Understand Aging in Contaminant Bioavailability and Remediation

1
Understand Aging in Contaminant Bioavailability
and Remediation

• Jay Gan and Daniel Schlenk
• Department of Environmental Sciences
• UC Riverside
• jgan_at_ucr.edu
• dschlenk_at_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
Freely dissolved Concentration
Bioaccumulation or toxic effect
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., EST, 2000
Morrison et al., EST, 2000
7
Project Aims

1. Optimize a bioavailability method to measure
   aging effect
2. 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

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.,
EST, 2014
9
Approach
mixing
2g sediment 20 mL water
centrifuge
extraction
concentrating
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. and in Hornyhead
Turbot after feeding worms to fish
18
(No Transcript)
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
PI Dan Schlenk
PI Jay Gan
Ph.D. Student Allison Taylor
Postdoc Charles Liao
Ph.D. Student Scott Coffin
Collaborators Joe Gully, Jerry Tang,
LACSD Keith Maruya, Wayne Lao, SCCWRP Prof.
M. Brenner, Univ. Florida