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International audience; The widespread use of pesticides in agriculture during the last several decades has contaminated soils and different Critical Zone (CZ) compartments, defined as the area extended from the top of the vegetation canopy to the groundwater table, and it integrates interactions of the atmosphere, lithosphere, biosphere, and hydrosphere. However, the long-term fate, storage, and transfer dynamics of persistent pesticides in CZ in a changing world remain poorly understood. In the French West Indies, chlordecone (CLD), a toxic organochlorine insecticide, was extensively applied to banana fields to control banana weevil from 1972 to 1993 after which it was banned. Here, to understand CZ trajectories we apply a retrospective observation based on marine sediment core analyses to monitor long-term CLD transfer, fate, and consequences in Guadeloupe and Martinique islands. Both CLD profiles show synchronous chronologies. We hypothesized that the use of glyphosate, a postemergence herbicide, from the late 1990s onward induced CZ modification with an increase in soil erosion and led to the release of the stable CLD stored in the soils of polluted fields. CLD fluxes drastically increased when glyphosate use began, leading to widespread ecosystem contamination. As glyphosate is used globally, ecotoxicological risk management strategies should consider how its application affects persistent pesticide storage in soils, transfer dynamics, and widespread contamination.

International audience; In Guadeloupe, the use between 1972 and 1993 of chlordecone, an organochlorine insecticide, has permanently contaminated the island’s soil, thus contaminating the food chain at its very beginning. There is today a strong societal requirement for an improved mapping of the contaminated zones. Given the extent of the areas to be covered, carrying out soil tests on each plot of the territory would be a long and expensive process. In this article, we explore a method of demarcating polluted areas. The approach adopted consists in carrying out, using surface water analyses, a hydrological delimitation that makes it possible to distinguish contaminated watersheds from uncontaminated ones. The selection of sampling points was based on the spatial analysis of the actual and potential contamination data existing at the beginning of the study. The approach was validated by soil analyses, after having compared the contamination data of the watersheds with the soil contamination data of the plots within them. The study thus made it possible to highlight new contaminated areas and also those at risk of contamination and to identify the plots to be targeted as a priority during future analysis campaigns by State services.

International audience; The actual health risk and associated diseases induced by the presence of pesticides and other organic pollutants in most environmental media worldwide are largely underestimatedbecause current analytical methods measure only the extractable fraction of the pollutant, whereas there is now ample evidence that a large part of pollutants are trapped as bound residues in complex organo-mineral matrixes, and are thus unanalyzable by current tools. Once trapped, pollutants can be stored for long periods, then released in the biosphere upon suitable conditions such as soil erosion and climate change. This ‘resurrection’ and underlying mechanisms of trapping, storage and release are poorly known. Here we discuss the limit of knowledge on bound pollutants and their later release, with examples of organochlorines in glaciers, vineyards and banana plantations. Unexpectedly, soil application of a modern pesticide such as glyphosate, can lead to the resurrection of ancient, actually banned pesticides such as chlordecone and dichlorodiphenyltrichloroethane (DDT) (Fig. 1).

International audience; Chlordecone (CLD), used to control the Cosmopolites sordidus banana weevil and released from polluted banana plantations, continues to contaminate ecosystems in the French Caribbean. Edible plants have been actively studied for risk prevention, but trees have not, even though they could play a significant role in future remediation strategies. CLD contents were analysed in 24 pioneer trees belonging to 13 species found in abandoned banana plantations inGuadeloupe, at three contaminated sites on Nitisols (Site 1) and Andosols (Sites 2 and 3). Samples were taken from each tree: wood in the basal part of the trunk and soil at its foot and their CLD content was measured by the analytical laboratory for the Drôme département (26) in Valence, France. Mean CLD contents in the top 30-centimetre soil layer from sites 1, 2 and 3 were 2,543 ± 702, 5,251 ± 1,102 and 875 ± 865 μg/kg dry soil respectively. Of the trees, 96% werecontaminated. The CLD content in trees growing on Nitisols (3,406 ± 1,658 μg/kg dry wood) was at least 5 times higher than in trees growing on Andosols (299 ± 314 and 226 ± 378 μg/kg), but no clear relationships were found with soil CLD contents. Calculations of available CLD dissolved in the soil liquid phase using equations and soil datasets in the literature showed higher available CLD contents in Nitisols than in Andosols and a linear relationship between CLD available in soil and concentrations of CLD in wood, regardless of the type of soil. Trees growing on Nitisols are the plants most highly contaminated by CLD of all the plants in which this compound has been studied so far. With a plant-to-soil bioconcentration ratio around 150 l/kg, the consistent CLD uptake efficiency of the trees needs to be taken into account in further research for CLD remediation.; Le chlordécone (CLD), utilisé pour lutter contre le charançon du bananier Cosmopolites sordidus et libéré par des bananeraies polluées, continue de contaminer les écosystèmes des Antilles françaises. Les plantes comestibles ont été activement étudiées pour la prévention des risques, mais pas les arbres, alors même qu'ils pourraient jouer un rôle important dans les stratégies de dépollution. Les teneurs en CLD ont été analysées sur 24 arbres pionniers appartenant à 13 essences présentes dans des bananeraies abandonnées en Guadeloupe, sur trois sites contaminés sur nitisols (site 1) et andosols (sites 2 et 3). Des échantillons de bois ont été prélevés sur chaque arbre dans la partie basale du tronc et dans le sol à son pied. Leur teneur en CLD a été mesurée par le laboratoire d'analyses départemental de la Drôme (26) à Valence, France. Les teneurs moyennes en CLD dans la couche supérieure de 30 centimètres du sol des sites 1, 2 et 3 étaient respectivement de 2 543 ± 702, 5 251 ± 1 102 et 875 ± 865 µg/kg de sol sec. Parmi les arbres, 96 % étaient contaminés. La teneur en CLD des arbres poussant sur nitisols (3 406 ± 1 658 µg/kg de bois sec) était au moins cinq fois plus élevée que celle des arbres sur andosols (299 ± 314 et 226 ± 378 µg/kg), mais aucune relation nette n'a été établie avec la teneur en CLD du sol. Le calcul du CLD disponible dissous en phase liquide dans le sol, à l'aide d'équations et de séries de données pédologiques de la littérature, a montré des teneurs en CLD disponible plus élevées dans les nitisols que dans les andosols et une relation linéaire entre le CLD disponible dans le sol et les concentrations de CLD dans le bois, quel que soit le type de sol. Les arbres poussant sur nitisols sont les espèces végétales les plus fortement contaminées par le CLD parmi toutes celles dans lesquelles ce composé a été étudié jusqu'à présent. Avec un rapport de bioconcentration plante-sol d'environ 150 l/kg, l'efficacité soutenue d'absorption de CLD par les arbres doit être prise en compte dans les recherches futures sur la dépollution des milieux contaminés par le chlordécone.

