TitleThe application of a micrometeorological technique to measure air-water exchange of polychlorinated biphenyls
NameSandy, Andy Larry (author), Rodenburg, Lisa A (chair), Miskewitz, Robert (co-chair), Miller, Mark (internal member), Reinfelder, John (internal member), McGillis, Wade (outside member), Rutgers University, Graduate School - New Brunswick,
Polychlorinated biphenyls--Air content--Measurement,
DescriptionIn this study, a micrometeorological technique was applied for the first time to investigate the air-water exchange of polychlorinated biphenyls (PCBs). By measuring the concentrations of PCBs at two heights above the water surface as well as in the dissolved phase, air-water exchange fluxes and mass transfer coefficient (vaw), also known as air-water exchange velocity, were determined for individual PCB congeners in the Hudson River. The average gas-phase ΣPCB concentration was 1.1 ng m-3, and ranged from 0.62-2.2 ng m-3, these values are elevated over regional background by about a factor of 6. The atmospheric stability factor of water vapor (φw), which were used to correct PCB fluxes for non-neutral conditions, ranged from 1.0-3.2 (roughly neutral to stable conditions). Vertical ΣPCB fluxes ranged from +0.5 μg m-2 d -1 to +13.5 μg m-2 d-1. Individual congener fluxes ranged from negative to +1.3 μg m-2 d-1. Mono through tri homologues accounted for about half of ΣPCB fluxes, with tetra through hexa accounting for the other half. The average daily ΣPCB flux was 4 μg m-2 d-1, which suggests that about 400 kg ΣPCBs volatilize from this water body over the three summer months. Dissolved-phase PCB concentrations ranged from 2.5 to 32 ng L-1, while concentrations in the suspended particle phase ranged from 5.3 to 14 ng L-1. The derived vaw values for individual congeners averaged 0.81 m d-1, with a median of 0.49 m d-1 and a range of 0.042 to 8.4 m d-1. Average uncertainty in vaw is about 70%. Compared to other studies, our vaw values are more precise (lower uncertainty) and more selective (measured for individual congeners) than values determined by the Whitman two-film model. The results from multiple regression analysis indicate that the relationship of vaw with meteorological and PCB physicochemical properties were significant. However, minute r2 values suggest that other parameters may play a pivotal role on vaw in this system. Future studies should extend the range of temperature and wind speed over which vaw is measured and should also focus on understanding the role of the surface micro layer and surfactants on air/water exchange of PCBs.
NoteIncludes bibliographical references
Noteby Andy Larry Sandy
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.