Temporal and Spatial Trends of Atmospheric Polychlorinated Biphenyl Concentrations near the Great Lakes

Abstract

Polychlorinated biphenyl (PCB) concentrations were measured in the atmosphere at six regionally representative sites near the five Great Lakes from 1990 to 2003 as part of the Integrated Atmospheric Deposition Network (IADN). Concentration data for several individual PCB congeners and for total PCBs were analyzed for temporal and spatial trends after correcting for the temperature dependency of the partial pressures. Atmospheric PCB concentrations are decreasing relatively slowly for tetra- and pentachlorinated congeners, an observation that is in agreement with primary emissions modeling. Relatively rapid decreases in PCB concentrations at the sites near Lakes Michigan and Ontario may reflect successful reduction efforts in Chicago and Toronto, respectively. Atmospheric PCB concentrations near Lakes Superior and Huron are now so low that the air and water concentrations may be close to equilibrium. Atmospheric PCB concentrations at sites near Lakes Michigan, Erie, and Ontario are relatively higher than those measured at sites near Lakes Superior and Huron. The highest PCB level was observed at the site near Lake Erie, most likely due to nearby urban activity. However, this relatively higher concentration is still 6-10 times lower than that previously reported at the Chicago site. A correlation between average gas-phase PCB concentration with local population indicates a strong urban source of PCBs. The temperature dependence of gas-phase PCB concentrations is similar at most sites except at Burnt Island on Lake Huron, where very low concentrations, approaching virtual elimination, prevent reliable temperature correlation calculations.

Hexabromocyclododecanes, polybrominated diphenyl ethers, and polychlorinated biphenyls in radiometrically dated sediment cores from English lakes, ~ 1950–present

“…This is consistent with previous studies of airborne contamination with PBDEs (Harrad and Hunter, 2006;Sun et al, 2007). Given these observations, coupled with the abundant use of our target contaminants in consumer goods and construction materials and the greater prevalence of these in densely-populated areas; we believe contamination in these lakes results largely from diffuse emissions from the built environment.…”

The Lake Michigan contaminant transport and fate model, LM2-toxic: Development, overview, and application

“…These rates were applied starting on January 1, 1996. C) Continued Recovery (Slow) -Same as Scenario B, except the atmospheric components (vapor-phase concentration, wet and dry deposition) declined with a 20-year half-life (Buehler et al, 2002, Sun et al, 2007. D) No Atmospheric Deposition -Same as Scenario A, but starting on January 1, 1996, the atmospheric loads (dry and wet deposition) were set to zero.…”

Inventory of PCBs in Chicago and Opportunities for Reduction in Airborne Emissions and Human Exposure

“…Average concentrations due to this inventory would be 1.26 ng m −3 for ΣPCBs and 19.03 pg m - for PCB 11,roughly matching observed ambient concentrations in the city of 1.13 ng m −3 and 24 pg m −3 , respectively. 25, 27, 69 …”