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Identifying the drivers of soil organic carbon (SOC) stock changes is of the utmost importance to contribute to global challenges like climate change, land degradation, biodiversity loss, or food security. Evaluating the impacts of land use and management practices in agriculture and forestry on SOC is still challenging. Merging datasets or making databases interoperable is a promising way, but still has several semantic challenges. So far, a comprehensive thesaurus and classification of management practices in agriculture and forestry has been lacking, especially while focusing on SOC storage. Therefore, the aim of this paper is to present a first comprehensive thesaurus for management practices driving SOC storage (DATA4C+). The DATA4C+ thesaurus contains 224 classified and defined terms related to land management practices in agriculture and forestry. It is organized as a hierarchical tree reflecting the drivers of SOC storage. It is oriented to be used by scientists in agronomy, forestry, and soil sciences with the aim of uniformizing the description of practices influencing SOC in their original research. It is accessible in Agroportal (http://agroportal.lirmm.fr/ontologies/DATA4CPLUS, last access: 24 March 2022) to enhance its findability, accessibility, interoperability, and reuse by scientists and others such as laboratories or land managers. Future uses of the DATA4C+ thesaurus will be crucial to improve and enrich it, but also to raise the quality of meta-analyses on SOC, and ultimately help policymakers to identify efficient agricultural and forest management practices to enhance SOC storage.

Most of the plastic-based solutions used in bio-manufacturing are today incinerated after use, even the not “bio-contaminated”. Bioprocessing bags used for media and buffer preparation and storage represent the largest amount today. The aim of this work was to technically assess the feasibility of the mechanical recycling of bioprocessing bags. Materials from different sorting and recycling strategies have been characterized, for their suitability of further use. Quantitative physical and mechanical tests and analysis (FTIR, DSC, TGA, density, MFI, color, tensile, flexural, and Charpy choc) were performed. The data show that these recycled plastics could be oriented towards second use requiring physical properties similar to equivalent virgin materials. A comparative life cycle assessment, based on a theoretical framework, shows that mechanical recycling for end of life presents the advantage of keeping material in the loop, without showing a significant statistical difference compared to incineration with regards to the climate change indicator.

International audience

In archaeological contexts, physicochemical soil analyses are essential to distinguish between the anthropogenic characteristics of the soil and those resulting from soil formation processes. This involves several physicochemical characterisations of samples, which have been used since the first half of the last century in various regions of the world, but only recently in French Guiana. Ferralsols from French Guiana, and from the neotropics in general, are known to be acidic and nutrient poor, with particular properties. The choice of an appropriate methodology is important to understand the observed values and ultimately to compare the results between different projects. This chapter therefore presents each analysis and expected interpretations in light of past human activities.

This chapter presents the concepts that are essential to understanding the open and complex system of the soil. This major compartment of terrestrial ecosystems is continuously exposed to transformations, alterations, material and energy flows, infiltration, erosion and bioturbations, which may be entirely natural or more or less human induced. All these effects vary at different spatial scales, depending on geology, relief and climate, and give each soil a particular set of characteristics. A global vision of the soil system makes it possible to reconstruct the dynamics of their formation and to evaluate the role that human activities can play in the structure and composition of the current soil. In the frame of historical ecology projects, soils can be considered pedological archives of human history.

International audience; This study focuses on the corrosion behaviour of Ti-6Al-2Sn-4Zr-2Mo-Si alloy in presence of NaCl deposit in air at 560 °C. The active oxidation mechanism at the origin of the corrosion phenomenon enhancement in presence of solid NaCl is thought to be connected to the formation of both external and internal thick oxidation areas. Thermodynamic calculations allowed showing the role played by the different alloying elements in the forma-tion of the external oxide and detailed TEM characterisations brought new insights regarding the nature and origin of the internal oxidation area.

