaz ; Tomographie Aux Rayons X ; Sciences De La Terre ; Alternance Humectation Dessication ; Protoxyde D'Azote ; Milieux Et Changements Globaux ; État Hydrique
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 4
    Language: English
    In: Vadose Zone Journal 8 , ., 2015
    Description: Water in soil is known to be a key factor for controlling N2O emissions because N2O is mainly produced by denitrification in anoxic environments. In this study, we proposed a methodology to image the water and soil structure of a soil sample with X-ray computed tomography while controlling the hydric state and monitoring N2O fluxes. We used a multistep outflow system to apply two wetting–drying cycles to an undisturbed soil. The soil core was scanned with coarse-resolution X-ray computed tomography, one time during wetting and several times during drying, to measure quantitative and qualitative indicators of the pore network. Nitrous oxide emissions were higher during the first (C1) than during the second (C2) wetting–drying cycle for both the wetting and the drying phases. Fluxes increased quickly after the beginning of the drying phase to reach a peak after 5 h. Differences in the intensity of N2O emissions between the two cycles were attributed to differences in the water saturation, air-phase connectivity, and relative gas diffusion coefficient, which led to more or less N2O production, consumption, and entrapment in the soil. The speed of the N2O emissions at the beginning of the drying phase depended on the rate of increase of the air-filled pore volume and connectivity, and was especially well described by the estimated relative gas diffusion coefficient. Parameters of the soil structure were not able to explain completely the intensity of N2O emissions during drying; N2O production and consumption factors were also involved.
    Keywords: N2o ; Earth Sciences ; Flux Hydrique ; Structure Du Sol ; Émission De Gaz ; Modélisation ; Eau Du Sol ; Flux De Gaz ; Tomographie Aux Rayons X ; Sciences De La Terre ; Alternance Humectation Dessication ; Protoxyde D'Azote ; Milieux Et Changements Globaux ; État Hydrique
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 5
    Language: English
    In: 2014; Biogeochemical Processes at Air-Soil-Water Interfaces and Environmental Protection ASWEP, Imola, ITA, 2014-06-23-2014-06-26,, 2014
    Description: N2O fluxes can increase largely due to small increase of the soil water-filled pore space (WFPS). In models, the relationship between N2O fluxes and the WFPS is often described as a continuous exponential curve starting at a WFPS of about 0.62. However, some laboratory and field measurements have evidenced that this relationship could rather be described as Gaussian. To improve our knowledge of this crucial curve for N2O flux modeling, we have developed a laboratory experiment where the wetting and drying dynamics of undisturbed soil cylinders were strictly controlled during N2O flux measurements. We observed that N2O flux peaks could occur during the wetting phase, but more surprisingly we also observed brief and intense peaks during the drying phase. We then hypothesized (1) that N2O was produced and entrapped during the wetting phase, and was emitted from gas pockets and soil solution during the drying phase and, (2) that the addition of a gas transport and a gas-liquid equilibrium modules to an empirical biogeochemical model of N2O emissions could allow the description of the brief peaks observed during soil drying. We build such a model. It was first tested with the experimental data. We also studied its sensitivity to the WFPS parameter. We generated 200 realizations of hydric conditions and bulk densities to estimate the soil gas diffusivity. WFPS was set to be constant during the 7 simulated days. Simulated N2O fluxes plotted against WFPS appeared to be bell-shaped whatever the simulation time, combining the effects of the low N2O production for WFPS0.9. The WFPS generating the maximum simulated N2O fluxes shifted with time, from 0.76 after 12 h, to 0.79 after 168 h, because of an increase over time of the gas concentration gradient between the soil surface and the atmosphere. The study highlighted the role of diffusional processes in soil N2O emissions and the importance to take them into account in N2O modeling.
    Keywords: Modélisation ; Indice D'Eau ; Espace Poral ; Sciences De La Terre ; Earth Sciences ; Émission D'Azote ; Flux D'Azote ; Protoxyde D'Azote ; Porosité Saturée En Eau
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 6
    Language: English
    In: 2014; Biogeochemical Processes at Air-Soil-Water Interfaces and Environmental Protection ASWEP, Imola, ITA, 2014-06-23-2014-06-26,, 2014
    Description: N2O fluxes can increase largely due to small increase of the soil water-filled pore space (WFPS). In models, the relationship between N2O fluxes and the WFPS is often described as a continuous exponential curve starting at a WFPS of about 0.62. However, some laboratory and field measurements have evidenced that this relationship could rather be described as Gaussian. To improve our knowledge of this crucial curve for N2O flux modeling, we have developed a laboratory experiment where the wetting and drying dynamics of undisturbed soil cylinders were strictly controlled during N2O flux measurements. We observed that N2O flux peaks could occur during the wetting phase, but more surprisingly we also observed brief and intense peaks during the drying phase. We then hypothesized (1) that N2O was produced and entrapped during the wetting phase, and was emitted from gas pockets and soil solution during the drying phase and, (2) that the addition of a gas transport and a gas-liquid equilibrium modules to an empirical biogeochemical model of N2O emissions could allow the description of the brief peaks observed during soil drying. We build such a model. It was first tested with the experimental data. We also studied its sensitivity to the WFPS parameter. We generated 200 realizations of hydric conditions and bulk densities to estimate the soil gas diffusivity. WFPS was set to be constant during the 7 simulated days. Simulated N2O fluxes plotted against WFPS appeared to be bell-shaped whatever the simulation time, combining the effects of the low N2O production for WFPS0.9. The WFPS generating the maximum simulated N2O fluxes shifted with time, from 0.76 after 12 h, to 0.79 after 168 h, because of an increase over time of the gas concentration gradient between the soil surface and the atmosphere. The study highlighted the role of diffusional processes in soil N2O emissions and the importance to take them into account in N2O modeling.