L'ensemble des activités en lien avec l'eau du lac de Guiers au Sénégal a potentiellement des conséquences importantes sur son état écologique. Cet article part du constat que la pollution par les pesticides concentre l'essentiel des débats et des actions entreprises tandis que l'enrichissement en nutriments des eaux du lac (représentant un risque d'eutrophisation) n'est un problème que rarement évoqué. Ce constat conduit les auteurs à s'interroger sur les facteurs sociopolitiques qui conduisent à " l'invisibilisation " de certaines causes de dégradation des milieux aquatiques. En nous appuyant sur une enquête de terrain auprès des gestionnaires et usagers du lac, nous montrons les concurrences entre les différents services administratifs qui conduisent à diverses formes de segmentation des causes de dégradation et à la sélection de l'une d'entre elles. Nous montrons ensuite comment cette formalisation du problème est diffusée et renforcée par la mise en oeuvre de bonnes pratiques agricoles, essentiellement centrées sur la question des produits phytosanitaires et relayées par des acteurs territoriaux. Cette analyse de la construction institutionnelle de l'ignorance est enfin complétée par une étude des représentations que les usagers se font de la dégradation de leur lac, permettant d'identifier les dynamiques sociales, les conflits et les jeux de pouvoir autour de l'appropriation de l'espace et de l'accès à l'eau, qui conduisent à l'invisibilisation du problème de l'eutrophisation.

PurposeIn tropical cropping systems, pesticides are extensively used to fight pests and ensure high crop yields. However, pesticide use also leads to environmental and health impacts. While pesticide emissions and impacts are influenced by farm management practices and environmental conditions, available Life Cycle Inventory (LCI) emission models and Life Cycle Impact Assessment (LCIA) toxicity characterization models are generally designed based on temperate conditions. There is, hence, a need for adapting LCI and LCIA models for evaluating pesticides under tropical conditions. To address this need, we aim to identify the characteristics that determine pesticide emissions and related impacts under tropical conditions, and to assess to what extent LCI and LCIA models need to be adapted to better account for these conditions.MethodsWe investigated the state-of-knowledge with respect to characteristics that drive pesticide emission patterns, environmental fate, human and ecological exposures, and toxicological effects under tropical conditions. We then discuss the applicability of existing LCI and LCIA models to tropical regions as input for deriving specific recommendations for future modeling refinements.Results and discussionOur results indicate that many pesticide-related environmental processes, such as degradation and volatilization, show higher kinetic rates under tropical conditions mainly due to higher temperatures, sunlight radiation, and microbial activity. Heavy and frequent rainfalls enhance leaching and runoff. Specific soil characteristics (e.g., low pH), crops, and cropping systems (e.g., mulching) are important drivers of distinct pesticide emission patterns under tropical conditions. Adapting LCI models to tropical conditions implies incorporating specific features of tropical cropping systems (e.g., intercropping, ground cover management), specific drift curves for tropical pesticide application techniques, and better addressing leaching processes. The validity domain of the discussed LCI and LCIA models could be systematically extended to tropical regions by considering tropical soil types, climate conditions, and crops, and adding active substances applied specifically under tropical conditions, including the consideration of late applications of pesticides before harvest and their effect on crop residues and subsequent human intake.ConclusionsCurrent LCI and LCIA models are not fully suitable for evaluating pesticide emissions and impacts for crops cultivated in tropical regions. Models should be adapted and parameterized to better account for various characteristics influencing emission and impact patterns under tropical conditions using best available data and knowledge. Further research is urgently required to improve our knowledge and data with respect to understanding and evaluating pesticide emission and impact processes under tropical conditions.

La révision par l'Union européenne de sa réglementation phytosanitaire est l'occasion unique pour la filière banane de se réinventer. Les menaces qui pèsent sur l'utilisation du mancozèbe par le secteur de la production et de l'exportation pourraient en effet rebattre les cartes à un point tel qu'il pourrait y avoir un avant et un après. Revue de détail par le Cirad de ce monde d'après.

Dans le contexte des Antilles, entre climat très favorable aux adventices et monocultures très dépendantes des intrants, la pression herbicide est importante. En Martinique la pollution par ces molécules, via des mécanismes de transfert fortement spatialisés à l'échelle des bassins versants, dégrade la qualité de l'eau des rivières. Dans ce contexte, la thèse propose, en s'appuyant sur la construction d'une méthode de conception collective originale, des organisations territoriales innovantes pour générer des changements coordonnés dans des systèmes de production agricoles visant à réduire durablement la concentration d'herbicides dans les rivières. La démarche est mise en oeuvre sur un bassin versant particulièrement concerné par la pollution herbicide et combine : un diagnostic du système sociotechnique, une phase d'atelier de conception innovante inspirée de la théorie C-K et une phase visant à évaluer les concepts innovants en simulant leur mise en oeuvre dans un jeu sérieux. Les innovations portent tant sur la répartition spatiale de techniques innovantes sur le territoire du bassin versant que sur les dispositifs, aménagements, organisations à créer pour assurer leur succès et leur durabilité. La thèse s'inscrit à la fois dans une agronomie des territoires et dans une agronomie de la conception innovante.

Overreliance on synthetic insecticides in global agriculture is the outcome of a “pesticide treadmill,” in which insecticideinduced pest resistance development and the depletion of beneficial insect populations aggravate farmers’ pesticide dependencies. Examples of the pesticide treadmill have been witnessed repeatedly over the past seven decades, prompting the question whether the rapid uptake and usage patterns of neonicotinoid insecticides and their associated environmental impact are in accordance with this recurrent phenomenon. We hypothesize a conceptual framework in which treadmills are enforced by enabling or disabling drivers within four domains: pest management decisions at the farm level, characteristics of farming landscapes, science and technology, and societal demands. These drivers then tend to create a self-enforcing pesticide “lock-in.” We then analyze several post-1950s historical case studies with reference to this framework, e.g., those involving sprays of the highly hazardous DDT and methyl-parathion, in which the pesticide treadmill was initiated, sustained, and broken, and compare this with current patterns in neonicotinoid use. Historical case studies further illustrate how treadmills occur in three phases in which (i) a limited number of insecticides are routinely used, (ii) resistance development of pests results in the increased crop injury, prompting increased frequency of applications with a wider range of products, (iii) breaking out of the pesticide “lock-in” by policy change and adoption of alternative technologies that lowered chemical inputs and improved agro-ecosystem functioning. The analysis shows similarities as well as differences between neonicotinoid usage patterns and historic pesticide treadmills, and provides guidance on how to effectively avoid or dismantle pesticide treadmills in global agriculture.

International audience; Background and aims: Agroforestry systems combining trees with crops or pastures have been widely used to reduce water, soil, and nutrient losses and associated water pollution from agricultural lands in both temperate and tropical regions. However, reviews on improvement/efficiency and the scope of such reductions by soil, management, climate, and hydrological processes are limited.Methods: This paper synthesized the available evidence on the reduction in surface runoff, soil erosion, nutrient, and pollutant losses (e.g., herbicides, pesticides, and antibiotics) to quantify the effectiveness of agroforestry systems on water quality improvement based on published studies.Results: On average, agroforestry systems reduced surface runoff, soil, organic carbon, and related nutrient losses by 1–100%, 0–97%, –175–92%, and –265–100%, respectively, with average values of 58%, 65%, 9%, and 50%, respectively. They also lowered herbicide, pesticide, and other pollutant losses by –55–100% (49% on average).Conclusions: Reduction efficiency of agroforestry systems is site-dependent and varies widely depending on different biophysical factors. A comprehensive science-based review is needed to generalize agroforestry design and site adaptability for water and soil conservation where climatic, geographical, ecological, and socio-economic conditions are relatively similar in the world.

