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Dioxins (PCDD/Fs) in San Francisco Estuary

Dioxins (PCDD/Fs) in San Francisco Estuary. Mike Connor, Donald Yee , Jay Davis, Christine Werme RMP Annual Meeting May 2004. Dioxins- Background. Polychlorinated dibenzo dioxins and furans (PCDD/Fs) Toxic compounds w/ 4 (TCDD/F) to 8 (OCDD/F) chlorines

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Dioxins (PCDD/Fs) in San Francisco Estuary

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  1. Dioxins (PCDD/Fs) in San Francisco Estuary Mike Connor, Donald Yee, Jay Davis, Christine Werme RMP Annual Meeting May 2004

  2. Dioxins- Background • Polychlorinated dibenzo dioxins and furans (PCDD/Fs) • Toxic compounds w/ 4 (TCDD/F) to 8 (OCDD/F) chlorines • 2,3,7,8 TCDD toxicity equivalent factors (TEQs) • Toxicity TCDD/F >> OCDD/F • Concentrations TCDD/F << OCDD/F • Concentrations often near detection limits • Data less abundant than other pollutants • PCBs w/ TEQs addressed in PCB conceptual model

  3. Dioxins- Available Data Analytical Issues • Concentrations not detected (water, sediment) • ND = 0 (optimist) or ND = MDL (pessimist) • TCDD/F and other more toxic dioxins less abundant • NDs = (possible large) impact on TEQs • Temporal and spatial variability • NOAA-EMAP sediment site replicates > 10x differences • Refinery effluent 10xincrease sample size – 2x decrease in average concentration and variability (RSD%)

  4. Dioxins- Sources • Combustion by-products • Yard waste, wood, vehicle fuel, municipal and medical incineration • Chlorine process by-products • Pesticides, wood pulp bleaching, PVC • Dioxins have legacy component, but also • Ongoing point/disperse sources (USEPA national inventory) • 1987: Incineration > smelting > yard burning > pulp bleaching • 2002: Yard burning > home fireplace ~coal burning ~ sludge (land) > diesel ~ 2,4-D (land)

  5. Dioxins- National Source Trends nonpoint point

  6. Dioxin- Fish Tissue Concentrations

  7. Impacted Organisms

  8. Ecosystem Transfers

  9. Loss Pathways ? ? ??

  10. Sources and Loading Pathways ? ? ? ?? ??

  11. Dioxins- Information Gaps • Better quantitative data • Improvements in analyses and extent of data • Prioritizing (given high analytical costs) • Monitoring biological receptors • Most direct relationship to impacts • Spatial and time integrators • Largest loads and reservoirs • Rivers and tributaries (conveying current and legacy deposits) • Sediment deposit profiles (history and distribution)

  12. Dioxins- Management Options, Long Term Prospects • Easier steps taken possible even w/o further information (addressing other issues): • Fish consumption advisories (PCBs, Hg) • Restrictions on yard burning (general air quality) • Wood-burning advisories, construction/remodel restrictions • Harder steps (needing better information to prioritize) • Addressing watershed and in-bay legacy • Have past and current changes had impact?

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