Sediment contamination

1
Toxicity test data used in a weight-of-evidence
Sediment contamination Sediment toxicity Benthic
community structure Results used to identify and
map areas of unimpacted to clearly impacted
sediments Current RMP toxicity tests are those
recommended for the accepted statewide SQO
methods for bays and estuaries, EXCEPT
2
Excerpt from SQO Staff Report - Table 5.2 List of
candidate sediment toxicity tests
The SQO recommends the use of sediment water
interface (SWI) samples
3
Mussel embryo development
48-h exposure Sublethal endpoint
Sediment elutriate VS. Sediment-water interface
exposure
4

• The TRC needs to decide if the RMP should adopt,
  add, or study the sediment-water interface (SWI)
  bivalve test in 2008.

5
What are the issues?

• Comparison to historic RMP/other programs
• Interpretation (Ecological Relevance)
• Cost

6
Comparison to historic RMP data

• 1999 - 2001 Bivalve Methods Study
• 48-hr. sublethal development test
• Elutriate (14 dil. VS. SWI intact cores)
• 14 stations (52 samples).

7
RMP 1999-2001 Elutriate SWI bivalve development
tests (N52)
Rivers
Davis Point
Napa River
Grizzly Bay
Red Rock
Yerba Buena Is
 
Horseshoe Bay
Alameda
San Bruno Shoal
San Jose (LEMP)
Coyote Creek
Redwood Creek
South Bay
8
Amphipod and Bivalve Sediment Toxicity Results
1993-2001
(BF21)
Grizzly Bay
Napa River
Davis Point
Rivers
Horseshoe Bay
Yerba Buena Island
Redwood Creek
San Jose
Coyote Creek
(BA21)
South Bay
Pulse of the Estuary, 2003
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Interpretation

• SWI tests are thought to be more ecologically
  relevant
• However, not much in known about contaminant flux
  and exposure
• SCCWRP study (4 samples) to determine if
  homogenized sediments can be left to equilibrate
  and used in the SWI test.

10
Recommendation

• RMP ST should switch to the intact SWI method to
  be comparable to recommended SQO methods that
  have been endorsed by a panel of national experts
  
• However, this will result in a NEW toxicity
  measure and will not be comparable with historic
  RMP data
• (largely an issue in Suisun Bay Lower South
  Bay Regions)
• Consider adding elutriate tests in Suisun Bay and
  Lower South Bay Regions and evaluate chemistry in
  the test water of both tests to begin to
  understand differences in contaminant exposures.

11
Cost
20 more per sample
12
Cost
13
RMP 1999-2001 Elutriate SWI bivalve development
tests (N52)
Rivers
Davis Point
Napa River
Grizzly Bay
Red Rock
Yerba Buena Is
 
Horseshoe Bay
Alameda
San Bruno Shoal
San Jose (LEMP)
Coyote Creek
Redwood Creek
South Bay
14
Further Study

• Evaluate the comparability of intact SWI cores vs
  homogenized sediment on a variety of sediments in
  order to make a confident assessment that the two
  sampling methods can be used and are equally
  ecologically relevant.
• SCCWRP is beginning to investigate (4 samples)
• RMP?