Proceedings of the International Symposium on Environmental Behavior and Ecological
Impacts of Persistent Toxic Substances, March 18-20 2004, Matsuyama, Japan.
Assessment of Endocrine Disrupting and Cytotoxic Chemicals in a
Coastal Nature Reserve in Hong Kong
Hiu Lam Wong†, John Giesy#, William Ho Lim Siu† and Paul Kwan Sing Lam†*
†Department of Biology and Chemistry, City University of Hong Kong,
Tat Chee Avenue, Kowloon, Hong Kong
#National Food Safety and Toxicology Center, Department of Zoology, and Institute for
Environmental Toxicology, Michigan State University, East Lansing,
Michigan 48824-1311, USA
The Mai Po Marshes Nature Reserve (MPMNR), located in the Pearl River Estuary, is
situated within an important Ramsar site. A Chau is a small island in Starling Inlet on the
northeastern side of Hong Kong (Fig. 1). Seawater, sediment, bulk deposition and biota
were collected from the above two sites, and the concentrations of a range of
environmental contaminants were determined by instrumental and bioanalytical methods
to examine the biological impact of these chemicals on the ecosystem.
Pearl River
A Chau
Mai Po
Fig 1 Pearl River Estuary showing
Fig 2 The Mai Po Marshes Nature Reserve
the study sites
showing different habitats
Although the concentrations of chlordane, dieldrin, DDTs, and HCHs in the sediments
were higher than the threshold effects levels or even probable effects levels promulgated
by USEPA, concentrations of these chemicals in the biota were generally low, suggesting
low degrees of bioconcentration and bioaccumulation in Mai Po, particularly inside the
tidal shrimp ponds, gei wais (Fig. 2). In general, a lower level of OC contamination was
found at A Chau as compared to Mai Po (Connell et al., 2003), probably reflecting the
importance of the Pearl River as a source of OC pollution (Richardson et al., 2000).
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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.
Although HCB, DDTs, HCHs, cyclodienes and dioxin-like PCBs were detected in
atmospheric depositions, the contribution of atmospheric depositions to OC
contamination was small compared to the aquatic pathway. A negative flux of OCs might
exist transferring these contaminants from the sediments to other environmental
compartments.
Cell-based bioassays and instrumental analyses revealed low levels of dioxin-like
compounds in various biological compartments, reflecting the relatively low risk posed
by these chemicals to the Mai Po wetlands. Further study indicated that the dioxin-like
activities detected were attributable to acid liable compounds, e.g., PAHs (Fig 3).
Raw Extracts
Fig 3 Comparison of Dioxin-like activities in raw
Acid Treated
and acid treated samples with TCDD standard.
Sign Level
Response magnitude is presented as percentage of
70
60
% TCDDmax
50
the maximum response observed for 120.735 pg
40
30
2,3,7,8-TCDD
20
maximum
10
±
standard/well
standard
(%
deviation).
TCDD
The
abbreviations of the locations are: A Chau (AC),
)
(W
)
(W
FP
G
W
W
)
)
N
B(
AC
(W
(D
)
FP
(D
)
(D
)
G
W
N
B
AC
-10
(D
)
0
gei wai (GW), mudflat (NB), and fish pond (FP).
Dry Season (D), Wet Season (W).
In this study, certain unknown polar cytotoxic compounds were found in fish samples
collected from Mai Po, while no cytotoxicity was evident in fish samples from A Chau
(Fig 4).
Fig 4 Cytotoxicity (mean ± standard deviation) of
F1
different fractions (F1, F2, F3) of the biota samples
F2
from Florisil fractionation. The dashed horizontal
F3
120.0
Sign Level
% Viability
100.0
line illustrates 3 times mean viability of the solvent
80.0
blank. The abbreviations of the samples are:
60.0
Boleophthalmus boddaeris (MD), Mugil cephalus
40.0
(MU), Mylio marcocephalus (MY) Tilapia zilli (TP)
20.0
from Mai Po; Gobiidae spp. (AC) from A Chau; and
0.0
MD (W)
MD(D)
MU
MY
TP
Blk
AC
solvent blank (Blk). Dry season (D) and Wet Season
(W).
Polar estrogenic compounds were found in the Mai Po sediments. Seasonal variations
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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 also observed among sites due to varying hydrological conditions (Fig 5).
Dry Season
120.00
Fig 5 Luciferase induction (mean ± standard
Wet Season
Sign Level
100.00
deviation) in MVLN-luc cell bioassay with
% E2-max
sediment samples.
Response magnitude is
80.00
presented as percentage of the maximum
60.00
response observed for 68.1 pg E2 standard/well
40.00
(% E2 maximum). The abbreviations of the
20.00
locations are: A Chau (AC), gei wai (GW),
mudflat (NB), and fish pond (FP).
0.00
AC
NB
GW
FP
Overall, results of the present study indicate that the management practices currently
adopted in MPMNR (regular flushing of the gei wais) are effective in reducing the
concentrations of toxic contaminants in fish inside the gei wais, thus minimizing the
potential risks to waterbirds and human. Notwithstanding, DDTs, HCHs and other
cyclodienes might still be important in accounting for the risks to ecological systems in
Mai Po. In addition, estrogenic and cytotoxic compounds detected in this area might
reflect the potential hazards to the biota in Mai Po.
References
Connell, D.W., Fung, C.N., Minh, T.B., Tanabe, S., Lam, P.K.S., Wong, B.S.F., Lam, M.H.W., Wong, L.C.,
Wu, R.S.S. & Richardson, B.J. (2003). Risk to breeding success of fish-eating Ardeids due to persistent
organic contaminants in Hong Kong: evidence from organochlorine compounds in eggs. Water
Research, 37, 459-467.
Richardson, B.J., Lam, P.K.S., Wu, R.S.S. (2000). The Coast of Hong Kong. In C. Sheppard, ed, Seas at the
Millennium: an Environmental Evaluation. Vol. II. (Ed. C. Sheppard). Elsevier Science, pp 535-547.
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