International audience; Chlordecone, applied on soils until 1993 to control banana weevil, has polluted water resources in the French West Indies for more than 40 years. At the watershed scale, chlordecone applications were not homogenous, generating a spatial heterogeneity of the pollution. The roles of climate, hydrology, soil, agronomy, and geology on watershed functioning generate a temporal heterogeneity of the pollution. This study questions the interactions between practices and the environment that induce such variability. We analyzed hydrological and water pollution datasets from a 2-year monitoring program on the Galion watershed in Martinique (French West Indies). We conjointly analyzed (i) weekly chlordecone (CLD) concentration monitored on 3 river sampling sites, (ii) aquifer piezometric dynamics and pollutions, and (iii) agricultural practices on polluted soils. Our results showed that chlordecone pollution in surface waters are characterized by annual trends and infra-annual variations. Aquifers showed CLD concentration 10 times higher than surface water, with CLD concentration peaks during recharge events. We showed strong interactions between rainfall events and practices on CLD pollution requiring a systemic management approach, in particular during post-cyclonic periods. Small sub-watershed with high CLD pollution appeared to be a substantial contributor to CLD mass transfers to the marine environment via rivers and should therefore receive priority management. We suggest increasing stable organic matter return to soil as well as external input of organic matter to reduce CLD transfers to water. We identified hydrological conditions-notably drying periods-and tillage as the most influential factors on CLD leaching. In particular, tillage acts on 3 processes that increases CLD leaching: organic matter degradation, modification of water paths in soil, and allophane clay degradation.

International audience; In the French West Indies, the chlordecone (organochloride pesticide) pollution is now diffuse becoming new contamination source for crops and environment (water, trophic chain). Decontamination by bioremediation and chemical degradation are still under development but the physical limitations of these approaches are generally not taken into account. These physical limitations are related to the poor physical accessibility to the pesticides in soils because of the peculiar structural properties of the contaminated clays (pore volume, transport properties, permeability, and diffusion). Some volcanic soils (andosols), which represent the half of the contaminated soils in Martinique, contain nanoclay (allophane) with a unique structure and porous properties. Andosols are characterized by pore size distribution in the mesoporous range, a high specific surface area, a large pore volume, and a fractal structure. Our hypothesis is that the clay microstructure characteristics are crucial physico-chemical factors strongly limiting the remediation of the pesticide. Our results show that allophane microstructure (small pore size, hierarchical microstructure, and tortuosity) favors accumulation of chlordecone, in andosols. Moreover, the clay microporosity limits the accessibility of microorganisms and chemical species able to decontaminate because of poor transport properties (permeability and diffusion). We model the transport properties by two approaches: (1) we use a numerical model to simulate the structure of allophane aggregates. The algorithm is based on a cluster-cluster aggregation model. From the simulated data, we derived the pore volume, specific surface area, tortuosity, permeability, and diffusion. We show that transport properties strongly decrease because of the presence of allophane. (2) The fractal approach. We characterize the fractal features (size of the fractal aggregate, fractal dimension, tortuosity inside allophane aggregates) and we calculate that transport properties decrease of several order ranges inside the clay aggregates. These poor transport properties are important parameters to explain the poor accessibility to pollutants in volcanic soils and should be taken into account by future decontamination process. We conclude that for andosols, this inaccessibility could render inefficient some of the methods proposed in the literature.

L'utilisation abusive des pesticides sur les légumes constitue des sources potentielles de contamination pour les consommateurs et l'environnement. La présente étude a été initiée pour caractériser les pratiques de traitements phytosanitaires des cultures maraîchères et les risques sanitaires et environnementaux liés à l'usage des pesticides. Une enquête a été réalisée auprès de 47 producteurs maraîchers dans les bas-fonds de Bamadougou et de Doumanaba dans la région de Sikasso pour caractériser leurs pratiques. Des échantillons d'eau d'irrigation, de sol, de produits végétaux et de pesticides ont été prélevés et analysés pour déterminer les teneurs en résidus de pesticides et de matières actives. Les résultats ont montré que les chenilles étaient les bio-agresseurs les plus importants et que la lutte chimique était la plus utilisée contre ces nuisibles. Il ressort de nos résultats de l'utilisation de ATTAKAN C 344 SE (insecticide du cotonnier) sur les cultures maraîchères, de l'emploi de formulation EC pour le traitement des semences et de la réutilisation des emballages vides. Les teneurs en matières actives détectées étaient nettement inférieures à celles déclarées sur l'étiquette pour ATTAKAN C 344 SE utilisé sur la tomate dans le bas-fond de Doumanaba. Outre les matières actives des deux formulations commerciales (ATTAKAN C 344 SE et LAMBDA SUPER 2,5 EC) utilisées l'année de l'étude par deux exploitants maraîchers, les résidus d'autres substances ont été détectés. Il s'agit de l'Heptachlore dans l'eau d'arrosage à Ziguéna, du Lindane dans le sol à Ziguéna et à Bamadougou, de la Perméthrine dans le sol à Bamadougou et du Chlorothalonil dans le sol à Ziguéna. Les mauvaises utilisations révélées par les enquêtes et les résultats d'analyse au laboratoire sont des indicateurs qui témoignent des risques pour les consommateurs et l'environnement.

International audience; Plants were sampled from four different types of chlordecone-contaminated land in Guadeloupe (West Indies). The objective was to investigate the importance of biological and agri-environmental parameters in the ability of plants to bioaccumulate chlordecone. Among the plant traits studied, only the growth habit significantly affected chlordecone transfer, since prostrate plants concentrated more chlordecone than erect plants. In addition, intensification of land use has led to a significant increase in the amount of chlordecone absorbed by plants. The use of Bayesian networks uncovers some hypothesis and identifies paths for reflection and possible studies to identify and quantify relationships that explain our data.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU [ADD1_IRSTEA]Hydrosystèmes et risques naturels; International audience; RECOTOX is a cross-cutting initiative promoting an integrated research to respond to the challenges of monitoring, understanding, and mitigating environmental and health impacts of pesticides in agroecosystems. The added value of RECOTOX is to develop a common culture around spatial ecotoxicology including the whole chain of pressure-exposure-impact, while strengthening an integrated network of in natura specifically equipped sites. In particular, it promotes transversal approaches at relevant socioecological system scales, to capitalize knowledge, expertise, and ongoing research in ecotoxicology and, to a lesser extent, environmental toxicology. Thus, it will open existing research infrastructures in environmental sciences to research programs in ecotoxicology of pesticides.

Background: Reducing the risks and impacts of pesticide use on human health and on the environment is one of the objectives of the European Commission Directive 2009/128/EC in the quest for a sustainable use of pesticides. This Directive, developed through European national plans such as Ecophyto plan in France, promotes the introduction of innovative cropping systems relying, for example, on integrated pest management. Risk assessment for human health of the overall pesticide use in these innovative systems is required before the introduction of those systems to avoid that an innovation becomes a new problem. Objectives: The objectives of this work were to assess and to compare (1) the human exposure to pesticides used in conventional and innovative cropping systems designed to reduce pesticide needs, and (2) the corresponding risks for human health. Methods: Humans (operator and residents) exposure to pesticides and risks for human health were assessed for each pesticide with the BROWSE model. Then, a method was proposed to represent the overall risk due to all pesticides used in one system. This study considers 3 conventional and 9 associated innovative cropping systems, and 116 plant protection products containing 89 different active substances (i.e. pesticides). Results: The modelling results obtained with BROWSE showed that innovative cropping systems such as low input or no herbicide systems would reduce the risk for human health in comparison to the corresponding conventional cropping systems. On the contrary, BROWSE showed that conservation tillage system would lead to unacceptable risks in the conditions of our study, because of a high number of pesticide applications, and especially of some herbicides. For residents, the dermal absorption was the main exposure route while ingestion was found to be negligible. For operators, inhalation was also a predominant route of exposure. In general, human exposure to pesticides and human health risks were found to be correlated to the treatment frequency index TFI (number of registered doses of pesticides used per hectare for one copping season), confirming the relationship between the reduction of pesticide use and the reduction of risks. Conclusions: Assessment with the BROWSE model helped to identify cropping systems with decreased risks from pesticides for human health and to propose some improvements to the cropping systems by identifying the pesticides that led to unacceptable risks. Keywords: BROWSE model, Human exposure, Plant protection products, Risk assessment, Cropping system