The refractory materials required for waste-to-energy boilers endure severe working conditions, such as exposure to heat and hot oxidation / corrosion. Thanks to their high temperature properties cobalt-based alloys may respond to these properties requirements. In this work two model alloys based on cobalt and rich in chromium were elaborated by casting and samples were prepared by cutting and polishing. These samples were exposed, one to a hot complex gaseous mixture particularly aggressive reproducing the atmosphere in WtE boilers in service (presence of water vapor, di-oxygen, carbon di-oxide, hydrogen chloride), and the other to synthetic ashes, both for more than two hundreds hours. After test the samples were characterized by X-ray diffraction and SEM observations. On sample exposed to the complex gas stream a {10 to 15μm}-thick oxide scale formed on the surface of the sample exposed to the gas mixture. It involved all the elements of the alloy and it obviously developed both inwards and outwards as suggested by the position of the oxidized carbides.

Plastics have numerous properties that render them superior to other materials in many applications. Since the past 50 years, the use of plastics has dramatically increased in our daily lives. However, household refuse and industrial disposal of plastic materials is a major environmental concern. Because of legal requirements, which have been enforced to protect the environment, there is a pressing need to develop methods to recycle plastic waste. Mechanical recycling has emerged as the most economical, as well as the most energetic and ecologically efficient option. After introducing the mechanical recycling concept, this review will focus on the strategies that have been used for compatibilization of blends of mixed thermoplastic waste.

Assessment of soil organic carbon stocks (SOCs) is highly relevant considering that SOCs is the central driver in climate change mitigation and soil fertility. In Madagascar, a first attempt at mapping SOCs on a national scale was undertaken in 2009 with previous soil data. Advanced research on soil carbon mapping on a global scale is required to enable better land use decisions. This study aims to (i) evaluate the drivers of soil organic carbon (SOC) storage in the first 30 cm soil layer on a national scale from spatially explicit explanatory environmental variables and a recent soil database and (ii) update the spatial distribution of SOCs at this scale through digital mapping. A spatial model was established using randomForest, a decision tree algorithm and based on 10 pedoclimatic, topographic, and vegetation variables. The model was developed with 1993 available soil plot data (collected from 2010 to 2015) and their environmental information (“VALSOL-Madagascar” database). These data were divided into two sets: a first set (n = 835) used for model calibration and a second set (n = 358) for external validation. Results showed that mean annual temperature (MAT, °C), mean annual precipitation (MAP, mm), elevation (m) and Normalized Difference Vegetation Index (NDVI) were the most important predictors of SOCs. The retained prediction model had a Root Mean Squared Error (RMSE) equal to 25.8 MgC·ha− 1. The predicted SOCs from fitted models ranged from 28 to 198 MgC·ha− 1 with total SOCs to 4137 TgC. Depending on soil type, Ferralsols (35 to 165 MgC·ha− 1) and Andosols (48 to 198 MgC·ha− 1) had relevant results related to the number of soil profiles (n = 856 and 171 respectively). Despite the need for in-depth analysis, the model and map produced in the present study has greatly improved our knowledge of the spatial distribution of SOCs in Madagascar and reduced uncertainty compared to the former map. This map provides new perspectives in sustainable land management in Madagascar.

