Uptake and depuration kinetics of lead (Pb) and biomarker responses in the earthworm Eisenia fetida after simultaneous exposure to decabromodiphenyl ether (BDE209)

•Uptake and depuration kinetics of Pb in presence of BDE209 were first explored.•The presence of BDE209 facilitated the Pb release into soil solutions.•The presence of BDE209 enhanced the bioavailability of Pb in earthworms.•Co-exposure of Pb with BDE209 resulted in obvious impairment of earthworm health.

Lead (Pb) and BDE209 (decabromodiphenyl ether) are the main contaminants at e-waste recycling sites, and their potential toxicological effects on terrestrial organisms have received extensive attention. However, the impact on earthworms of exposure to the two chemicals remains almost unknown. Therefore, indoor incubation tests were performed on control and contaminated soil samples to determine the uptake and toxicity of Pb in the presence of BDE209 to the earthworm Eisenia fetida. The results have demonstrated that the presence of BDE209 facilitated the release of Pb into soil porewater. Compared with exposure to Pb alone, simultaneous exposure to BDE209 significantly enhanced the Pb uptake rate at the level of p<0.05, while decreased the depuration rate, ultimately resulting in a larger bioaccumulation factor (BAF) value. Additionally, BDE209 addition reduced the antioxidant enzymatic activities [superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione-s-transferase (GST)] and total antioxidant capacity (T-AOC). The decline trend in antioxidant enzymatic activities and T-AOC might explain an increase in lipid peroxidation reflected by the observed augment in malondialdehyde (MDA) level. Moreover, a biomarker of the lysosomal membrane stability, measured by neutral red retention time (NRRT), was also investigated. The NRRT obviously declined in the joint presence of BDE209, indicating a distinct time–response relationship. The results of these observations have provided a basic understanding of the potential eco-toxicological effects of joint heavy metal and BDE209 exposure on terrestrial invertebrates in a multi-contamination context of ecosystems.