Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame-retardants (BFRs) that bioaccumulate and cause liver, thyroid, and neurotoxic effects. These compounds are ubiquitous in the environment and undergo long-range atmospheric transport to the Arctic. However little is known about the fate of PBDEs in the aquatic ecosystems. Current study of PBDE photolysis is limited to experiments conducted in organic solvents or mixtures of water and miscible solvents, which limits the applicability of these results to natural conditions. In the present study, we examined the direct and indirect photodegradation of 2,2’,4,4’-tetrabromodiphenyl ether (BDE-47) in ultrapure (Milli-Q) water and aqueous solutions of arctic dissolved organic matter (DOM) isolated from seeps located adjacent to the Sagavanirktok River on the north slope of the Brooks Range, Alaska. Our results reveal overall slow photodegradation for BDE-47, with slightly faster rates in solutions of DOM (4.53±0.07 mg DOC L-1) compared to Milli-Q (half-lives of 21.9 +3.6/-2.7 hr-1 and 31.4 +3.2/-2.7 hr-1, ±95% CI, respectively). However, no significant increase in rate was observed at higher concentrations of DOM. Similar to previous studies of PBDE photolysis in organic solvents, gas chromatograph mass spectrometry analysis of the degraded solutions reveals the presence of the debromination products BDE-28 and -17. Yet surprisingly, these products only account for ~20% of the total parent compound loss. Thus our results suggest that the photo-products formed from PBDE photolysis in aqueous solutions significantly differs from those previously reported in the literature based upon experiments conducted in organic solvents (neat and in mixtures with water). Photo-products previously reported as minor constituents, such as hydroxylated BDEs or the potentially toxic dibenzofurans, may comprise a significant fraction of PBDE degradates. Our current study is focused on identification and quantification of these unknown photo-products.

Does debromination dominate BDE-47 photodegradation in natural environments?

249th National Meeting (2015)

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