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Allison Taylor, Jie Wang, Daniel Schlenk and Jay Gan Department of Environmental Science University of California, Riverside, CA 92521 Priority Organic Pollutants (HOCs) Chlorinated pesticides PCBs/PBDEs FACT 1: Strong sorption

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SLIDE 1

Allison Taylor, Jie Wang, Daniel Schlenk and Jay Gan Department of Environmental Science University of California, Riverside, CA 92521

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SLIDE 2

“Priority” Organic Pollutants (HOCs)

  • Chlorinated pesticides
  • PCBs/PBDEs

FACT 1:

  • PAHs

Strong sorption

  • Dioxins
  • Chlorinated pesticides
  • PCBs/PBDEs

FACT 2:

  • PAHs

Aged

  • Dioxins

2

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SLIDE 3

DDT

  • Paul Hermann Müller, Nobel Prize in Physiology or

Medicine, 1948

  • During World War II, control malaria

and typhus among civilians and troops

  • Agricultural insecticide since 1945
  • Banned in 1972 in the U.S.

3

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SLIDE 4

Aging and Bioavailability

plant roots microbes

  • rganic matter

dissolved OM Freely dissolved benthic invertebrates

4

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SLIDE 5

5

plant roots benthic invertebrates microbes

  • rganic matter

dissolved OM Freely dissolved Bioaccessible

Aging and Bioavailability

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SLIDE 6

6

plant roots benthic invertebrates microbes

  • rganic matter

dissolved OM Freely dissolved Bioaccessible Non-accessible

Aging and Bioavailability

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SLIDE 7

7

plant roots benthic invertebrates microbes

  • rganic matter

dissolved OM Freely dissolved Bioaccessible Non-accessible

Aging and Bioavailability

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SLIDE 8

Measuring Bioavailability

Reversibly bound Freely dissolved Irreversibly bound Reversibly bound Freely dissolved Irreversibly bound Reversibly bound Freely dissolved Irreversibly bound Equilibrium sampling

Total concentration Bioaccessibility Cfree

Reichenberg and Mayer, ET&C, 2006, 1239-1245

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SLIDE 9

Bioavailability

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

Total concentration Bioaccessible Concentration Freely dissolved Concentration Risk Bioavailability Freely dissolved concentration Cfree

The potential for a chemical to undergo spontaneous processes, e.g., diffusion and partitioning

Bioaccessibility

The actual amount of a chemical that is or may become available within a given time and under given conditions

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SLIDE 10

Bioavailability Methods

Bioaccessibility

  • Partial desorption
  • Weak acid extraction
  • Mild solvent extraction
  • Gut fluid extraction
  • Cyclodextrin extraction
  • Tenax adsorption

extraction

  • Isotope dilution

method (IDM)

Cfree

  • Passive samplers
  • DGT
  • Polyethylene devices

(PEDs)

  • Semi-permeable

membrane devices (SPMDs)

  • Polyoxymethylene

(POM)

  • Solid phase micro-

extraction (SPME)

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SLIDE 11

—

Health Warnings:

Study I. Aged POPs at the Palos Verdes Superfund Site

US EPA, 2010

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SLIDE 12

A Sediment Core Experiment

  • Hypothesis:
  • Contaminant aging has resulted in

reduced bioavailability.

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SLIDE 13

210Pb Dating

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SLIDE 14

Total Concentrations

Total concentration profiles of PCBs and DDTs in (A) 8C and (B) 3C cores in µg/kg dry weight (d.w.) of sediment.

1860 1880 1900 1920 1940 1960 1980 2000 . 5 . x 1

1

1 . x 1

2

1 . 5 x 1

2

2 . x 1

2

Total Concentration (µg/kg) Year

PCB 153 PCB 70 PCB 52

1860 1880 1900 1920 1940 1960 1980 2000 . 2 . x 1

3

4 . x 1

3

6 . x 1

3

8 . x 1

3

1 . x 1

4

Total Concentration (µg/kg) Year

p,p'-DDD p,p'-DDE

  • ,p'-DDE

1920 1940 1960 1980 2000 0.0 5.0x10

2

1.0x10

3

1.5x10

3

2.0x10

3

Total Concentration (µg/kg) Year

PCB 153 PCB 70 PCB 52

1920 1940 1960 1980 2000 0.0 2.0x10

4

4.0x10

4

6.0x10

4

8.0x10

4

1.0x10

5

Total Concentration (µg/kg) Year

p,p'-DDD p,p'-DDE

  • ,p'-DDE

A) B)

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SLIDE 15

Tenax Results

3C 8C

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SLIDE 16

Conclusions I

  • DDT residues were extensively “aged”.
  • Due to aging, only a very small fraction of DDTs in the marine

sediment was “bioaccessible”.

