Biomagnification of higher brominated PBDE congeners in an urban terrestrial food web in north China based on field observation of prey deliveries.

As an important group of brominated flame retardants, polybrominated diphenyl ethers (PBDEs) persist in the wildlife food webs. However, the biomagnification of PBDEs has not been adequately studied in the terrestrial food webs. In this study, a terrestrial food web composed of common kestrels, sparrows, rats, grasshoppers, and dragonflies in the urban environment from northern China was obtained. A field prey delivery study, reinforced by δ¹³C and δ¹⁵N analyses, indicates that sparrows are the primary prey items of common kestrels. Concentrations of PBDEs were in the following order: common kestrel > sparrow > rat > grasshopper and dragonfly with BDE-209 as the dominant congener. Biomagnification factors (BMFs) were calculated as the ratio between the lipid normalized concentrations in the predator and prey. The highest BMF (6.9) was determined for BDE-153 in sparrow/common kestrel food chain. Other higher brominated congeners, such as BDE-202, -203, -154, -183, -197, and -209, were also biomagnified in this terrestrial food chain with BMF of 1.3-4.7. BDE-47, -99, and -100 were found to be biodiluted from sparrow to common kestrel (BMFs < 1). Measured BMF values for BDE-153, -47, -99, and -100 were consistent with predicted values from a nonsteady-state model in American kestrels from another study. Retention factors and metabolism of BDE congeners may be confounding factors influencing the measured BMFs in this current study.