Predictability of the Evolution of the Soil Structure using Water Flow Modeling for a Constructed Technosol

International audienceThis paper focuses on the rela on between the structure of a constructed Technosol and its hydraulic characteris cs during its early pedogenesis. The method is based on a 3-yr comparison of, on one hand, experimental measurements from an in situ gravita on lysimeter and, on the other hand, a modeling approach with HYDRUS-1D. The change of water fl ow pa erns with me was described. It was consistent with previous results for constructed Technosol aggrega on. Apart from seasonal varia ons, the specifi city of the hydraulic func oning of the constructed Technosol was shown to be due to the nature of its technogenic parent materials. The in situ evolu on of the hydrodynamics has been established and partly linked to external factors (climate, vegeta on). The direct modeling and the op miza on of the parameters over fi rst a 3-yr period and then three 9-mo periods accurately represented global water fl ow trends at the pedon scale. However it failed to simulate precisely the main events, such as massive leachate ou low. An evolu on with me of some of the hydraulic proper es was shown, expressing the structuring of the soil. The existence of two dis nct me-scales (slow and steady/fast and cyclic) of the evolu on of hydraulic parameters was then formulated as a new hypothesis. Abbrevia ons: Hz, horizon; TDR, me domain refl ectometry

Caractérisation du fonctionnement thermo-hydrique in situ d'une toiture végétalisée extensive

International audienceThere are several issues related to the development of green roofs : a better understanding and estimation of their thermic and hydric performances as well as the strong necessity to develop innovations. This study is primarily based on the monitoring of a large-scale in situ green-roof that instrumented with temperature sensors, capacitive tensi-ometers and dielectric sensors. This experimental device was completed by a weather station monitoring few microcli-matic parameters (ambient temperature, humidity, wind speed and direction). The analysis of the results has lead to a better understanding of the seasonal behavior of the extensive green roof (EGR). Indeed, EGR contribution for thermal insulation has been estimated and reached maximum reduction of temperature of 24°C in summer and a temperature gain of 5°C in winter. In spring, the EGR succeeded in storing almost the whole rainfall. The substrate appeared to play an important role on the coupled thermo-hydric performances of the EGR and needed further characterization.Il existe aujourd'hui plusieurs enjeux liés au développement des toitures végétalisées à la fois pour une meilleure connaissance et évaluation de leurs propriétés (e.g. performance énergétique des bâtiments équipés, rétention en eau), mais aussi sur un réel besoin d'innovation. Ces travaux s'appuient sur le monitoring d'une toiture végétalisée équipée de grande taille, mise en place sur un bâtiment. Elle est instrumentée à l'aide de capteurs de température, de tensiomètres capacitifs et de sondes diélectriques. Ce dispositif expérimental est complété d'une station météorologique mesurant les paramètres microclimatiques (température extérieure, hygrométrie, vitesse et direction du vent). L'analyse des résultats des expériences in situ ont permis de dégager des résultats sur le comportement saisonnier de la toiture végétalisée (TVE). En effet, il est possible d'estimer la contribution de ce type de système à l'isolation thermique dans des conditions climatiques extérieures qui varient en hiver avec un gain de 5°C et en été avec une réduction de 24°C. Le suivi des données a aussi démontré qu'au printemps la TVE pouvait stocker l'essentiel des précipitations. La contribution forte du substrat au fonctionnement thermo-hydrique est ensuite évoquée ainsi que la nécessité de mieux caractériser ce couplage