International audience; The honeybee (Apis mellifera) has to cope with multiple environmental stressors, especially pesticides. Among those, the herbicide glyphosate and its main metabolite, the amino-methylphosphonic acid (AMPA), are among the most abundant and ubiquitous contaminant in the environment. Through the foraging and storing of contaminated resources, honey-bees are exposed to these xenobiotics. As ingested glyphosate and AMPA are directly in contact with the honeybee gut microbiota, we used quantitative PCR to test whether they could induce significant changes in the relative abundance of the major gut bacterial taxa. Glyphosate induced a strong decrease in Snodgrassella alvi, a partial decrease of a Gillia-mella apicola and an increase in Lactobacillus spp. abundances. In vitro, glyphosate reduced the growth of S. alvi and G. apicola but not Lactobacillus kunkeei. Although being no bee killer, we confirmed that glyphosate can have sublethal effects on the honeybee microbiota. To test whether such imbalanced microbiota could favor pathogen development, honeybees were exposed to glyphosate and to spores of the intestinal parasite Nosema ceranae. Glyphosate did not significantly enhance the effect of the parasite infection. Concerning AMPA, while it could reduce the growth of G. apicola in vitro, it did not induce any significant change in the honeybee microbiota, suggesting that glyphosate is the active component modifying the gut communities.

In this study, we investigated the management of long-term environmental pollution by organic pollutants such as organochlorine pesticides. We set out to identify conditions that are conducive to reducing pollution levels for these persistent molecules and then propose a conceptual model of organochlorine fate in water. Our approach looked at spatio-temporal changes in pollutant contents in surface water (SW) and groundwater (GW) on a large scale, in order to decipher the respective roles of soil, geology, hydrology and past treatment practices. The case of chlordecone (CLD) on the island of Martinique (1100 km2) was selected given the sampling campaigns carried out since 2007 over more than 150 sites. CLD, its metabolite chlordecone-5b-hydro (5bCLD) and the metabolite-to-parent-compound ratio were compared. As regards the spatial variability of water contamination, our results showed that banana cropping areas explained the location of contaminated SW and GW, whereas the combination of soil and geology factors explained the main spatial variability in the 5bCLD∕CLD ratio. For temporal variability, these conditions defined a high diversity of situations in terms of the duration of pollution, highlighting two groups: water draining old geological formations and ferralsols or vertisols vs. recent geology and andosols. A conceptual leaching model provided some key information to help interpret downward trends in CLD and 5bCLD observed in water. Lastly, a conceptual model of organochlorine fate is proposed to explain the diversity of the 5bCLD∕CLD ratio in water. Our conclusions highlight the combined role of soil and groundwater residence time for differentiating between conditions that are more conducive, or not, to the disappearance of CLD from the environment. This paper presents a model that provides an overall perception of organochlorine pesticide fate in the environment.

International audience; Non-point source pollution is a cause of major concern within the European Union. This is reflected in increasing public and political focus on a more sustainable use of pesticides, as well as a reduction in diffuse pollution. Climate change will likely to lead to an even more intensive use of pesticides in the future, affecting agriculture in many ways. At the same time, the Water Framework Directive (WFD) and associated EU policies called for a “good” ecological and chemical status to be achieved for water bodies by the end of 2015, currently delayed to 2021–2027 due to a lack of efficiency in policies and timescale of resilience for hydrosystems, especially groundwater systems. Water managers need appropriate and user-friendly tools to design agro-environmental policies. These tools should help them to evaluate the potential impacts of mitigation measures on water resources, more clearly define protected areas, and more efficiently distribute financial incentives to farmers who agree to implement alternative practices. At present, a number of reports point out that water managers do not use appropriate information from monitoring or models to make decisions and set environmental action plans. In this paper, we propose an integrated and collaborative approach to analyzing changes in land use, farming systems, and practices and to assess their effects on agricultural pressure and pesticide transfers to waters. The integrated modeling of agricultural scenario (IMAS) framework draws on a range of data and expert knowledge available within areas where a pesticide action plan can be defined to restore the water quality, French “Grenelle law” catchment areas, French Water Development and Management Plan areas, etc. A so-called “reference scenario” represents the actual soil occupation and pesticide-spraying practices used in both conventional and organic farming. A number of alternative scenarios are then defined in cooperation with stakeholders, including socio-economic conditions for developing alternative agricultural systems or targeting mitigation measures. Our integrated assessment of these scenarios combines the calculation of spatialized environmental indicators with integrated bio-economic modeling. The latter is achieved by a combined use of Soil and Water Assessment Tool (SWAT) modeling with our own purpose-built land use generator module (Generator of Land Use version 2 (GenLU2)) and an economic model developed using General Algebraic Modeling System (GAMS) for cost-effectiveness assessment. This integrated approach is applied to two embedded catchment areas (total area of 360,000 ha) within the Charente river basin (SW France). Our results show that it is possible to differentiate scenarios based on their effectiveness, represented by either evolution of pressure (agro-environmental indicators) or transport into waters (pesticide concentrations). By analyzing the implementation costs borne by farmers, it is possible to identify the most cost-effective scenarios at sub-basin and other aggregated levels (WFD hydrological entities, sensitive areas). Relevant results and indicators are fed into a specifically designed database. Data warehousing is used to provide analyses and outputs at all thematic, temporal, or spatial aggregated levels, defined by the stakeholders (type of crops, herbicides, WFD areas, years), using Spatial On-Line Analytical Processing (SOLAP) tools. The aim of this approach is to allow public policy makers to make more informed and reasoned decisions when managing sensitive areas and/or implementing mitigation measures.

International audience; Some volcanic soils like andosols contain short-range order nanoclays (allophane) which build aggregates with a tortuous and fractal microstructure. The aim of the work was to study the influence of the microstructure and mesoporosity of the allophane aggregates on the pesticide chlordecone retention in soils. Our study shows that the allo-phane microstructure favors pollutants accumulation and se-questration in soils. We put forth the importance of the meso-porous microstructure of the allophane aggregates for pollutant trapping in andosols. We show that the soil contamination increases with the allophane content but also with the mesopore volume, the tortuosity, and the size of the fractal aggregate. Moreover, the pore structure of the allophane aggregates at nanoscale favors the pesticide retention. The fractal and tortuous aggregates of nanoparticles play the role of nanolabyrinths. It is suggested that chlordecone storage in allophanic soils could be the result of the low transport properties (permeability and diffusion) in the allophane aggregates. The poor accessibility to the pesticide trapped in the mesopore of allophane aggregates could explain the lower pollutant release in the environment.

