Proceedings of the International Symposium on Environmental Behavior and Ecological
Impacts of Persistent Toxic Substances, March 18-20, 2004, Matsuyama, Japan.
Ecological Risk Assessment of Environmental Contaminants for
Waterbirds
James Chung Wah Lam†, Shinsuke Tanabe‡, John Giesy#, Hiu Lam Wong†,
Bryan Sui Fai Wong║ and Paul Kwan Sing Lam†*
†Center for Coastal Pollution and Conservation, Department of Biology and Chemistry, City University of
Hong Kong, Kowloon, Hong Kong SAR,
‡Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5,
Matsuyama 790-8577, Japan
#National Food Safety and Toxicology Center, Department of Zoology, and Institute for Environmental
Toxicology, Michigan State University, East Lansing, Michigan 48824-1311, USA
║Agriculture, Fisheries and Conservation Department, Hong Kong SAR Government, Hong Kong
Waterbirds have traditionally served as sentinels for monitoring environmental
hazards due to their ability to integrate contaminant levels from a broad range of areas,
and consequently reflect the pollutant hazards to wildlife as well as human health. In
this study, eggs of Little Egrets, LE (Egretta garzetta), Black-crowned Night Herons, NH
(Nycticorax nycticorax) and Bridled Terns, BT (Sterna anaethetus) were collected from
northwestern and northeastern parts of Hong Kong (Fig. 1), and were analyzed for
congener-specific PCBs, organochlorine (OC) pesticides and various metals and
metalloids. The likelihood of potential hazards of these toxic contaminants was then
evaluated against corresponding reference values from the literature.
Concentrations of ΣCHLs,ΣDDTs, and ΣPCBs in eggs of LE, collected from
northwestern parts of Hong Kong were the highest (P < 0.05) among the three species,
whereas concentrations in eggs of NH and BT were comparable to each other (Fig. 1).
Fig. 1. Sampling locations and
concentrations of various
Night Heron
1800
Bridled Tern
*
-1
Concentration (ngg , fresh wt.)
1600
*
1400
1200
1200
1000
-1
Little Egret
1800
1800
1400
Concentration (ngg , fresh wt.)
-1
Concentration (ngg , fresh wt.)
1600
800
600
400
200
Σ HCH
800
1400
1200
Σ CHLs
Σ DDT
Organochlorines
Σ PCBs
800
600
400
significant difference
200
Σ HCH Σ CHLs
400
200
Σ DDT
from the other species,
Tukey test, P < 0.05).
0
Σ CHLs
Σ DDT Σ PCBs
Organochlorines
600
Σ HCH
contaminants in eggs of
waterbirds (*indicates
1000
0
0
1000
1600
Σ PCBs
Organochlorines
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Proceedings of the International Symposium on Environmental Behavior and Ecological
Impacts of Persistent Toxic Substances, March 18-20, 2004, Matsuyama, Japan.
Notwithstanding potential species-specific differences, contaminant concentrations
in the bird eggs indicate that the western waters of Hong Kong are more contaminated by
OCs as compared to the northeastern coastal region (Fig. 2).
CHLs
HCHs
DDTs
BT
p,p'-DDT
NH
γ-HCH
LE
LE
0%
20%
40%
60%
80%
Composition (%)
heptachlor
epoxide
NH
trans-chlordane
cis-chlordane
LE
0%
100%
Species
NH
β-HCH
Species
Species
p,p'-DDE
p,p'-DDD
heptachlor
BT
α-HCH
BT
20%
40%
60%
Composition (%)
80%
100%
0%
20%
40% 60% 80%
Composition (%)
100%
Fig. 2. Percentage composition of HCH isomers, DDT isomers and CHLs in eggs of waterbirds.
β -HCH and p,p’-DDE were the dominant isomers of Σ HCHs and Σ DDTs
respectively. The most toxic chlordane, heptachlor epoxide, accounted for 20 – 80% of
Σ CHLs. Contribution of di-ortho-PCBs constituted >70% of the PCB congeners
measured in the eggs of waterbirds, while the most toxic co-planar PCBs accounted for
<1% among the three groups (Fig. 3). In general, the bioaccumulation patterns of PCB
congeners in the eggs of waterbirds in this investigation were similar to other studies
(Guruge et al., 2001; Zimmermann et al., 1997).
TEQs
PCBs
12
Conc. (pgg , fresh wt.)
10
di-ortho
non-ortho
mono-ortho
NH
-1
Species
BT
LE
*
Avian-TEQs
*
8
H4IIE-TEQs
6
4
2
0%
50%
0
100%
LE
Composition (%)
Fig. 3. Percentage composition of PCB
NH
BT
Species
Fig. 4. Distribution of avian-TEQs &
H4IIE-TEQs in eggs of waterbirds (*
congeners in eggs of waterbirds.
indicates significant difference from the
other species, Tukey test, P < 0.05).
Avian-TEQs and H4IIE-TEQs in eggs of waterbirds are shown in Fig. 4. Both
calculations indicate that TEQs of eggs of LE from the northwestern part of Hong Kong
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Proceedings of the International Symposium on Environmental Behavior and Ecological
Impacts of Persistent Toxic Substances, March 18-20, 2004, Matsuyama, Japan.
were the highest among all three species. In addition, concentration patterns of
dioxin-like compounds were similar to those of OCs, again suggesting a relatively higher
level of contamination by dioxin-like compounds in the northwestern as compared to the
northeastern parts of Hong Kong.
15
14
Endrin
13
Dieldrin
Heptachlor epoxide
12
β-HCH
11
avian-TEQs
10
H4IIE-TEQs
Hg
HQs
9
(HQs) of various
contaminants in
eggs of waterbirds.
Se
8
Fig. 5. Hazard quotients
7
6
5
4
3
2
1
0
LE
NH
BT
Species
Estimated hazard quotients (HQs) of various contaminants in eggs of waterbirds are
shown in Fig. 5. HQs were calculated by dividing the measured concentrations of
specific contaminants in the target species with critical effect concentrations below
which no observed adverse effect is expected. HQs of dioxin-like contaminants,
mercury and selenium in the eggs of all species of waterbirds exceeded unity, indicating
potential risks of these contaminants in the selected waterbirds. HQ of toxic heptachlor
epoxide in eggs of LE was greater than unity and this was a sign of chlordane pollution in
the northwestern waters of Hong Kong.
This study was funded by the Hong Kong Research Grants Council (CityU1112/02M).
Reference
Guruge, K.S., Tanaka, H. Tanabe, S. (2001). Concentration and toxic potential of polychlorinated biphenyl congeners
in migratory oceanic birds from the North Pacific and the Southern Ocean. Marine Environmental Research 52,
271 – 288.
Zimmermann, G., Dietrich, D.R., Schmid, P., Schlatter, C. (1997). Congener-specific bioaccumulation of PCBs in
different water birds species. Chemosphere 34, 1379 – 1388.
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