Gas-Phase Deposition of Polychlorinated Biphenyls (PCBs) to a Water Surface Sampler

Abstract

In this study a water surface sampler (WSS) was utilized to directly measure gas phase deposition of polychlorinated biphenyls (PCBs). The measured gas phase PCB fluxes averaged about 880 ± 660 ngm⁻²d⁻¹, which was higher than the fluxes calculated using simultaneously measured air and water concentrations for natural surface waters. These large fluxes were due to fact that the measured fluxes were only in the absorption direction since deposited PCBs were continuously removed from the system using an XAD column resulting in the maximum possible flux rate from the air to the WSS water. Ambient air PCBs were also sampled simultaneously with a modified high volume sampler. The gas phase PCB concentrations changed between 0.90 and 4.46 ngm⁻³ (2.18 ± 1.16 ngm⁻³). The mass transfer coefficients (MTCs), calculated by dividing the fluxes by the gas phase concentrations was 0.40 ± 0.36 cms⁻¹. The average MTC was comparable with those calculated using a similar configuration of a WSS.

Key Words :

• PCB
• Air-water exchange
• MTC
• Flux
• Deposition
• Water surface sampler

ACKNOWLEDGMENT

The support of Mustafa Odabasi and Nedim Vardar in field sampling and laboratory analysis is greatly appreciated.