Dechlorane Plus and Other Flame Retardants in a Sediment Core from Lake Ontario

Our previous research on atmospheric samples suggested that Lake Ontario might receive significant amounts of Dechlorane Plus (DP), a highly chlorinated flame retardant, from the atmosphere and from inputs from DP's manufacturing facility in Niagara Falls, New York. To confirm this suspicion, a sediment core from the central basin of Lake Ontario was analyzed for the two isomers of DP, for polybrominated diphenyl ethers (PBDEs), and for 1,2-bis(2,4,6-tribromophenoxy)ethane (TBE). The results showed that the concentration of DP in sediment increased rapidly starting in the mid-1970s and reached its peak concentration (310 ng g-1 dry weight) in the mid-1990s. The peak flux and total inventory of DP were estimated to be 9.3 ng cm-2 yr-1 and 120 ng cm-2, respectively. These values suggest that the total burden of DP in Lake Ontario is ∼20 tons and that the maximum load rate was ∼2 tons per year. The highest concentrations of PBDEs and TBE were found in the surficial sediment, with average concentrations of 2.8, 14, and 6.7 ng g-1 d.w. for PBDE3-7 (tri- through hepta-BDEs), BDE-209, and TBE, respectively. The surface fluxes were 0.08, 0.43, and 0.20 ng cm-2 yr-1, and the inventories were 0.87, 3.9, and 1.8 ng cm-2 for PBDE3-7, BDE-209, and TBE, respectively. The concentration of DP in Lake Ontario sediment exceeds that of the brominated flame retardants combined.