Assessment of PAHs and PCBs in
sediment in aquatic systems in
Durban, South Africa, using
chemical and biological analysis
Natasha Vogt
Rialet Pieters
Brent Newman
John Giesy
Introduction
• PAHs & PCBs
– Formed unintentionally by burning
& byproducts
– Urbanised and industrialised areas
– Bioaccumulate & biomagnify – top
predator
– Health risks
– Share a common mechanism of
action by binding to the AhR
Determination of compounds
• Chemical analysis
– Previous knowledge is needed to know what
compounds could be present—targeted analysis
– Determining the direct impact these compounds
have in the environment is challenging—action
within organisms and effects of mixtures are
unknown
– Estimate toxicity by:
• Comparing the pollutant loadings to SQGs
• Or convert to a TEQ—compares the compounds present
to the toxicity of TCDD
• But this is only an estimation
Determination of compounds
• H4IIE Bioassay
– Detect AhR ligands
– Binding activates the detoxifying mechanism—
which indicates toxicity
– The binding ability of the compound is directly
proportional to their toxicity
– Response of the ligand binding quantified by
comparing its response to that of TCDD’s—BEQ
– Used to screen for biological interactions
– Used in polluted areas to detect the presence of
AhR ligands—ones that could be missed by
chemical analysis
Determination of risk
• Chemical concentrations, TEQs and BEQs can
be compared to SQGs
• Useful to assess the risk posed by a multitude
of chemicals with a common mechanism of
action
• BUT would using these three methods reveal
the same risk levels?
Durban Bay
• Third largest city in South
Africa
• 3.5 million inhabitants
• Many living in poverty,
and lack basic services
• The harbour was the
busiest port in South
Africa, and second to
Melbourne, in the
southern hemisphere
• It is expected that this
area would be highly
impacted by pollutants
Methods
• Sediment was
collected (n=33)
• Chemical analysis:
–
25 PAHs includes the
16 priority PAHs, and
–
22 PCBs, dioxin-like
and non dioxin-like
•
Biological analysis:
–
H4IIE targeting for
persistent and nonpersistent AhR
ligands
Methods
• Targeting for the compounds:
– ASE to extract the compounds
– PCB extract was treated with sulphuric acid to
degrade PAHs
– PAH fraction GPC’ed to collect the fraction
containing the PAHs
– GPC to remove sulphur
Results
• ∑PAHs: ubiquitous across sites
• 6–3 235 ng.g-1
• ∑PCBs: detected infrequently across sites
•
<DL–113 ng.g-1
TEQ (ng.g-1)
BEQ (ng.g-1)
PAH fraction
2.11x10⁻⁴–4.14x10⁻2
<DL–7.66x10-1
PCB fraction
<DL–3.0x10⁻⁴
<DL–9.35x10-3
Comparison to SQGs
AMA 1
AMA 2
AMA 3
CAN 1
DBAY 1
DBAY 2
DBAY 3
DBAY 4
DBAY 5
DBAY 6
DBAY 7
DBAY 8
DBAY 9
DBAY 10
ISI 2
ISI 4
ISI 5
ISI 7
ISI 8
IVC 1
IVC 2
UMB 1
UMB 2
UMB 3
UMB 4
UMB 5
UMB 7
UMB 8
UMB/UMH
UMH 1
UMH 3
UMH 5
UMH 6
AMA 1
AMA 2
AMA 3
CAN 1
DBAY 1
DBAY 2
DBAY 3
DBAY 4
DBAY 5
DBAY 6
DBAY 7
DBAY 8
DBAY 9
DBAY 10
ISI 2
ISI 4
ISI 5
ISI 7
ISI 8
IVC 1
IVC 2
UMB 1
UMB 2
UMB 3
UMB 4
UMB 5
UMB 7
UMB 8
UMB/UMH
UMH 1
UMH 3
UMH 5
UMH 6
Effects range low (ERL): utilised in estuarine and marine environments (Long
et al., 1995)
Threshold effect concentration (TEC): utilised for freshwater environments
(MacDonald et al., 2000)
Canadian SQG: utilised for the BEQ and TEQs, in terms of TCDD (CCME., 2001)
∑PAH23
∑PAH16
ERL
TEC
0
1000 2000 3000 4000 5000 6000 7000 8000
Concentration (ng.g-1)
∑PCB
∑dl-PCB
∑ndl-PCB
ERL
TEC
0
20
40
60
Concentration
80
(ng.g-1)
100
120
PAHs
0.9
0.045
BEQ (ng.g-1)
0.8
TEQ (ng.g-1)
0.04
0.7
0.035
0.6
0.03
0.5
0.025
0.4
0.02
0.3
0.015
0.2
0.01
0.1
0.005
0
0
PCBs
0.1
0.00035
BEQ (ng.g-1)
TEQ (ng.g-1)
0.09
0.0003
0.08
0.07
0.00025
0.06
0.0002
0.05
0.00015
0.04
0.03
0.0001
0.02
0.00005
0.01
0
0
PAH overview
AMA 3
UMB 1
AMA 1
DBAY 6
33%DBAY
> SQG
9
UMH 3
DBAY 2
BEQ
UMB 5
UMB 7
DBAY 4
TEQ
∑PAH16
3%DBAY
> SQG
5
21%ISI>8SQG
DBAY 7
DBAY 3
18% > SQG
*
IVC 1
CAN 1
ISI 5
15% > SQG
PCB overview
BEQ
UMB 1
UMB 4
6% > SQG
TEQ
∑dl-PCB
0% > SQG
DBAY 8
DBAY 6
27%
DBAY>1SQG
DBAY 4
DBAY 10
ISI 8
DBAY 7
DBAY 3
4
9% >ISISQG
9% > SQG
.
Conclusion
• Comparison of the bioassay results to that of the
chemical and the subsequent TEQ results shows
that the H4IIEs are more sensitive to detecting a
wide range of AhR ligands
• H4IIE assay can be used as a screening tool to
detect for AhR ligands prior to chemical analysis
(costly)
• Bioassays can be utilised to fill in the gaps
between chemical analysis and possible lurking
compounds