Observatoire Terre et environnement de Lorraine

Summary Large surface areas covered with man‐made materials are subject to pedogenetic evolution. However, pedogenetic processes in the resulting Technosols are seldom fully assessed. This work was conducted to identify and characterize the processes occurring on deposits of industrial technogenic materials. A former settling pond of the iron and steel industry where a forest has established since termination of the industrial activity approximately 50 years ago was chosen. A 2‐m deep pit was opened, and a series of layers of the soil profile were sampled. The macro‐ and micro‐structure were studied, and soil samples were analysed for structural, chemical and mineralogical assessment (chemical analyses, X‐ray diffraction, infrared and Mössbauer spectroscopies, scanning and transmission electron microscopies coupled with energy dispersion spectrometry). Results showed that the profile was composed of a succession of sub‐horizontal layers arranged in two groups according to their structure and composition, linked to the composition of the industrial effluent. Group 1 was composed of iron‐, carbonate‐ and aluminosilicate‐rich layers exhibiting a compact structure. Group 2 contained manganese‐rich layers with a friable structure. Pedogenetic processes of various intensities were detected at different depths. Besides an accumulation of organic matter at the surface, transformations of minerals were recorded all along the soil profile, with weathering, leaching and precipitation of new phases. Phenomena occurred primarily in specific zones, such as cracks and interfaces between two layers. In conclusion, the soil maintained characteristics of the original industrial material and displayed several stages of pedogenesis, which were controlled chronologically by climatic and biological factors.

Metals can be immobilized on biochars by precipitation with carbonate. The distribution of metal–carbonate phases at the surface of biochars and the conditions of their formation, however, are unknown. Electron microscopy and X‐photon spectroscopy were used to characterize carbonate phases in various morphological groups of particles of a wood‐derived biochar, both before and after a metal‐sorption experiment. Our results showed that the distribution of metals at the surface of biochar particles depended on the corresponding wood tissues and the presence of carbonate phases. Metals were particularly concentrated (i) within calcium carbonate crystals in bark‐derived particles, which originated from calcium oxalate crystals formed prior to pyrolysis, and (ii) as new phases formed by the reprecipitation of carbonate on specific tissues of biochar. The formation of biochar carbonate phases and their redistribution by dissolution–precipitation mechanisms may primarily control the localization of metals on biochar particles and the durability of metals immobilization. Core Ideas Carbonate phases in wood‐derived biochars can immobilize metals in solution. Some carbonate phases result from oxalate crystals transformation during pyrolysis. Metals are immobilized within preexisting calcium crystals or in new precipitates. The new precipitates are localized on specific features inherited from wood tissues.

Summary One major challenge facing soil micromorphology is the direct quantification of aggregation. This study proposes a generic protocol to quantify aggregation properties directly in undisturbed soil samples by image analysis of soil thin sections. We worked on a constructed T echnosol proposed as an experimental model with controlled characteristics. Two sampling campaigns were conducted in 2008 and 2010 on an in situ plot, where 24 undisturbed soil samples were collected each year. Thin sections were prepared, scanned to generate images and processed using the protocol developed. Aggregates from 50 to 2000 µm equivalent diameters were monitored. Six aggregate properties were quantified: number, area, perimeter, eccentricity, shape and equivalent diameter. A synthetic mean index of aggregation ( MIA ia ) was calculated from image analysis. We confirmed that aggregation is closely related to porosity, as highlighted by the MIA ia . Three aggregate properties: number, area and shape were selected as the indicators most representative of aggregation evolution during the early stages of pedogenesis. In further developments, direct (image analysis) and indirect (stability tests) methods for the quantification of aggregation could be proposed as complementary ways of describing and quantifying total quantities of stable macroaggregates in soils. Résumé L'un des défis de la micromorphologie en sciences du sol est de pouvoir quantifier globalement et de manière directe l'agrégation. Cette étude propose un protocole générique de quantification directe des paramètres d'agrégation par analyse d'images de lames minces d'échantillons de sols non perturbés. Nous avons travaillé sur un Technosol construit proposé comme un modèle expérimental présentant des caractéristiques connues. Deux campagnes d'échantillonnage ont été conduites en 2008 et 2010 sur une parcelle expérimentale in situ , au cours desquelles 24 échantillons non perturbés de T echnosols ont été collectés chaque année. Des lames minces ont été réalisées, scannées et les images obtenues ont été analysées à l'aide du protocole spécifiquement développé. Les agrégats de diamètres compris entre 50 et 2000 µm ont été suivis au cours du temps. Pour cela six paramètres ont été quantifiés : nombre, surface, périmètre, excentricité, forme et diamètre équivalent. Un indice synthétique : I ndice M oyen d' A grégation en analyse d'image ( IMA ai ) a été calculé. Nous avons confirmé que l'agrégation est étroitement corrélée à la porosité, cette relation étant plus marquée en utilisant l' IMA ai . Trois paramètres descriptifs des agrégats sont sélectionnés comme indicateurs de l'évolution de l'agrégation dans les stades précoces de la pédogenèse. Des perspectives de développement résident dans l'utilisation complémentaire de méthodes directes (analyse d'images) et indirectes (tests de stabilité) de quantification de l'agrégation pour décrire et quantifier l'ensemble des macroagrégats et leur fraction stable dans les sols.

