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Conference Papers Year : 2019

Reduction of chlordecone environmental availability by soil amendment of biochars and activated carbons

Abstract

Chlordecone (Kepone or CLD) was formerly used in French West Indies as an insecticide. Despite its formal ban in 1993, high levels of this pesticide are still found in soils. Sequestering matrices like biochars or activated carbons (ACs) may decrease the bioavailability of halogenated compounds like CLD when added to contaminated soils. The present study intends (i) to produce contrasted sequestering matrices in order to (ii) assess their respective efficiency to reduce CLD environmental availability. This study involved two experimental steps. The first one consisted in the production of contrasted sequestering media (Biochars and ACs) using pyrolysis and distinct activation processes on two lignocellulosic precursors: oak wood (Quercus ilex) and coconut shell (Cocos nucifera). The chemical activation was made with phosphoric acid and physical activation with carbon dioxide and steam. Their physico-chemical properties were then characterized. In the second step, the CLD environmental availability was assessed either in an OECD artificial soil or in an Antillean contaminated nitisol (2.1 µg CLD per g of soil Dry Matter) amended with 5% of biochar or 5% of AC (mass basis). Main characteristics for coconut and oak biochars and ACs determined by nitrogen adsorption at 77K shows that mixed microporous and mesoporous structures (ranging from 30 % to 70%), high pore volume (ranging from 0.38 cm3.g-1 to 2.00 cm3.g-1) and a specific (BET) surface areas from 299.9 m2.g-1 to 1285.1 m2.g-1 resp. The amendment by lignocellulosic biochars did not limit CLD environmental availability in contrast to ACs which resulted in a significant reduction of the environmental availability in both artificial and natural soils. Thus, ACs amendment reduced CLD-transfer by at least 65% (P<0.001) for both lignocellulosic matrices (at the exception of coco activated with steam displaying a 47%-reduction). These results confirm quality and extent of porosity are of particular importance in the retention process of CLD in aged soil. This study leads to conclude that AC introduced in CLD contaminated soils could significantly reduce CLD transfer to fauna and biota.
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Dates and versions

hal-03954079 , version 1 (24-01-2023)

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Attribution - NonCommercial - NoDerivatives

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  • HAL Id : hal-03954079 , version 1

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Ronald Ranguin, Corine Jean-Marius, Christelle Yacou, Valerie Jeanne-Rose, Sarra Gaspard, et al.. Reduction of chlordecone environmental availability by soil amendment of biochars and activated carbons. 35th International Conference on Geochemistry and Health, Society for Environmental Geochemistry and Health SEGH, Jul 2019, Manchester, United Kingdom. pp.50. ⟨hal-03954079⟩
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