Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Virginia Institute of Marine Science


Rebecca M. Dickhut


Surface microlayer (SM) samples were collected with a rotating cylinder sampler from the York and Elizabeth River estuaries of southern Chesapeake Bay every other month from May 1994 through June 1995. Total suspended particle concentration (TSP) concentrations in the SM were found to be up to 1000 times higher than in the corresponding subsurface water, and to be exponentially associated with the wind speed at sampling. A relatively larger POC/TN ratio in the Elizabeth River SM compared with that in the York River SM was also observed. No seasonal trends were noticed in the SM characteristics; however, TSP, POC, and TN concentration in the SM were significantly related with wind speed. Dissolved and particle-associated PAHs were measured in the SM of both the York and Elizabeth Rivers. Particulate PAH concentrations were exponentially related with TSP as well as POC at both study sites, but a significant relationship between dissolved PAHs and DOC was observed only at the York River site. PAHs were significantly enriched in the SM of both sites relative to the subsurface water concentrations. In the particulate phase, the enrichment factors ranged from 5 to 140 and 5 to 5,300 for the Elizabeth and York Rivers, respectively. Enrichment factors in the dissolved phase were much smaller; 1 to 10 for the Elizabeth River site and 2 to 20 for the York River site. Furthermore, both particle-associated and dissolved phase enrichment factors were strongly influenced by wind speed at the Elizabeth River site, whereas, only particulate phase enrichment factors were dependent on wind speed at the York River site. Photodegradation and particle sorption kinetics of PAH compounds was also examined in selected SM samples. PAH concentrations in the SM were observed to decrease exponentially with solar irradiance. Photodegradation half lives were affected by TSP and DOC concentration, submergence depth and seasons. Sorption of PAHs to SM particles were observed to have an initial rapid uptake followed by a much slower approach to steady state. In the Elizabeth River SM, the organic carbon normalized partition coefficient (K&\rm\sb{lcub}oc,app{rcub}&) at steady state was significantly higher than in York River SMs.



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