Selenium in San Francisco Bay

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Selenium in San Francisco Bay

• Status Possibly Impaired
• Standards
• Relevant Beneficial Uses
• Fishing, wildlife habitat, rare and endangered
  species
• Water Quality Objectives
• 5 ppb (total in water) attained everywhere but
  Alviso Slough
• Narrative for bioaccumulation much improvement
  1986 - 2002
• Reserved in CTR pending agency consultations
• Conceptual Model
• Importance of chemical speciation
• Uncertainties
• Risk assessment, future loads, Alviso Slough

Dr. Khalil E. Abu-Saba khalila_at_lwa.com
www.cleanestuary.org
Dr. Scott Ogle Rocks!
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The Tone What captures the imagination
WILD (Wildlife Habitat)
The story of migrating birds is the story of a
promise, a promise to return. They fly, often
thousands of miles, beset with danger, for a
single reason to survive. Their migration is a
fight for life. Winged Migration
http//www.werc.usgs.gov/scoter/maps.html
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isnt always the issue.

• Original Basis for Impairment
• Selenium in diving ducks exceeded risk assessment
  thresholds for people who hunt and eat ducks
• OEHHA Consumption Advisory as published in
  (older) CDFG game regulations
• Technical basis published in Fan et al. (1989)

COMM Uses of water for commercial or
recreational collection of fish, shellfish, or
other organisms in oceans, bays, and estuaries,
including, but not limited to, uses involving
organisms intended for human consumption or bait
purposes.
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Things Change
2002
1988
Changes in San Francisco Bay diving duck tissue
selenium concentrations over time. Base Graphs
courtesy of the Regional Monitoring Program/San
Francisco Estuary Institute.
Dr. Scott Ogle Rocks!
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sometimes for the better.
Selenium concentrations in white sturgeon,
1986-2000. Base Graphs courtesy of the Regional
Monitoring Program/San Francisco Estuary
Institute.
Dr. Scott Ogle Rocks!
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But why? Chemical Speciation
dissolved selenate
dissolved selenite
particulate elemental selenium
pythoplankton / particulate organo-selenium
dissolved organo-selenium
Particles
Solution
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Biogeochemical Transformation
transport
transform
Ag drainage
Sac. R.
bioaccumulate
Refineries
90 load reduction by 1998
Ocean
bacteria
Ocean
dissolved selenate
dissolved selenite
bacteria
(sulfate inhibited)
Evasion
particulate elemental selenium
pythoplankton / particulate organo-selenium
dissolved organo-selenium
Dimethylselenide
clams
birds and fish
people
Invasive Hyperaccumulator
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Load Reduction
Dr. Scott Ogle Rocks!
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Key Uncertainties
1) Why is Alviso Slough so high in Selenium?
2) What is future irrigated agriculture load?
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Another Key Uncertainty