BACKGROUND AND STATUS of RMP SEDIMENT STUDIES RMP
BACKGROUND AND STATUS of RMP SEDIMENT STUDIES RMP EEWG MEETING September 6, 2007
RMP SEDIMENT COMPONENTS 1. Status and Trends • Sediment Characteristics (grain-size, TOC, etc. ) • Sediment Toxicity (Eohaustorius and elutriate – larval bivalves) 2. Pilot and Special Studies 3. Collaborative Studies
RMP PILOT AND SPECIAL STUDIES • Benthic Pilot Study (Thompson et al. , 2000) • Development of Toxicity Tests (Weston, 1995) • Wetlands Pilot Study (Collins et al. 1995) • Sediment Work Group / Atlas (Thompson et al. 1999) • Episodic Toxicity / TIE studies (Anderson et al. 2007) • Influence of chem. & phys. factors on benthos (Melwani, Thompson, 2007)
COLLABORATIVE STUDIED • Local Effects Monitoring Program (BACWA, 1994 -1996) • Cis. Net (1999 -2001, EPA / UCD) • EMAP SF Estuary Surveys (EPA, NOAA) • State Board Bio. Criteria (SWRCB, SCCWRP) • SQO 2005 -present (SWRCB, SCCWRP) - Several publications - Delta Sediment Survey • Non-Indigenous Benthos (DWR) (EPA, 2000) • Long Term Sediment Management Study (ACOE, BCDC) • Delta Dredged-Sediment Reuse Study (CALFED, RB 5)
CONCEPTUAL MODELS • Mechanisms of Exposure and Effects - Sediment Atlas, 1999 • Toxicity Dose – Response - Anderson et al. , 2007 • Benthic Response to “Disturbance” - Thompson et al. , 2004
WHAT HAVE WE LEARNED? SEDIMENT CONTAMINATION • Sediments may contain elevated levels of several contaminants. - As, Cu, Zn, Ni - DDT, PAHs, Chlordanes - Mixtures • Highest concentrations in muddy sediments near margins, mouths of tributaries, Ports, BPTCP ‘hotspots’.
WHAT HAVE WE LEARNED? SEDIMENT TOXICITY • Sediment toxicity is widespread and persistent in San Francisco Estuary • Different results for different tests • More toxicity in wet season, and at margins • Toxicity has been associated with: - Chlordanes Mixtures Cu ions in pore water, Suisun Bay Non-polar organics, Redwood Ck. Pyrethroids in some tributaries, Delta
WHAT HAVE WE LEARNED? BENTHOS • Assemblage distribution and composition - have we sampled all of them? • Assemblages distribution changes in response to fresh water inflows • Species composition and abundances within assemblages may change in response to contamination, sediment type, salinity, different in different parts of the Estuary. • Causes mostly unknown. Associated with specific mixtures, interaction of factors
MANAGEMENT CONTEXT • TMDLs in place that include sediments as sources • SQO will be Implemented in next few years. • RMP role: continue to provide information to RB and participants. • Stressor ID: Must know cause and effect to effectively implement TMDLs, source controls.
INFORMATION NEEDS AND NEXT STEPS • Stressor Identification for SQOs • Identify contaminants that cause toxicity, benthic impacts • SQO Phase II, Delta sampling • Include benthic sampling in S & T • Revised Long-Term Sediment Studies Plan for RMP
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