PARENT SESSION
MA9- Contaminant Mass Budgets in Urbanized Estuaries
Chair: Baker, Joel1, 1 PO Box 38, 1 Williams Street, Solomons, MD, USA
8:00 AM to 12:00 PM - Monday, 18 November 2002
Room Ballroom E
(240) Toxic loadings from combined sewer overflows (CSOs) to the tidal Anacostia River.
Hwang, Hyun-Min*,1, Foster, Gregory1, 1 Department of Chemistry, George Mason University, Fairfax, VA, USA
ABSTRACT- In order to assess the potential water quality impact of the input of organic contaminants through stormwater runoff and sewers to the tidal Anacostia River, combined sewer overflow (CSO) samples (20 L) were collected at 6 sites during high-flow storm events. It has been reported that 8 billion liters of untreated runoff (storm water overflow + raw sewage) are discharged annually through CSOs into the Anacostia River, which is one of three the most polluted hotspots flowing into Chesapeake Bay. Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in separate dissolved and particulate phases, which were extracted using the Goulden large-sample extractor and Soxhlet, respectively. After Al/Si cleanup, analytes were quantified using a gas chromatography equipped with a mass selective detector for PAHs and electron capture detector for PCBs. The storm flow concentrations ranged from 7.5 to 41.3 
g/L for total (dissolved + particulate) PAHs and 0.3 to 1.9 g/L for total PCBs and are much higher than the concentrations in base flow. Approximately 60% of the total PAHs and PCBs was in the particulate fraction, which had a positive relationship with the amount of suspended solid in the samples. Due to the long residence time (e.g., 35 days) of water in the lower Anacostia River, contaminants in particulate phase settle mostly within the tidal portion of the river. Estimated input of PCBs and PAHs demonstrate that CSOs are significant sources of threat to the lower Anacostia River. Further sampling will improve the uncertainties in mass loading calculations.
Key words: Combined Sewer Overflows, Anacostia River, PAHs, PCBs