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The first estimates of atmospheric deposition fluxes of polychlorinated biphenyls (PCBs) to the Hudson River Estuary are presented. Concentrations of PCBs were measured in air, aerosol, and precipitation at nine sites representing a variety of land-use regimes at regular intervals from October 1997 through May 2001. Highest concentrations in the gas phase were observed at urban sites such as Camden and Jersey City (ΣPCB concentrations averaged 3250 and 1260 pg m-3, respectively). In great portions of the state encompassing forested, coastal, and suburban environments, gas-phase EPCB concentrations were essentially the same (averaging 150-220 pg m-3). This spatial trend suggests that atmospheric PCBs arise from highly localized, urban sources which influence atmospheric concentrations and deposition fluxes over a distance of a few tens of kilometers. Atmospheric EPCB deposition fluxes (gas absorption + dry particle deposition + wet deposition) ranged from 7.3 to 340 μg m-2 yr-1 and increased with proximity to urban areas. While the magnitude of the fluxes increased with urbanization, the relative proportions of wet, dry, and gaseous deposition remained largely constant Because the Hudson River Estuary is adjacent to urban areas such as Jersey City, it is subject to higher depositional fluxes of PCBs. These depositional fluxes are at least 2-10 times those estimated for the Chesapeake Bay and Lake Michigan. Inputs of PCBs to the Hudson River Estuary from the upper Hudson River and from wastewater treatment plants are 8-18 times atmospheric inputs, and volatilization of PCBs from the estuary exceeds atmospheric deposition of low molecular weight PCBs. [ABSTRACT FROM AUTHOR]