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Mercury in SF Bay The 8-Minute Conceptual Model California Regional Water Quality Control Board San...
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Transcript of Mercury in SF Bay The 8-Minute Conceptual Model California Regional Water Quality Control Board San...
Mercury in SF Bay The 8-Minute
Conceptual Model
California Regional Water Quality Control BoardSan Francisco Bay Region
RMP Annual MeetingMay 4, 2004
Richard Looker ([email protected])
2
The 30 Second Conceptual Model
Bacteria in wetlands, mudflats and sloughs
Mercury in sediment
Methylmercury available for bioaccumulation
Mercury Discharges(Elemental and Inorganic)
Methylating Regions--
1. Mass budget
3. Bioaccumulation
2.Transformations & Transport
• Significance and magnitude of loads?
• Variability and Predictability of Loads?
• Details of the active sediment layer?
Inputs ~ 1200 kg/yr:
Outputs ~ 1700 kg/yr:
~ 100 kg Hg in Water
~ 60,000 kg Hg in Active Sediment
~ 10,000 kg Hg In Air Shed (20 km top)1. Mass Budget
15 cmActive Sediment
• Where is methylation happening? (controlling factors?)
• Transport details? (erosion, sediment movement?)
Hg in Water
2. Transformations & Transport
Me-Hg inBenthos
Me-Hg inSediment
Hg inSediment
Deposition Evasion
Export
BurialErosion
Me-Hg inWater
Me-Hg inFish
Import
Active Sediment
• What is the food web structure?
• What are food web concentration patterns?
3. Bioaccumulation(Me-Hg concentrations
shown relative to water)
Me-Hg inWater
Me-Hg inSediment
1
10
100-200
??
200
3000
Eggs: 6000
6
Wildlife and Fish Tissue are Indicators of Impairment
Too much Hg in fish – TMDL target is 0.2 ppm
Too much Hg in bird eggs– TMDL target < 0.5 ppm
Indicators for Management– Concentrations in small and large fish– Bird egg concentrations– Prey items for birds, fish– Sediment Me-Hg, Total Hg
7
What RMP Can/Could Do to Help
Gather risk management information (5 yrs.)– Fish consumption patterns among humans– Contamination patterns
Track food web concentrations (5 yrs.) Track bird egg concentrations (5 yrs.) Investigate significance of sources (5 yrs.)
– Relative bioavailability (from chemistry)– Residence time issues (from transport)
Keep on sampling water, sediment, fish
8
What RMP Could Do To Help (but needs some help to do it)
Coordinate Hg-related research (ASAP)– Disseminate results– Ensure intercomparability of results– Ensure research addresses management needs
There is currently no coordination between large number of research efforts.
We will not have another chance like this in terms of resources so there is a desperate need to make the most of this opportunity.