National audience; 19 prototypes de systèmes de culture ont été testés sur quatre sites contrastés (Picardie, Bourgogne et deux sites dans la région de Toulouse). Ces systèmes de grandes cultures ont été conçus selon les principes de Protection Intégrée pour limiter l’usage des pesticides en général et des herbicides en particulier. Les combinaisons de leviers alternatifs ont permis de gérer durablement la flore adventice avec peu d’herbicides, et de baisser l’usage de l’ensemble des pesticides. Certains systèmes permettent de concilier faible IFT et bonne performance économique. Trois sites ont été instrumentés pour collecter des eaux de drainage et mesurer les transferts de substances actives. Ces dispositifs ont permis d’établir un lien entre les IFT cumulés et les quantités de substance transférées dans les eaux, à l’échelle d’un site et sur trois années de mesure, confirmant ainsi le lien entre l’usage de pesticides et leur impact. Les prototypes fondés sur le semis direct ont été décevants: ils ont nécessité beaucoup d’herbicides pour maîtriser les adventices, les quantités de substances actives transférées sous ces parcelles ont été importantes, et les performances économiques ont été moyennes.

Chlordecone, an organochlorine insecticide, continues to pollute soils in the French West Indies. The main source of human exposure to this pollutant is food. Root vegetables, which are staple foods in tropical regions, can be highly contaminated and are thus a very effective lever for action to reduce consumer exposure. We analyzed chlordecone contamination in three root vegetables, yam, dasheen and sweet potato, which are among the main sources of chlordecone exposure in food in the French West Indies. All soil types do not have the same potential for the contamination of root vegetables, allophanic andosols being two to ten times less contaminating than non-allophanic nitisols and ferralsols. This difference was only partially explained by the higher OC content in allophanic soils. Dasheen corms were shown to accumulate more chlordecone than yam and sweet potato tubers. The physiological nature of the root vegetable may explain this difference. Our results are in good agreement with the hypothesis that chlordecone uptake by root vegetables is based on passive and diffusive processes and limited by transport and dilution during growth.

La pollution diffuse par les pesticides est en enjeu majeur pour un bon état des hydrosystèmes et en raison de leurs impacts sur la santé humaine. Depuis des années, les politiques publiques tentent de limiter leur usage et leur impact sur l'environnement. Pourtant, les tonnages de pesticides utilisés par l'agriculture stagnent ou même augmentent, et les flux mesurés dans les cours d'eau ne diminuent pas. Face à ce constat d'échec, les politiques publiques, en quête d'une plus grande efficacité, se territorialisent et se veulent plus participatives. Les réseaux territoriaux d'acteurs institutionnels, en charge de la mise en oeuvre des actions agroenvironnementales sur le terrain, sont en quête d'outils d'aide à la décision afin de pouvoir évaluer l'impact potentiel des mesures agro-environnementales et de les localiser de manière la plus efficace et la moins coûteuse possible. L'objectif de la thèse est de répondre à cette demande en proposant un système d'information, collaboratif et multi-échelles. Une première contribution de la thèse est un modèle pour la conception et la mise en oeuvre opérationnelle d'un Système d'Information en appui à la Gouvernance des Programmes d'Action (SIGPA). Le modèle SIGPA décrit l'ensemble de la démarche d'appui à la gouvernance des programmes d'action pesticides. Ce modèle est générique et applicable à différents contextes. La deuxième contribution est une méthode de modélisation des échanges d'information au sein du réseau d'acteurs institutionnels, réseau qui s'est constitué autour d'un programme d'action " Captage Grenelle " dans le bassin de la Charente. Le modèle conceptuel " acteurs " modélise, d'une part, les échanges entre acteurs et, d'autre part, la production par ces mêmes acteurs de l'information mobilisée dans le réseau. Une troisième contribution est un modèle " scénarios " qui organise l'information pour la prise de décision sur les actions agro-environnementales à mettre en place dans le territoire. La méthode développée pour qualifier les systèmes et les pratiques agricoles et évaluer par différents indicateurs les scénarios agricoles, co-construits avec les acteurs, constitue une quatrième contribution. La cinquième contribution est l'entrepôt de données spatial et les cubes multidimensionnels construits à partir des besoins des acteurs pour restituer les indicateurs mobilisés en accompagnement du programme d'action à différents niveaux de granularité spatiale (îlot du RPG, sous-bassin, zone prioritaire...). Les modèles conceptuels et le système d'information proposés sont des outils de communication et d'échange au sein du réseau d'acteurs. Ces outils permettent de faire émerger, de manière interactive, les solutions les plus efficaces et les moins coûteuses pour limiter la pollution diffuse par les pesticides. Plusieurs prototypes d'entrepôt ont été implémentés à partir des données du BAC Coulonge. L'intérêt et la qualité des restitutions ont été discutés avec les acteurs. En permettant la capitalisation des données et des connaissances acquises par les réseaux d'acteurs au fil des programmes d'action, la démarche mise en oeuvre s'inscrit est conforme au modèle OSAGE préconisé par Loireau et al (2017), modèle qui décrit le processus de conception d'un observatoire agro-environnemental, multifonctionnel.

International audience; Persistent organic pollutants like organochlorine pesticides continue to contaminate large areas worldwide raising questions concerning their management. We designed and tested a method to link soil and water pollution in the watershed of the Galion River in Martinique. We first estimated the risk of soil contamination by chlordecone by referring to past use of land for banana cultivation and took 27 soil samples. We then sampled surface waters at 39 points and groundwater at 16 points. We tested three hypotheses linked to the source of chlordecone pollution at the watershed scale: (i) soils close to the river, (ii) soils close to the sampling point, (iii) throughout the sub-watershed generated at the sampling point. Graphical and statistical analysis showed that contamination of the river increased when it passed through an area with contaminated plots and decreased when it passed through area not contaminated by chlordecone. Modeling showed that the entire surface area of the watershed contributed to river pollution, suggesting that the river was mainly being contaminated by the aquifers and groundwater flows. Our method proved to be a reliable way to identify areas polluted by chlordecone at the watershed scale and should help stakeholders focus their management actions on both hot spots and the whole watershed. (C) 2016 Elsevier B.V. All rights reserved.

Many studies have shown the role of agriculture in the selection and spread of resistance of Anopheles gambiae s.l. to insecticides. However, no study has directly demonstrated the presence of insecticides in breeding sources as a source of selection for this resistance. It is in this context that we investigated the presence of pesticide residues in breeding habitats and their formal involvement in vector resistance to insecticides in areas of West Africa with intensive farming. This study was carried out from June to November 2013 in Dano, southwest Burkina Faso in areas of conventional (CC) and biological cotton (BC) growing. Water and sediment samples collected from breeding sites located near BC and CC fields were submitted for chromatographic analysis to research and titrate the residual insecticide content found there. Larvae were also collected in these breeding sites and used in toxicity tests to compare their mortality to those of the susceptible strain, Anopheles gambiae Kisumu. All tested mosquitoes (living and dead) were analyzed by PCR for species identification and characterization of resistance genes. The toxicity analysis of water from breeding sites showed significantly lower mortality rates in breeding site water from biological cotton (WBC) growing sites compared to that from conventional cotton (WCC) sites respective to both An. gambiae Kisumu (WBC: 80.75% vs WCC: 92.75%) and a wild-type strain (49.75% vs 66.5%). The allele frequencies L1014F, L1014S kdr, and G116S ace -1R mutations conferring resistance, respectively, to pyrethroids and carbamates / organophosphates were 0.95, 0.4 and 0.12. Deltamethrin and lambda-cyhalothrin were identified in the water samples taken in October/November from mosquitoes breeding in the CC growing area. The concentrations obtained were respectively 0.0147ug/L and 1.49 ug/L to deltamethrin and lambdacyhalothrin. Our results provided evidence by direct analysis (biological and chromatographic tests) of the role of agriculture as a source of selection pressure on vectors to insecticides used in growing areas.

