Modeling the Atmospheric Transport and Deposition of PCDD/F to the Great Lakes


Mark D. Cohen, Roland R. Draxler, Richard Artz, Barry Commoner, Paul Bartlett, Paul Cooney, Kim Couchot, Alan Dickar, Holgar Eisl, Catherine Hill, James Quigley, and Joyce E. Rosenthal


Environmental Science and Technology, Vol. 36, pp. 4831-4845, 2002


Abstract - Atmospheric deposition is a significant loading pathway for polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxin) to the Great Lakes.  An innovative approach using NOAA's HYSPLIT atmospheric fate and transport model was developed to estimate the 1996 dioxin contribution to each lake from each of 5700 point sources and 42,600 area sources in a U.S./Canadian air emissions inventory.  These unusually detailed source-receptor  modeling results show that deposition to each lake arises from a broad geographical region, with significant contributions from up to 2000 km away. The source categories contributing most significantly to 1996 dioxin deposition appear to be municipal waste incineration, iron sintering, medical waste incineration, and cement kilns burning hazardous waste.  Model-predicted air concentrations and deposition fluxes were consistent with ambient measurement data, within the uncertainties in each, but there may be a moderate tendency toward underestimation using midrange emission estimates. The most likely reason for this tendency appears to be missing or underestimated emission sources, but in-situ atmospheric formation of octa-chlorinated dibenzo-p-dioxin (OCDD) and hepta-chlorinated dibenzo-p-dioxin (HpCDD) may have also contributed. Despite uncertainties, the findings regarding the relative importance of different sources types and source regions appear to be relatively robust and may be useful in prioritizing pollution prevention efforts.


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