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Understand Aging in Contaminant Bioavailability and Remediation

This research project aims to understand the aging effect of contaminants in Superfund site sediments and its implications for bioavailability and remediation. The study includes method optimization, evaluation of aging effect in sediments, investigation of carbon amendment on aging, and applications in risk assessment and monitoring. Results will inform the selection of appropriate remediation strategies and risk management measures.

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Understand Aging in Contaminant Bioavailability and Remediation

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  1. Understand Aging in Contaminant Bioavailability and Remediation Jay Gan and Daniel Schlenk Department of Environmental Sciences UC Riverside jgan@ucr.edu dschlenk@ucr.edu

  2. Outline • What did we propose to do? • How are we doing it? • Expected results and implications

  3. Bioavailability Freely dissolved concentration Cfree The potential for a chemical to undergo spontaneous processes, e.g., diffusion and partitioning Accessibility The actual amount of a chemical that is or may become available within a given time and under given conditions Total concentration Bioaccessible Concentration Bioaccumulation or toxic effect Freely dissolved Concentration Bioavailability Reichenberg and Mayer, 2006, Environ. Toxicol. Chem. 25, 1239-1245

  4. Aged Contaminants • Superfund site contaminants: • Released from historical use, misuse, accidents or incidents • Have aged extensively • e.g., PCBs, DDT, OC pesticides banned in 1970s • Residues have “aged” for decades !! • 1947 – 1983: Montrose manufactured DDT at its plant near Torrance, California • Discharged DDT wastewater into Los Angeles sewers that emptied into the Pacific Ocean off White Point on the Palos Verdes Shelf.

  5. plant roots Non-accessible organic matter microbes Bioaccessible Benthic invertebrates Dissolved OM Freely dissolved

  6. Aging Decreases Bioavailability Alexander M., ES&T, 2000 Morrison et al., ES&T, 2000

  7. Project Aims • Optimize a bioavailability method to measure aging effect • Evaluate relationship of age and bioavailability of DDTs in Superfund site sediments • Understand effects of black carbon amendment on aging • Incorporation of aging effect in risk assessment and remediation monitoring

  8. Aim 1: Method Optimization Accessible concentration : Ce (µg/kg) fraction : E (fraction) Isotope Dilution Method • Stable isotope analogs • Centrifuge • Liquid-liquid extraction • Sediment extraction Delgado et al., Environ. Poll. 2013 Jia et al., ES&T, 2014

  9. Approach mixing 2g sediment + 20 mL water centrifuge concentrating extraction GC-MS/MS Delgado et al., 2013 Jia et al., 2014

  10. Aim 2: Aging Effect in Superfund Site Sediments Palos Verdes Shelf

  11. Approach • Obtain sediment cores from LACSD: • Archived and new samples • 2-cm increments • Use 210Pb dating to estimate age of sediment samples • Contracted to Prof. M. Brenner, Univ. Florida • Measure E values of DDTsin sediment • As a function of depth • As a function of age • Validate bioavailability with bioaccumulation assays • Evaluate relationships between age and bioavailability

  12. Aim 3: Carbon Amendment and Aging • Amendment materials such as carbon are increasingly used in remediation • Carbon alters sediment properties by providing more micro/nanopores and aromatic sites • Carbon amendment may accelerate “aging” • Different carbon materials may exert different influences on aging • Information may be used for selecting amendment materials

  13. Aim 4: Applications • Confirm bioavailability estimates • Sediment cores Palos Verdes • McGrath Lake sediments • Estimate accumulation to food fish • Determine BAFs from sediments to biota • Calculate risk factors for human consumption of food fish

  14. IDM validation-2 IDM vs. Bioaccumulation Neanthes Arenaceodentata California halibut (Paralichthys californicus) Seafood consumption

  15. McGrath Lake

  16. Freshwater sediment bioavailability Chironomus tentans

  17. Effects of PV sediment treatment on DDT concentrations in Neanthes sp. and in Hornyhead Turbot after feeding worms to fish

  18. Risk Assessment • Draft Update of Human Health Ambient Water Criteria (USEPA OW May 2014) • BAFs calculated from EPI Suite (Arnot & Gobas model) • Trophic level breakdown • TL2 benthic filter feeders • TL3 forage fish • TL4 predatory fish • Dietary Exposure (NHANES) • Seafood Habits of Recreational Anglers in Santa Monica Bay • Southern California Coastal Water Research Project • Chemicals in Fish: Consumption of Fish and Shellfish in California and the United States • Office of Environmental Health Hazard Assessment (OEHHA) • Santa Monica Bay Seafood Consumption study

  19. Focus of Risk Assessment • Consumption patterns for Subsistence Anglers vs NHANES age groups. • Daily, Monthly and Lifetime Dose estimates • Non-cancer Hazard Quotient • POD Cancer Endpoints • Cancer Slope Factor (EPA 2008) • Thresholds from CalEPA and OEHHA

  20. Research Team PI Dan Schlenk PI Jay Gan Ph.D. Student Scott Coffin Ph.D. Student Allison Taylor Postdoc Charles Liao Collaborators: Joe Gully, Jerry Tang, LACSD Keith Maruya, Wayne Lao, SCCWRP Prof. M. Brenner, Univ. Florida

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