  • DDTs in surface sediment also showed very low bioaccessibility.
  • DDT residues were “aged” elsewhere before deposition onto the
  • cean floor
  • Implications:
  • Risks much lower than expected from total concentration
  • EPA decided to use MNA (“monitored natural attenuation”)

instead of capping.

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SLIDE 17

Isotope-labeled HOCs Historically-contaminated soil Eisenia fetida ultrasonic extraction SPE purification

Bioaccumulation assay

Study II. A Direct Method to Test Aging

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SLIDE 18

Isotope-labeled HOCs Historically-contaminated marine sediment Nereis virens SPE purification ultrasonic extraction

Bioaccumulation assay

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SLIDE 19

Isotope-labeled HOCs Historically-contaminated freshwater sediment Lumbriculus variegatus SPE purification ultrasonic extraction

Bioaccumulation assay

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SLIDE 20

Isotope-labeled HOCs Historically-contaminated soil/sediment Tenax beads Spiked soil/sediment centrifuging & transferring beads ultrasonic extraction transferring

Tenax desorption

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SLIDE 21

PCB52 PCB70 DDE DDD DDT 0.0 0.4 0.8 1.2

Bioaccessibility

native HOCs labeled HOCs

soil A

PCB52 PCB70 DDE DDD DDT 0.0 0.4 0.8 1.2

soil B

PCB52 PCB70 DDE DDD DDT 0.0 0.4 0.8 1.2

sediment 8C

PCB52 PCB70 DDE DDD DDT 0.0 0.4 0.8 1.2

sediment 6C

PCB52 PCB70 DDE DDD DDT 0.0 0.4 0.8 1.2

sediment FW

Tenax F24h of native HOCs were consistently smaller than those for isotope labeled HOCs, suggesting reduced bioaccessibility due to aging

Tenax 24h total

C F C =

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SLIDE 22

PCB52 PCB70 DDE DDD DDT 5 10 15 20

Biota-to-soil/sediment accumulation factors

native HOCs labeled HOCs

soil A

PCB52 PCB70 DDE DDD DDT 4 8 12

soil B

PCB52 PCB70 DDE DDD DDT 0.0 0.1 0.2 0.3

sediment 8C

PCB52 PCB70 DDE DDD DDT 0.0 0.1 0.2 0.3

sediment 6C

PCB52 PCB70 DDE DDD DDT 1 2 3 4 sediment FW

The BSAF values of native HOCs were consistently lower than those for isotope labeled HOCs, clearly indicating aging effect on bioavailability of POPs in environmental matrices

BSAF = Cworm / flip Ctotal / foc

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SLIDE 23
  • 1

1 2 3

  • 1

1 2 3 log labeled HOCs/native HOCs (Tenax) log labeled HOCs/native HOCs (worm) y = (0.95±0.09)x + (-0.12±0.14) R

2=0.82

p<0.05

  • Ratios of labeled HOCs to native HOCs accumulated in earthworm, against against

with the ratios of Tenax F24h.

  • Highly significant linear correlation, with R2 = 0.82, and slope close to 1.
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SLIDE 24

Conclusions II

  • Compared to freshly spiked chemicals, bioaccumulation of

aged residues was much lower

  • The same conclusion was made in marine sediment,

freshwater sediment and soil, for different invertebrates

  • The use of chemically based measurement closely

predicted bioaccumulation

  • The use of isotope labels is a direct and convincing

technique to demonstrate the effect of aging on contaminant bioavailability.

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SLIDE 25
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SLIDE 26

Funding $upport