Probing the debromination of the flame retardant decabromodiphenyl ether in sediments of a boreal lake.
After decades of use of polybrominated diphenyl ethers (PBDEs) as flame retardants, a large reservoir of these toxins has accumulated in ecosystems worldwide. The present study used an innovative approach to examine whether the fully brominated PBDE decabromodiphenyl ether (decaBDE) degrades to more toxic congeners in aquatic environments. The authors incubated intact sediment microcosms with high-purity [(13)C]decaBDE in a remote boreal lake to assess its debromination under ambient conditions. Although the addition of [(13)C]decaBDE increased total PBDE concentrations in sediment more than 10-fold, the relative amount of [(13)C]decaBDE in sediment did not change significantly over a 1-mo incubation. However, observation of small quantities of lower-brominated [(13)C]BDEs lent support to the hypothesis that decaBDE is slowly debrominated. The authors observed a significant increase in octaBDEs and nonaBDEs in profundal, but not littoral, sediment over 30 d. A second experiment in which sediment was incubated under different light and oxygen regimes yielded a surprising result-oxygen significantly stimulated the formation of octaBDEs and nonaBDEs. The authors also conducted a large-scale in situ enclosure experiment in which they followed the fate of experimentally added decaBDE in sediment over 26 mo, but that study yielded little evidence of decaBDE debromination. Overall, the authors suggest that the debromination of decaBDE occurs very slowly, if at all, in natural sediment of boreal lakes, in contrast to the rapid degradation kinetics reported by most laboratory-based studies, which are usually conducted by dissolving decaBDE in organic solvents. The findings reinforce the need for field studies on contaminant fate to inform environmental policy decisions.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Diane M
DM
Orihel
Aquatic Contaminants Research Division, Environment Canada, Burlington, Ontario, Canada.
Tommy
T
Bisbicos
Aquatic Contaminants Research Division, Environment Canada, Burlington, Ontario, Canada.
Colin T R
CT
Darling
Freshwater Institute, Fisheries & Oceans Canada, Winnipeg, Manitoba, Canada.
Alain P
AP
Dupuis
Aquatic Contaminants Research Division, Environment Canada, Burlington, Ontario, Canada.
Mary
M
Williamson
Aquatic Contaminants Research Division, Environment Canada, Burlington, Ontario, Canada.
Derek C G
DC
Muir
D002170:Canada; D002849:Chromatography, Gas; D005411:Flame Retardants / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry*; D055768:Halogenated Diphenyl Ethers / Q000032:analysis*; D060106:Lakes / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D014874:Water Pollutants, Chemical; C010902:decabromobiphenyl ether
BDE-209; Brominated flame retardant; Experimental lakes area; Polybrominated diphenyl ether (PBDE); Reductive debromination