Halogenated flame retardants in the sediments of the lower Great Lakes and region-wide discoveries

Le résumé fourni par la source

This work aims to provide updated information and insights on the contamination by halogenated flame retardants (HFRs) of the Great Lakes sediments. Thirty HFRs, including polybrominated diphenyl ethers (PBDEs), dechlorane plus (DPs), and other chlorinated (CFRs) or brominated (BFRs) chemicals, were measured in 400 sediment surface grab and core segment samples from Lakes Erie and Ontario. The data were combined with those from Lakes Superior, Michigan, and Huron to provide a comprehensive region-wide analysis. Together, the target HFRs in the Great Lakes sediment amount to approximately 420 tonnes. Among the five lakes, Lake Ontario had the highest concentrations of CFRs, while Lake Erie had the largest mass accumulation of BFRs. Regression analyses identified latitude and longitude of the sites, and sediment organic content, as the most descriptive of the observed spatial distribution patterns. The data from cores indicate that the net flux has been decreasing in recent decades for most HFRs, including PBDE replacements 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EHTBB), with average halving time of 20–65 years. However, at most locations, inputs of decabromodiphenyl ethane (DBDPE) exhibited no clear declining trend. Concentration ratios of less halogenated compounds to their respective “parents” increase with increasing sediment depth, suggesting that dehalogenation has occurred over past decades. Principal component, correlation, and hierarchical clustering analyses of the data suggest similarities and differences among HFRs in their sources and environmental behavior. These findings contribute to the scientific knowledge basis for planning future surveillance, research, and management activities in the region and beyond. • Sediment in Lakes Erie and Ontario are heavily polluted by flame retardants. • The contamination tends to decrease northwards and westwards in the region. • Inputs to sediment are decreasing for PBDEs and some their replacement chemicals. • Dehalogenation has occurred within the sediment over past decades. • Correlations among analytes suggest commonality in their environmental behavior.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.