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Polybrominated Diphenyl Ethers in the Sediments of the Great Lakes. 4. Influencing Factors, Trends, and Implications
journal contribution
posted on 2006-12-15, 00:00 authored by An Li, Karl J. Rockne, Neil Sturchio, Wenlu Song, Justin C. Ford, Dave R. Buckley, William J. MillsA total of 199 sediment samples were collected from 16
locations in the five Laurentian Great Lakes, and each
was analyzed for 10 congeners of polybrominated diphenyl
ethers (PBDEs) as well as selected polychlorinated
biphenyls (PCBs). This paper presents a comprehensive
analysis on previously published results for individual lakes.
The total accumulation of nine tri- to hepta-PBDE
congeners (∑9BDEs) in the sediments of all the Great
Lakes was estimated to be approximately 5.2 ± 1.1 tonnes,
and that of decabromodiphenyl ether (BDE209) was 92 ±
13 tonnes, around year 2002. The inventories of ∑9BDEs and
major individual PBDE congeners show strong dependence
on the latitude of sampling sites, and such dependence
is believed to reflect both the influence of urbanization,
which shows south-to-north gradient in the region, and the
general direction of long-range transport of airborne
pollutants in the northern hemisphere. From the 1970s to
2002, the increases in PBDE input flux to the sediments are
exponential at all locations, with doubling times (t2)
ranging from 9 to 43 years for ∑9BDEs, and from 7 to >70
year for BDE209. The longer t2 values found in sediments
compared with those in human and fish in the region suggest
the slower response of sediment to emissions. The
correlations between the concentrations of ∑9BDEs or
BDE209 in surface sediments and latitude are strengthened
by normalization of the concentrations with sediment
contents of the organic matter or organic carbon, but not
soot carbon. Multivariate linear regression equations
were developed using data obtained with sediment segments
deposited after 1950. All the regressions are statistically
significant; and the three independent variablesyear of
deposition, latitude, and organic matter content of the
sedimentsaccount for 73% and 62% of the variations in
the concentrations or the fluxes of ∑9BDEs and BDE209,
respectively, in the Great Lakes sediments.