The accumulation and transformation of 2,2',4,4'-tetrabrominated diphenyl ether (BDE47), one congener of the flame retardants polybrominated diphenyl ethers (PBDEs), in soil-feeding fauna are still unknown. Using radioactivity tracer, we incubated 14C-labelled BDE47 in soil for 21 days in the presence and absence of the geophagous earthworm Metaphire vulgaris. BDE47 accumulated in the earthworm predominantly via oral ingestion of soil, giving a biota-soil accumulation factor (BSAF) value of 1.3 for radioactivity at the end of incubation, and was mostly located in intestine, followed by clitellum (organs region) and skin of earthworms. Accumulation was accompanied by significant decrease of BDE47 concentration in soil porewater and BDE47 mineralization in soil. BDE47 was transformed in the earthworm gut into two metabolites with higher polarities than BDE47. The results provide for the first time insights into accumulation and transformation of lower-brominated congeners of PBDEs in geophagous earthworms, being helpful for environmental risk assessment of PBDEs.
Keywords: 2,2',4',-tetrabrominated diphenyl ether (BDE47); Bioaccumulation; Biotransformation; Earthworm; Polybrominated diphenyl ethers (PBDEs).