L'utilisation de pesticides n'est pas sans impact sur l'environnement ni sur la sante humaine. La societe civile mauricienne s'est recemment emparee de la question suite a des detections de pesticides dans des legumes preleves dans les marches de l'ile. Mais quelles sont les marges de manœuvre des producteurs pour faire face a cette demande societale ? Comme les methodes de production etaient jusqu'ici peu documentees, nous avons mene une enquete aupres de 298 producteurs de legumes afin d'analyser leurs pratiques phytosanitaires et d'en evaluer les impacts sur l'environnement. Cette enquete vise a repondre aux questions suivantes : Quels sont reellement les usages de pesticides des producteurs ? Quelles contraintes supportent-ils ? Les producteurs sont plutot âges (60 % ont plus de 50 ans) et peu d'entre eux ont une formation initiale de base. Pres des deux tiers d'entre eux ne sont pas proprietaire du foncier. Dans ces conditions, les producteurs pratiquent une agriculture d'opportunisme visant a optimiser leur parcelle dans le temps et dans l'espace. Aucun risque, aucune perte. La grande majorite des producteurs protegent leurs cultures par des traitements phytosanitaires preventifs contre les nombreux bio-agresseurs recenses. Entre 11 et 53 traitements par an sont ainsi effectues selon les successions culturales entreprises. Pres de 60 insecticides et fongicides sont couramment utilises par les producteurs. L'outil d'aide a la decision « Phyto'Aide » nous a permis d'evaluer, ex ante, le risque du transfert de ces substances vers l'environnement. Ces risques s'averent importants pour tous les pesticides car les bonnes pratiques phytosanitaires sont peu ou pas respectees par les producteurs. Dans ces conditions, de nouvelles strategies de protection contre les bioagresseurs s'averent necessaires. Nous proposons dans cet article differentes pistes d'amelioration, mais aussi une strategie d'accompagnement de ces producteurs pour faire face a une demande societale d'une production saine et sure.

Throughout Southeast Asia, government agencies are promoting good agricultural practices (GAP) standards for improving food safety, avoiding potential nontariff barriers to exports, and ultimately securing farmers' health and revenues. This paper presents an analysis of the adoption of a public standard in Thailand, the Rice Q-GAP where Q stands for “quality.” In the Central Plains of Thailand, a major rice production area, rice is produced by relatively small farms but with very intensive use of chemical inputs, making it challenging to promote production standards. Our study investigates the factors influencing the adoption of standards and the differences in cultivation practices between adopters and nonadopters. Governmental agencies have organized training activities throughout the country about rice production and Q-GAP standards. That training is likely to have an important influence on Q-GAP adoption. We investigate the potential selection bias in training delivery, using a recursive bivariate probit model whereby training is successively an explanatory variable for the Q-GAP adoption and a variable to be explained. Our model suggests that lack of labor availability is an essential factor related to nonadoption. Belonging to farmers associations and groups is also shown to be an important factor of adoption. Unexpectedly, training has a slight negative effect on Q-GAP adoption. A possible explanation is that when concrete information about the program is delivered, some farmers make an informed decision not to participate; this reinforces the idea that the main factors that could hamper further adoption are not related to information but to real farm constraints and farmers' rational behavior. The paper also found some small but significant differences in terms of farmers' practices related to adoption. The most convincing change is the reduction in the number of pesticide applications by adopters. (Resume d'auteur)

Past applications of chlordecone, a persistent organochlorine pesticide, have resulted in diffuse pollution of agricultural soils, and these have become sources of contamination of cultivated crops as well as terrestrial and marine ecosystems. Chlordecone is a very stable and recalcitrant molecule, mainly present in the solid phase, and has a strong affinity for organic matter. To prevent consumer and ecosystem exposure, factors that influence chlordecone migration in the environment need to be evaluated. In this study, we measured the impact of incorporating compost on chlordecone sequestration in andosols as a possible way to reduce plant contamination. We first characterized the transfer of chlordecone from soil to plants (radish, cucumber, and lettuce). Two months after incorporation of the compost, soil-plant transfers were reduced by a factor of 1.9-15 depending on the crop. Our results showed that adding compost modified the fractal microstructure of allophane clays thus favoring chlordecone retention in andosols. The complex structure of allophane and the associated low accessibility are important characteristics governing the fate of chlordecone. These results support our proposal for an alternative strategy that is quite the opposite of total soil decontamination: chlordecone sequestration.

The use of insecticidal proteins known as Cry or Bt, either as biopesticides used in agriculture or as vector control or originating from commercial genetically modified crops (GM), is increasing rapidly. The fate of these proteins in the environment depends strongly on their adsorption on the organo–mineral complexes of soil. Environmental monitoring requires the quantification of the proteins and this entails their chemical extraction from soil. Three Cry proteins, Cry1Ac, Cry1C and Cry2A, present in commercial biopesticide formulations or synthesized by GM plants or both were studied. The adsorption of trace amounts of Cry proteins on over 40 types of soil with contrasting properties was measured in dilute suspension. After a short incubation the extraction yield was measured with a previously tested alkaline solution that contained surfactant and another protein. Each of the proteins had a strong affinity for soil. No soil property was observed to determine either the affinity for soil or the extraction yield. There was no simple relation between the affinity (assessed from the distribution coefficient, Kd) and the extraction yield, although there was a significant inverse relation (P < 0.05) for two of the proteins, Cry1Ac and Cry2A. The proteins differ in both their affinity for soil and their extraction yields. We conclude that these insecticidal proteins will be largely immobile in soil, but that routine environmental monitoring can give only semi-quantitative values for protein in soil.

Insecticidal Cry, or Bt, proteins are produced by the soil-endemic bacterium, Bacillus thuringiensis and some genetically modified crops. Their environmental fate depends on interactions with soil. Little is known about the toxicity of adsorbed proteins and the change in toxicity over time. We incubated Cry1Ac and Cry2A in contrasting soils subjected to different treatments to inhibit microbial activity. The toxin was chemically extracted and immunoassayed. Manduca sexta was the target insect for biotests. Extractable toxin decreased during incubation for up to four weeks. Toxicity of Cry1Ac was maintained in the adsorbed state, but lost after 2 weeks incubation at 25 °C. The decline in extractable protein and toxicity were much slower at 4 °C with no significant effect of soil sterilization. The major driving force for decline may be time-dependent fixation of adsorbed protein, leading to a decrease in the extraction yield in vitro, paralleled by decreasing solubilisation in the larval gut.

The aim of this study was to identify primary flow paths involved in the chlordecone (CLD) river contamination and quantify the CLD fluxes to assess CLD pollution levels and duration according to a typical catchment of the banana cropping area in the French Indies (Guadeloupe): the Perou Catchment (12 km(2)) characterized by heavy rainfall (5686 mm year(-1)). Three sub-catchments (SC1, SC2 and SC3) were studied during the hydrological year 2009-2010: a pedological survey combined with a spatialized hydrochemical approach was conducted. The average soil concentration is higher in the Perou Catchment (3400 mu g kg(-1)) than in the entire banana cropping area in Guadeloupe (2100 mu g kg(-1)). The results showed that CLD stocks in soils vary largely among soil types and farming systems: the weakest stocks are located upstream in SC1 (5 kg ha(-1)), where a majority of the area is non-cultivated; medium stocks are located in Nitisols downstream in SC3 (9 kg ha(-1)); and the greatest stocks are observed in SC2 on Andosols (12 kg ha(-1)) characterized by large farms. The annual water balance and the hydro-chemical analysis revealed that the three sub-catchments exhibited different behaviors. Perou River contamination was high during low flows, which highlighted that contamination primarily originated from groundwater contributions. The results showed that only a small part of the catchment (SC2), contributing little to the water flow, comprises a major CLD contribution, which is in agreement with the highly contaminated andosol soils observed there. Another significant result considers that at least 50 years would be required to export the totality of the actual CLD soil stocks retained in the topsoil layer. The actual time for soil remediation will however be much longer considering (i) the necessary time for the chlordecone to percolate and be stored in the shallow aquifers and (ii) its travel time to reach the river.rights reserved.

