Historical trends of PBDEs and HBCDs in sediment cores from Sydney estuary, Australia

This paper presents the first historical data on the occurrence of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDs) in estuarine sediment from Australia. Sediment cores and surficial sediment samples were collected from four locations within Sydney estuary, Australia. Large increases in concentrations were observed for all compounds between 1980 and 2014, especially for BDE-209 (representative usage of Deca-BDE commercial mixture), which was found in surficial sediment at an average concentration of 42 ng/g dry wt (21-65 ng/g dry wt). PBDE congeners representative of both the Penta- and Octa-BDE commercial mixtures (∑6PBDEs) were also found in their highest concentrations in surficial sediments (average: 1.3 ng/g dry wt; range: 0.65-2.5 ng/g dry wt). PBDE concentrations in surficial sediments were relatively high when compared with those presented in the available literature. This suggests that their input into the Sydney estuary has not decreased since their bans almost a decade earlier. After a sharp increase in the 1990s, HBCD concentrations peaked at an average of 3.5 ng/g dry wt (1.8-5.3 ng/g dry wt) in surficial samples. With global legislation on HBCDs allowing its usage for the next 10 years, it is expected that its input into the estuary is likely to continue.