Abstract The main carrier of primordial heavy noble gases in chondrites is thought to be an organic phase, known as phase Q, whose precise characterization has resisted decades of investigation. Indirect techniques have revealed that phase Q might be composed of two subphases, one of them associated with sulfide. Here we provide experimental evidence that noble gases trapped within meteoritic sulfides present chemically and thermally driven behavior patterns that are similar to Q gases. We therefore suggest that phase Q is likely composed of two subcomponents: carbonaceous phases and sulfides. In situ decay of iodine at concentration levels consistent with those reported for meteoritic sulfides can reproduce the 129 Xe excess observed for Q gases relative to fractionated solar wind. We suggest that the Q‐bearing sulfides formed at high temperature and could have recorded the conditions that prevailed in the chondrule‐forming region(s).

[début du texte] L'Anthropocène est une époque qui se caractérise à la fois par la forte pression que les activités humaines exercent sur les sols mais, également, par les attentes de plus en plus marquées de la société vis-à-vis de ces milieux. Dans ce cadre, la modélisation quantitative de la pédogenèse est un outil qui reste à développer pour mieux relever les défis de cette nouvelle ère et évaluer l'évolution future des sols ainsi que des services écosystémiques associés.

Historiquement, le territoire est polarisé par une ville moyenne (Bitche) à forte tradition militaire depuis la seconde moitié du XVe siècle. Cette présence militaire séculaire a profondément marqué de son empreinte le paysage et la biodiversité, de même que le tissu économique local, l'organisation des services publics, l'action politique, l'aménagement du territoire, les pratiques culturelles, les modalités de circulation et les mentalités. Toutefois, le rythme des restructurations de la Défense sur fond de crise économique et d'incessantes réformes administratives semble avoir profondément affecté les équilibres historiques du Pays de Bitche depuis les années 1990. De fait, le Pays de Bitche apparait comme un territoire en mutation.Vouloir saisir les mutations d'un territoire nécessite de prêter attention aux différentes temporalités d'un lieu : ce qu'il a été, ce qui le façonne et ce qu'il est en train de devenir. C'est ainsi que cet ouvrage est organisé en trois grandes séquences considérant les paysages (historiques, géographiques, biologiques, politiques et sociaux) comme autant d'héritages façonnant, peu ou prou, les dynamiques contemporaines. Ces trois séquences sont elles-mêmes abordées au prisme des regards disciplinaires complémentaires relevant des sciences de la nature, des sciences de la Terre et des sciences humaines.

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Le Collège Données de la recherche du Comité pour la science ouverte émet sept recommandations pour aider à la formalisation et à la mise en œuvre d'une politique des données de la recherche au sein des établissements de la recherche et de l'enseignement supérieur.

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Many factors affect soil porosity but major of them are soil fauna, plant roots and the climate. Many studies attempted to investigate the effect of these factors on the evolution of soil porosity separately. The objective of this study is, based on an in situ experiment including three major porosity factors, propose a conceptual model of soil macroporosity evolution. In situ observation and quantification of the evolution of macroporosity under the influence of each agent separately and the three agents combined allow to propose a model for each case. Results show that the evolution of macroporosity due to plant roots is linear and reachs its maximum at the end of the plant cycle. Earthworms create and destruct macroporosity during the up and down movement for food searching. At long term, the consequence of earthworm action results to an increase of macroporosity. Wetting and drying cycle has the same effect as earthworm. At the beginning, when soil shrinks, it leads to a creation of macroporosity that could be disturbed by swelling during soil humectation. Some soil particles migrate in the shrink and reduce the surface of macroporosity. When faced to many wetting drying cycles, the surface of macropores increase during time. Mathematical algorithms and computing are necessary to formalize this model and long-term experiment is needed to validate it.