International audience; Background :Bacillus thuringiensis produces insecticidal proteins known as Cry and its efficiency and absence of side-effects make it the most widely used biopesticide. There is little information on the role of soils in the fate of Cry proteins from commercial biopesticide formulations, unlike toxins from genetically modified crops that have been intensively studied in recent years. The persistence of Cry in soil was followed under field and laboratory conditions. Results : Sunlight accelerated loss of detectable Cry under laboratory conditions but little effect of shade was observed under field conditions. The half-life of biopesticide proteins in soil under natural conditions was about one week. Strong temperature effects were observed, but they differed for biopesticide and purified protein, indicating different limiting steps. Conclusion : For the biopesticide the observed decline in detectable protein was due to biological factors, possibly including the germination of B. thuringiensis spores and was favoured by higher temperature. In contrast for purified proteins, the decline in detectable protein was slower at low temperature, probably because the conformational changes of the soil-adsorbed protein, that cause fixation and hence reduced extraction efficiency, are temperature dependent.

Crisis Management of Chronic Pollution: Contaminated Soil and Human Health deals with a long term pollution problem, generated by the former use of organochlorine pesticides. Through a case study of the chlordecone pollution in the French West Indies, the authors illustrate a global and systemic mobilization of research institutions and public services. This "management model", together with its major results, the approach and lessons to be learned, could be useful to other situations. This book gathers all the works that have been carried out over the last ten years or more and links them to decision makers' actions and stakeholders' expectations. This reference fills a gap in the literature on chronic pollution.

We address the problem of the comparative environmental fate of a pesticide, chlordecone (CLD), and a related compound, chlordecone-5b-hydro (CLD-5b-hydro). We used a large database including data from two types of contaminated volcanic soils, andosol and nitisol, and thirteen crops grown in the French West Indies in historically polluted soils. We performed in-depth statistical analysis of the effect of different parameters (soil type, crop, organ, etc.) on the ratio of CLD-5b-hydro to CLD in both soils and plants. The environmental fate of the two compounds differed depending on the type of soil. Proportionally, more CLD-5b-hydro than CLD was measured in nitisols than in andosols. Compared to CLD, we also found a preferential transfer of CLD-5b-hydro from the soil to the plant. Finally, mobilization of the two compounds differed according to the species of crop but also within the plant, with increasing ratios from the roots to the top of the plant. The properties of the compound played a key role in the underlying processes. Because CLD-5b-hydro is more soluble in water and has a lower Kow than CLD, CLD-5b-hydro (1) was more easily absorbed from soils by plants, (2) was less adsorbed onto plant tissues and (3) was transported in greater quantities through the transpiration stream. Due to the amounts of CLD-5b-hydro we measured in some plant parts such as cucurbit fruits, an assessment of the toxicity of this CLD monodechlorinated product is recommended.

International audience; The former use of chlordecone (CLD) in the French West Indies has resulted in long-term pollution of soils and subsequently of food chains. In contaminated areas, free-range ducks used to control weeds in orchards may be exposed to CLD through polluted soil ingestion. The question arises whether they may be consumed. Muscovy ducks were raised on a guava orchard planted on a soil moderately contaminated (410 mu g CLD/kg dry matter). Ducks were raised indoor up to 6 weeks of age and allowed to range freely outdoors thereafter. Twenty-nine females were sequentially slaughtered by groups of 2 to 5 ducks, after 4, 16, 19, 22 or 26 weeks spent in the orchard or after 16-17 weeks in the orchard followed by 3, 6 or 9 weeks in a closed shelter for depuration. CLD concentration increased from 258 to 1051,96 to 278,60 to 169 and 48 to 145 mu g/kg fresh matter (FM) as the exposure through grazing increased from 4 to 22 weeks, in liver, abdominal fat and leg with and without skin, respectively. Eggs collected in the orchard contained up to 1001 mu g CLD/kg FM. All these values exceeded the Maximum Residue Limit (MRL) of 20 mu g/kg FM. CLD concentration in all tissues was divided by around 10 within the 9-week confinement period. Despite this quite rapid decontamination, it is estimated that 12-13 weeks would be required to achieve the MRL in liver and in eggs, and 5-6 weeks in leg muscle. Such durations would be too long in practice. Thus, the consumption of products from free-range ducks should be avoided, even in areas mildly contaminated with CLD.

International audience

I-PHY de la méthode INDIGO® est un indicateur qui permet d'évaluer les impacts des pesticides sur l'environnement à l'échelle de la parcelle. Basé sur un système expert, il prend en compte les caractéristiques des substances actives (sa), de la parcelle et les conditions d'application. Il renvoie un score I-PHYsa sous la forme d'une note sur 10. Dans ces conditions, I-PHY est un indicateur robuste dont les résultats permettent d'identifier des pratiques à risque pour l'environnement. Cependant, le simple résultat sous la forme d'un score ne fait pas pour autant d'I-PHY un outil d'aide à la décision en l'état. Nous proposons dans cet article d'utiliser les marges de progrès entre les différents scores (IPHY min et max) pour construire des arbres de régression permettant d'identifier les variables à l'origine du score et d'utiliser I-PHY comme outil d'aide à la décision. A titre d'illustration de notre méthode, nous avons étudié les risques environnementaux liés à l'usage de la lambda-cyhalothrine chez trois producteurs d'agrumes à la Réunion. Cette analyse nous a permis d'identifier les leviers techniques mobilisables par ces producteurs.

International audience; In the French West Indies, chlordecone (CLD), an organochlorine pesticide, which is highly persistent in the environment, was applied in banana plantations from 1972 to 1993 against the banana weevil Cosmopolites sordidus. Pollution surveys conducted in 2001 by the French Department of Health revealed the presence of chlordecone in soils, rivers, springs over large areas in Guadeloupe and Martinique islands. Contamination of drinking water, food crops, aquatic species by CLD has been observed as well as its presence in blood of men, pregnant women and newborns. There is therefore a large social concern about the extent and evolution of CLD pollution in the French West Indies and its impact on human health and ecosystems. From 2008 to 2012 a multidisciplinary project CHLORDEXCO took place to study the CLD fate in water, soils and the contamination characteristics of aquatic species and food crops. Here, we summarize results obtained on the processes controlling the spatial and temporal patterns of soil and water contamination at the scale of the banana cropping area in Guadeloupe and of the Perou catchment. The main soils in the contaminated areas are andosols and nitisols and formed from the weathering of volcanic ashes. They have a high organic carbon content and high content of secondary minerals, allophane for andosols and halloysite for nitisols. An analysis of the spatial distribution of CLD in soil over 1045 field plots showed that the soil type had a strong impact. Andosols, with a high sorption capacity (Koc 20 000 L/kg), had the highest CLD concentrations and stocks, unlike Nitisols, which had 10-fold lower sorption capacities. A significant « farm effect », due to between-farm variations of application times and amounts, was also noticed. The observed stocks of CLD clearly correspond to the accumulation in soil of successive treatments and thereby confirm the high persistence of CLD in soil also observed in incubation studies in soil microcosms. Soil column studies of the transport of aged CLD however showed that CLD concentration in percolation water varied little (5 to 10 μg/L) and were of same magnitude for both soils although their sorption properties and hydrodynamic behaviours differed with larger macropore flow in the andosols. At catchment scale, contamination of surface waters was permanent with CLD concentrations one order of magnitude less than in percolation water. Temporal variations of contamination were due to dilution effects caused by water from uncontaminated uphill areas. CLD concentrations were highest in base flow indicating that the main pathway of applied CLD to surface waters is by percolation and groundwater flow. In conclusion, contamination of soil and water in the banana cropped areas of the French West Indies is general and permanent. If no soil remediation strategies can be elaborated this severe environmental contamination will last over centuries as estimated by Cabidoche et al. (2009, Environ. Poll., 57, 1697-1705). Since CLD propagates mainly by subsurface flow, buffer strips, usually recommended in many regions to limit the pollution of water by pesticides, will not be useful.

