Reduction in the transfer of persistent organic pollutants from soils to laying hens with biochar and activated carbon amendments
Résumé
Polychlorinated Biphenyls (PCBs), Dioxins, Furans (PCDD/Fs), and Chlordecone (CLD) are Persistent Organic Pollutants (POPs) polluting soil which acts as a reservoir. Due to involuntary ingestion of soil by free-ranged animals, they may transfer to animal food stuffs as they are highly bioaccumulative. In this frame, the amendment of contaminated soil with porous matrices like biochars and Activated Carbons (ACs) has been suggested as promising technique for trapping these organic contaminants in soil in order to reduce their bioavailability in animals. In this study, the efficiency of six carbonaceous matrices was assessed (3 biochars and 3 activated carbons). Three distinct samples of artificial soil were produced according to OECD guidelines 207 (1984) one contaminated by CLD only, the second contaminated by a mix of PCBs, Dioxins, and Furans (1 DL-PCB, 6 NDL-PCBs, 6 PCDDs, 5 PCDFs), and the third sample remained uncontaminated. Each soil sample was amended by 2% (by weight) of one of the six biochars or ACs. The relative bioavailability of pollutants was then measured in forty-eight laying hens aging 22-weeks (n=3 per treatment of each soil) and fed on a daily basis with 80 g of pellets per 2kg of BW containing 10% of soil. After 20 days of oral exposure, the CLD concentration in liver and eggs of hens were analyzed by LC-MS/MS and PCB or PCDD/F ones by CPG-HRMS. A slight decrease in the concentration of contaminants was observed with the biochar amendments, while two of the activated carbons significantly reduced the concentrations of pollutants in the liver and eggs (p< 0.001). Furthermore, the significant reductions obtained with the two efficient activated carbons were compound dependent as follows: PCDD/Fs > DL-PCB with reduction of 74% to 78% of PCDD/Fs in liver and 83% in eggs. For DL-PCB (PCB77), this decrease ranged from 42 to 55% in liver and 53% to 66% in eggs. Only a slight reduction of CLD and NDL-PCB concentrations was obtained with these activated carbons. Thus, this study allows to highlight: (i) the ability of activated carbons amendments in highly reducing the bioavailability of soil organic contaminants to laying hens and (ii) the dependence of the contaminant reduction on both nature of the pollutant and characteristics of the matrix.