Antillean contaminated soils amendment with microwave prepared sargassum biochar: A promising solution to reduce chlordecone transfer to laying hens and piglets?

International audience

إنجليزي. The use of Sargassum spp., a brown invasive algae, for the production of biochars (BCs) or activated carbons (ACs) and their efficiency to sequestrate chlordecone (CLD) in soil has been recently suggested. The objective of this study was to assess the potential of microwave prepared Sargasso biochar (BCS) amendment in Andosol on the bioavailability of chlordecone in laying hens and piglets, when exposed to this matrix. The efficiency of BCS was compared to a commercial activated carbon, DARCO® (ACD), used as a positive control and to an unamended soil. Samples of CLD-contaminated Andosol were amended with 2% of each carbonaceous matrix and let maturing for 3 months. Thereafter, adequate doses of soil were administered into the laying hens and piglets diets every day during the exposure phase, to simulate involuntary soil ingestion which may happen in practical conditions when animals are reared outside. Finally, bioavailability tests were carried out on target tissue (liver, muscle, adipose tissues and egg yolk). The results showed that the highest reduction of CLD bioavailability was obtained with ACD in both animal species. For laying hens, ACD showed reductions of around 60% (liver: 59%, muscle: 57% and egg yolk: 56%) whereas the BCS showed reduction of around 30% (liver: 31%, muscle: 26% and egg yolk: 30%) compared to the unamended soil. For piglets, only the liver showed interpretable results with reduction of 65% with ACD and 41% with BCS. Overall, BCS is efficient reducing CLD availability but in a lower extend than ACD. This discrepancy may be explained by the variations of physico-chemical characteristics that exist between the two matrices, resulting, from the additional activation phase for DARCO®. Therefore, to improve the efficiency of BCS it would be interesting to move towards DARCO® characteristics by determining out the optimal microwave pyrolysis parameters.