Concentrations and spatial variations of polybrominated diphenyl ethers and other organohalogen compounds in Great Lakes air

Air samples were analyzed from urban, rural, and remote sites near the Grea t Lakes to investigate the occurrence, concentrations, and:spatial and temp oral differences of polybrominated diphenyl ethers (PBDE) in air. The conce ntrations of PBDEs were compared to those of other organohalogen compounds such as PCBs and organochlorine pesticides. The samples were collected in 1 997-1999 as part of the Integrated Atmospheric Deposition Network (IADN). T o minimize the variability of the data, we selected only samples taken when the atmospheric temperature was 20 +/- 3 degreesC. PBDEs were found in all samples, indicating that these compounds are widely distributed and that t hey can be transported through the atmosphere to remote areas. The total co ncentrations of PBDEs were similar to some of the organochlorine pesticides such as Sigma DDT and ranged from 5 pg/m(3) near Lake Superior to about 52 pg/m(3) in Chicago. In fact, the spatial trend was well correlated to thos e of PCBs. Our results indicate a relatively constant level from mid-1997 t o mid-1999. At 20 +/- 3 degreesC, about 80% of the tetrabromo homologues ar e in the gas phase and about 70% of the hexabromo homologues are associated with the particle phase. Thus, particle-to-gas partitioning in the atmosph ere is an important process for these compounds.