Uso da micropedologia na descrição de processos pedogenéticos em Tecnossolos

International audienceTechnosols are characterized by the presence of mineral and organic parent materials of technogenic origin (e.g. agricultural or urban wastes, industrial by-products, building materials, transported natural materials). In view of the continual increase of such man-made soils, there is a true need of understanding their functioning and evolution. Micropedology, i.e. morphological and analytical characterization of pedofeatures on soil sections, appears as a relevant approach to take into account the diversity and the specificity of Technosols in the knowledge of their pedogenetic processes. Micropedology was investigated at microscopic and submicroscopic scale on four Technosols. Therefore, it determined specific features of anthropogenic constituents allowing in situ monitoring until the early stages of Technosol pedogenesis. Organic matter dynamics, soil porosity evolution, impact of faunal activity or hydric conditions on Technosol structure were investigated. Moreover, as Technosol components and deposition modes are diverse, one can expect numerous interfaces. In that way, micropedology appeared particularly well adapted to study these local interfaces as sites of favoured pedogenesis. Supplemented with overall physico-chemical soil analyses, characterization of Technosol pedogenic features using micropedology improves the understanding of their functioning and evolution. In addition, according to the environmental context, such data also give useful information for the Technosol management.RESUMEN Los Tecnosoles se caracterizan por la presencia de materiales orgánicos y minerales de origen tecnogenético (p.ej. residuos agrícolas o urbanos, subproductos industriales, materiales de construcción, materiales naturales transportados, etc.). Dado el aumento continuo de estos tipos de suelos antrópicos, es necesario comprender su funcionamiento y evolución. La micropedología, definida como la caracterización morfológica y analítica de microestructuras de láminas de suelo, es una herramienta estándar para el estudio de los mismos. La micropedología ofrece un enfoque relevante para el conocimiento de los procesos edafogenéticos de los Tecnosoles, ya que permite considerar la diversidad y la especificidad de los mismos. Cuatro tipos de Tecnosoles fueron investigados mediante técnicas de micropedología a escala fotónica y de ultraestructura. Así, fue posible determinar las características de los constituyentes antropogénicos y realizar un seguimiento in situ hasta las fases tempranas de la edafogénesis de estos Tecnosoles. Se investigaron procesos como la dinámica de la materia orgánica, la evolución de la porosidad y el impacto de la actividad de la fauna o de las condiciones hídricas en la estructura de los Tecnosoles. Además, ya que los Tecnosoles son muy diversos tanto en sus componentes como en el modo en que estos componentes se organizan, es esperable que existan numerosas interfaces entre horizontes de suelo. De este modo, la micropedología se adapta muy bien al estudio de estas interfaces locales donde se dan procesos edafogenéticos. La caracterización micropedológica de las microestructuras de los Tecnosoles, complementada con análisis físico-químicos generales, incrementa de modo sustancial la comprensió

Fonctionnement et évolution pédogénétiques de Technosols issus d'un procédé de construction de sol

Human activities induce growing impacts on soils. This has produced derelict lands that need thorough reclamation to minimize their negative effect on the environment. A better knowledge and control of the evolution of highly anthropized soils is needed in order to achieve a sustainable management of these sites. This work emphasizes on both the development of a process of soil construction with wastes and by-products (paper sludge, treated industrial soil, compost) and the study of the functioning and pedogenic evolution of the constructed soils. The project relies on both in situ pilot scale application and lab-scale experiments. The characterization of the parent materials and their compounding highlighted their properties and their originalities compared to geological or pedological materials. The study of the functioning of constructed soils demonstrated that they could fulfil the soil basic functions. In this way, the process has been able to achieve the reclamation of the pedological cover and initiate the ecological resilience. The nature, the intensity and the kinetics of the pedogenic processes have been identified. It appeared that the reactions were very fast and that they sometimes strongly differ from the natural local pedo-climate (e.g. dissolution of gypsum, amorphous silica). We suggest that they will spontanuously evolve to analogous natural form of soils. Our results are confronted with the present classification of the Technosols and some propositions are made in favour of a more genetic-oriented way. Some thoughts about the modelling of the pedogenesis of very anthropized soils are proposed. At last, this work evocates the basis for the development of a decision tool for the pedo-engineering approachLa restauration des fonctions des sols est une étape clé de la requalification des sites dégradés par les activités humaines. Ces opérations nécessitent de disposer de procédés de remise en état du couvert pédologique favorisant la résilience écologique. Ils génèrent de nouveaux sols dont il faut prévoir l'évolution. Notre objectif est de caractériser le fonctionnement et la pédogenèse de sols construits à l'aide d'un nouveau procédé fondé sur la formulation de déchets et sous-produits (terre industrielle traitée, sous-produit papetier, compost). Dans ce but, des colonnes en laboratoire ainsi que des parcelles lysimétriques in situ ont été mises en place. Des paramètres descriptifs des fonctionnalités et de la pédogenèse des sols construits ont été mesurés. Les résultats ont montré que les matériaux parents présentent des propriétés aptes à remplir des fonctions comme la fourniture d'éléments ou la rétention en eau. Les sols construits remplissent les rôles de support de végétation, d'échange/filtre et de support de la biodiversité comme des sols naturels. Les premiers stades de leur évolution pédogénétique se caractérisent par leur intensité, leur rapidité et leur caractère non habituel (e.g. dissolution conjointe de gypse et de calcite). La prospective sur l'évolution des sols construits démontre que, de Technosols, ils évoluent vers des types de sols analogues aux sols naturels. Ce cheminement nous conduit à proposer une évolution de la classification des sols très anthropisés sur des critères génétiques. Enfin, les bases de la modélisation de la pédogenèse des sols très anthropisés sont posées ainsi que celles d'un outil d'aide à la décision pour le génie pédologiqu

Mieux connaître la pédogenèse et le fonctionnement des Technosols pour optimiser les services écosystémiques rendus

