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Sequestering a persistent organochlorine with organic fertilizer and organic amendment to increase food safety in Martinique

Fernandes P., Woignier T., Clostre F., Soler A., Rangon L., Lesueur Jannoyer M.. 2015. In : 20th World Congress of Soil Science: Soils embrace life and universe, Jeju, Korea, June 8-13, 2014. s.l. : s.n., 2 p.. World Congress of Soil Science. 20, 2014-06-08/2014-06-13, Jeju (Corée, république de).

Chlordecone is an environmentally persistent insecticide that was intensively used in banana cropping systems. Although its use was restricted 20 years ago, chlordecone permanently pollutes soils and consequently continues to contaminate crops, water resources, and food chains. This pesticide was recently suspected of being implicated in the increasing incidence of prostate cancer and in the impaired development of young children. Given the proven risks to human health, the release of chlordecone from polluted soil needs to be controlled to reduce contamination of the different food chains. Natural decontamination of the soil through lixiviation will take decades to centuries. The persistence of chlordecone in soils is explained by i) its physicochemical properties: low solubility in water, hydrophobicity, which gives it a high affinity for organic matter and ii) its poor biodegradability related to its peculiar chemical structure with high steric hindrance. Chlordecone pollution concerns a large area, meaning chlordecone-polluted sites require efficient cost-effective in situ treatments. To date, phytoextraction and microbial degradation have not really been efficient in the case of diffuse pollution of chlordecone in the soil. Thus, sequestering chlordecone in the soil could be an alternative way to reduce its availability for crops and water resources. We then chose to study the ability of two different organic matters to sequestrate this molecule in the two main contaminated soil types presenting different characteristics: andosols, with amorphous clays (allophane), and nitisols, with crystalline 1/1 clays. We tested two types of organic matter: an organic fertilizer and an organic amendment. For each experiment (in microcosm, in pots and at field scale), the same quantities (5% w/w) of organic fertilizer or organic amendment were incorporated into both contaminated soils. During these experiments, we measured during three months the effects of organic fertilize

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