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Sediment contamination Sediment toxicity Benthic community structure

Sediment Quality Assessment. 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

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Sediment contamination Sediment toxicity Benthic community structure

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  1. Sediment Quality Assessment 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tests are those recommended for the accepted statewide SQO methods for bays and estuaries, EXCEPT… Draft Data - Do not cite or quote

  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of candidate sediment toxicity tests The SQO recommends the use of sediment water interface (SWI) samples Draft Data - Do not cite or quote

  3. Mussel embryo development 48-h exposure Sublethal endpoint Sediment elutriate VS. Sediment-water interface exposure Draft Data - Do not cite or quote

  4. The TRC needs to decide if the RMP should adopt, add, or study the sediment-water interface (SWI) bivalve test in 2008. Draft Data - Do not cite or quote

  5. What are the issues? • Comparison to historic RMP/other programs • Interpretation (Ecological Relevance) • Cost Draft Data - Do not cite or quote

  6. Comparison to historic RMP data 1999 - 2001 Bivalve Methods Study • 48-hr. sublethal development test • Elutriate (1:4 dil. VS. SWI intact cores) • 14 stations (52 samples). Draft Data - Do not cite or quote

  7. RMP 1999-2001 Elutriate & SWI bivalve development tests (N=52) 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Yerba Buena Is Horseshoe Bay Alameda San Bruno Shoal San Jose (LEMP) Coyote Creek Redwood Creek South Bay Draft Data - Do not cite or quote

  8. Amphipod and Bivalve Sediment Toxicity Results 1993-2001 Legend: (BF21) Grizzly Bay Napa River Davis Point Rivers Horseshoe Bay Yerba Buena Island Redwood Creek San Jose Coyote Creek (BA21) South Bay Draft Data - Do not cite or quote Pulse of the Estuary, 2003

  9. 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. Draft Data - Do not cite or quote

  10. Recommendation • RMP S&T 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. Draft Data - Do not cite or quote

  11. Cost $20 more per sample Draft Data - Do not cite or quote

  12. Cost Draft Data - Do not cite or quote

  13. RMP 1999-2001 Elutriate & SWI bivalve development tests (N=52) 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 Draft Data - Do not cite or quote

  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? Draft Data - Do not cite or quote

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