Spatiotemporal Trends of Anthropogenic and Naturally Occurring Polybrominated Diphenyl Ethers in Long-Term White-Tailed Eagle Feather Collections

Using archived feathers from Norwegian, Swedish, and Greenlandic white-tailed eagles (Haliaeetus albicilla), we investigated long-term (1866–2015) spatiotemporal trends of polybrominated diphenyl ethers (PBDEs) and their methoxylated analogues (MeO-PBDEs). Concentrations of BDE 47 (constituting 47–65% of ∑PBDEs) were significantly increased in feathers from Sweden, while those of other congeners remained at similar levels between Sweden and Norway. Among the naturally occurring MeO-PBDEs, 6-MeO-BDE 47 exhibited higher levels in Sweden while 2′-MeO-BDE 68 concentrations were similar across regions. Concentrations of BDE 47 and 6-MeO-BDE 47 were not intercorrelated in Swedish eagles, highlighting the significance of anthropogenic input and natural origin, respectively, possibly associated with enhanced primary production in the Baltic region. Such a natural origin was further supported by the presence of MeO-PBDEs in 35 historical feathers originally collected from 1866 to 1957. Furthermore, in eagles from Norway and Sweden, less brominated PBDEs exhibited significantly increasing trends until the 1990s that declined considerably thereafter, whereas no apparent decrease was observed for BDE 153 or 154. By comparison, all PBDE congeners showed nonlinear but insignificant changes in Greenland. Additionally, the Swedish eagles showed significantly increased levels of ∑MeO-PBDEs, primarily driven by 6-MeO-BDE 47. Our findings indicate that further evaluation of the sources and impacts of more highly brominated PBDEs and MeO-PBDEs is warranted.