Soil microstructure and organic matter: keys for chlordecone sequestration.
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.
IRD UMR 237 Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale PRAM B.P. 214 Petit Morne, 97232, Le Lamentin, Martinique; CNRS 7263 - Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale PRAM B.P. 214 Petit Morne, 97232, Le Lamentin, Martinique. Electronic address: thierry.woignier@imbe.fr.
T
T
Woignier
P
P
Fernandes
A
A
Soler
F
F
Clostre
C
C
Carles
L
L
Rangon
M
M
Lesueur-Jannoyer
D007631:Chlordecone / Q000302:isolation & purification*; D006812:Humic Substances; D010575:Pesticides / Q000302:isolation & purification*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000302:isolation & purification*; D014961:X-Ray Diffraction
D006812:Humic Substances; D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; D007631:Chlordecone
Allophane; Fractal structure; Organic matter; Organochlorine; Pesticide contamination