Les sols sont une ressource essentielle a preserver pour la production d'aliments, de fibres, de biomasse, pour la filtration de l'eau, la preservation de la biodiversite et le stockage du carbone. En tant que reservoirs de carbone, les sols sont par ailleurs appeles a jouer un role primordial dans la lutte contre l'augmentation de la concentration de gaz a effet de serre. Ils sont ainsi au centre des objectifs de developpement durable (ODD) des Nations unies, notamment les ODD 2 « Faim zero », 13 « Lutte contre le changement climatique », 15 « Vie terrestre », 12 « Consommation et production responsables » ou encore 1 « Pas de pauvrete ». Cet ouvrage presente un etat des lieux des sols africains dans toute leur diversite, mais au-dela, il documente les capacites de stockage de carbone selon les types de sols et leurs usages en Afrique. Il propose egalement des recommandations autour de l'acquisition et de l'interpretation des donnees, ainsi que des options pour preserver, voire augmenter les stocks de carbone dans les sols. Tous les chercheurs et acteurs du developpement impliques dans les recherches sur le role du carbone des sols sont concernes par cette synthese collective. Fruit d'une collaboration entre chercheurs africains et europeens, ce livre insiste sur la necessite de prendre en compte la grande variete des contextes agricoles et forestiers africains pour ameliorer nos connaissances sur les capacites de stockage de carbone des sols et lutter contre le changement climatique. Cet ouvrage est une contribution du reseau Carbone des sols pour une agriculture durable en Afrique (Casa). Les objectifs du reseau Casa s'inscrivent dans le cadre de l'Action commune de Koronivia pour l'Agriculture (Koronivia Joint Work on Agriculture, KJWA). Adoptee en 2017, lors de la 23e conference des Parties (COP 23), la KJWA fournit un cadre pour renforcer la place de l'agriculture dans les discussions internationales sur le climat, a la fois pour son role dans la reduction de la concentration en gaz a effet de serre dans l'atmosphere et sa necessaire adaptation face au changement climatique.

Titanium alloys are widely used in aerospace applications due to their good ratio of weight versus mechanical properties. When exposed to air at 560°C, Ti6242S titanium alloy presents very good oxidation resistance: a very thin oxide layer forms at its surface and oxygen dissolution inside the metallic material is rather limited. However, in real functioning conditions of the plane, near seas or oceans, the atmosphere contains NaCl, that can crystallise at the surface of hot parts. An active corrosion mechanism is established in these conditions, with catastrophic effect on the material behaviour at high temperature: very thick and brittle oxide scales and very important damaging of the metal outer part. Another issue is the formation of Na2SO4 specie by reaction of NaCl with kerosene combustion gases (SO2/SO3), leading to mixed NaCl/Na2SO4 deposits. The effect of exposure conditions on the mechanical properties of titanium alloy Ti6242S was evaluated through tensile tests performed on the raw alloy and after oxidation in air at 560°C of the specimens: without any deposit, with NaCl solid deposit, with NaCl/Na2SO4 solid deposit. The evolution of mechanical properties was interpreted in connexion with the microstructural modifications that occur during the high temperature ageing.

International audience; In French Guiana, the general environmental context and the growing need for energy and food products, linked to population growth, are responsible for increasing pressure on natural resources through land use changes. Low impact practices are emerging in the aim of reconciling production and environmental objectives. In French Guiana slash and burn practices are still used to increase agricultural area, and lead to a large loss of carbon. A field survey was carried out in order to understand the place of soil in farmers' choices, and to obtain a description of production systems and practices, focusing on identifying those with low impact on carbon dynamics. This step was realized through specific soil carbon stock measurements. Our results show that the "soil object" is mastered by farmers in terms of physical properties, and organic matter is a recognized indicator which is used to inform spatial management of farming systems. Farmers mobilizing low-impact practices have efficient production systems for their economic and environmental benefits.; En Guyane, les questions environnementales et le besoin croissant en énergie et produits alimentaires liés à la croissance démographique exercent une pression accrue sur les ressources naturelles par le changement d'affectation des sols qu'ils engendrent. Des agriculteurs testent cependant des pratiques à faible impact conciliant objectifs de production et respect de l'environnement. Une prospection dans les systèmes de production agricoles guyanais, basée sur des enquêtes de terrain, a permis la description de ces pratiques ; parmi celles-ci, les pratiques à faible impact sur la dynamique du carbone ont été sélectionnées dans des systèmes maraîchers et arboricoles, pour des mesures spécifiques des stocks de carbone des sols. En Guyane, la pratique de la défriche est toujours active afin d'étendre les surfaces agricoles utiles. Cela induit des pertes de carbone importantes. Nous cherchons donc à identifier des pratiques qui permettent de compenser ces pertes. La place du sol dans les prises de décision des agriculteurs a été appréhendée et des mesures spécifiques des stocks de carbone des sols ont complété l'enquête, pour mieux comprendre les logiques des pratiques mises en oeuvre et en cerner les effets. Nos résultats montrent que les agriculteurs maîtrisent « l'objet sol » dans ses composantes physiques ; la matière organique est un indicateur reconnu qui conditionne l'organisation des cultures sur l'exploitation. En Guyane, les agriculteurs mobilisant des pratiques à faible impact ont des systèmes de production efficients au niveau économique et environnemental (carbone et gaz à effet de serre). Mots clés : système de culture / Amazonie / petite agriculture tropicale Abstract-Identification and evaluation of agricultural practices that store soil carbon, a first step towards low impact agriculture. In French Guiana, the general environmental context and the growing need for energy and food products, linked to population growth, are responsible for increasing pressure on natural resources through land use changes. Low impact practices are emerging in the aim of reconciling production and environmental objectives. In French Guiana slash and burn practices are still used to increase agricultural area, and lead to a large loss of carbon. A field survey was carried out in order to understand the place of soil in farmers' choices, and to obtain a description of production systems and practices, focusing on identifying those with low impact on carbon dynamics. This step was realized through specific soil carbon stock measurements. Our results show that the "soil object" is mastered by farmers in terms of physical properties, and organic matter is a recognized indicator which is used to inform spatial management of farming systems. Farmers mobilizing low-impact practices have efficient production systems for their economic and environmental benefits.

