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Soil microstructure and added organic matter: keys for chlordecone sequestration

Fernandes P., Jannoyer-Lesueur M., Clostre F., Soler A., Rangon L., Woignier T.. 2012. In : 4th International Congress of the European Soil Science Societies Eurosoil 2012, Bari, Italy, 02-06 July 2012. s.l. : s.n., 1 p.. International congress of the european soil science societies Eurosoil 2012. 4, 2012-07-02/2012-07-06, Bari (Italie).

The scientific and economic context of our study is related to the pollution of the soils, fresh and marine water by a persistent organochlorine pesticide (chlordecone) in a tropical context. The former application of chlordecone results today in a diffuse pollution in agricultural soils, which are sources of contamination for cultivated roots, tubers, vegetables and terrestrial and marine ecosystems. Chlordecone is a very though and stable molecule (considered as a POP), it is mainly present in solid phase and has a strong affinity with organic matters. To prevent consumers and ecosystems exposure, it is thus necessary for us to evaluate the factors that influence chlordecone migration in the environment. In our research, we studied the impacts of clay microstructure on the chlordecone retention. We showed that allophane aggregates had a great ability to trap chlordecone mainly due to their fractal structure. We also measured the effects of added composts on chlordecone lability and transfer rate from soil to plant . We show that compost addition modifies the fractal structure of allophane clays favouring the chlordecone retention. These results allow us to propose a new strategy in opposition to the complete soil decontamination: the chlordecone sequestration.

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