[debut du texte] La reconstitution virtuelle de la structure d'un sol donne, pour une large gamme de sol, represente un enjeu important en pedologie.

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Ce rapport s'adresse à un large public allant des chercheurs et ingénieurs dans nos disciplines et d'autres domaines, aux étudiants et aux décideurs. Il vise à donner un panorama à jour des recherches en Sciences de la Terre et des outils structurant notre communauté. Il se base sur l'analyse d'environ un millier de dossiers (concours, promotions, évaluations individuelles et de laboratoires) et d'auditions émanant des chercheurs et des candidats de la section 18, ainsi que des propositions de médailles et d’accueil en délégation CNRS. A partir d’une sélection d'illustrations schématisant des exemples représentatifs de changements de paradigme, sont présentées quelques avancées réalisées ces dix dernières années et les défis scientifiques et méthodologiques, sans pouvoir être totalement exhaustifs.

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Ce guide tient à rappeler les bonnes pratiques pour la gestion des données de la recherche tout au long de leur cycle de vie , de leur production à leur diffusion et valorisation. Le guide traite également de la gestion des échantillons qui peut s’avérer aussi nécessaire pour une réutilisation ou un partage.

Peatlands are environments that provide many essential ecological and heritage functions. The Bitche military camp (Moselle, France), although active for more than a century, has allowed the maintenance of wetlands that are now classified as Natura 2000 sites. Through the study of two peat sequences collected inside the camp, the main objectives of this study were to identify the current and past anthropic (particularly military) impact on the peatlands and to reconstruct the vegetation history. Radiocarbon dating and palynological analysis enabled the environmental changes affecting the landscape since the Neolithic period to be highlighted. Throughout this period, the area is characterised by a dominant forest environment with the persistence of pine. The modern period is marked by phases of opening up due to the establishment of agro-pastoral activities. Although contemporary anthropisation is poorly identified in the pollen records, geochemical analyses have revealed a significant accumulation of metals (Cu, Pb and Zn) in the surface horizons, probably linked to military activity. Weaker marking at depth could also reflect an older source of contamination. Despite these high metal contents, their mobility seems relatively limited due to their strong affinity with the organic matter of the peat horizons.

Contamination of training grounds due to energetic compounds is a persistent problem both in France and in the United States. With the development of new insensitive munitions, a new set of compounds is being introduced to the environment. The new compounds are more soluble and therefore can have greater mobility in the environment and higher potential for contaminating ground and surface waters. This study is evaluating fate and transport of traditional explosive compound 1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and new ones: 3-nitro-1,2,4-triazol-5-one (NTO) and 2,4-dinitroanisole (DNAN) in two environments with contrasting climatic conditions, in Camp Militaire de Bitche, in Moselle region of France, location of OHM Bitche County observatory, with wet conditions and organic soils, and in Fort Huachuca, AZ, an arid environment, in close vicinity of the Human-Environment Observatory (OHM) Pima County. Soils have been collected at both locations at or in proximity of military installations. We are conducting adsorption and transformation experiments to determine fate and transport parameters for the surface soils for both locations as well as subsoils, which are rarely examined and parameters for which are assumed. We are performing transformation experiments for both aerobic and anaerobic conditions to reflect the effect of prolonged water saturation on fate of studied compounds. Role of microorganisms in the transformation will be examined. Once parameters have been determined we will conduct modeling for both locations and several climate scenarios (current climate and projected changes in the future) to predict potential contamination.

Le fort développement industriel du début du XX e siècle, puis son déclin à la fin du siècle dernier, ont fortement impacté des surfaces considérables de sol. Dans un contexte de raréfaction des sols et de pressions foncières croissantes, la remédiation et la réhabilitation de ces sols fortement anthropisés sont des enjeux forts. Au-delà de la nécessité d’éliminer la pollution présente et les risques associés pour l’environnement et la santé, la restauration et la refonctionnalisation de ces friches et sols délaissés méritent d’être prises en considération. La possibilité de valoriser ces sols non seulement pour des usages comme la production de biomasse non alimentaire, mais aussi comme réserve de biodiversité est mise en avant dans cet article. Souvent perçues au départ comme un handicap, les friches industrielles peuvent ainsi devenir un véritable atout qu’il convient de valoriser.

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