International audience; The $^{10}$Be, $^{137}$Cs and $^{210}$Pb$_{xs}$ radionuclide fallout has been used for the last several decades to quantify various soil and geomorphological processes and their rates, on different time scales. However, a basic assumption of the studies relying on these radionuclides is that they have a strong affinity for soil particles and that their mobility in soil solution and losses through leaching can be neglected. Another area of the scientific literature deals with the radionuclide mobility in soils as solute. In that context, the objective of this work is to determine the pedological conditions under which this hypothesis of poor solute mobility of radionuclides is valid. To this end, meteoric $^{10}$Be, $^{137}$Cs and $^{210}$Pb$_{xs}$ concentrations were measured in six soil profiles representative of 5 soil types contrasted in terms of physico-chemical properties: an Andosol and a Luvisol under pasture, a Ferralsol and a Leptosol under forest and a Podzol both under forest and cultivation. The main soil properties (soil pH, organic carbon (OC) content, particle size distribution and specific extractions) were measured. The

International audience; Land use affect soil C and microbial structure, especially in tropical dry areas. The objective of this study was to evaluate the effects of the land use on physical, chemical, and microbiological attributes of soils from Brazilian semiarid. We analyzed soil physical, chemical, total carbon stocks (TCS), water-soluble carbon (WSC), microbial biomass carbon (MBC) and microbial structure of soil from forest, no irrigation maize, succession areas (Anadenanthera falcate and Tabebuia alba) and secondary shrubby vegetation. The use of soil influences C stock. The forest soil showed higher TCS and MBC. The conversion in T. alba reduced in 9% soil total bacteria. The multivariate analysis showed that TCS, MBC and FAMEs contributed to separation of natural forest and other areas in the superficial layer. This study indicates that the conversion of forest into successional areas can decrease by up to 44% TCS and 68% MBC. The present study provided alarming data concerning the impact of land use on quality of soil in a tropical dry region in Northeastern Brazil. Our results provide an alternative tool for the management of deforested dry areas that could serve as guideline for management plan to sustainability for agricultural impacted dry areas.