Aujourd'hui encore, les utilisations agricoles de pesticides génèrent des pollutions des cours d'eau qui posent des problèmes environnementaux et sanitaires. Afin de limiter et d'anticiper ces pollutions, il est nécessaire de disposer de méthodes d'évaluation des effets des systèmes de culture sur la pollution par les pesticides des eaux de rivière. Dans certaines zones, telles que les zones volcaniques tropicales, cette connaissance des effets des pratiques des agriculteurs qui cultivent des fruits et légumes (horticulteurs) sur la ressource en eau est extrêmement limitée. L'objectif de cette thèse est de développer une méthode d'évaluation des effet des systèmes de cultures sur la contamination par les pesticides de l'exutoire d'un bassin versant qui soit adaptée aux conditions de l'horticulture en zone volcanique tropicale. Pour cela, nous avons sélectionné un petit bassin versant de 131 ha sur lequel deux dispositifs de suivis ont été mis en oeuvre entre 2011 et 2013: (1) un suivi des pratiques agricoles auprès des agriculteurs du bassin versant et (2) un suivi du régime hydrologique et de la pollution de l'eau par les pesticides à son exutoire. En raison de la complexité agronomique, géologique et hydrologique des bassins versants volcaniques tropicaux horticoles, et afin de produire un outil d'évaluation générique, nous avons développé un modèle agro-hydrologique de transferts de pesticide : WATPPASS. Il synthétise les connaissances sur le fonctionnement agro-hydrologique des bassins versants et simule les effets des pratiques agricoles sur les processus mis en cause dans les transferts de pesticides. WATPPASS reproduit correctement le fonctionnement hydrologique du bassin versant d'étude et les types de contamination de pesticides observés à l'exutoire. Les écarts par rapport aux mesures sont analysés et discutés et des améliorations du modèle sont proposées. WATPPASS est ainsi un outil performant qui peut servir d'outil d'évaluation des effets des systèmes de culture sur la qualité de l'eau, en particulier pour classer des scénarii d'évolution des systèmes de culture à l'échelle de bassins versants. La méthodologie proposée a permis d'identifier les molécules dont les usages actuels sont à risque ainsi que les principales combinaisons de facteurs engendrant des pollutions.

Les Kazakhs sont des consommateurs traditionnels de lait d'espèces non-conventionnelles comme la chamelle. Pour autant, les régions d'élevage camelin dans ce pays, bien que basées sur un mode extensif et un accès à des ressources naturelles, n'en sont pas moins fragilisées par les risques de pollution, l'environnement du pays étant affectées par la présence de métaux lourds, pesticides et radionucléides. L'objectif de la thèse a été (a) d'évaluer l'impact de cette pollution sur la qualité du lait de chamelle et du shubat (lait fermenté), et (b) d'évaluer les capacités de détoxification des produits laitiers. Pour aborder la question de l'impact de la pollution, plusieurs niveaux d'analyses ont été mis en oeuvre: (i) A l'échelle régionale, des cartes d'indice de pollution ont été établies autour de 13 fermes de zones polluées (Almaty, Sud Kazakhstan, Atyraou et Kyzylorda) afin de comparer le niveau de pollution des différentes matrices (sol, eau, plante) selon la distance aux sources de pollution. (ii) A l'échelle des matrices environnementales (sol, plante, eau), deux métaux lourds majeurs (Pb et Cd) ont été déterminés dans les échantillons de sols (7,76-131,08 ppm et 0,08-0,39 ppm, respectivement), l'eau (Pb entre 5,9-13,6 ppm et Cd 0,05-0,25 ppm), les plantes (0,50-2,30 ppm et >0,05-0,56 ppm, respectivement). Un lien entre indice de pollution et métaux dans les sols a été observé, montrant l'impact de la proximité et de la nature des sources de polluants sur la contamination des sols. On observe également une corrélation étroite entre teneur en Pb et Cd au sein des différentes matrices. Cependant, les teneurs dans le sol sont indépendantes des teneurs dans l'eau ou les plantes. Les teneurs en pesticides dans l'eau sont inférieures à celles des normes internationales. Dans les fourrages, les teneurs en DDT et ses dérivés ont été plus élevées que dans le sol. Cela signifie que les résidus de pesticides peuvent être également d'origine atmosphérique et donc inhalés par les animaux (iii) Dans le lait et le shubat, la concentration en métaux lourds dans cinq régions (Almaty, Atyraou, Kyzylorda, Taraz et Sud Kazakhstan) a été en moyenne faible en Cu (< 0,05 ppm), normale en Zn (près de 5 ppm) et Cd, mais un peu élevée pour Pb. Nos résultats ont été relativement élevés pour le DDT total dans le lait de toutes les régions sauf Kyzylorda et supérieurs pour le HCH total dans le lait des régions d'Almaty et d'Atyraou. (iv) Les relations entre environnement et lait ont été testées montrant l'absence de lien entre contamination de l'environnement en métaux lourds et celle du lait et shubat. Aucune relation non plus n'a été observée pour les pesticides, à l'exception du lindane et 4,4-DDD. Pour tester l'effet détoxifiant, il a été procédé en deux étapes. D'abord l'isolement et l'identification des souches de bactéries lactiques (BAL) du afin de tester leur capacité à fixer Pb et Cd. Au total, 138 souches ont été isolées à partir de 25 échantillons laitiers. Une étude qualitative pour détecter la capacité des BAL à fixer les métaux lourds a été réalisée. Parmi 118 souches testées, seules 5,1% d'entre elles n'ont cultivé ni Pb ni sur Cd, 36 % ayant eu la capacité de fixer Pb ou Cd, et 9% les deux. Les 45 souches montrant les meilleurs résultats ont été retenues pour identification par des méthodes moléculaires (rRNA16S). Selon les résultats de séquençage, la plupart de souches appartiennent aux genres Enterococcus ; Lactobacillus, secondairement Lactococcus et Leuconostoc. Dans un second temps, un test physiologique (in vivo) a été réalisé sur 80 cobayes divisés en 8 groupes traités par le Pb et des souches de BAL. La quantité de Pb dans les fèces des groupes traités par le lait fermenté ayant contenu ou pas du Pb était relativement élevé par rapport aux groupes témoin et celui recevant de l'eau enrichie de Pb (groupe Pb). La distribution du Pb dans les organismes de cobayes du groupe EauPb s'est révélée dans l'ordre crois