This work focuses on strongly anthropized soils – Technosols – and presents some thoughts about their contribution to address the societal issues of urban and industrial areas. It starts with an introduction and a literature review on the soil anthropization dynamics, the specific features in terms of composition, functioning and evolution of Technosols and outlines the researches about the ecosystem services they could provide. Then five distinct questions are tackled. The first one is about pedological engineering and more specifically about how to construct functional soils with by-products to revegetate and reclaim derelict lands. The second one focuses on the way such constructed Technosols can fulfill functions of biomass production, filter/exchange, carbon storage and biodiversity habitat. The third question deals with the pedogenesis of constructed soils by presenting results about soil structure dynamics in relation with their hydraulic properties, minerals weathering, transfer of particles and the impact of such processes on the ecosystem functions they can provide. The forth addresses the development of a methodology to assess the ecosystem services provided by the Technosols and lays the basis for a decision support tool dedicated to urban planning. At last, the research project is evocated through different axis that shall all contribute to an optimization of the level of ecosystem services provided by the soils from strongly anthropized areas.Ce Mémoire s’intéresse aux sols fortement anthropisés – les Technosols – et propose une réflexion sur la manière dont ils peuvent contribuer à répondre aux enjeux sociétaux qui se posent aux espaces urbains et industriels. Il débute par une introduction puis une analyse de la littérature scientifique pour comprendre la dynamique d’anthropisation des sols, les spécificités de composition, de fonctionnement et d’évolution des Technosols, en évoquant également les travaux qui ont été menés sur les services écosystémiques qu’ils peuvent rendre. Ensuite, cinq questions sont déclinées. La première traite du génie pédologique et plus spécifiquement de la manière de construire des sols fonctionnels pour végétaliser des milieux fortement anthropisés. La seconde s’intéresse à la manière dont les Technosols construits peuvent assurer des fonctions de support de végétation, de filtre et d’échange, de stockage de carbone et d’habitat pour la biodiversité. La troisième porte sur la pédogenèse de ces mêmes sols artificiels en déclinant des processus de dynamique de la structure, d’évolution des phases minérales, de transfert de particules et les impacts que ces évolutions peuvent avoir sur leur fonctionnement. La quatrième partie aborde la question de l’évaluation des services écosystémiques rendus par les Technosols en général, en déclinant les bases d’un outil d’aide à la décision. La dernière partie évoque le projet de recherche qui vise à développer des recherches pour optimiser les services écosystémiques rendus par les sols fortement anthropisés

Functionning and pedogenic evolution of technosols coming from a soil contruction process

La restauration des fonctions des sols est une étape clé de la requalification des sites dégradés par les activités humaines. Ces opérations nécessitent de disposer de procédés de remise en état du couvert pédologique favorisant la résilience écologique. Ils génèrent de nouveaux sols dont il faut prévoir l’évolution. Notre objectif est de caractériser le fonctionnement et la pédogenèse de sols construits à l’aide d’un nouveau procédé fondé sur la formulation de déchets et sous-produits (terre industrielle traitée, sous-produit papetier, compost). Dans ce but, des colonnes en laboratoire ainsi que des parcelles lysimétriques in situ ont été mises en place. Des paramètres descriptifs des fonctionnalités et de la pédogenèse des sols construits ont été mesurés. Les résultats ont montré que les matériaux parents présentent des propriétés aptes à remplir des fonctions comme la fourniture d’éléments ou la rétention en eau. Les sols construits remplissent les rôles de support de végétation, d’échange/filtre et de support de la biodiversité comme des sols naturels. Les premiers stades de leur évolution pédogénétique se caractérisent par leur intensité, leur rapidité et leur caractère non habituel (e.g. dissolution conjointe de gypse et de calcite). La prospective sur l’évolution des sols construits démontre que, de Technosols, ils évoluent vers des types de sols analogues aux sols naturels. Ce cheminement nous conduit à proposer une évolution de la classification des sols très anthropisés sur des critères génétiques. Enfin, les bases de la modélisation de la pédogenèse des sols très anthropisés sont posées ainsi que celles d’un outil d’aide à la décision pour le génie pédologiqueHuman activities induce growing impacts on soils. This has produced derelict lands that need thorough reclamation to minimize their negative effect on the environment. A better knowledge and control of the evolution of highly anthropized soils is needed in order to achieve a sustainable management of these sites. This work emphasizes on both the development of a process of soil construction with wastes and by-products (paper sludge, treated industrial soil, compost) and the study of the functioning and pedogenic evolution of the constructed soils. The project relies on both in situ pilot scale application and lab-scale experiments. The characterization of the parent materials and their compounding highlighted their properties and their originalities compared to geological or pedological materials. The study of the functioning of constructed soils demonstrated that they could fulfil the soil basic functions. In this way, the process has been able to achieve the reclamation of the pedological cover and initiate the ecological resilience. The nature, the intensity and the kinetics of the pedogenic processes have been identified. It appeared that the reactions were very fast and that they sometimes strongly differ from the natural local pedo-climate (e.g. dissolution of gypsum, amorphous silica). We suggest that they will spontanuously evolve to analogous natural form of soils. Our results are confronted with the present classification of the Technosols and some propositions are made in favour of a more genetic-oriented way. Some thoughts about the modelling of the pedogenesis of very anthropized soils are proposed. At last, this work evocates the basis for the development of a decision tool for the pedo-engineering approach

