Seasonal air-water exchange fluxes of polychlorinated biphenyls in the Hudson River Estuary

Yan, S.; Rodenburg, L.A.; Dachs, J.; Eisenreich, S.J.

Seasonal air-water exchange fluxes of polychlorinated biphenyls in the Hudson River Estuary

2008

Yan, S. | Rodenburg, L.A. | Dachs, J. | Eisenreich, S.J.

Polychlorinated biphenyls (PCBs) were measured in the air and water over the Hudson River Estuary during six intensive field campaigns from December 1999 to April 2001. Over-water gas-phase PCB concentrations averaged 1100 pg/m3 and varied with temperature. Dissolved-phase PCB concentrations averaged 1100 pg/L and displayed no seasonal trend. Uncertainty analysis of the results suggests that PCBs with 5 or fewer chlorines exhibited net volatilization. The direction of net air/water exchange could not be determined for PCBs with 6 or more chlorines. Instantaneous net fluxes of PCBs ranged from +0.2 to +630 ng m-2 d-1. Annual fluxes of [summation operator]PCBs were predicted from modeled gas-phase concentrations, measured dissolved-phase concentrations, daily surface water temperatures and wind speeds. The net volatilization flux was +62 μg m-2 yr-1, corresponding to an annual loss of +28 kg/yr of PCBs from the Hudson River Estuary for the year of 2000. Investigation of the air-water exchange of PCBs in the Hudson River Estuary suggests that PCBs with 5 or fewer chlorines undergo net volatilization.

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