Temporal Trends of Polychlorinated Biphenyls in Precipitation and Air at Chicago

摘要

Polychlorinated biphenyl (PCB) concentrations in precipitation (1997-2003) and in the atmospheric gas phase (1996-2003) collected in Chicago,IL,are reported.These data were obtained as part of the Integrated Atmospheric Deposition Network.For comparison,PCB concentrations at a remote site.Sleeping Bear Dunes on the northeastern shore of Lake Michigan,are also reported.Much higher PCB concentrations in both precipitation (7.1 +- 0.9 ng/L) and the gas phase (1.4 +- 0.1 ng/m3) at Chicago compared to Sleeping Bear Dunes (1.1 +- 0.1 ng/L and 0.1 +- 0.08 ng/m3,respectively) indicate that Chicago is a source of PCBs to the Great Lakes.A long-term decreasing trend of PCB concentrations in precipitation was observed at Chicago with a half-life of 6.8 +-3.1 years.The corresponding half-life for PCB concentrations in the gas phase was 7.7 +- 1.1 years.The significant long-term decrease of PCB concentrations in precipitation and the gas phase in Chicago suggests that regulatory efforts are working,at least in this city.