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Modulation de l’absorption intestinale de la chlordécone (CLD) par l’utilisation de substances séquestrantes : application à l’élevage en zones contaminées

Abstract : The contamination of agricultural soils by chlordecone threatens the sustainability of outdoor farming in the West Indies. In order to maintain the latter while protecting consumers of terrestrial animal products, several strategies are being studied. This thesis is focused on one of them which consists of sequestering chlordecone in order to significantly reduce its bioavailability for the animal. The experimental approach was carried out in stages, based on three pillars: biochar or activated carbon as sequestering materials, the use of artificial soils and the concept of relative bioavailability to assess sequestration performance. Tests conducted with activated charcoal (based on dates kernels, coconut or lignite) have shown that chlordecone is sequestered in an aqueous medium or in animals, but for the latter it only works if chlordecone and sequestering matrix had a prolonged contact time (or maturation) with ingestion by the animal. These results show the interest of in situ sequestration, ie directly in the contaminated soil likely to be ingested by the animals. As activated charcoal has a high cost, a priori less expensive carbonaceous materials have been tested: biochars based on various wood species. These biochars produced at two pyrolysis temperatures (500 and 700 ° C) were characterized from a physical point of view (porosity) and selected via an in vitro environmental availability test. In vivo tests (on piglets) did not show that these selected biochars were able to effectively sequester chlordecone, since the relative bioavailability was not different from one (reference = standard soil without organic matter). The presence of peat in the artificial soil does not prevent trapping by exogenous carbonaceous matrices. The in vitro test used and the in vivo test give equivalent tendencies to reduce the relative bioavailability, which is interesting in a logic of validation of the in vitro test. These positive results show that the strategy of sequestration by highly carbonaceous materials is possible, requires properties of microporosity and access to pores close to those of an activated carbon, but contingent on the experimental conditions implemented, they must be continued and validated on natural soils
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Submitted on : Monday, June 25, 2018 - 9:14:23 AM
Last modification on : Tuesday, March 17, 2020 - 3:11:32 AM
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  • HAL Id : tel-01822378, version 1

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Sarah Yehya. Modulation de l’absorption intestinale de la chlordécone (CLD) par l’utilisation de substances séquestrantes : application à l’élevage en zones contaminées. Sciences agricoles. Université de Lorraine, 2017. Français. ⟨NNT : 2017LORR0259⟩. ⟨tel-01822378⟩

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