Soil microstructure and organic matter: Keys for chlordecone sequestration
Woignier T. | Fernandes P. | Soler A. | Clostre F. | Carles C. | Rangon L. | Lesueur Jannoyer M.
Past applications of chlordecone, a persistent organochlorine pesticide, have resulted in diffuse pollutionof agricultural soils, and these have become sources of contamination of cultivated crops as well as ter-restrial and marine ecosystems. Chlordecone is a very stable and recalcitrant molecule, mainly presentin the solid phase, and has a strong affinity for organic matter. To prevent consumer and ecosystemexposure, factors that influence chlordecone migration in the environment need to be evaluated. In thisstudy, we measured the impact of incorporating compost on chlordecone sequestration in andosols asa possible way to reduce plant contamination. We first characterized the transfer of chlordecone fromsoil to plants (radish, cucumber, and lettuce). Two months after incorporation of the compost, soil-planttransfers were reduced by a factor of 1.9-15 depending on the crop. Our results showed that addingcompost modified the fractal microstructure of allophane clays thus favoring chlordecone retention inandosols. The complex structure of allophane and the associated low accessibility are important charac-teristics governing the fate of chlordecone. These results support our proposal for an alternative strategythat is quite the opposite of total soil decontamination: chlordecone sequestration. (Résumé d'auteur)
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