selenium in san francisco bay status: possibly impaired standards: –relevant beneficial uses:...
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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
www.cleanestuary.org
Dr. Khalil E. Abu-Saba
Dr. Scott Ogle Rocks!
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
The Tone:
What captures the
imagination…
http://www.werc.usgs.gov/scoter/maps.html
WILD
(Wildlife Habitat)
…isn’t always the issue.
Exposure
Health
Deficient Toxic
Human Dietary requirements = 40 - 300 g / day
Human NOEL = 850 g / day
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.
1986 2002 1986 2002 1986 2002
San Pablo South Bay Suisun
1988 2002
Dr. Scott Ogle Rocks!
Things Change…
Changes in San Francisco Bay diving duck tissue selenium concentrations over time. Base Graphs courtesy of the Regional Monitoring Program/San Francisco Estuary Institute.
Selenium concentrations in white sturgeon, 1986-2000. Base Graphs courtesy of the Regional Monitoring Program/San Francisco Estuary Institute.
…sometimes for the better.
Dr. Scott Ogle Rocks!
dissolved selenate
dissolved selenite
dissolved organo-selenium
particulate elemental selenium
pythoplankton / particulate organo-selenium
Particles Solution
But why?Chemical Speciation
dissolved selenate
dissolved selenite
Ag drainage
Refineries
dissolved organo-selenium
particulate elemental selenium
pythoplankton / particulate organo-selenium
Evasion
clams
birds and fish people
90% load reduction by 1998
bacteria
(sulfate inhibited)
Dimethylselenide
transport
transform
bioaccumulate
bacteria
Sac. R.
OceanOcean
Biogeochemical Transformation
Invasive Hyperaccumulator
5.49
0.270.02
0
1
2
3
4
5
6
Mean 1987-88 May 2000 August 2000
Sele
nit
e C
on
cen
trati
on
(µ
g/L S
e)
Before
After
Refinery "A"
59.06
4.882.48
0
10
20
30
40
50
60
70
Mean 1987-88 May 2000 August 2000
Sele
nit
e C
on
cen
trati
on
(µ
g/L S
e)
Before
After
Refinery "B"
4.32
0.06 0.09
0
1
2
3
4
5
Mean 1987-88 May 2000 August 2000
Sele
nit
e C
on
cen
trati
on
(µ
g/L S
e)
Before
After
Refinery "C"
50.22
1.56
4.78
0
10
20
30
40
50
60
Mean 1987-88 May 2000 August 2000
Sele
nit
e C
on
cen
trati
on
(µ
g/L S
e)
Before
After
Refinery "D"
22.19
0.16 0.040
5
10
15
20
25
Mean 1987-88 May 2000 August 2000
Sele
nit
e C
on
cen
trati
on
(µ
g/L S
e)
Before
After
Refinery "E"
0.031
0.06
0.015 0.016
0.049
0.104
0
0.02
0.04
0.06
0.08
0.1
0.12
April 1986 Sept 1986 April 1999 Nov 1999
Sele
nit
e C
on
cen
trati
on
(µ
g/
L S
e)
mean Selenite
maximum Selenite Before
After
Northern San Francisco Bay
Load Reduction
Dr. Scott Ogle Rocks!
Key Uncertainties
50,000 kg1,000,000
- 160,000,000 kg Se
2,000 - 20,000 kg Se / yr
Selenium Reservoir
in San Joaquin
Valley
AB
C
D
E
0
5
10
Artesia
n slo
ugh
Alviso
Slou
gh
Guada
lupe
Slough
Lower
Sou
th B
ay
South
Bay
Centra
l Bay
North
Bay
Sel
eniu
m (
ug
/L)
CTR Chronic Objective
1) Why is Alviso Slough so high in Selenium?
2) What is future irrigated agriculture load?
Another Key Uncertainty
y = 0.0036x
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100
( Fines)< 63microns %
[Se]
(ug
/g)
Mar.' 93, Aug. '94 - Aug. '01
Aug '93
Feb '94
Linear (Mar.' 93, Aug. '94 -Aug. '01)Linear (Aug '93)
Grizzly Bay