A toxicokinetic study of decabromodiphenyl ether (BDE-209) in marine planktonic food web-adsorption/absorption kinetics, biotransformation, transfer patterns along the food chain

Abstract

Concerns about the residual decabromodiphenyl ether (BDE-209) in marine environments are still existing as its ban of commercial use. Systematically toxicokinetic analysis of BDE-209 in planktonic food chains was conducted in this study, including the bioaccumulation, biotransformation, and transfer patterns of BDE-209 in the Chlorella sp.-Brachionus plicatilis/Tigriopus japonicus food chains. Based on the regression of pseudo-first-order (PFO), pseudo-second-order (PSO), and intraparticle diffusion model, the bioaccumulation of Chlorella sp. for BDE-209 could be concluded as the fast adsorption (12.83 × 10⁻⁴ ng h⁻¹ cell⁻¹) process followed by the fast absorption (10.04 × 10⁻⁴ ng h⁻¹ cell⁻¹) process, both of which were rate-limiting steps (k_diff,1 = 11.04 × 10⁻⁴ ng h^−0.5 cell⁻¹; k_diff,2 = −3.13 × 10⁻⁴ ng h^−0.5 cell⁻¹). Debromination of BDE-209 happened before oxidation in Chlorella sp. cells, and hydrogen peroxide (H₂O₂) stress accelerated the two processes, especially the debromination. Chlorella sp. showed a higher log BCF value (2.53 L kg⁻¹) than B. plicatilis (1.54 L kg⁻¹) and T. japonicus (2.29 L kg⁻¹), and the main way for zooplankton BDE-209 uptake was feeding on contaminated Chlorella sp. The BMF values of BDE-209 along the two food chains were both < 1, showing the biodilution effect. This is the first toxicokinetic study of BDE-209 for marine plankton in lab, provided solid data basis for evaluating the ecological risks of BDE-209 in marine environments, with great ecological significance.