Dioxins PCDDFs in San Francisco Estuary

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 gtgt OCDD/F
• Concentrations TCDD/F ltlt 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 gt 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 gt smelting gt yard burning gt
  pulp bleaching
• 2002 Yard burning gt home fireplace coal burning
  sludge (land) gt diesel 2,4-D (land)

5
Dioxins- National Source Trends
nonpoint
point
6
Dioxin- Fish Tissue Concentrations
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Impacted Organisms
9
Ecosystem Transfers
10
Loss Pathways
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Sources and Loading Pathways
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12
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)

13
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?