International audience; The work reported here is the first study aimed at providing a full screening of a real unsortable non-recycled post-consumer WEEE stream free of brominated flame retarded plastics, separated using on-line X-ray detection, toward its recycling. In the existing sorting lines, up to 40% of plastics from waste electrical and electronic equipment (WEEE) stream can be rejected, herein named unsortable plastics. To have the most representative homogeneous sample for physico-chemical characterizations, a sampling method was developed to overcome the heterogeneity of the investigated 500 kg batch. The batch screening on both representative samples (∼500 μm size) and 100 plastic fractions (∼20 mm size), by means of routine techniques used in the plastic industry, has allowed to quantify reliably the main polymers included in the studied batch; ∼50% styrene-based polymers, ∼15% polypropylene (PP), ∼15% polycarbonate (PC), ∼1–4% polyamide (PA), polyethylene (PE), polyvinyl chloride (PVC), poly (ethylene terephthalate) (PET), poly (methyl methacrylate) (PMMA) and ∼8% of multi-layer plastics, paints and thermosets. The identification of the ∼8.0% inorganic phase by X-ray fluorescence spectrometry revealed the presence of several additives/charges commonly incorporated in plastic materials, such as calcium carbonate and talc. The studied batch was then subjected to electron beam irradiation at 50 and 200 kGy doses, as a means of compatibilization between the batch components. The mechanical properties and thermal behavior of irradiated samples pointed out the crucial role of the residual free radical scavenger agents present in post-consumer WEEE streams, leading to significantly different properties compared to those of irradiated virgin polymer blends highlighted in the literature.

Tropical environments are considerable contributors to overall soil carbon loss to the atmosphere. Land use effects on soil chemical attributes have been well documented mainly in humid environments; however, less attention has been paid to the changes in soil enzymatic activities in dry ecosystems that is a sensitive indicator in ecological processes, due to its importance in soil dynamics and microbial activity. The present study is part of interdisciplinary project that investigated the effect of land cover type and seasonal variation on absolute and specific enzymatic activities per unit of soil organic carbon (SOC) and per microbial biomass carbon (MBC). We assessed five different land use type (Tropical dry forest-TDF, protected area with Angico –ANA, protected area with Ipe-TAB, Scrub area-SCR and agricultural area with maize-M) and five areas of each land use in three layers: 0–0.05, 0.05–0.10 and 0.10–0.20 m. The samples were collected at rainy season 1 in April 2014 (RS1), dry season October 2015 (DS) and rainy season 1 April 2016 (RS2). The conversion of the preserved area provided a reduction in absolute enzymatic activities, especially in the SCR and M. The reductions were of 76% for β-glucosidase, 95% for urease and 72% for acid phosphatase. The specific enzymatic activities per unit of MBC increased with the change of soil use, except in M. The enzymatic activity per unit of SOC in the TDF area was higher in relation to the other areas evaluated, except for specific activity of acid phosphatase. The land use type influenced the absolute and specific soil enzyme activities, but not show a clear trend of seasonal effect.

In soil science, structural features of soils are an important attribute; soils can be characterised by proportional size distribution of aggregates and the pore space between and within those aggregates. The objective of this study was to evaluate the relationship between the visible and near infrared (Vis-NIR) spectra and microaggregates from a collection of Ferralsols. Our dataset consists of 56 spectra from seven soil profiles of kaolinitic and oxidic–gibbsitic Ferralsols. Soils were characterised according to their morphological features: those with a typical porous massive structure and those with a cohesive massive structure. Size distribution of five classes of microaggregate was determined (1000–2000 μm, 500–1000 μm, 250–500 μm, 105–250 μm and CIE) and the absorption intensities of kaolinite ( IKa) and gibbsite ( IGb). The predominant fraction of microaggregates exhibited sizes between 250 and 1000 μm (Φ250–1000). The proportional increase of this microaggregate class in the soils increased the scattering and variability of reflected light, particularly when soil samples showed more than 0.50 g g−1 of Φ250–1000. The microaggregate size explained over 55% of reflectance intensity variability of wavelengths in the Vis-NIR regions, principally on reflectance intensity and concavity of the spectra at 436 nm, 546 nm and 2236 nm, which decreases with increased proportion of Φ250–1000. Thus, different structural features of Ferralsols can be directly evaluated through Vis-NIR spectroscopy, even in samples sieved through 2.00 mm. These results highlight the potential use of Vis-NIR spectroscopy in studies of soil classification, soil physical behaviour and soil physical fertility and environmental studies, principally by a new method of analysing bulk density and structure of soil directly from the soil spectra, without the need for predictive models. As well as spectra, RICIE, IKa and IGb can be used to characterise the various structural features of Ferralsols.

