Enrichment And Transformation Of PBDEs And Their Derivatives In Earthworms

Polybrominated diphenyl ethers(PBDEs)and their derivatives,hydroxylated PBDEs(OH-PBDEs)and methoxylated PBDEs(MeO-PBDEs),have been identified in various environmental media and organisms.Due to their global distribution,environment persistence and potential accumulation,PBDEs are at potential threat to ecosystems.The soil-animal system is an important part of the natural ecosystem.Accumulation and transformation of PBDEs and their derivatives by animal is an important environmental process when considering the risks associated with their soil contamination.However,only very limited investigations have been conducted to study the behaviors of PBDEs and their derivatives in the soil-animal system.In this study,the earthworm(eisenia fetida)was selected as the test animal,the uptake and elimination kinetics and transformation of BDE-47,6-OH-BDE-47 and 6-MeO-BDE-47 was studied to reveal the accumulation and metabolism characteristics of PBDEs,OH-PBDEs and MeO-PBDEs in the soil-animal system.This study will be helpful to comprehensively understand the migration and fate of PBDEs in soil environment,providing the basis for the environmental safety risk assessment of PBDEs.The main results of the study were summarized as follows:1.BDE-47,6-OH-BDE-47 and 6-MeO-BDE-47 could be absorbed quickly by earthworm from the soil and the results showed that the uptake and elimination kinetics of PBDEs can be fitted well by the one-compartment first order kinetic model.2.The bioaccumulation factors(BAFs)of different compounds were in the order of 6-MeO-BDE-47＞6-OH-BDE-47＞BDE-47.3.Debromination for BDE-47,6-OH-BDE-47 and 6-MeO-BDE-47 could be observed in earthworm,while both BDE-47 and 6-OH-BDE-47 could undergo methoxylation metabolism to produce MeO-PBDEs with their nethoxylation rate being significantly higher than those of debromination.There was no transformation from OH-PBDEs or MeO-PBDEs to PBDEs in earthworm.4.6-OH-BDE-47 could undergo rapid methoxylation metabolism in earthworms,and its methoxylation metabolites can further undergo debromination.At the same time,6-OH-BDE-47 could undergo debromination and isomerization metabolism in earthworms,and then be oxidized to MeO-PBDEs.