Services écosystémiques rendus par les SUITMAS (Soils of Urban, Industrial, Traffic, Mining and Military Areas)

Services écosystémiques rendus par les SUITMAS (Soils of Urban, Industrial, Traffic, Mining and Military Areas). International symposium on Ecosystem services: their contributions and relevance in urban environments Tour

Les sols, terrains et bâtiments de l’agriculture urbaine

Chapitre 3International audienc

How lysimetric facility can contribute to monitor Technosols dynamics.

International audienceThe dynamic of water in soils is mainly controlled by a set of hydraulic properties that are characteristic of each type of soil and that reflect the architecture – more generally defined as soil structure - of such a specific porous medium. Structural changes are induced by external factors (e.g. climate, biology, human action) and are the result of pedogenetic processes that modify the solid phase and redistribute ions and particles. Consequently, changes in the poral volume and in the size and the connectivity of soil pores are observed that significantly influence regulating ecosystem services that can be provided. The temporal and spatial dynamics of these properties is complex to highlight and poorly studied, especially as the soil processes in natural soils are slow at human timescales. To question this crucial issue, we chose to focus our study on the dynamics of Technosols porosity as a result of seasonal climatic variations, vegetation and early pedogenic evolution – which kinetic is known to be much faster - (Lin, 2011; Séré et al., 2012). Our purpose is then to develop an original approach to characterize, in a continuous way, the evolution of soil’s structure. To do so, a natural soil and SUITMAs - from a Luvisol to a Spolic Garbic Technosol (Histic) -, within an anthropization gradient, have been studied. They have been studied under two treatments (with or without vegetation) in monitored 2 m3 lysimetric columns over a 3 to 6 years’ time sequence. Water balances have been performed as well as the monitoring of water transfer at different depths. Experimental data have been compared to a modelling approach that relied on the use of Hydrus 1D (Simunek et al., 2008). The results exhibit contrasted hydraulic behaviors that are mainly correlated to the age of the soils and the level of human influence. Only cyclic variations – for example on the amount of water that is stored (Figure) - were visible on natural and slightly anthropogenic soils that were attributed to seasonal factors (e.g. climate and vegetation). In addition to that cyclic changes, more drastic acyclic evolutions were observed on the Technosols that demonstrated their significant settlement and an evolution of the porosity due to their early pedogenesis (Figure). An inverse modelling approach led to the estimation of hydraulic parameters that confirmed that findings by highlighting an evolution of poral architecture with time

Mineralization of organic artefacts: implication for carbon early dynamics in Technosols

International audienceTechnosols are soils strongly impacted by human activities. They often contain high quantity of artefacts (i.e. parent materials from anthropogenic origin) that impact their functioning, notably their carbon (C) cycle. The resistance to degradability of a wide and representative range of organic artefacts found in Technosols was assessed under controlled conditions. Artefacts tested were green waste compost (GWC), papermill sludge (PS), biochar (BC), coal (CO) and coke (CK). Artefacts were mixed with mineral materials and sometimes with natural organic matter to create artificial soil materials. Four methods were used to assess the resistance to degradability of these materials during a two-month incubation experiment: i) CO2 fluxes measurement, including the modeling of kinetics parameters; ii) particle size-density fractionation method; iii) Rock-Eval analysis (related to thermal resistance to degradation); iv) δ13C analysis.After the incubation, organic artefacts global degradability was strongly variable, ranked as follow: PS >> GWC >> BC > CO ≈ CK. Chemical signature of artefacts did not vary widely through the experiment except for PS. Most of the C loss originated from coarse light particles, while C in finer particles was more protected. Rock-Eval and δ13C analyses permitted to differentiate C of natural organic matter from C of artefacts, 20% to 1% of the C mineralized was from artefacts (for PS and BC respectively). Notably, we recorded negative priming effects for artificial soils BC, CO and CK when mixed with natural organic matter.All the methods employed provided complementary information on the resistance to degradability of artefacts. Typology of organic artefacts can be addressed according to the results from this study: (i) highly to moderately mineralizable artefacts; (ii) weakly mineralizable artefacts and (iii) very weakly mineralizable artefacts. This might imply different strategies for the management of the Technosols to optimize their carbon sequestration