Summary Large inputs of woody debris to soil can improve the soil. We examined the fate of woody debris buried in soil after fire-free forest conversion to cropland in French Guiana. We measured the mass loss of woody debris > 4 mm on five sampling dates for 4 years after deforestation. Composition of the organic matter of woody debris was analysed with Rock-Eval pyrolysis, which enabled us to distinguish a labile carbon pool (Clab) and a resistant carbon pool (Cres). Decomposition of woody debris followed a first-order function with a half-life of 17.6 months. During the decomposition of woody debris > 4 mm, the C:N ratio, hydrogen index (HI) and pyrolysed carbon below 400°C (R400) decreased, suggesting that decarboxylation and dehydrogenation of woody debris occurred. Both Clab and Cres stocks decreased with time, but the decrease in Clab was faster. There was little humification of the debris and no long-term biogeochemical preservation of a woody debris fraction, which accords with the first-order decay observed. We conclude that the benefits of ligno-cellulosic inputs for soil organic carbon contents in a tropical humid climate occur during the first year following deforestation. Resume Les apports massifs de debris de bois au sol peuvent ameliorer le sol. Nous avons examine sur un site en Guyane le devenir de debris de bois enfouis dans le sol, suite a la conversion sans brulis de foret en cultures. Nous avons mesure le stock des debris de bois > 4 mm jusqu'a 4 annees apres deforestation. Les transformations de la matiere organique des debris ont bois ont ete analysees par la pyrolyse Rock-Eval, nous permettant de distinguer un compartiment de carbone labile (Clab) et un compartiment de carbone resistant (Cres) dans ces debris. La decomposition des debris de bois suit une decroissance exponentielle de premier ordre, avec une demi-vie de 17,6 mois. Durant la decomposition des debris, le rapport C/N, l'indice d'hydrogene (HI) et le carbone pyrolyse avant 400°C (R400) diminuent, suggerant des processus de decarboxylation et deshydrogenation qui se mettent en place rapidement apres l'enfouissement des debris. Les stocks de Clab et Cres diminuent tous deux au cours du temps, avec une cinetique plus rapide pour Clab. Ces resultats indiquent une faible polymerisation de la matiere organique des debris, et une absence de preservation biogeochimique d'une partie des debris, en accord avec la decroissance exponentielle observee. Cette etude suggere que les benefices des amendements ligno-cellulosiques pour la matiere organique des sols sont de courte duree en milieu tropical humide.

Currently cobalt-based alloys are seemingly not really envisaged for constituting waste-to-energy boilers, although that the WtE working conditions are similar to those encountered in some applications in which Co-based superalloys are successfully used. To test the behavior of the cast chromium-rich cobalt-based alloys’ family, two model alloys belonging to the later one were cast and samples were exposed during more than ten days to a hot complex gaseous mixture and to synthetic ashes. After test the samples were characterized by X-ray diffraction and SEM observations. The results of the characterization of the first sample, the one exposed to the hot complex gaseous atmosphere, were presented in the first part of this work. This second part concerns the post-mortem analysis of the second sample, the one immersed in ashes. It appears first that this one was not protected by any external oxide scale. Instead, a mixture of oxides and chlorides formed and reaction between these corrosion products with ashes obviously led to an intermediate liquid phase. Internal oxidation/chloridation of the chromium carbides network obviously occurred over a 500μm-depth from the surface happened. The responsibility of an active oxidation mechanism analogous to what was earlier observed on steels is envisaged.