North Atlantic Oscillation signatures in the atmospheric concentrations of persistent organic pollutants: An analysis using Integrated Atmospheric Deposition Network-Great Lakes monitoring data

Abstract

Spring average air concentrations of hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), dieldrin, and two low-molecular-weight polychlorinated biphenyls (PCBs) measured around the Great Lakes during the 1990s showed strong association with the North Atlantic Oscillation (NAO). Decadal air monitoring of persistent organic pollutants (POPS) around the Great Lakes revealed that air concentrations of the aforementioned compounds tend to increase in the positive mode of the NAO. During the same time period, western and northwestern North America experienced warmer-than-normal springs, enhancing volatilization of these compounds from reservoirs accumulated because of past and current use. Atmospheric flows associated with the NAO then transported these compounds from source regions to downwind locations such as the Great Lakes. Roughly reversed situations occurred during the negative mode of the NAO, which was linked to lower POP air concentrations observed around the Great Lakes. Interannual fluctuations of the air concentrations of these POPs significantly correlated with the 1000-500-hPa thickness of the atmospheric layer to the west of the Great Lakes and changes in zonal wind over the western United States. Results indicate that the NAO index may be a useful factor for florecasting interannual fluctuations of POP air concentrations in North America. Copyright 2004 by the American Geophysical Union.