SETAC North America 28th Annual Meeting A Mass Budget of Polybrominated Diphenyl Ethers in San Francisco Bay, CA John J. Oram, Lester J. McKee, Christine E. Werme, Mike S. Connor, and Daniel R. Oros SETAC North America 28th Annual Meeting November 2007

Conceptual Model Total Export Total Load Inventory Depth PBDEs ?

Pieces of the Mass Budget Inventory Water and sediment monitoring External Loads Local Watersheds The Delta Wastewater Atmospheric Deposition Losses Golden Gate Outflow Degradation Volatilization

Bay Inventory Inventory* 33.5 ± 2.6 kg BDE 47 151.6 ± 45.4 kg BDE 209 * Spatially unbiased GRTS value

Guadalupe River WY 2005 Lower (Urban) Upper (Rural) WY05 WY06 SSC (mg/L) WY05 WY06 WY 2005 Lower (Urban) Upper (Rural)

Mallard Island (the Delta) BDE-47 (ng/L) SSC (mg/L) Use Flow-Weighted Mean Concentration

Spatial Congener Patterns BDE 47 : BDE 209 (concentration basis) Why less BDE 209 at Delta? Atmospheric deposition 47 more volatile than 209 Dissolved loads 47 more soluble than 209 Long residence time of Delta 1.2 0.2

Summary of Loads (kg)

Hindcast – Estimation/Verification of Loads BDE 47 From Field Studies: BDE 47 ~11-28 kg/yr BDE 209 ~22-24 kg/yr Missing Something… Missing source? Study years differ 209 QA/QC Model parameters incorrect? BDE 209 Time (years)

Emerging Conceptual Model Total Export Outflow >> Degradation >> Volatilization Total Load 11-28 (25) kg/yr BDE 47 22-24 (100) kg/yr BDE 209 ~34 kg BDE 47 ~152 kg BDE 209 Depth PBDEs ? Erosion / Deposition Poorly Known