Jay Gan and Daniel SchlenkDepartment of Environmental Sciences

UC Riverside

jgan@ucr.edudschlenk@ucr.edu

Outline

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

Bioavailability

Reichenberg and Mayer, 2006, Environ. Toxicol. Chem. 25, 1239-1245

Total concentration

BioaccessibleConcentration

Freely dissolved

Concentration

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

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.

organic matter

Dissolved OM

microbes

Benthic invertebrates

plant roots

Non-accessible

Bioaccessible

Freely dissolved

Aging Decreases Bioavailability

Morrison et al., ES&T, 2000

Alexander M., ES&T, 2000

Project Aims1. Optimize a bioavailability method to

measure aging effect2. Evaluate relationship of age and

bioavailability of DDTs in Superfund site sediments

3. Understand effects of black carbon amendment on aging

4. Incorporation of aging effect in risk assessment and remediation monitoring

Aim 1: Method Optimization

Isotope Dilution Method0

*

w*w

e CC

CC

T

e

C

CE

Accessibleconcentration : Ce (µg/kg)fraction : E (fraction)

• Stable isotope analogs• Centrifuge • Liquid-liquid extraction• Sediment extraction

Delgado et al., Environ. Poll. 2013Jia et al., ES&T, 2014

9

isotope-labeled HOCsnative HOCs

extraction

2g sediment + 20 mL water

concentratingGC-MS/MS

centrifuge

mixing

Approach

Delgado et al., 2013Jia et al., 2014

Aim 2: Aging Effect in Superfund Site Sediments

Palos Verdes Shelf

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

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

Aim 4: ApplicationsConfirm bioavailability estimates

Sediment cores Palos VerdesMcGrath Lake sediments

Estimate accumulation to food fishDetermine BAFs from sediments to biotaCalculate risk factors for human consumption

of food fish

14

Neanthes Arenaceodentata California halibut (Paralichthys californicus)

Log Ce (g/kg-OC)

1 2 3 4 5 6

Log

Cb

(g/

kg-li

pid

)

0

1

2

3

4

5PV8CPV6C

IDM vs. Bioaccumulation

Seafood consumption

IDM validation-2

Chironomus tentans

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

Focus of Risk AssessmentConsumption patterns for Subsistence

Anglers vs NHANES age groups.Daily, Monthly and Lifetime Dose estimatesNon-cancer Hazard Quotient POD Cancer Endpoints

Cancer Slope Factor (EPA 2008)Thresholds from CalEPA and OEHHA

Research Team

PI Jay Gan PI Dan Schlenk

Ph.D. Student Allison Taylor

PostdocCharles Liao

Ph.D. Student Scott Coffin

Collaborators: Joe Gully, Jerry Tang, LACSDKeith Maruya, Wayne Lao, SCCWRPProf. M. Brenner, Univ. Florida