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Earl Byron, Christine Arenal.

A Bioaccumulation Model of the Effects of DDTs and PCBs at the Palos Verdes Shelf: A Tool to Determine Risk and in Support of Remediation. Earl Byron, Christine Arenal. Historical Contamination of a Significant Area of the Southern California Coast. The Palos Verdes Peninsula.

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Earl Byron, Christine Arenal.

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  1. A Bioaccumulation Model of the Effects of DDTs and PCBs at the Palos Verdes Shelf: A Tool to Determine Risk and in Support of Remediation. Earl Byron, Christine Arenal.

  2. Historical Contamination of a Significant Area of the Southern California Coast The Palos Verdes Peninsula

  3. Montrose DDT Plant LACSD outfalls Why is there a Problem?

  4. Palos Verdes Shelf Continental shelf Continental slope

  5. Human Health as well as Ecological Risk Sealions, pelicans, and people…all eat fish!

  6. tDDT Sediment Contours (1992 - 2003)

  7. PCB Sediment Contours (1992, 1998)

  8. Basic Conceptual Site Model Major DDT & PCB Transfer Pathways PCBs DDT

  9. Conceptual Site Model for Ecological Risk Release/Transfer Mechanisms Exposure Media Source Receptors Water Column Invertebrates Mammals DDT drives Eco Risk Water Water Column Fish Raptors Biota Diffusive Flux Piscivorous Birds Suspended Sediments Bioaccumulation Benthic Fish Surface Sediments Surface Sediments Erosion & Resuspension Benthic Invertebrates Bioturbation Deep Sediments Deep Sediments

  10. Sediment Characterization: Routine Monitoring and Special Studies Vibracores Box Cores = Volumes of Data!

  11. Fish Tissue: Routine Monitoring and Special Studies Trawling for Turbot

  12. Evaluating Ecological Risks from DDTs and PCBs • Evaluating risks to marine invertebrates and fish from sediment, water, and diet: PVS area. • Evaluating risks to marine mammals and seabirds from dietary exposure: Greater SCB. • Bulk sediment, porewater, water-column, and fish tissue concentrations of organochlorine contaminants derived from sediment sources. • Consumer tissue concentrations derived from mechanistic modeling.

  13. The Bight vs. the PV Shelf Study Area

  14. Exposure and Risk: InvertebratesWeight of Evidence • Marine invertebrate communities were most degraded near the outfall. • Sediments were toxic to bioassay organisms in many areas of PVS, particularly near the outfall area. • Porewater concentrations exceeded aquatic toxicity values for exposure to marine invertebrates (0.0072 ppb)(applying acute/chronic ratio of 18 to acute value). • Bulk sediment concentrations up to 30 cm deep exceeded potentially toxic concentrations, particularly in the areas nearest the outfalls (2 ppm @1%TOC).

  15. Assessment Endpoints and Measures of Exposure and Effects: Fish Community Assessment Endpoints Attribute Level Measures of Exposure and Effects • Community structure and function • Support of fish and wildlife species (i.e., as a food source) Community, Population • Sediment DDT and PCB concentrations • Water column concentrations (very limited data) • Measured concentrations in fish tissue (limited whole-body, fillet) • Literature-based benchmarks • Whole-body • Water quality criteria • Site-specific reproduction and population studies Receptors: White Croaker, Kelp Bass, Sanddabs

  16. Food Chain Model to Evaluate Response Actions • Incorporate new fish tissue data (MSRP/EPA sampling and analysis results) • Updated Eco and Human Health Risk determinations • Use of the model to predict changes in risk associated with response actions

  17. Information Needed for EcoRisk Modeling • List of appropriate receptors • Food chain information • Strong sediment quality and fish tissue databases • GIS database for fish, sediment, and all receptor foraging ranges • Knowledge of receptor home ranges and food habits • Literature information on organochlorine partitioning and metabolism (mechanistic model components)

  18. Comparing the Need for BSAF vs. a Mechanistic Foodweb Model • Data density and availability is key. • BSAF: Good sediment and GIS data coverage and knowledge of receptor home range. • BSAF at PVS: Estimated fish home ranges and continuous sediment coverage. All tied to sediment using GIS. • Mechanistic Model at PVS: Only as needed to translate dietary uptake to tissue concentrations of higher consumers.

  19. BSAF Challenges for PVS • Deciding on boundaries for assessment • GIS challenges: contouring, subareas • Determining fish home ranges • Choosing appropriate surrogate species • Assigning surrogate species to receptor diets • Determining foraging ranges of marine mammals and birds

  20. 2.5 2 1.5 1 .5 0 -.5 -1 -1.5 -2 -2.5 -3 -3.5 -3 -2.5 -2 -1.5 -1 -.5 0 .5 1 Y = .214 + .75 * X; R^2 = .766 Predicted Fish Tissue Concentrations Based on BSAFs White Croaker, BSAF model Fish tissue concentration (Log mg/kg DDT WW) Average sediment concentration (Log mg/kg DDT DW) 2 - 10 km home range Also, fillets converted to whole-body concentrations.

  21. California Sea Lion Distribution

  22. Exposure Analysis Goal: Combine spatial distribution of tDDT and tPCB contamination with the home ranges of bird and mammal receptors to predict exposure • Oral Exposure (dietary) • sediment to fish regression (BSAF); allows calculation of fish or sediment concentrations where actual data not available • Target Organ Exposure • Empirical (site-specific measured data - egg and blubber)

  23. Data Required for Exposure Analysis • Sediment contaminant data • Contaminant data for dietary items (fish, birds, mammals) • Measured concentrations in receptor tissues/target organs • Locations of tissue samples for each receptor • Identification of SCB locations used by each receptor • Seasonality (percent time receptor spends in SCB) • Foraging ranges from breeding, nesting or resting areas • Foraging depths • Diet composition (development of surrogate diet) • The importance of pelagic versus benthic dietary items • Literature-derived body weights and food ingestion rates for receptors

  24. Adult Female Sea Lion:Oral dosage – Summer range *

  25. Bald Eagle:tDDT oral dosage. # #

  26. Ecological Risk Conclusions • Measured and modeled results of invertebrates, fish, bird, and sea lion exposure levels throughout SCB indicate link to contaminated sediments at PVS. • Risks are small in some areas, but measurable at locations throughout the SCB. • The choice or receptors and area for evaluation influences the strength of the link to PVS sediments.

  27. Using Food Web Model to Evaluate Remedial Actions: Important considerations. • PVS study area versus SCB • Choice of receptors: Demersal fish; and a coastal, piscivorous bird. • Receptors closely tied to PVS. • Human health vs. Eco drivers • Short vs. long-term effects

  28. PVS Bioaccumulation Model: Baseline Results • Oral dosages from the model were compared to primary and secondary literature values for NOECs and LOECs for tDDT and PCBs. • Risk was demonstrated as usually greatest for species foraging at the PVS area. Species at risk, and their modeled diet included: • Brown Pelican (fish) • Double Crested Cormorant (fish) • Peregrine Falcon (gulls) • Bald Eagle (fish, gulls, sea lion carcasses) • California sea lion (fish) • Nursing pups

  29. Future remediation? An ability to evaluate the effects of sediment changes using high site-fidelity species and to project risks for far-ranging receptors [as verified by continued monitoring] Palos Verdes, experimental capping photos

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