Environmental fate of chlordecone in coastal habitats: recent studies conducted in Guadeloupe and Martinique (Lesser Antilles)
Résumé
The organochlorine pollution by chlordecone, an insecticide spread in the past in banana plantations, is now recognized as a major ecological, economic and social crisis in Guadeloupe and Martinique Islands. Due to its physical and chemical properties, this molecule is particularly persistent in the natural environment. Volcanic soil of Guadeloupe and Martinique contain allophanes (amorphous clays), which favor chlordecone trapping due to their structure and physical properties. Thus, with this trapping ability, allophanes could constitute a vector allowing chlordecone to contaminate runoff waters, and finally the sea. In the present publication, several studies recently conducted in the Lesser Antilles have been compiled in order to evaluate the desorption of chlordecone from allophanes when arriving in the estuarine environment and to determine the transfer of chlordecone along marine trophic food webs. The experiments showed that 20% of the initial quantity of chlordecone was released from allophones in estuarine conditions and 10% in marine environment. These results could explain the high level of contamination found in the suspended organic matter and zooplankton in the coastal areas located downstream the contaminated watersheds. The contamination of the marine food webs of mangroves seagrass beds and coral reefs, is dominated by a contamination 'by bath" in littoral waters containing chlordecone and by bioamplification seawards.
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