1. Understand Aging in Contaminant Bioavailability and Remediation
Jay Gan and Daniel Schlenk
Department of Environmental Sciences
UC Riverside

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

3. Bioaccumulation or toxic effect
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
Freely dissolved
Concentration
Bioaccumulation or toxic effect
Bioavailability
Reichenberg and Mayer, 2006, Environ. Toxicol. Chem. 25,

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. Benthic invertebrates Dissolved OM
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 Delgado et al., 2013 Jia et al., 2014 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 DDTs in 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
Effects of PV sediment treatment on DDT concentrations in Neanthes sp. and in Hornyhead Turbot after feeding worms to fish

19. 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

20. 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

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