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 Pérou Catchment (12 km2) 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 Pérou Catchment (3400 ?g kg?1) than in the entire banana cropping area in Guadeloupe (2100 ?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. Pérou 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. (Résumé d'auteur)

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.

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. (Résumé d'auteur)

La chlordécone, insecticide organochloré de synthèse, était utilisée dans les bananeraies antillaises avant 1993. Pourtant, elle contamine encore les ressources en eau, certaines denrées, et des organismes aquatiques. Très tôt, la recherche agronomique s'est mobilisée pour répondre aux questions posées pour la gestion de cette crise : Où sont les sols pollués? Est-ce une pollution durable ? La molécule est peu mobile. Des cartes de risques, fondées sur leur occupation rétrospective en bananeraies, aboutissent à 1/5e de la SAU polluée en Guadeloupe, 2/5e en Martinique. Les sols riches en matière organique retiennent fortement la chlordécone. Elle ne se dégrade pas dans les sols aérés, seules les eaux de percolation peuvent la dissiper. Sa persistance est donc longue, d'un à quelques siècles selon les sols. La dépollution artificielle n'est pas actuellement opérationnelle. Il faut donc gérer cette pollution. Pour réduire l'exposition de la population et la contamination des denrées, les agriculteurs doivent disposer de systèmes de culture et d'élevage compatibles avec les niveaux de chlordécone des sols, restés fertiles. Un outil est disponible, il prend en compte le niveau de pollution de la parcelle et la contamination des cultures: certaines sont très contaminées (tubercules), d'autres indemnes (fruits d'arbres, banane, ananas, tomate,...). (Résumé d'auteur)

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. (Résumé d'auteur)

La chlordécone, insecticide organochloré, était utilisée pour lutter contre le charançon du bananier (Cosmopolites sordidus) de 1971 à 1993. La chlordécone est peu mobile et se dégrade à une vitesse très lente, voire nulle dans les sols aérés. Sa persistance est donc longue, et la dépollution artificielle n'est pas opérationnelle actuellement. Cependant les sols restent fertiles même si ils constituent la principale réserve et source de pollution. Il faut donc gérer cette pollution. Cela implique des changements au sein des agrosystèmes, tant sur le choix des productions possibles que sur certaines pratiques agronomiques pour réduire les impacts sanitaires. Pour les espèces cultivées sur les parcelles polluées, certains organes sont très contaminés (tubercules), d'autres indemnes (fruits d'arbres, banane, ananas, tomate, etc.). Un outil de gestion est disponible pour les producteurs afin d'anticiper le choix des cultures et de réduire le risque d'exposition des consommateurs. Réciproquement, les systèmes de culture ont une incidence sur la dispersion de la molécule à l'échelle d'une parcelle et d'un bassin versant. La chlordécone contamine les ressources et les organismes aquatiques via les eaux de percolations issues des parcelles polluées. Cet article fait le point sur les principaux résultats disponibles et les projets en cours sur la gestion des agrosystèmes et les processus de transferts de la chlordécone vers l'environnement ainsi que leurs impacts sur les écosystèmes aquatiques. (Résumé d'auteur)