allison taylor, jie wang, daniel schlenk and jay gan department … · 2019-05-13 · allison...
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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: • PAHs Strong sorption • Dioxins
• Chlorinated pesticides
• PCBs/PBDEs FACT 2: • PAHs Aged • Dioxins
2
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
Aging and Bioavailability plant roots
microbes
organic matter
dissolved OM Freely dissolved benthic invertebrates
4
5
plant roots
benthic invertebrates
microbes
organic matter
dissolved OM
Freely dissolved
Bioaccessible
Aging and Bioavailability
6
plant roots
benthic invertebrates
microbes
organic matter
dissolved OM
Freely dissolved
Bioaccessible
Non-accessible
Aging and Bioavailability
7
plant roots
benthic invertebrates
microbes
organic matter
dissolved OM
Freely dissolvedBioaccessible
Non-accessible
Aging and Bioavailability
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
Bioavailability
Reichenberg and Mayer, 2006, Environ. Toxicol. Chem. 25, 1239-1245
Total concentration
BioaccessibleConcentration
Freely dissolved
ConcentrationRisk
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
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)
� Health Warnings:
Study I. Aged POPs at the Palos Verdes Superfund Site
US EPA, 2010
A Sediment Core Experiment•Hypothesis:
• Contaminant aging has resulted in reduced bioavailability.
210Pb Dating
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
0.05.0x10
1
1.0x102
1.5x102
2.0x102
Total Concentration (µg/kg)Ye
ar
PCB 153 PCB 70 PCB 52 1860
1880
1900
1920
1940
1960
1980
2000
0.02.0x10
3
4.0x103
6.0x103
8.0x103
1.0x104
Total Concentration (µg/kg)
Year
p,p'-DDD p,p'-DDE o,p'-DDE
1920
1940
1960
1980
2000
0.05.0x10
2
1.0x103
1.5x103
2.0x103
Total Concentration (µg/kg)
Yea
r
PCB 153 PCB 70 PCB 52
1920
1940
1960
1980
2000
0.02.0x10
4
4.0x104
6.0x104
8.0x104
1.0x105
Total Concentration (µg/kg)
Yea
r
p,p'-DDD p,p'-DDE o,p'-DDE
A) B)
Tenax Results
3C 8C
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 ocean floor
• Implications:• Risks much lower than expected from total concentration• EPA decided to use MNA (“monitored natural attenuation”)
instead of capping.
Isotope-labeled HOCs
Historically-contaminated soil
Eisenia fetida ultrasonic extraction
SPE purification
Bioaccumulation assay
Study II. A Direct Method to Test Aging
Isotope-labeled HOCs
Historically-contaminated marine sediment
Nereis virens
SPE purification
ultrasonic extraction
Bioaccumulation assay
Isotope-labeled HOCs
Historically-contaminated freshwater sediment
Lumbriculus variegatus
SPE purification
ultrasonic extraction
Bioaccumulation assay
Isotope-labeled HOCs
Historically-contaminated soil/sediment
Tenax beads
Spiked soil/sediment
centrifuging &transferring beads
ultrasonicextraction
transferring
Tenax desorption
PCB52 PCB70 DDE DDD DDT0.0
0.4
0.8
1.2
Bio
acce
ssib
ility
native HOCs labeled HOCs
soil A
PCB52 PCB70 DDE DDD DDT0.0
0.4
0.8
1.2soil B
PCB52 PCB70 DDE DDD DDT0.0
0.4
0.8
1.2sediment 8C
PCB52 PCB70 DDE DDD DDT0.0
0.4
0.8
1.2sediment 6C
PCB52 PCB70 DDE DDD DDT0.0
0.4
0.8
1.2sediment FW
Tenax F24h of native HOCs were consistently smaller than those for isotope labeled HOCs, suggesting reduced bioaccessibility due to aging
Tenax24h
total
CFC
=
PCB52 PCB70 DDE DDD DDT0
5
10
15
20 B
iota
-to-s
oil/s
edim
ent a
ccum
ulat
ion
fact
ors
native HOCs labeled HOCssoil A
PCB52 PCB70 DDE DDD DDT0
4
8
12soil B
PCB52 PCB70 DDE DDD DDT
0.0
0.1
0.2
0.3sediment 8C
PCB52 PCB70 DDE DDD DDT0.0
0.1
0.2
0.3
sediment 6C
PCB52 PCB70 DDE DDD DDT0
1
2
3
4sediment 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 / f lipCtotal / foc
-1 0 1 2 3-1
0
1
2
3
log
labe
led
HO
Cs/
nativ
e H
OC
s (T
enax
)
log labeled HOCs/native HOCs (worm)
y = (0.95±0.09)x + (-0.12±0.14)R2=0.82p<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.
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.
Funding $upport