PM07 Pollutant Chemistry Transport, Cycling and Fate
Exhibit Hall
8:00 AM - Monday
(PM077) An Improved Model of the Long Term Fate of PCBs in San Francisco Bay.
Davis, J1, Leatherbarrow, J1, Lionberger, M2, Schoellhamer, D2, 1 San Francisco Estuary Institute, Oakland, CA, USA2 U.S. Geological Survey, Sacramento, CA, USA
ABSTRACT- PCBs are currently a high regulatory priority in San Francisco Bay and the subject of a TMDL. In work funded by the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP), a multi-box mass budget model was developed to improve understanding of the long term fate of PCBs in San Francisco Bay. This model is incorporated into an existing tidally-averaged salinity box model of San Francisco Bay, which is used because the hydrodynamics of the model segments have been formulated and previously calibrated with salinity, a conservative tracer. The Bay is represented by 51 segments composed of 2-layers representing the channel and the shallows. Calculations are made using a daily time step. Sediment dynamics were parameterized, calibrated, and validated using extensive suspended sediment concentration data collected for the RMP over the past 10 years and changes in bathymetry observed from 1950 to 1990. PCB fluxes into and out of each box were calculated primarily using equations developed previously for a one-box model of the Bay. Improvements incorporated in this version of the model include a more realistic treatment of sediment mixing, sediment erosion and deposition, and a quantification of the aggregate uncertainty of the model estimates. Preliminary results from the model will be presented. This work will provide a foundation for modeling the fate of persistent, particle-associated contaminants in the Bay in support of RMP monitoring and TMDL development and implementation for years to come.
Key words: san francisco bay, pcbs, pollutant fate, models