PARENT SESSION
PM18 - TMDLs
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P392) PCB Loads from Wastewater Effluent Discharged in the San Francisco Estuary.
Yee, Donald*,1, Leatherbarrow, Jon1, Davis, Jay1, Brooks, Georgina2, Hoover, Dale2, 1 San Francisco Estuary Institute, Oakland, CA, USA2 Axys Analytical, Sidney, BC, Canada
ABSTRACT- Despite a ban on their manufacture and use in most applications, PCBs continue to enter the environment through a number of pathways, including wastewater discharges. PCB congeners were measured in effluents from four large municipal wastewater treatment plants and five petroleum refineries that discharge to the San Francisco Estuary. The sum of 40 congeners measured ranged 1-8 ng/L in municipal wastewater. Concentrations in samples taken in the wet and dry seasons typically differed by less than 35%, and these differences did not correspond to a simple model of dilution by rainwater infiltration into the wastewater stream. Up to five-fold differences in average PCB concentrations were found among municipal wastewater treatment plants. The sum of the 40 PCB congeners measured in refinery effluents ranged from 1-2 ng/L. Annual loads in wastewater from all these dischargers based on this collected data total 2-3 kg/year, assuming concentrations through the rest of the year are comparable to those in measured samples. Although loads of PCBs via wastewater are smaller than those entering the Estuary from other pathways, as loads from other pathways are reduced, additional reductions in wastewater discharges may be needed to achieve water quality objectives.
Key words: PCB, wastewater, loads, estuary