    Keywords: Modélisation ; Indice D'Eau ; Espace Poral ; Sciences De La Terre ; Earth Sciences ; Émission D'Azote ; Flux D'Azote ; Protoxyde D'Azote ; Porosité Saturée En Eau
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 7
    Language: English
    In: Proceedings of the Complex Soil Systems Conference “A Path to Improved Understanding of Complex Soil Systems”. 2014; Complex Soil Systems “A Path to Improved Understanding of Complex Soil Systems”, Berkeley, USA, 2014-09-03-2014-09-05, p.51, 2014
    Keywords: Eau Du Sol ; N2o ; Hysteresis ; Sciences De La Terre ; Earth Sciences ; Alternance Humectation Dessication ; Émission D'Azote ; Teneur En Eau ; Protoxyde D'Azote ; Séchage ; Humidification ; État Hydrique ; Mouillage
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 8
    Language: English
    In: Proceedings of the Complex Soil Systems Conference “A Path to Improved Understanding of Complex Soil Systems”. 2014; Complex Soil Systems “A Path to Improved Understanding of Complex Soil Systems”, Berkeley, USA, 2014-09-03-2014-09-05, p.51, 2014
    Keywords: Eau Du Sol ; N2o ; Hysteresis ; Sciences De La Terre ; Earth Sciences ; Alternance Humectation Dessication ; Émission D'Azote ; Teneur En Eau ; Protoxyde D'Azote ; Séchage ; Humidification ; État Hydrique ; Mouillage
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 9
    Language: English
    In: SOIL, 2018, Vol.4(1), pp.83-92
    Description: The central importance of soil for the functioning of terrestrial systems is increasingly recognized. Critically relevant for water quality, climate control, nutrient cycling and biodiversity, soil provides more functions than just the basis for agricultural production. Nowadays, soil is increasingly under pressure as a limited resource for the production of food, energy and raw materials. This has led to an increasing demand for concepts assessing soil functions so that they can be adequately considered in decision-making aimed at sustainable soil management. The various soil science disciplines have progressively developed highly sophisticated methods to explore the multitude of physical, chemical and biological processes in soil. It is not obvious, however, how the steadily improving insight into soil processes may contribute to the evaluation of soil functions. Here, we present to a new systemic modeling framework that allows for a consistent coupling between reductionist yet observable indicators for soil functions with detailed process understanding. It is based on the mechanistic relationships between soil functional attributes, each explained by a network of interacting processes as derived from scientific evidence. The non-linear character of these interactions produces stability and resilience of soil with respect to functional characteristics. We anticipate that this new conceptional framework will integrate the various soil science disciplines and help identify important future research questions at the interface between disciplines. It allows the overwhelming complexity of soil systems to be adequately coped with and paves the way for steadily improving our capability to assess soil functions based on scientific understanding.
    Keywords: Soil Stability ; Evaluation ; Agricultural Production ; Modelling ; Agricultural Management ; Biodiversity ; Soil Stability ; Food Production ; Water Quality ; Raw Materials ; Biological Activity ; Decision Making ; Soil Improvement ; Soil Science ; Terrestrial Environments ; Interactions ; Water Quality ; Soil Management ; Modelling ; Raw Materials ; Raw Materials ; Soil Sciences ; Water Quality ; Soils ; Framework ; Stability ; Nutrient Cycles ; Mathematical Models ; Agricultural Production ; Biodiversity ; Nutrients (Mineral) ; Soils ; Decision Making ; Water Quality ; Biodiversity ; Biodiversity;
    ISSN: SOIL
    E-ISSN: 2199-398X
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  • 10
    Language: English
    In: SOIL Discussions, 10/04/2017, pp.1-15
    ISSN: SOIL Discussions
    E-ISSN: 2199-3998
    Source: CrossRef
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